Table of Content

10 June 2018, Volume 37 Issue 6

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The advances of ecological restoration monitoring: Analysis of the latest three world congresses on ecological restoration.

ZHANG Shao-liang, LIU Run, HOU Hu-ping, YANG Yong-jun

2018, 37(6):  1605-1611. 

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Monitoring the whole processes and elements of ecological restoration is required to evaluate the liability of the selection of ecological restoration techniques, the effectiveness ofrestoration project management, the comparability of the implementing effectiveness of restoration projects, and the success criteria of ecological restoration. However, the globally accommodated monitoring protocol of ecological restoration is still under exploration. Based on the reports presented on the latest three world congresses of ecological restoration (SER) and statistical analysis, we reviewed the research progress in monitoring technology, protocol and indicators of ecological restoration. We predict the research trends of the monitoring of ecological restoration would be as follows: (1) Monitoring techniques will develop toward to automation, integration of intelligence and network, all aspects of ecological restoration project, and tech-intensity. (2) The monitoring indicator system and standards of ecological restoration will achieve consensus. (3) The trend of synthetic monitoring and multi-discipline intersection will be more obvious. (4) The monitoring results will be more and more widely used.

Micro-landform modification and its application in coal-mining subsidence area: A review.

LI Si-jia, WANG Jin-man, WAN De-peng, BAI Zhong-ke

2018, 37(6):  1612-1619. 

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Underground coal-mining leads to severe surface subsidence and thus accelerates soil erosion in the subsidence area. The effects of micro-landform modification on the control of soil and water losses have been observed. However, the theoretical studies of micro-landform modification are still insufficient, and the underlying mechanisms on the control of soil and water losses are unclear. To explore the basic theory of micro-topography modification and analyze its effect mechanisms on soil erosion and vegetation restoration in coal-mining subsidence area, we reviewed the research progresses on micro-landform modification and its application in coal-mining subsidence area. There are three main contents, including the micro-landform features and the law of soil and water loss in coal-mining subsidence area, the measures of micro-landform modification, and the application of micro-landform modification and its effects on ecologicalenvironment. The results showed that: (1) the underground coal-mining can result in new micro-landform changes. (2) The measures of micro-landform modification affect soil moisture, soil fertility, soil erosion, and vegetation restoration, with many of the underlying mechanisms being unclear; (3) The micro-landform modification has positive effects on soil and water conservation and vegetation restoration in coal-mining subsidence area, but related research is not profound enough and needs to be further strengthened. Considering the deficiencies of the current theoretical research and practical application, we put forward future researches on the micro-landform modification in coal-mining subsidence lands, including developing information acquisition methods for micro-landform and its transformation in coal mining subsidence area, exploring the hydrological processes of micro-landform, deepening the underlying mechanism analysis of the micro-landform modification in coal mining subsidence area, and developing the designing modes and technical system of microlandform.

Influence of secondary iron-oxide mineralization induced by dissimilatory iron reduction bacteria on fraction transformation of heavy metals in soil.

LUO Hai-lin, TANG Jia, ZHOU Pu-xiong, YU Zhen, FU Gui-hua, ZHOU Shun-gui

2018, 37(6):  1620-1627. 

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Heavy metals in soil have the characteristics of persistent accumulation, high toxicity, and difficult to migrate. The fraction transformation is an important process influencing the toxicity and migration of heavy metals. It could be harmful to human health if heavy metals transferred into crops, water and atmosphere. Under anaerobic conditions, the existence of abundant iron and microbial Fe(III) dissimilatory reduction in soils provide favorable conditions for the formation of secondary iron minerals with different crystalline forms in the natural environment. Secondary iron minerals induced by microorganisms have unique morphology and characteristics, including nanoparticles, high surface area, and high reactivity, which play important roles in the transformation of soil heavy metals. In this review, we summarized the impacts of secondary iron mineralization driven by ironreducing bacteria on the transformation of heavy metals in soils. The secondary iron mineralization directly influences the fate of heavy metals. Thus, better understanding of the mechanisms is fundamental to its application in bioremediation.

Effects of artificial measures on surface recovery of gold mining area in Altai Mountain.

ZHAO Xin-feng, XU Hai-liang, WANG Xi-yi, XU Qiao, YUAN Kai-ye, YANG Yong-qiang, ZHANG Peng

2018, 37(6):  1628-1635. 

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To promote the vegetation recovery in gold mining area, different measures wereapplied in the abandoned field of the gold mining area in Altai Mountain, which is a conservation region for the source of Irtysh River and Ulungur River. We evaluated the effects of these measures on the restoration of soil and vegetation. The results showed that: (1) Gold mining altered topography. The altitude difference of the gold mining area increased from 2-3 m per 100m long to approximately 5 m after the destruction of gold mining. The parent material of soils was seriously damaged. Compared with the natural grassland, the soil/gravel ratio decreased by 98.5% and plant aboveground biomass decreased by 96.8% in the abandoned filed. Soil and vegetation factors were the key factors for ecological restoration. (2) Under covering soil treatment, the number of plant species was increased. The vegetation diversity index under the treatment of basin irrigation and corralling flock was significantly higher than that under drip irrigation and mud spraying treatment. The soil/gravel ratios under basin irrigation measure were 19.1 and 5.8 times as high as that of drip irrigation and mud spraying. (3) Under the measures of covering soil + basin irrigation and covering soil + corralling flock, plant biomass was significantly higher than that of other combined measures (P<0.01) and the soil/gravel ratio was relatively high. Consi dering the recovery effect and the cost of the basin irrigation measure, we concluded that the basin irrigation is of great significance to the ecological restoration of the gold mining area.

Community dynamics of artificial vegetation in a reclaimed spoil from a semi-arid opencast coal mine in 2010-2015.

ZHAO Bing-qing, GUO Dong-gang, BAI Zhong-ke, ZHAO Zhong-qiu

2018, 37(6):  1636-1644. 

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Vegetation restoration is an effective way to recover the ecological environment in mining area. However, our understanding of ecological processes in restoration is lacking. Two datasets in the year 2010 and 2015 from a 1 hm² permanently fixed monitoring plot (a mixed forest of Robinia pseudoacacia, Ulmus pumila and Ailanthus altissima) in Antaibao opencast coal mine, Shanxi Province, China, were used to analyze the dynamics of tree species composition, density and size class structure. The results showed that one species disappeared while another one appeared during 2010 to 2015. Importance value (IV) of R. pseudoacacia decreased significantly, whereas that of U. pumila substantially increased, indicating that the dominant species changed from R. pseudoacacia toU. pumila.The number of individuals with diameter at breast height (DBH) ≥1 cm increased from 2125 to 3531, with 768 dying and 2174 recruiting. The average annual mortality and recruitment rates were 8.97% and 19.13%, respectively. R. pseudoacacia had the highest mortality, while U. pumila had the highest recruitment. The basal area of the trees increased from 6.92 m²·hm^-2 to 8.63 m²·hm^-2. The changes of the basal area ofR. pseudoacacia were the largest among all the species. The annual average growth rate of tree DBH increased with the increases of DBH size classes. The DBH size class structure of community did not vary significantly during 2010 to 2015. Individuals with small DBH had higher mortality compared with large ones. DBH size class distribution of dead trees in 2015 was similar to that of the living tree species in 2010. The population of the three dominant tree species increased or decreased with an annual rate of >5%, indicating fast individual turnovers for those species. Amongwhich,R. pseudoacacia had the highest decline rate in population size (-10.36%), whereas U. pumila  had the highest increment rate (39.39%).

The dynamics of vegetation coverage and its influencing factors in Yushenfu coalmine.

TAN Xue-ling, YAN Qing-wu, WANG Jin, ZHANG Hai-rong

2018, 37(6):  1645-1653. 

