关键词: 非点源污染, 流域, 关键“源”景观, 景观格局, 调控, “源-汇”理论

Abstract: To clarify the environmental impacts of higher-place shrimp pond aquaculture, we analyzed the concentrations of total nitrogen (TN), total carbon (TC), and total organic carbon (TOC) in the sediments sampled from three types of shrimp aquaculture in the Dongying Town of Haikou City. The sediments were sampled from four layers: 0-5 cm (t1), 5-10 cm (t2), 10-15 cm (t3), and 15-20 cm (t4). The concentrations of TC, TOC, TN in the soil outside the embankment of shrimp ponds were 5.66, 6.95 and 2.49 times higher than that of 〖JP2〗shrimp ponds, respectively, a phenomenon caused by the infiltration of wastewater from the higherplace shrimp〖JP〗 ponds. Additionally, the concentrations of TC, TOC and TN in the sediments were 7.36, 8.68 and 4.41 times higher than the background value, which was caused by accumulation of baits and shrimp excrement. The concentrations of TN, TC and TOC in the sediments of the bottom auxiliary sand were the highest in the surface layer and 2 to 27 times higher than that in the deep soil. In the bottom auxiliary cement shrimp pond, the concentrations of TN, TC and TOC in the crack were the highest in the third layer of soil, showing a trend of t3>t1>t2>t4. The concentrations of TN, TC and TOC on the outer side of shrimp pond dike showed a significant decrease from the surface layer to the deep layer. The TOC and TN in the surface sediments in shrimp ponds and the residues of bait and shrimp dung during culture were seriously exceeded the standard after the discharge of wastewater. The organic nitrogen and organic index of surface sediments of the unwashed shrimp pond after draining wastewater were classified as III moderate pollution and Ⅱ mild pollution, while both organic nitrogen and organic index of the bait and shrimp manure residues during the culture were classified as IV heavy pollution. The organic index in the lateral soil of the shrimp ponds embankment was III moderate pollution, while organic nitrogen rating was IV heavy pollution. The C∶N ratio in the sediments of the shrimp pond was low, which was conducive for the formation of humus stemmed from residual baits and biological excretions in sediments. If humus is not cleaned in time, it will reduce aquaculture water quality.

Key words: ‘source-sink&rsquo, landscape pattern, non-point source pollution, watershed, regulation, landscape., theory, key ‘source&rsquo