The Occurrence Form And Pollution Evaluation Of Phosphorus In The Sediments Of Qilihai Lagoon In Changli

Phosphorus is the most basic nutrient of marine life and it plays a crucial role in the primary production of biogeochemistry marine ecosystems.Sediment is an important carrier of phosphorus cycle in the lagoon environment.The adsorption/desorption of phosphorus makes it the "source" or "sink" of phosphorus.The interaction between phosphorus and overlying water in sediments,on the one hand,is deposited into the sediment by precipitation in the water body and,on the other hand,the mineralization of phosphorus in sediments through interstitial water in overlying water,will affect the algae blooms of the lagoon.One of the most intense mineralizations is the surface sediment,which will explain in part the changes in phosphorus content and distribution in sediment through vertical direction.In addition,there is an intrinsic relationship between phosphorus adsorption,physico-chemical properties and phosphorus active components.Studying the forms,distribution characteristics,physical and chemical properties and adsorption characteristics of phosphorus in sediments can help enrich our understanding of the biogeochemical cyclic behavior mechanism of phosphorus in lagoon environment.In this paper,the phosphorus morphology,physicochemical properties,adsorption kinetics curves and Sorption isotherm of phosphorus in sediments were collected from 11 sampling sites in Qilihai Lagoon,Changli.Studied the content and distribution of phosphorus in surface and column sediments.Single factor standard index was used to analyze the pollution level of phosphorus in the sediments of Qilihai Lagoon.The main conclusions are as follows:(1)The content of total phosphorus(TP)in the surface sediments of Qilihailagoon in Changli was between 195.9 and 541.5 mg/kg.The distribution trend was mainly in the west of the eastern central region.The content of inorganic phosphorus(IP)was 106.22-385.00 mg/kg,and the content of Ca-P was 86.86-230.12 mg/kg,the content of Fe/Al-P was 72.81-305.91 mg/kg,and the content of organic phosphorus(OP)was between 40.39 and 137.19 mg/kg.The peak of phosphorus content was found in the sample point of 10#,while the phosphorus content in sample points of 1#,2#,4#,5#and 11#were generally low.IP is the main component in the phosphorus form of each sampling point,while OP is the least dominant form of phosphorus.(2)With the increase of depth,the content of TP in most sampling points increases,which is beneficial to the accumulation of TP.the bottom sediments of most sampling sites are fine sand,which is easier to adsorb phosphorus.In 2-16 cm depth,the content of TP in most sampling sites was generally low and concentrated.The content of IP and Ca-P decreased with the decrease of depth.The content of Ca-P increased with the decrease of depth,and the content of Ca-P decreased with depth,in the range of 0 cm to 10 cm,the increase of the content decreases with the depth,but the depth of the section larger than 10cm shows the increase of wave;OP is the lowest phosphorus form of TP,and decreases with depth.(3)Correlation analysis shows that the content of TP in Qilihai lagoon is influenced by the content of IP,and the high active Fe/Al-P is the most important influence.The content of TP was significantly correlated with IP and Ca-P content,and the content of IP was significantly correlated with the content of Ca-P and Fe/Al-P.TOC is generally related to the content of phosphorus form,which has significant correlation with TP,OP,Fe/Al-P,and has correlation with IP but the correlation coefficient is lower than the previous three.The size of the particle size has some correlation with the phosphorus content,but the correlation is not significant.(4)The adsorption kinetics of phosphorus in the sediments of Qilihai lagoon accords with the first order kinetic equation.At 24h,it was basically in equilibrium.The adsorption of phosphorus by sediment occurs mainly in 0-12h.The EPC0 of both sample points was higher,which indicated that the sediment was contaminated with the outer phosphorus and the tendency to release phosphorus into the overlying water body.(5)The concentration of TP and TOC in the surface sediments of 11 sampling sites in the study area did not exceed the lowest level.The sediment in the vicinity of the lowest sampling point has been contaminated,but most benthic organisms(such as amphioxus)are still capable of withstanding the potential environmental hazards associated with their concentrations and the need to pay attention to the amount of nutrient input to the lagoon,measures should be taken to reduce the amount and accumulation of endogenous pollution and prevent the occurrence of eutrophication.