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To clarify the dynamics of fractional vegetation coverage (FVC) in Yushenfu coalmine, the spatiotemporal distribution and inter-annual changes of FVC were assessed using the pixel dichotomy model, linear regression trend and correction coefficient for topographic areas, based on the MOD13Q1 of MODIS data during 2005-2016. The relationships between FVC change and topography, land-use and land-cover change (LUCC) and mining activity were analyzed. The results showed that: (1) In the study period, FVC in Yushenfu coalmine showed drastic changes. The area with low VC was distributed in the south of Wulanmulun River and the north of Wuding River, while the area with high FVC was located in Shenfu mining and the south of Yuheng mining. (2) The inter-annual changes of FVC showed an improved trend with first descending and then raising from northeast to southwest, and areas with FVC improvement accounted for more than 90% of Yushenfu coalmine. (3) In the areas within elevation 899-1000 m, slope 8-12 degrees and plain, the mean FVC was the highest. The area ratio of vegetation improved type was the largest at the elevation 1000-1437 m, slope 4-28 degrees and hill. In addition, the overall vegetation situation of LUCC in 2010-2015 was better than that in 2005-2010, and vegetation was dominated by improved type. (4) Comparing the FVC in the ore occurrences, workshop, dumps, subsided land and buffer zone showed that mining activity had obvious influence on vegetation.

Effects of adding hill-skill soil and straw on the properties of ferrous mill tailings substrate and plant growth.

YU Hai-bo, CHI Guang-yu, CHEN Xin, MA Jian, SHAO Yu-fei

2018, 37(6):  1654-1661. 

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The use of ferrous mill tailings as reclamation substrate is an effective way for resource utilization. Based on potted culture method, we examined the impacts of hill-skill soil and straw addition on the properties of ferrous mill tailings substrate and the growth of Amorpha fruticosa seedlings. There were five addition levels of hillskill soil (0%, 25%, 50%, 75%, and 100%) and three addition levels of straw (1%, 3%, and 5%). The results showed that adding hill-skill soil reduced substrate bulk density, total and available P content, and increased field moisture holding capacity, cation exchange capacity, total and available K content. Adding straw reduced substrate bulk density and improved field moisture capacity, cation exchange capacity, totalorganic C, total N and P, available N and K content. The incorporation of hill-skill soil into ferrous mill tailings increased plant height, root length, ground diameter, crown width and biomass of A. fruticosa seedlings, while adding straw increased first and then decreased plant height, root length, ground diameter, crown width and biomass (3% addition > 1% and 5% addition). Comprehensive analysis indicated that A. fruticosa seedlings grew best in the treatment of 3% straw + 100% hill-skill soil.A. fruticosa seedlings grew well in the treatment of 3% straw + 50% hill-skill soil, with each index being significantly different from that of the treatment of 1% straw + 0% hill-skill soil (P<0.05). The application of 3% straw + 50% hillskill soil could be suitable as the formula for reclamation to realize the resource utilization of ferrous mill tailings.

Differences of soil microbial diversity and community composition between reclaimed woodland and grassland in coal waste pile and their influencing factors.

ZHANG Rong, YU Ya-jun

2018, 37(6):  1662-1668. 

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We explored the diversity and composition of soil microbial community in 0-10 and 10-20 cm soil layers in the reclaimed woodland (R-S) and reclaimed grassland (R-G) in Lu’an coal waste pile, Changzhi, Shanxi Province, using the method of phospholipid fatty acid (PLFA). The effects of environmental factors on the soil microbial community composition were analyzed. The results showed that: (1) PLFA richness index (S) and Shannon diversity index (H) of 0-10 cm and 10-20 cm soil layers in R-G were all higher than that in R-S (P<0.05), but there was no significant difference in Pielou evenness index (E) in both soil layers between the two plots. (2) In both soil layers, the contents of total microbial PLFAs, fungi PLFAs (F), actinomycetes PLFAs (A), Grampositive bacteria PLFAs (G+), Gram-positive bacteria/Gramnegative bacteria and fungi/bacteria were all higher in R-S than that in R-G (P<0.05). However, the contents of bacteria PLFAs (B) and Gram-negative bacteria (G-) in those plots were different for the two soil layers, being higher in 0-10 cm in R-S than that in R-G (P<0.05), but lower in 10-20 cm soil layer in R-S than that in R-G. (3) The principal component analysis indicated that the soil microbial community structure and composition were significantly affected by the types of reclamation. The redundancy analysis  showed that the soil physicochemical properties affected the contents of soil microbial PLFAs. Among them, soil available phosphorus (AP), soil pH and cation exchange capacity (CEC) were the main factors affecting microbial community composition. The contents of soil microbial PLFAs were positively correlated with AP and CEC, while negatively correlated with soil pH.

Experimental study on soil pollution and restoration in magnesite area.

ZHANG Zuo-jin, JIA Chun-yun, DAI Shu-juan, FANG Yue-meng, TAI Pei-dong

2018, 37(6):  1669-1675. 

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Magnesium oxide dusts produced during calcination fall to the soil surface and easily form magnesian soil crust in magnesite mining area, which would reduce soil porosity, weaken soil infiltration rate, and be harmful to soil quality. Using a soil column leaching device, an experiment was carried out to examine the influence of magnesium oxide dust on soil infiltration and the processes of soil remediation. Soil crust was formed by adding magnesium oxide dust to the soil column, gypsum was used as a modifier to inhibit the formation of crusts, and the morphological changes of soil crusts were observed by scanning electron microscope (SEM). The results showed that the control group after leaching for two times, the soil infiltration rate was stable at 0.367 mm·min^-1. After adding magnesium oxide to the soil, the soil infiltration rate was significantly decreased to 0.214 mm·min^-1. When gypsum and magnesium oxide were combined added into soil column, the soil infiltration rate was stable at 0.425 mm·min^-1 after leaching for two times, suggesting that the soil infiltration rate increased significantly after gypsum addition compared to that contaminated by magnesium oxide dust. The SEM diagram showed that the soil surface after adding gypsum exhibited a reticular structure and that the porosity and stability of the soil surface were improved, which would increase the permeability of the soil.

Effects of land subsidence caused by coal mining on the spatial variation of soil total nitrogen and organic matter concentrations in loess area.

ZHANG Ya-fu, WANG Jin-man, ZHU Yu-cheng

2018, 37(6):  1676-1684. 

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Coal mining causes land subsidence and changes soil fertility. For a better land reclamation in mining area, including soil reconstruction and vegetation restoration, soil nutrient status in subsidence area should be examined. In this study, the subsidence area from Anjialing No. 3 underground coal mine in Pinglu District, Shuozhou City, Shanxi Province was taken as the research area. Soil samples of different profiles from four different plots (unmined area, subsided area 1, subsided area 2, and reclaimed area) were collected to analyze the contents of soil total nitrogen and organic matter. The spatial variation of those characters was examined using classic statistics and geostatistics methods. Soil total nitrogen and organic matter contents at the 0-20 cm layer in the subsided areas were lower than those in the unmined area. However, soil total nitrogen contents at deeper soil layers in the subsided areas were higher than those in the unmined area and an opposite pattern was found for soil organic matter. The soil organic matter content in reclaimed area was higher than that in the subsided areas. Total nitrogen contents at different soil layers in the reclaimed area did not show a clear regularity compared to the subsided areas. Land subsidence increased the variability of soil organic matter and total nitrogen at horizontal direction, whereas land reclamation decreased such spatial variability. Our results can provide a theoretical and technical reference for land reclamation in subsided lands in loess area.

Effect of chloride ions on biological oxidation of pyrite and the biomineralization behavior in wastewater system.

QIAO Xing-xing, DONG Yan, LEI Yong-sheng, ZHOU Li-xiang, LIU Fen-wu

2018, 37(6):  1685-1692. 

