Characterization Of Primary Productivity And Carbon Forms In The Subsided Small Lakes Around The Huainan And Huaibei Coalmine Subsidence Areas

Extensive land subsidence and submergence have occurred in the Huainan and Huaibei coal mine areas. As result, landscapes of many small subsided lakes have formed. Accordingly, agricutal cultivation ecosystem has been transformed to freshwater ecosystem, which leads to the productivity changed permanently within the lands across the mine areas. Therefore, characterization of their productivitiy in the water column of the subsided lakes has fundmental meaning to undersand the structure and function of such ecosystems and evalutaiton the environmental impacts of mining activities.Five small subsided lakes around Huainan "Panxie" coalmine areas and three subsided small lakes around Huaibei "Zhu-Yang Zhuang" coalmine areas were set to address the eutrophication characteristics.Furthermoe, three sites in the Huainan coalmine areas (PXS-1, PXS-3and PXS-5), and two sites in the Huaibei coalmine areas (HBZH and HBNH), were selected to study their primary productivity (PP) and carbon pools in one-year investigation period with four seasons in2012and2013. The analyzed carbon pools are in forms of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and particulate organic carbon (POC). Then the relationships between PP, carbon pools and other environmental factors and zoology effect estimate of primary productivity were discussed.(1) Three lakes (PXS-1、PXS-5、HBDH) in eight sites can be classified into "meso-eutrophic" level because they are influenced by people’s activities,but the lake at PXS-3site of maintaining natural state or protecting better water areas(HBZH and HBNH) can be classified into "meso trophic-light eutrophic", which is the lowest nutrition state in Huainan and Huaibei coalmine subsidence areas as the origin of eutrophication progress.Human activities can improve their processes for eutrophication of such lakes in a relatively short term.(2) Averge values of primary productivity (GPP) in five subsided small lakes is between82.4and2305.4mgC·m-2·d-1, which is consistent to their waters nutrition state. Meanwhile, primary productivity reflects seasonal distribution, with the summer’s values higher than winter and spring’s values.(3) Averaged POC concentration is between0.9and4.0mgC·L-1, and it is between 36.0and70.4mgC·L-1for DIC. DIC concentration in the Huaibei waters is higher than that in the Huainan waters due to the different alakliity. DOC concentration is from2.0to11.1mgC·L-1.There was obviously pimary productivity and carbon turnover efficiency in the small subsided lakes of higher eutrophic states. The primary productivity in the water column of Huainan waters is greater than that in the Huaibei coal mine areas.(4) The primary productivity presents significantly positive correlations between PP and NPP, R, Chl-a, TN, TP, DOC and POC, of which Chl-a has a0.914linear relationship with PP.(5) All five sites have net primary production as typically autotrophic waters. The fishery production potential in one year was estimated to16to156tons, with higher fishery production potential in the Huainan subsided small lakes than those in the Huaibei waters.Finally, the differential principles and strategies, aimed at help regionally waters ecological rehabilitation, restoration and conservation, were proposed based on the research results.The research results possess particular theoretical value and practical significance to relevant practice of Huainan and Huaibei mining areas water resource management.