Study on temporal and spatial distribution and eutrophication of nutrients in Sanya River
To understand the nutrient pollution status of Sanya River,a seasonal survey was conducted in the Sanya River basin from June 2018 to May 2019 to analyze the spatial and temporal distribution characteristics and influencing factors of nitrogen and phosphorus nutrient salts in the water column.The state of eutrophication was evaluated,and further the flux of nutrients into the sea through Sanya River was estimated.The results show that the seasonal variation of nutrient concentration in Sanya River is significant.The concentrations of DIN ranged from 0.028 mg·L-1 to 2.096 mg·L-1,with an average concentration of(0.700±0.279)mg·L-1,with a sequential increase in spring,summer,autumn and winter NO3--N and NH4+-N are the main forms of DIN present in the water column.The concentrations of DIP ranged from 0.007 mg·L-1to 0.442 mg·L-1,with an average concentration of(0.140±0.066)mg·L-1,with a sequential increase in autumn,winter,spring,and summer.The spatial distribution of N and P nutrients was similar,with low concentration in the upstream and estuaries and high concentrations in the middle and downstream.The environmental characteristics of river sections,anthropogenic activities,rainfall and tide are the main factors affecting the nutrient distribution in the Sanya River.The results of eutrophication index(EI)evaluation showed that the upper reaches and estuaries of Sanya River are moderately eutrophic in all seasons,while the middle and lower reaches are eutrophic and heavily eutrophic.The N/P in spring,summer and autumn indicate that most rivers are in nitrogen limitation,and most of the river were suitable for algal survival in winter,with the risk of algal blooms.Based on nutrient concentrations and the average annual runoff of Sanya River,it was estimated that the annual flux of DIN,NO3--N,NC2--N,NH4+-N and DIP into the sea are 118.37,70.93,11.18,38.67 and 23.75 t,respectively.
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NSTL
万方数据