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Understanding the effects of chloride ions (Cl^-) on the biooxidation of pyrite is beneficial for revealing the formation mechanism of acid mine drainage (AMD). Meanwhile, uncovering the biomineralization behavior in wastewater system has implication for clarifying the regulation of AMD production by biomineralization behavior. In this study, the effects of Cl^- on the pyrite biooxidation were investigated (the liquid medium required for microorganism growth was notadded into systems). The synthetic behavior of secondary iron minerals in the wastewater system was examined through flask experiment. Results showed that there was no significant difference of pyrite biooxidation efficiency between the treatments without Cl^- addition and with 8.2 mmol·L^-1 of Cl^- addition. The biooxidation efficiency of pyrite was promoted when the initial Cl^- concentration was 16.5 mmol·L^-1. The biooxidation efficiency of pyrite was significantly inhibited when the initial Cl^- concentration reached 49.4-65.8 mmol·L^-1. For example, the total Fe concentrations were 1204.56, 1218.09, 1431.50 and 796.48 mg·L^-1 at day 68 when the initial concentrations of Cl^- were 0, 8.2, 16.5, and 65.8 mmol·L^-1, respectively. There were obvious microbial erosion pits on the surface of biooxidized pyrite in all treatments. However, no secondary iron minerals were observed on the surface of biooxidized pyrite. After the pyrite biological oxidation in different treatments, 54.3%-79.5% of total Fe ions mainly presented as Fe²⁺ type. The filtrate obtained by filtering in different treatments was cultured and the systems eventually produced secondary iron minerals (such as jarosite) when Fe²⁺ was gradually oxidized completely. Thus, Cl^- concentrations played a role in regulating biological oxidation of pyrite. When the Fe ions are separated from the pyrite system and Fe²⁺ gradually are oxidized to Fe³⁺, a large amount of secondary iron minerals can be synthesized in systems. Our results provide theoretical support for clarifying the formation of AMD and the synthesis of secondary iron minerals in the AMD system.

Effects of phosphorated materials on the concentrations of rare earth elements in soil solution.

JIN Shu-lan, HU Zhong-jun, QIU Qiu-ping, HUANG Yi-zong, HU Ying, CHENG Wei

2018, 37(6):  1693-1701. 

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Mining of rare earth minerals can cause serious rare earth pollution to the soils. In this study, four types of phosphorated materials (superphosphate, phosphate rock, bone charcoal and monocalcium phosphate) were added into two types of soil polluted by rare earth in Xunwu and Longnan counties of Jiangxi Province, respectively, to examine their influences on the concentrations of rare earth elements (REE) in soil solution. Results showed that the addition of phosphorated materials significantly decreased the concentrations of 15 types of REE in soil solution, with the amplitude of reduction between 20.8% and 99.2%. The order of the reduction percentage of different types of REE was as follows: light REE of La, Ce, Pr, Nd and Sm > middle REE of Eu, Gd, Tb, Dy > heavy REE of Y, Ho, Er, Tm, Yb and Lu. Adding 2.5%-5% of superphosphate, phosphate rock, bone charcoal and monocalcium phosphate decreased REE concentration by 55.3%-99.2%, 86.8%-99.1%, 80.7%-99.3% and 9.8%-96.2% respectively. These results suggested that application of phosphorated materials could remediate the rare earth polluted soils and reduce the pollution of REE.

The effects of acid mine drainage on the erosion of carbonatite in carbonate rocks.

XIA Yu, WU Pan, ZHANG Rui-xue, ZHU Jian, WANG Yue-zhu, SONG Chuan-xiao， LI Ling

2018, 37(6):  1702-1707. 

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We quantified the effects of acid mine drainage on the erosion rate of seven carbonate rocks with different ages, to screen for appropriate passive packing. The results showed that the mean erosion rate of carbonate rocks in response to acid mine drainage was 4.88×10^-4 g·cm^-2·d^-1 in 60 days, which is at least ten times faster than karst water erosion. The calcite Mesocrystalline dolomite in Baizuo Formation showed higher erosion rate than other limestones. The microstructure and the composition of rock surface material were measured by Scanning Electron Microscope and Energy Dispersive Spectrometer. It was found that the iron oxides on the surface of rocks from different ages were lepidocrocite. The crystallization rate of calcium sulfate on rock surface was one of the key factors controlling the erosion rate of carbonatite in carbonate rocks. Additionally, the dissolution of magnesium carbonate was an important factor driving the crystallization rate of calcium sulfate.

Geochemical process of karst groundwater as affected by the leakage of phosphogypsum stock dump.

ZHA Xue-fang, QIN Ying-ji, WU Pan, HAN Zhi-wei, LI Xue-xian, YE Hui-jun, LI Ling

2018, 37(6):  1708-1715. 

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We measured the hydrochemical composition of leachate in phosphogypsum stock dumps and the surrounding groundwater in Mapingchang Town, Fuquan City, Guizhou Province, analyzed the pollution source of groundwater by principal component analysis, and then inferred the geochemical process of karst groundwater under the influence of leachate leakage by PHREEQC inverse modeling. Results showed that the leachate was strongly acidic. EC of the leachate was as high as 8750 μS·cm^-1. The main pollutants were TP, SO₄^2- and F^-. The leachate characteristics were mainly related to the wet phosphoric acid process. Facaidong groundwater (G1) was affected by the leakage from phosphogypsum stock dump, TP, SO₄^2- and F^- in which were much higher than the prescribed limit of GB 3838-2002 and GB/T 3838-93. Longjing groundwater (G10) was probably influenced by the surrounding factories (phosphate fertilizer factories and abandoned ordinary superphosphate factories). Both sites showed increasing SO₄^2- and decreasing HCO₃^-, and the hydrochemical type became SO₄-Ca. The rest of the sampling sites were HCO₃-Ca type, mainly from the natural geological waterrock reaction. The results from PHREEQC simulation showed that leachate speeded up the waterrock reaction and karst development. After PO₄^3- and Fe entered groundwater system, the hydroxyapatite, Fe(OH)₃, and vivianite would be formed under certain reaction conditions.

Biochemical indices of Polytrichum communeHedw. in arsenic-rich coal mines reflect the characteristics of arsenic oxidative stress.

WU Yi-fan, WU Pan, ZHANG Rui-xue, ZHANG Chi-peng, LIANG Long-chao, XIONG Yi

2018, 37(6):  1716-1722. 

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We measured soluble protein concentration, hydrogen peroxide (H₂O₂) concentration, total antioxidant level and other biochemical indices of samples of dominant moss Polytrichum commune Hedw., which were collected from the acid mine wastewater basin of arsenic-rich coal district and nearby unpolluted area in the upper reaches of Maoshitou Reservoir of Xingren County, Guizhou Province. The biogeochemical characteristics of P. commune in the arsenicrich coal district under the conditions of arsenic oxidative stress were examined. The results showed that P. commune absorbed arsenic which was involved in metabolism. The soluble protein concentration in P. commune in the polluted area was lower, with a lowest value of 0.151 mg·g^-1 in the water outlet of mine hole, while the value was up to 0.404 mg·g^-1 in the unpolluted area. The concentration of soluble protein had negative correlation with arsenic concentration across all sampling locations. The belowground part of P. commune had lower soluble protein concentration than aboveground part. The active oxygen (ROS) in P. commune was accumulated, indicating that the arsenic oxidative stress on P. commune. The H₂O₂ concentration of P. commune in the polluted area was up to 5.93 μmol·g^-1, being obviously higher than that in the unpolluted area (3.37 μmol·g^-1). The belowground part had lower H₂O₂ concentration than the aboveground part. The H₂O₂ concentration had a positive correlation with the arsenic concentration. P. commune in the polluted area was resistant to the arsenic oxidative stress to a certain degree. The total antioxidant level was significantly decreased under extremely high concentration of arsenic. The ferric reducing/antioxidant power (FRAP value) of site A3 was 0.577. The arsenic concentration was relatively low in the sampling locations after site A3, with the FRAP value being generally stable.

