Study On Water Environment Characteristics And Risk Of Phosphorus Release From Coastal Soil In Hefei Round-city-park

The maintenance of ecological balance in urban landscape water bodies plays a very important role.In this paper,six main landscape water bodies in Hefei Round-city Park were taken as an object.Water samples were collected at a frequency of once every half month from October 2018 to September 2019.The characteristics of water quality changes in each water body were analyzed,and water environmental quality and eutrophication were carried out.The evaluation was based on the collection of coastal soil samples of each water body at a frequency of once a quarter,the analysis of soil nitrogen and phosphorus forms,and the evaluation of the risk level of phosphorus release from the shore soil,with a view to providing a basis for the environmental protection of the landscape water bodies in Hefei Round-city Park.The main research results were obtained as follows:?1?The p H value of each landscape water body was moderately weak alkaline;the EC value ranged from 400 to 500?S·cm^-1;the TN concentration of each landscape water body was significantly higher than the Surface Water Environmental Quality Standard?GB3838-2002?Class V standard 2 mg·L^-1);TP concentration ranged from0.15 to 0.4 mg·L^-1;COD was 30 to 60 mg·L^-1;Chl-a was 35 to 55 mg·m^-3,relevant indicators have not improved significantly due to the relocation of government departments.?2?The fluctuations of phosphorus pollution indicators in each landscape water body were relatively obvious,and the fluctuations of nitrogen pollution indicators were relatively small.EC and ORP generally showed an upward trend.Most of the COD and Chl-a indicators showed a significant upward trend.Analysis of water quality differences showed that the water bodies of Xiaoyaojin Park and Baohe Park were significantly different from those of Nanfei River and Heichiba;The cluster analysis classified the Hechiba and Nanfei River as a severely polluted water body,Yuhuatang and Yinhe Park as a heavily polluted category,and Xiaoyaojin and Baohe Park as a less polluted category.?3?According to the evaluation results of the Water quality index method,WQI?TN?=100 in each landscape water body,TN all exceeded the standard seriously,and the pollution of NH₄⁺-N,TP,and COD in Xiaoyaojin and Baohe Park were relatively light.According to the results of Bayesian evaluation,the water pollution of Nanfei River was serious,and the water pollution of Baohe Park was light.?4?The comprehensive nutrition state index method evaluation results showed that TLI>70 in Nanfei River was in a state of severe eutrophication;TLI<70 in the other landscape water bodies were in a moderate eutrophication state;the set pair analysis method results showed that the Nanfei River,Heichiba,Yuhuatang water bodies were basically at the eutrophication level.The water bodies of the park and Baohe Park were basically in the state of eutrophication.?5?Various nitrogen and phosphorus indexes of the waterfront soil in Yuhuatang and Yinhe Park were relatively high.The average TN value of each soil was between1180 mg·kg^-1 and 1800 mg·kg^-1,and the average TP value of each soil was between600 mg·kg^-1 and 1220 mg·kg^-1,the average value of each soil organic matter was between 6%and 7%;the average value of PSI of the coastal soil in each landscape water body was between 30 and 55?mg?L?·?100g·?mol?^-1,the average DPS value was more than 5.0%,it means that there is a risk of phosphorus release from coastal soil to water bodies.?6?According to the difference analysis,the soils in the shores of Yuhuatang and Yinhe Park were similar to those in Xiaoyaojin Park and Baohe Park.There were significant differences in PSI,PSI,and DPS;according to the correlation analysis,PSI of the coastal soil in each landscape water body was generally positively correlated with Al_ox,Fe_ox,Al_ox+Fe_ox,and negatively correlated with P_ox and DPS.?7?The average soil ERI value of each landscape water body was between 14%and 40%,and generally showed a pattern of higher in winter and lower in summer;the cluster analysis results classified the ERI of the Yuhuatang and Yinhe Park coastal soils into a high-risk category,and the remaining coastal waters belonged to the category class of medium release risk.