菹草(Potamogeton crispus)叶面CaCO3-P沉淀物产生的关键影响因子分析OA北大核心CSTPCD

The microenvironment formed by photosynthesis of submerged macrophytes is favourable for the formation of CaCO3-P co-precipitation of calcium and phosphorus in the water column.However,the ability of calcium and phosphorus to form CaCO3-P co-precipitation in the water column varies under different water environmental factors.In this study,Potamogeton crispus was used to investigate the impacts of different calcium concentrations(0,20,35,50,and 65 mg/L),alkalinity(0,100,200,300,and 400 mg/L CaCO3),phosphorus concentrations(0,0.1,0.2,0.3,and 0.4 mg/L),and temperatures(11,14,17,20℃)on the ability of P.crispus to reduce phosphorus and CaCO3-P co-precipitation.By analyzing the trend of the saturation index of the culture solution of the no-plant control group,this study revealed the law of plant-mediated CaCO3-P occurrence,and provided a theoretical basis for the selection of submerged macrophytes in the ecological restoration of lakes.The results showed that the total phosphorus(TP)and soluble reactive phosphorus(SRP)concentrations decreased significantly in the P.crispus culture group.There were significant differences between different treatment groups.As calcium concentration increased,TP and SRP concentra-tions decreased in all treatment groups,with a decreasing rate depending on the addition of calcium.In contrast,there were no sig-nificant changes in TP and SRP concentrations in the no P.crispus culture group.This suggested that P.crispus enhanced phosphor-us removal.In all the treatment groups,CaCO3-P co-precipitation increased with increasing alkalinity,with maximum CaCO3-P co-precipitation at an alkalinity concentration of 400 mg/L CaCO3.This suggested that P.crispus was more conducive to CaCO3-P co-precipitation in an alkaline water environment.Co-precipitation was highest at moderate phosphorus levels(0.2 mg/L),with an average of 23.12 mg co-precipitation per day for each P.crispus.The experiments verified that the natural water body phosphorus concentration has limited difference on the production of CaCO3-P co-precipitation in the leaves of P.crispus.The co-precipitation was highest at the medium temperature level(17℃),with an average of 16.61 mg co-precipitation per day for each P.crispus.This suggested that there was not much difference in the production of co-precipitation by P.crispus at the appropriate temperatures.These results indicated that alkalinity has a greater effect on CaCO3-P co-precipitation in P.crispus compared with phosphorus con-centration and temperature.Under the same water environment,the calcium carbonate saturation indices(calcite and aragonite sat-uration indices)of the control group without P.crispus were greater than 0,indicating a crystallisation tendency.However,no pre-cipitation was produced during the experimental period,whereas the treatment group with added P.crispus produced unequal a-mounts of CaCO3-P co-precipitation,which suggested that submerged macrophytes can reduce phosphorus by co-precipitation.This study can potentially provide theoretical support for water management of lake eutrophication.