Monitoring of heavy metal concentrations and source apportionment in ‘24-Curve’ Highway region using epiphytic mosses.

LIU Run, ZHANG Zhao-hui, SHEN Jia-chen, WANG Zhi-hui

2018, 37(6):  1723-1729. 

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With the increases of traffic mileage, the exhaust emission of motor vehicles has become one of the major air pollution sources. In this study, we took the typical mountain road ‘24-Curve’ Highway and the surrounding sites (the foot of mountain, hillside, martyrs cemetery, viewing platform) as the research objects, to examine the common traffic emissions of heavy metals Ni, Pb, Cu, Zn, Cr, Cd, Mn and Fe using epiphytic mosses as monitoring materials. Elemental enrichment factor and fuzzy cluster analysis were used to analyze the contents of heavy metals and possible sources in epiphytic mosses. The results showed that the average enrichment coefficients of Zn and Pb in the study area were 21.83 and 18.04, respectively. Its source was mainly the release of human activities. The pollution level of ‘24-Curve’ Highway was generally much higher than that of the surrounding sites, in which the enrichment coefficients of Zn and Cd were five and seven times higher than the lowest point, respectively. The results of fuzzy clustering and correlation analysis showed that the heavy metal pollution in the study area not only came from traffic emissions (Ni, Cd), road dust and the abrasion of vehicle related materials (Cu, Zn, Cr, Cd, Mn and Fe), but also was affected by the nearby mining activities (Pb, Zn, Fe, Mn).

Effects of exogenous melatonin on seed germination and physiological indices of rice under As³⁺ and As⁵⁺ stress.

HUANG Yi-zong, JIANG Hang, WANG Nong, LIU Yan

2018, 37(6):  1730-1737. 

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We investigated the effects of exogenous melatonin on seed germination and some physiological indices of rice under As³⁺ and As⁵⁺ stress. The results showed that 50 and 100 μmol·L^-1 melatonin addition had positive effects on seed germination and growth of rice seedlings under As stress. Melatonin addition significantly increased the activities of antioxidant enzyme, such as CAT, POD, SOD, but decreased MDA content and the rate of O₂^-_· production. At As³⁺ concentration of 50 μmol·L^-1, compared with the control treatment, adding 100 μmol·L^-1 melatonin significantly increased the activities of CAT, POD and SOD of rice seedlings by 54.2%, 100.1% and 43.1%, respectively, decreased MDA content and O₂^-_· producing rate by 44.1% and 55.6%. At the same concentration of As⁵⁺, adding 100 μmol·L^-1 melatonin increased the activities of CAT, POD and SOD of rice seedlings by 62.1%, 49.6% and 47.3%, decreased MDA content and the rate of O₂^-_· production by 33.1% and 34.8%, respectively. The results suggested that the application of melatonin could alleviate lipid peroxidation damage in rice under As³⁺ and As⁵⁺ stress, and effectively alleviate the toxic effects of As³⁺ and As⁵⁺ on rice.

Effects of exogenous melatonin on the growth of rice seedlings under As stress.

HUANG Yi-zong, JIANG Hang, WANG Nong, LIU Yan, HU Hong-qing

2018, 37(6):  1738-1743. 

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Effects of exogenous melatonin on the growth, physiological indices, and arsenic (As) accumulation of rice under As stress were investigated in solution culture. The results showed that melatonin addition alleviated the toxic effects of As on rice seedlings, and improved plant height, root length, and biomass of rice. Melatonin addition also significantly increased activities of antioxidant enzymes, such as POD, SOD, CAT, decreased MDA content and O₂^-_·producing rate. Compared to single As stress treatment, adding 0.1-100 μmol·L^-1 melatoninsignificantly increased POD activities in leaves and roots by 38.6%-62.9% (except for 0.1 μmol·L^-1 melatonin) and 37.4%-142.6%, SOD activities by 7.9%-27.3% and 63.1%-96.0%, CAT activities by 16.7%-66.7% and 41.6%-151.1%, but decreased MDA content by 24.2%-40.7% and 14.1%-51.9%, and O₂^-_· producing rate by 12.4%-21.7% and 28.3%-68.6%, respectively. Our results confirmed that melatonin addition with suitable concentration could increase the activities of antioxidant enzyme, alleviate lipid peroxidation damage, and improve the resistance of rice to As stress.

Effects of fertilization on lead uptake and accumulation by Cosmos sulphureus and Cosmos bipinnatus.

GUO Jin-jun, YANG Jun, HU Jian, YANG Jun-xing, GUO Jun-mei, LEI Mei, LI Chun-li, CAO Liu

2018, 37(6):  1744-1751. 

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A pot experiment was conducted to assess the phytoextraction potential for lead (Pb) of Cosmos sulphureus and Cosmos bipinnatus under different treatments of N, NP and NPK fertilizer applications in Pb contaminated soils collected from northern China. The results showed that fertilization significantly increased the biomass, shoot Pb concentrations and accumulation in both C. sulphureus and C. bipinnatus. Especially, NPK fertilization had strongest effects on Pb accumulation. Lead concentrations in the shoots ofC. sulphureus and C. bipinnatus under NPK treatment were 1.59-1.89 and 1.17-1.32 times as high as that under other treatments. The enrichment amounts of Pb in the shoots were 1.15-3.21 and 1.18-4.28 times as high as that under the control treatment, respectively. Fertilization treatment significantly improved the transport ability of Pb of both species. The bioconcentration factors (BCF) increased from 0.17 in the control to 0.22 in the NPK treatment for C. sulphureus, and from 0.29 in the control to 0.36 in the NPK treatment for C. bipinnatus. The metalenriched particles (MRG) were the major enriched position in the subcellular fractions of both species (more than 70%). In conclusion, C. sulphureus and C. bipinnatuscan be used as plant materials for remediation of Pbcontaminated soil. Moreover, NPK fertilizers can effectively improve remediation efficiency, and C. sulphureusperforms better than C. bipinnatus.

Effects of sewage sludge compost on the growth and heavy metal accumulation in landscape plant Syngonium podophyllum.

WANG Jing, MO Qi-feng, CHU Shuang-shuang, LAI Can, ZENG Shu-cai

2018, 37(6):  1752-1758. 

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We investigated the impacts of application rates of sewage sludge compost (SSC) on the growth and capacity of heavy metal accumulation in Syngonium podophyllum with a pot experiment, with the aim to provide a reference of SSC application in landscape construction. The results showed that the plant height growth and biomass accumulation were significantly increased under proportions of SSC to substrates ≥30%. The maximum accumulation of N, P, K, Cu, Zn, Pb and Cd in S. podophyllum occurred in the treatment of 100% SSC. The application rate of SSC had significant effects on the bioaccumulation factor (BAF) and translocation factor (TF) of heavy metals in S. podophyllum. Accumulation and transfer capacity of S. podophyllum for Cu, Zn, Pb were lower than those for Cd. When the application rate of SSC was ≤30%, the BAF of Cd in both aboveground and belowground parts of S. podophyllum were above 1, suggesting that S. podophyllum would be an ideal candidate for Cd extraction when SSC is used as garden fertilizer. In summary, BAFs for heavy metals in S. podophyllum ranked as Cd > Zn > Cu > Pb, which was consistent with the heavy metal concentrations in the substrate. S. podophyllumshowed good adaptation to SSC and resistance to heavy metals. The application rate of 30% not only promoted the growth of S. podophyllum, but also reduced the risk of heavy metal contamination in soil.

Characteristics of Fe(III) reduction and microbial community of Fe(III) reducing bacteria under different electron acceptors.

QIN Hai-hua, XIN Hong-wei, LIU Hong-yan

2018, 37(6):  1759-1764. 

