地质高背景地区土壤中铁锰结核形成机理——以广西桂中地区为例

doi:10.13292/j.1000-4890.202108.006

生态学杂志 ›› 2021, Vol. 40 ›› Issue (8): 2302-2314.doi: 10.13292/j.1000-4890.202108.006

• 农田地质高背景重金属污染专栏 • 上一篇下一篇

地质高背景地区土壤中铁锰结核形成机理——以广西桂中地区为例

季文兵〖HT5”〗1,2,3〖HT4〗〓杨忠芳〖HT5”〗3*〖HT4〗〓尹爱经〖HT5”〗1,2〖HT4〗〓芦园园〖HT5”〗1,2〖HT4〗〓应蓉蓉〖HT5”〗1,2*〖HT4〗〓杨〓琼〖HT5”〗3〖HT4〗〓刘〓旭〖HT5”〗3〖HT4〗
李博³,段轶仁³,王珏³,王懿铮³,余涛⁴,吴天生⁵,张起钻⁶

(¹生态环境部南京环境科学研究所，南京 210042；²国家环境保护土壤管理与污染控制重点实验室，南京 210042；³中国地质大学(北京)地球科学与资源学院，北京 100083；⁴中国地质大学(北京)数理学院，北京 100083；⁵广西壮族自治区地质调查院，南宁 530023；⁶广西壮族自治区地质矿产勘查开发局，南宁 530023)

出版日期:2021-08-10 发布日期:2021-08-10

Formation mechanisms of iron-manganese nodules in soils from high geological background area of central Guangxi.

JI Wen-bing^1,2,3, YANG Zhong-fang^3*, YIN Ai-jing^1,2, LU Yuan-yuan^1,2, YING Rong-rong^1,2*, YANG Qiong³, LIU Xu³, LI Bo³, DUAN Yi-ren³, WANG Jue³, WANG Yi-zheng³, YU Tao⁴, WU Tian-sheng⁵, ZHANG Qi-zuan⁶

(¹Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China; ²State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing 210042, China; ³School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China; ⁴School of Science, China University of Geosciences, Beijing 100083, China; ⁵Guangxi Institute of Geological Survey, Nanning 530023, China; ⁶Guangxi Bureau of Geology & Mineral Prospecting & Exploitation, Nanning 530023, China).

Online:2021-08-10 Published:2021-08-10

摘要/Abstract

摘要： 地质高背景的岩溶区土壤中普遍发育铁锰结核，且含量远高于非岩溶地区。为了解岩溶区土壤中铁锰结核的成因，选择广西桂中地区土壤(0～20 cm)中的铁锰结核为研究对象，通过光学显微镜(OP)、场发射扫描电子显微镜(FESEM)及能谱分析(EDS)，结合岩溶区复杂的成土过程，对地质高背景地区土壤中铁锰结核的形成过程进行分析。结果表明：岩溶区土壤中普遍发育两种结核，分别是铁结核和锰结核，宏观上结核呈现次圆状至椭圆状，粒径范围主要为0.5～4.0 mm，且均发育有环带结构和无环带结构结核。锰结核主要是以铁氧化物和锰氧化物为主，而铁结核内部是以铁氧化物为主。据上述结果和岩溶成土过程，提出地质高背景土壤中铁锰结核发育的过程：1)岩溶地区土壤在成土过程中，铁锰等元素发生不同程度的“浓集”作用，为结核的形成提供了丰富的物质来源；2)特殊的季节性干湿交替气候条件导致铁元素和锰元素的交替性沉淀，促进典型环带结构的形成，而无环带结构则可能代表结核形成的早期阶段；3)结核内部的微孔隙结构可以为微生物活动提供空间和物质流动提供通道，特殊气候环境条件富含有机质和微生物可能会促进铁锰结核的形成，最终形成岩溶区土壤中普遍发育的铁锰结核。

关键词: 铁结核, 锰结核, 成土过程, 交替性沉淀, 环带结构, 浓集作用

Abstract: Iron-manganese nodules are widely distributed in karst soil with high geological background, the content of which is much higher than that in nonkarst soils. To better understand the formation mechanism of iron-manganese nodules in karst soil, the nodules in the soil (0-20 cm) of central area of Guangxi were collected. The formation process of iron-manganese nodules in the soil of high geological background area was examined via the optical microscope (OP), field emission scanning electron microscope (FESEM), and energy spectrum analysis (EDS), combined with the complex soil forming process in karst area. The results showed that there were two kinds of nodules in the karst soil, i.e., iron nodules and manganese nodules. Generally, the nodules were sub-circular to elliptical in shape, and the particle size ranged from 0.5 to 4.0 mm. There were two kinds of iron-manganese nodules, with or without banded structure. Manganese nodules were mainly composed of iron oxides and manganese oxides, while iron oxides were mainly distributed in iron nodules. Based on those findings and the process of karst soil formation, the formation process of iron and manganese nodules in high geological background soil is summarized: (1) in the process of soil formation in karst area, iron and manganese were aggregated in different levels, which provides rich material sources for the formation of nodules; (2) the seasonal dry-wet cycling climate conditions led to the alternation precipitation of iron and manganese, which enhanced the formation of nodules; (3) the micropore structure in the nodules can provide space for microbial activities and channels for material flow, the special climate and environmental conditions rich in organic matters and microorganisms accelerate the formation of iron-manganese nodules, and eventually form iron-manganese nodules that are widely deve loped in karst soils.

Key words: iron nodule, manganese nodule, soil forming process, alternation precipitation, banded structure, concentrating.

李博, 段轶仁, 王珏, 王懿铮, 余涛, 吴天生, 张起钻. 地质高背景地区土壤中铁锰结核形成机理——以广西桂中地区为例[J]. 生态学杂志, 2021, 40(8): 2302-2314.

JI Wen-bing, YANG Zhong-fang, YIN Ai-jing, LU Yuan-yuan, YING Rong-rong, YANG Qiong, LIU Xu, LI Bo, DUAN Yi-ren, WANG Jue, WANG Yi-zheng, YU Tao, WU Tian-sheng, ZHANG Qi-zuan. Formation mechanisms of iron-manganese nodules in soils from high geological background area of central Guangxi.[J]. Chinese Journal of Ecology, 2021, 40(8): 2302-2314.

地质高背景地区土壤中铁锰结核形成机理——以广西桂中地区为例

Formation mechanisms of iron-manganese nodules in soils from high geological background area of central Guangxi.

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