Effects Of Photovoltaic Power Stations On Water Environmental Quality And Phytoplankton Community Structure In Coal Mining Subsidence Ponds

With the announcement of"carbon peaking and carbon neutrality",the low-carbon development of the power industry is facing several challenges.Building a new power system with clean energy as the main body is an important measure to achieve the"dual carbon"goal.As a new resource of clean energy,the water surface floating photovoltaic（PV）systems has been widely applied on the water bodies of coal mining subsidence ponds in recent years.However,there are few studies on the environmental impact of PV power stations in coal mining subsidence ponds.Therefore,this study conducted monitoring and research on the water quality indicators and phytoplankton community structure of photovoltaic subsidence ponds（scaffolding,floating）and non-photovoltaic subsidence pond in spring,summer,autumn and winter from March to December 2021,to reveal the correlation between phytoplankton and water environment factors.At the same time,the USEPA recommended model was used to evaluate the health risk of the subsidence pond water body.At the same time,the USEPA recommended model was used to evaluate the health risk of the subsidence pond water body.The influences of surface PV on water environment quality and phytoplankton community structure in coal mining subsidence ponds were explored.The results indicate that:（1）The characteristics of the influence of PV power stations on different water surface on the water environment quality of coal mining subsidence ponds indicate that photovoltaic power stations can increase DO and p H of coal mining subsidence pond water,reduce the light intensity,WT,COD,EC,TDS,WT,COD,EC,TDS,TN and chlorophyll a had no obvious effect on SD,TP and NH₃-N.Among them,the overall change order of DO and p H in different coal mining subsidence ponds is scaffolding photovoltaic subsidence pond>floating photovoltaic subsidence pond>non-photovoltaic subsidence pond;the overall change trend of light intensity,WT,COD and chlorophyll a in different coal mining subsidence ponds is non-photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond>floating photovoltaic subsidence pond;the overall change order of EC,TDS and TN is non-photovoltaic subsidence pond>floating photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond;the overall change trend of SD is floating photovoltaic subsidence pond>non-photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond;the overall change order of TP and NH₃-N is scaffolding photovoltaic subsidence pond>non-photovoltaic subsidence pond>floating photovoltaic subsidence pond.In addition,the photovoltaic power station reduces the heavy metal content in coal mining subsidence ponds to a certain extent.（2）The variation characteristics of the effect of PV power stations on the phytoplankton community structure in coal mining subsidence ponds with different water surfaces are as follows:PV power stations can slightly reduce the species and quantity of phytoplankton community composition in coal mining subsidence ponds,but not significant enough to change the overall community structure of phytoplankton.Overall,the number of dominant species of phytoplankton in different coal mining subsidence ponds in the same season changed as follows:non-photovoltaic subsidence pond>floating photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond.Photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond>floating photovoltaic subsidence pond;the changes of Shannon-Wiener diversity index and Pielou uniformity index of phytoplankton in different coal mining subsidence ponds are floating photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond>non-photovoltaic subsidence pond.（3）The correlation analysis between the light intensity and water environment factors in different coal mining subsidence ponds shows that the light intensity and electrical conductivity in the scaffolding photovoltaic coal mining subsidence pond are significantly negatively correlated;the light intensity and electrical conductivity in the floating photovoltaic coal mining subsidence pond are significantly positive.There is a significant positive correlation between light intensity and water temperature in non-photovoltaic subsidence ponds.The correlation analysis between the phytoplankton community structure index and water environment factors in different coal mining subsidence ponds showed that dissolved oxygen was significantly positively correlated with the phytoplankton community density in different coal mining subsidence ponds.In addition,the RDA analysis of the dominant species of phytoplankton community structure and water environment factors showed that the main environmental impact factors of the dominant species of phytoplankton in the scaffolding photovoltaic subsidence pond were COD and SD;the main environmental impact factor of the dominant species of phytoplankton in the floating photovoltaic subsidence pond was p H;The main environmental factors of phytoplankton dominant species in non-photovoltaic subsidence ponds were WT and p H.（4）The impact of PV power stations with different water surfaces on the health risk of coal mining subsidence pond water environment is not significant.In general,the change order of non-carcinogenic risk index and carcinogenic risk health value of six heavy metals Mn,Ni,Cr,Pb,Cu and As in different coal mining subsidence ponds for adults and children is consistent with non-photovoltaic subsidence pond>scaffolding photovoltaic subsidence pond>Floating photovoltaic subsidence pond.At the same time,the change trend of non-carcinogenic risk index and carcinogenic risk value of heavy metal elements in different coal mining subsidence ponds for adults and children is the same for adults>children.In addition,the non-carcinogenic health risk indices of heavy metals Mn,Ni,Cr,Pb,Cu and As in different coal mining subsidence ponds and non-photovoltaic coal mining subsidence ponds are all less than 1,which are at acceptable levels.The carcinogenic health risk values of the carcinogenic heavy metals Ni,Cr and As in different coal mining subsidence ponds were all lower than the USEPA recommended maximum limit of 1×10^-4/a.Figure[23]Table[14]Reference[166]...