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Sea sediments collected from Bohai were anaerobically enriched to obtain dissimilatory Fe(III)reducing bacteria. Characteristics of dissimilatory Fe(III) reduction by Fe(III)reducing bacteria were investigated under different electron acceptors. After fermentation for 12 h, the Fe(II) concentration of culture was (100.67±0.75) and (53.24±3.63) mg·L^-1 respectively, using ferric citrate and ferric hydroxide as electron acceptors. After 60 h, the Fe(II) concentration of culture was (118.95±1.47) and (119.74±3.96) mg·L^-1  respectively. The results indicated that soluble and insoluble electron acceptors could significantly affect Fe(III) reduction processes, but had no significant effect on the accumulation of Fe(II). Diversity of mixed culture and composition of dominant bacteria under different electron acceptors were analyzed by high throughput sequencing. Shannon diversity index of the bacterial community was 3.40 and 3.11 using ferric citrate and ferric hydroxide as electron acceptors, respectively, being higher than that of control group (with Shannon index 2.07). Such a result suggested that cultivation system with Fe(III) addition could significantly enhance the diversity of mixed culture. The dominant populations in the Fe(III)reducing bacteria were Clostridium_sensu_strictoand Romboutsia, belonging to Clostridiales, indicating that Clostridiales were the dominant bacteria in the mixed culture under Fe(III)reducing conditions.

Effects of elevated CO₂ on clonal growth of Phragmites australis subjected to Pb pollution.

ZHANG Na, LI Zhi-qiang, ZHU Yang-chun, ZHOU Jing, CHEN Jing, MU Chun-sheng, ZHANG Zhen-hua

2018, 37(6):  1765-1771. 

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Phragmites australis (common reed), with extensive distribution and high tolerance to stress, is widely used in pollution remediation. Vegetative propagation is the main way of population maintenance for common reed. It is unclear how Pb pollution would affect clonal growth of reeds under elevated CO₂. To explore responses of clonal reproduction to Pb pollution under elevatedCO₂, we imitated the ambient CO₂ and elevated CO₂ concentrations (380±20 and 760±20 μmol·mol^-1), and Pb pollution (0, 300, 500, 1500, 3000 mg·kg^-1) in phytotron. The number of axillary shoot buds first increased and then decreased with increasing soil Pb concentrations. The number and length of rhizomes, the number of rhizome and apical rhizome buds and total number of buds decreased with increasing soil Pb concentrations. Soil Pb concentrations had no effect on the number of axillary daughter shoots and total number of daughter shoots, but significantly increased the number of apical rhizome daughter shoots and Pb concentrations in organs. Elevated CO₂ increased rhizome growth, the number of each type of buds and daughter shoots, and plant absorption and accumulation of Pb. The concentration of Pb in roots was significantly increased, while the Pb accumulations in rhizomes, steams, and leaves were decreased by elevated CO₂. These results indicated that elevated CO₂ alleviated the negative effects of Pb pollution on clonal growth of common reed, increased clonal propagation and population stabilization through increasing phalanx growth with low cost, guerilla growth by spreading rhizomes, and the effective Pb allocation strategy.

Methods and indices for risk assessment of heavy metal pollution surrounding Pb-Zn tailing ponds.

LIANG Ya-ya, YI Xiao-yun, DANG Zhi, GAO Shuang-quan, WANG Qin, TANG Jie

2018, 37(6):  1772-1780. 

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Heavy metal risk assessment for the sites surrounding Pb-Zn tailing ponds is the basis for classifying the heavy metal pollution for the Pb-Zn tailing ponds into different levels, which may provide basis for the adaptive management of tailing ponds by environmental protection department. At present, the research in environmental risk assessment of the heavy metal pollution surrounding the Pb-Zn tailing pond sites is not enough. Here, we developed a method for evaluating heavy metal pollution risk of the Pb-Zn tailing ponds. In the construction of the evaluation system, this method mainly takes account of atmospheric environment and leakage water, as well as the toxicity of heavy metals. This method can quantitatively calculate each index and is easy to operate. Furthermore, we tested the feasibility and practicality of the method in a tailing pond site in Meizhou City, Guangdong Province. This study contributes to the establishment and improvement of the criteria and standards in heavy metal risk assessment for the surrounding area of the Pb-Zn tailing ponds.

Monitoring of heavy metals in farmland soils based on ASD and GaiaSky-mini.

YI Xing-song, LAN An-jun, WEN Xi-mei, ZHANG Yin, LI Yang

2018, 37(6):  1781-1788. 

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Heavy metal pollution in farmland soils has become an environmental issue that cannot be overlooked in modern society. Traditional chemical detection methods are relatively outdated, and it is urgently needed to carry out dynamic, rapid and largescale monitoring of soil heavy metals. In this study, heavy metal pollutions in farmland soils were monitored by using spectral data obtained from portable matter spectrometer (ASD) and onboard hyperspectral imaging system (GaiaSky-mini) respectively. The results showed that GaiaSky-mini spectroscopy can discriminate the maximum and minimum value of As from partial least squares regression (PLSR) prediction model of As, Cd, Cr, and Pb, and roughly estimate the Cd content of samples, with residual predictive deviation (RPD) values being 1.13 and 1.50, respectively. The ASD spectral data can roughly estimate As content and quantitatively estimate Cd content, with RPD values of 1.45 and 1.95 for As and Cd, respectively. By comparing the regression results of two data sources, it is suggested that spectral data acquired from low-altitude unmanned aerial vehicle (UAV) can monitor heavy metals in soil with wider spectral bands and higher spectral resolution, whereas ASD spectral data has higher precision. It is important to apply low-altitude UAV hyperspectral data in further research to carry out rapid and large-scale monitoring of soil heavy metal content.

Assessment of heavy metal pollution in  Gongchangling Iron Mine region, Liaoyang.

ZHANG Xiao-wei, WANG En-de, AN Jing

2018, 37(6):  1789-1796. 

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In this study, geoaccumulation index, potential ecological risk index and enrichment factor were used to evaluate the heavy metal pollution of Liaoyang Gongchangling Iron Mine area. The mining area was divided into seven subareas around stope and tailing pond, and soil samples from which were collected. The concentrations of heavy metals, including Cd, Cu, Zn, Pb and Cr in all the samples were measured, based on which the pollution situation was evaluated. The results showed that the evaluation results using the three methods were consistent. The heavy metal pollution in the studied area was serious, mainly caused by Cd and Cu. Cd pollution reached a serious level, Cu was in moderate level, and Zn, Pb and Cr pollution was light. Moreover, the pollution of heavy metals was closely related to human mining activities. The pollution in stope and tailing pond was significantly worse than that in surrounding subareas. More attention should be focused on the pollution of Cd and Cu in the process of ecological restoration and soil reclamation. Our results provide a basis for ecological risk assessment and a scientific reference for the improvement of ecological environment.

Distribution and ecological risk assessment of heavy metals in selenium-rich soil with high cadmium content of coal mining area in upper reaches of Guancheng River in Zhijin County, Guizhou.

YANG Yan, WU Pan, LI Xue-xian, ZHA Xue-fang

2018, 37(6):  1797-1806. 

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We investigated the contents of heavy metals, including Cd, Cr, Ni, Cu, Zn, Pb, As and Se, in coal (coal gangue) and soil around coal mining area in the upper reaches of Guancheng River in Zhijin County, Guizhou, and analyzed their potential sources. The status of soil contamination by heavy metals and potential risks were evaluated by single-factor pollution index, Nemerow multi-factor index, geo-accumulation index and potential ecological risk index. The results showed that contents of Cr, Se and Pb in coal (coal gangue) were higher than the global mean value in the coal. The contents of Ni, Cu, Zn and Cd were higher than global and national mean values, respectively. Except Pb, the average contents of Cd, Se, Cr, Zn, As, Cu in soil were higher than soil background values of in Guizhou, especially for Cd, Se and Cu. Soils in the study area were characterized by rich selenium (or excessive amounts of selenium) and high content of cadmium, with the occurrence of acidification. The sources of Cd, Cr, Ni, Zn and Se in soils were similar, which was related with coal mining activities. The evaluation results of singlefactor pollution index showed that the order of pollution of heavy metals in soil was Cd>Cu>Ni>Zn>Cr>As>Pb, and the comprehensive pollution of heavy metals in soils was at severe pollution level. Environmental risks of Cr, Ni, Cu, Zn, As and Pb in soils were slight, but environmental risk of Cd was high. The results of four evaluation methods were similar. The single-factor pollution index and geoaccumulation index for Cd were the highest. Meanwhile, the pollution level and potential ecological harm of Cd were the highest. Therefore, Cd made the greatest contribution to the potential ecological risk index.

Regulation of plant growth promoting rhizobacteria and lignin on remediation of POPs contaminated soil and their impacts on soil enzyme activity.

ZHENG Xue-hao, SUN Li-na, LIU Ke-bin, SUN Jia-jun, WANG Xiao-xu, ZHENG Jia-yu, MA Xin-yu, ZHANG Hong-ling, WANG Hui

2018, 37(6):  1807-1814. 

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Farmlands have increasingly been exacerbated by the persistent organic pollutants (POPs), with serious consequences on food security and human health. In this study, we assessed the remediation efficiency of different control measurements on the vegetable soil contaminated by two typical POPs (DDTs and PAHs) in the greenhouse. The degradation rates of DDTs and PAHs and the activities of three kinds of soil enzymes were measured. The results showed that the treatment of rhamnolipid strengthened plant microbial remediation under the coregulation of plant growth promoting rhizobacteria and lignin had the best effect, with the degradation rates of DDTs and PAHs being 27.48% and 53.26%, respectively. At the end of experiment, polyphenol oxidase and hydrogen peroxidase were activated, with the degree of activation being higher for polyphenol oxidase than hydrogen peroxide, whereas the phosphatase activity was inhibited. Results from Pearson bivariate correlation showed that polyphenol oxidase and phosphatase activities were significantly correlated with the degradation rates of DDTs and PAHs, indicating that they can be considered as micro-ecological indicators during the remediation of POPs contaminated soil.

 

Twig biomass allocation of woody species in evergreen broad-leaf forest, Wuyi Mountain.

SUN Meng-ke, CHENG Lin, WANG Man-tang, LI Man, SUN Jun, CHEN Xiao-ping, ZHONG Quan-lin, CHENG Dong-liang

2018, 37(6):  1815-1823. 

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As twigs are important components of woody plants, studying the twig’s biomass allocation strategy is beneficial to understand the optimal growth strategies of plants. In this study, we sampled twigs from 19 woody  species in an evergreen broad-leaf forest, Wuyi Mountain National Natural Reserve, Jiangxi, China. We analyzed the scaling relationships among twig’s leaf mass, leaf area, petiole mass, stem mass and leaf number of woody plants by standardized major axis (SMA) to explore the biomass allocation patterns at community scale and synusia scale. Model Type II regression was used to determine the numerical values of scaling exponents and normalization constants of scaling relationships. Isometric relationships were found among the twig mass, total leaf mass and stem mass at the community scale. Stem mass and total leaf mass in the tree layer and shrub layer also showed invariant isometric scaling. In contrary, the twig mass showed allometric relationship with stem mass at tree layer, but showed isometric relationship at shrub layer. Additionally, negative isometric relationships were found between individual leaf mass and leafing intensity. The negative relationship between leafing intensity and individual leaf mass does not hold in different life forms of plant classification in the analysis. The total petiole mass scaled allometrically (i.e.,α<1.0) with respect to total leaf mass and twig mass on twig level, which indicated that twigs need to allocate more biomass for the construction of transport tissues and support structures with the increase of leaf mass. Therefore, the petiole investment plays a key role in limiting the growth of twigs and leaves, with important influence on the optimum selection of twig and leaf size.

Effects of environmental factors and natural fire disturbance on species diversity in Kanas taiga forest.

CUI Qian, PAN Cun-de, LI Gui-hua, YU Ge-bi, CHEN Hong, LIU Jing, YANG Yu-ping, LIU Bo

2018, 37(6):  1824-1832. 

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Biodiversity is the basis for sustainable development of an ecosystem. Exploring the influences of environmental and disturbance factors on species diversity is important for maintaining ecosystem structure and function. Based on the investigation of 160 plots and the occurrence time and severity of natural fires in the Kanas taiga forest in Xinjiang, we analyzed the relationships between species diversity of forest communities and environmental and natural fire disturbance factors, and the relationships between species diversity of herb layer, shrub layer, and tree layer and species diversity ofcommunities by redundancy analysis. The results showed that species diversity in the herb layer was affected mainly by altitude, soil moisture, soil total nitrogen content, soil temperature, and fire severity. Species diversity in shrub layer was mainly affected by altitude, soil moisture, soil conductivity, and soil organic matter content. Tree layer species diversity was affected by altitude, soil moisture, soil organic matter content, soil total nitrogen content, and fire severity. Community species diversity was mainly affected by altitude, soil moisture, soil organic matter content, soil total nitrogen content, and fire severity. Moreover, herb layer and tree layer interacted with each other, and played a determining role in community structure. Species diversity patterns in the Kanas taiga forest were formed by the synthetic action of a variety of environmental factors and natural fires in which elevation played an important role.

Responses of soil temperature and soil water content to extreme snow event in a subtropical evergreen broad-leaved forest in Ailao Mountains, Yunnan, Southwest China.

TANG Xian-hui, ZHANG Yi-ping, WU Chuan-sheng, LUO Kang, LIANG Nai-shen

2018, 37(6):  1833-1840. 

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The frequency and intensity of extreme weather and the associated disturbances, such as extensive floods, droughts, and ice storms, have been increasing against the pronounced global warming. In recent years, southern China has suffered increasing frequency of severe ice storms. During early January 2015, a primary subtropical evergreen broadleaved forest in〖JP2〗 Southwest China experienced an extreme snow event that damaged the forest. Based on the automatically collected data from meteorological station, we analyzed the soil temperature and soil water content before and after this severe snow event. The results showed that extreme snow led to extensive canopy damage and formation of canopy gaps. There was obvious time lag in maximal soil temperature between the forest and the open areas at different depths. However, no palpable time lag was observed in 10 cm and 20 cm soil depths in the year when extreme snow occurred. Similarly, no time lag occurred in 10 cm soil one year after extreme snow event. Soil water content at different depths showed a peak in both the forest and open areas after extreme snow damage, and then soil moisture in the forest kept higher against normal years. The extreme snow damage had stronger influence on topsoil water content in rainy season than in dry season. The increases of soil temperature and soil water content caused by extreme snow event would accelerate soil respiration, which may reduce the strength of carbon sink in the forest.

Phylogenetic relationships of leaf carbon content and plasticity in alpine meadow plants.

GUO Mei-ling, YAO Bu-qing, SHI Guo-xi, WANG Fang-ping, WANG Wen-ying, MA Zhen, ZHANG Zhong-hua, ZHOU Hua-kun

2018, 37(6):  1841-1848. 

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Phylogeny greatly affects plant functional traits. It is still unclear whether leaf carbon content, leaf traits and their plasticity of alpine meadow plants are influenced by their genetic background. We measured foliar carbon content, specific leaf area and their plasticity of 12 dominant plants in alpine meadow ecosystems under soil nitrogen and phosphorus heterogeneous conditions and analyzed their differences at species and family levels and their phylogenetic conservatism. The results showed that, at species and family levels, foliar carbon contents and specific leaf area were significantly different (P<0.05) at different soil nitrogen conditions. The difference of carbon content was not significant under different soil phosphorus conditions, but the specific leaf area had significant difference (P<0.05). There was no correlation between foliar carbon content and specific leaf area, but their plasticity was positively correlated, indicating that the two traits of different species had similar response to variation of soil nitrogen and phosphorus. Meanwhile, no significant phylogenetic signal was detected in foliar carbon content, specific leaf area and their plasticity, suggesting that those traits and their plasticity were more affected by environmental changes than by their genetic background. This study is helpful to understand the process of carbon cycling in alpine meadow under the global change background, and would provide scientific basis for the restoration and management of degraded alpine meadow.

Soil carbon and nitrogen characteristics in different vegetation restoration types in the lithoid hilly area of North China.

DU Man-yi, FENG Huan-ying, ZHANG Lian-jin, PEI Shun-xiang, XIN Xue-bing, KONG Qing-yun, SUN Li-fang, SUN Chang-zhong

2018, 37(6):  1849-1855. 

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Vegetation restoration is one of the important strategies for environmental recovery in the lithoid hilly area of North China. We investigated the characteristics of soil carbon (C) and nitrogen (N) and their coupling under different restored vegetations (shrubland, Platycladus orientalis forest andPinus tabuliformis forest) in Jiulong Mountain, aiming to provide scientific basis for the selection of restoration tree species and reasonable management of forest ecosystems in this area. Our results showed that: (1) Soil organic carbon (SOC) concentration in each layer over 0-30 cm in shrubland was significantly higher than in P. orientalis forest and P. tabuliformis forest, while SOC concentration in P. orientalis forest and P. tabuliformis forest showed no significant variation. Soil total nitrogen (TN) concentration in each layer was the highest in shrubland and lowest in P. tabuliformis forest, and the difference among soil layers decreased with the depth. Moreover, soil C/N ratio of P. orientalis forest was significantly lower at 0-10 and 20-30 cm layers than that in shrubland andP. tabuliformis forest. (2) SOC and TN enriched in topsoil of the three ecosystems and decreased with the depth. For all the vegetation types, soil C/N ratio showed no significant difference among soil layers. Soil C/N ratio at 0-30 cm layers ranged from 18.40 to 21.97 for shrubland, from 11.70 to 12.52 for P. orientalis forest, and from 18.08 to 20.69 for P. tabuliformis forest, respectively. (3) SOC and TN concentrations were significantly correlated with most of soil physical and chemical properties. They were significantly positively correlated with the concentrations of soil hydrolysable N, available phosphorus, available potassium content (P<0.01) and significantly positively correlated with soil pH (P<0.05). (4) As an important vegetation recovery type in the lithoid hilly area of North China, shrubland had the advantages of higher SOC and TN concentrations, suggesting that using the shrub in non-commercial forest construction would be beneficial for increasing C sequestration in the future.

Effects of different fertilization treatments on soil microbial biomass and enzyme activities in maize-soybean rotation system.

ZHOU Dong-xing, LI Lei, LI Jing, NING Yu-cui, CAO Xu, WU Xin-hui, RONG Guo-hua

2018, 37(6):  1856-1864. 

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This experiment was conducted to investigate the effects of different fertilization regimes on soil microbial biomass carbon (SMBC), nitrogen (SMBN) and enzyme activities in a maize-soybean rotation system. There were seven treatments: (1) no fertilizer input (CK); (2) manure alone 7.5 t·hm^-2 (M1); (3) manure alone 15 t·hm^-2 (M2); (4) manure alone 22.5t·hm^-2 (M3); (5) chemical fertilizer (N 160 kg·hm^-2+P₂O₅ 75 kg·hm^-2+K₂O 75 kg·hm^-2) (T1); (6) manure 7.5 t·hm^-2 plus chemical fertilizer (N 81 kg·hm^-2+P₂O₅ 0kg·hm^-2+K₂O 67 kg·hm^-2) (T2); (7) manure 15 t·hm^-2 plus chemical fertilizer (N 120 kg·hm^-2+P₂O₅ 7 kg·hm^-2+K₂O 71 kg·hm^-2) (T3). Soil samples in 0-20 cm depth were collected in different growth stages and SMBC, SMBN, activities of soil invertase, catalase and urease were measured. There were significant differences in SMBC and SMBN among different treatments. Compared with M1 and M2 (on average), SMBC in T2 and T3 treatments increased by 32% and 21%, and SMBN increased by 38% and 28% at mature stage, respectively. Compared with that at maize mature stage, SMBC at soybean mature stage increased by 13%-51%, and SMBN increased by 85%-174%. T3 treatment had most significant effects on soil invertase activity in the different growth stages. The combined applications of organic and inorganic fertilizers- had greater effects on the activities of soil catalase and urease. Relative to the corn field, SMBC, SMBN and enzyme activities were increased with different degrees in the soybean field. SMBC, SMBN and enzyme activities were closely related to soil organic matter, nitrate, ammonium, available P and K contents in different treatments. Organic fertilizer application or combined application with chemical fertilizer could improve soil nutrients, urease activity, SMBC and SMBN, but no significant correlation was observed between catalase activity and fertilization level.

Effects of strong reductive approach on root-knot nematodes, the growth of tomato and soil physicochemical properties.

SHI Lei, ZHAO Hong-hai, LI Ming-liang, ZHANG Jin-bo, ZHANG Lei

2018, 37(6):  1865-1870. 

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Strong reductive approach refers to adding lots of organic materials into soil with waterflooding and plastic cover under high temperature. It is an effective, environmentfriendly, and broad-spectrum way to suppress soil-borne plant pathogens, but its application in controlling root-knot nematodes is limited. We investigated the efficacy of strong reductive approach in controlling root-knot nematodes and its effects on the physicochemical properties of soil after two months of tomato plant growth. The results showed that there was no significant difference in the quantity of 2 instar root-knot nematodes between strong reductive approach treatment and abamectin application. Strong reductive approach decreased the quantity of 2instar root-knot nematodes by 58.8%-97.2% compared with the control, and by 50.1%-96.6% compared with the waterlogging treatment. Strong reductive approach significantly increased root length, root surface area, and aboveground biomass of tomato when the addition level of organic materials was 4.16 g·kg^-1. Strong reductive approach increased soil pH by 5.1%, soil total nitrogen by 12.8%, and soil organic matter 3.4% compared with the control. Our results suggested that strong reductive approach could effectively control the propagation of root-knot nematodes and improve the physicochemical properties of soil.

Effects of three arbuscular mycorrhizal fungi (AMF) species on the growth, physiology, and major components of essential oil of Atractylodes lancea.

LIANG Xue-fei, TANG Meng-jun, Lü Li-xin, ZHAO Xiang-yu, DAI Chuan-chao

2018, 37(6):  1871-1879. 

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To investigate the effects of arbuscular mycorrhizal fungi (AMF) on survival, growth, physiological characteristics, and essential oil accumulation of Atractylodes lancea plantlets, three strains of AMF, including Glomus etunicatum BGC AM0048 (A1), Glomus tortuosum BGC AM0001 (A2), and Glomus mosseae BGC AM0045 (A3), were used to inoculate A. lanceatissue culture seedlings in a greenhouse experiment. The results showed that the inoculation of AMF increased the survival rate of seedlings. The mycorrhizal infection rates in the three inoculated groups were in the order of A3 (63.39%), A2 (47.81%), A1 (42.41%) at 35 d after transplanting, and their positive effects on the growth of A. lancea followed the same order of infection rate, with A3 group showing the best performance. Compared to the control group, plant height, root length, and leaf number per plant in A3 group significantly increased by 21.9%, 65% and 38.7% respectively. The activities of disease resistance enzymes (PAL, PPO, β1,3glucanase), antioxidant enzymes (SOD, CAT and POD) as well as chlorophyll (a+b) content in the leaves of AMF treatment groups were improved at some extent. Moreover, AMF inoculation increased the accumulation of the major components (hinesol, βeudesmol and atractylodin) in the essential oil. Our results showed that there was difference in the preference of AMF for plants. G. mosseae BGC AM0045 (A3) could be used as an excellent fungal strain to inoculate A. lancea seedlings for the establishment of arbuscular mycorrhizae in artificial cultivation.

Effects of flooding stress on photosynthesis characteristics in leaves of native species Physocarpus amurensis and introduced species P. opulifolius.

XU Nan, LONG Jing-hong, ZHANG Wen-shi, YAN Xin, ZHANG He,NIE Xin, XU Hua-hua, ZHANG Hui-hui

2018, 37(6):  1880-1888. 

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To provide technical support for the promotion and cultivation of Physocarpus plants, the double setting pot method was used to examine the effects of flooding stress on the photosynthetic characteristics of leaves, including photosynthetic gas exchange and chlorophyll fluorescence, in native species P. amurensisand introduced species P. opulifolius. The net photosynthetic rates (P_n) of leaves of both species were significantly reduced after 15 days of flooding stress, along with decreased stomatal conductance (G_s) and transpiration rates (T_r). Our findings indicated that the decreased photosynthetic capacity of leaves of both species caused by flooding stress was related to the restriction of stomatal factors. Under flooding stress, the photosynthetic inhibition of P. opulifolius was mainly caused by stomatal changes, while that of native P. amurensis was caused by both stomatal and non-stomatal factors. The activity of the PSII reaction center of P. opulifoliusleaves was not significantly affected by flooding stress, which was mainly related to the increase of nonphotochemical quenching (NPQ) that reduced the excess light energy (1-q_P)/NPQ. In contrast, the photochemical activity of the PSII reaction center of native species P. amurensis was significantly reduced by flooding stress. Flooding stress signifi cantly increased the activity of the oxygen-evolving complex (OEC) of the PSII donor side in P. opulifoliusleaves and had little effects on the electron transfer of its acceptor side. Flooding stress significantly inhibited the electronic transfer ability ofQ_A toQ_B in the PSII acceptor side of P. amurensis, but the effect of flooding stress on the activity of OEC in the PSII donor side of P. amurensis was not found. After 15 days of flooding, the relative variable fluorescence (V_L) at the L point was significantly higher than that of P. opulifolius in the standardized O-K curve of P. amurensisleaves, indicating that the degree of thylakoid membrane degradation of P. amurensis leavesunderflooding stress was significantly higher than that of P. opulifolius.P. opulifolius was more resistant to flooding stress than P. amurensis, thus P. opulifolius should be promoted and cultivated in areas with lowlying water.

Effects of acclimation temperature on locomotion performance and behavior of pale chub.

FU Cheng, PENG Jiang-lan, FU Shi-jian

2018, 37(6):  1889-1896. 

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To examine the effects of acclimation temperature on locomotion performance and behavior of pale chub (Zacco platypus), fishes collected from Wujiang River were acclimated at 15 ℃ and 25 ℃ for three weeks, respectively. After that, the critical and faststart swimming performance and behavior (activity and hiding behavior) were measured. We found that fishes  acclimated under low temperature (15 ℃) had lower critical swimming speed and lower metabolic parameters (e.g.maximum metabolic rate, routine metabolic rate, and metabolic scope) than those acclimated under high temperature (25 ℃) (P<0.05). Furthermore, both the faststart maximum velocity and maximum acceleration, distance moved in 120 ms were lower for fished acclimated under lower temperature (P<0.05), whereas response latency showed no difference between two groups. The behavior exhibited substantial differences between two temperatures as fish acclimated at lower temperature showed decreased spontaneous activity and increased hiding behavior (P<0.05). Our results suggested that pale chub adaptively regulate its swimming performance and metabolic status at low temperature, whereas the behavior compensation mechanism such as decreased spontaneous activity and increased use of shelter as well as the unchanged faststart response latency might be adaptive strategies to cope with potential predators at low temperature.

Swimming ability of Schizothorax irregularis Ddy in Yarkand River.

LI Zhi-min, CHEN Ming-xi, JIN Zhi-jun, TU Zhi-ying, KE Sen-fan, ZHANG Ning, SHI Xiao-tao, LIU De-fu

2018, 37(6):  1897-1902. 

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The population of Schizothorax irregularis Ddy, an endemic species in Xinjiang, has declined rapidly due to hydroelectricity construction. Investigation of their swimming capability will provide the basis required for fishery passage facilities design. The induction velocity, critical swimming speed and burst swimming speed were measured by increasing velocity tests. The swimming endurance of S. irregularis was measured by fixed velocity tests. Induction velocity (1.41±0.28 BL·s^-1 or 24.50±4.13 cm·s^-1, BL: body length), critical swimming speed (6.04±1.21 BL·s^-1 or 117.61±12.34 cm·s^-1) and burst swimming speed (11.41±2.79 BL·s^-1 or 210.24±39.56 cm·s^-1) declined with the increases of body length. Results from swimming endurance tests showed that  the swimming time or swimming endurance significantly decreased with the increases of flow rate (80-135 cm·s^-1) and that swimming endurance was negatively related to swimming velocity. Eighty percent of fishes could pass the fishway when maximum velocity was less than 1.9 m·s^-1. Therefore, we suggest that when the target fish of fishway is S. irregularis, the minimum velocity in fishway should exceed 0.3 m·s^-1, the flow rate at entrance and vertical slot could range from 1.2 to 1.9 m·s^-1, and the main flow rate in the rest pool ranges from 0.3 to 1 m·s^-1.

Assessment of habitats for juvenile Eriocheir sinensisin Langshan and Xinkai shoals of the lower reaches of the Yangtze River.

WANG Lei, XU Dong-po

2018, 37(6):  1903-1909. 

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To investigate the habitat suitability for juveniles Eriocheir sinensis in Langshan sandbank and Xinkai sandbank of the lower reaches of Yangtze River, custombuilt netting gears were used to obtain the abundance  of juveniles and six water environmental factors from June 2016 to May 2017. Three factors including water depth, transparency and Chiromantes dehaani abundance were selected by the oneway analysis of variance, correlation analysis and canonical correspondence analysis. After that, habitat suitability curves were established and habitat suitability index was calculated. The results showed that sites with aquatic plants possessed high abundance of juvenile E. sinensis. Significant differences in turbidity, transparency and depth of water existed among different sites. The abundance of juvenile E. sinensis was significantly correlated to abundance ofC. dehaani, water depth, and water transparency. Sites withaquatic plants in both sandbanks had relatively high HSI (>0.5) than those with lower or no aquatic plants (generally lower than 0.4). Moreover, juvenile E. sinensispreferred shallow waters with aquatic plants and water transparency between 10 cm and 20 cm. Our results suggest that both sandbanks are suitable for the growth and development of juvenile E. sinensis and more protection is required.

Construction and optimization of ecological network for protected areas in Qinghai Province.

SHI Na-na, HAN Yu, WANG Qi, QUAN Zhan-jun, LUO Zun-lan, GE Jin-song, HAN Rui-ying, XIAO Neng-wen

2018, 37(6):  1910-1916. 

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The establishment of ecological networks can effectively connect fragmented ecological sources and thus enhance their biodiversity and ecological function. Based on the theories in ecology and conservation biology and the recognition of ecological sources and the establishment of ecological cost surface, a minimum cumulative resistance model (MCR) was used to build apotential ecological network for protected areas in Qinghai Province. The network was evaluated by a gravity model to extract important corridors and by connectivity indices to calculate itsconnectivity. After that, optimized ecological network and measurements were proposed. Results showed that meadows were the most important landscape component of the potential ecological corridors for protected areas in Qinghai Province. The established network increased connectivity among ecological sources. Interaction strength among different ecological sources varied greatly. The larger the interaction strength was, the more important the ecological source was. We proposed a “three nuclei, two verticals and three horizontals” pattern in the ecological network. Optimized measurements of the ecological network were proposed, such as protecting core ecological sources, amending ecological break points, and constructing “stepping stones”. Our results provide a scientific basis for the planning of biodiversity conservation in Qinghai Province.