Water Quality Criteria Study Of Heavy Metal Pollutant Copper In Bohai Bay

Bohai Bay is the innermost bay of the Bohai Sea,the single or combined pollution of heavy metals,organics,and new pollutants is a serious threat to its aquatic ecological environment.As one of the main pollutants,copper has a high potential risk to the entire area ecosystem due to its high toxicity,persistence,and refractory properties,which can seriously affect the utilization of marine environmental resources.Therefore,it is necessary to carry out the research on the tolerance limit of the copper in Bohai Bay environmental system,i.e.the water quality criteria（WQC）study of copper in Bohai Bay to deal with its potential hazards for aquatic organisms.At the same time,there are few kinds of research on seawater WQC used to protect marine aquatic organisms worldwide,and there has not yet been established the freshwater and seawater criteria for copper in China.Because of these situations,this subject is built around the construction of WQC of copper in Bohai Bay,focusing on the analyze of the criteria derivation data,and establishes a data set combined with experimental data;the criteria derivation methods and criteria modification method were explored,derived the corresponding WQCs recommended values,conducts a hierarchical assessment of the ecological risk of copper in Bohai Bay,and to provide guidance and reference for the comprehensive management of the Bohai Sea.The specific contents are as follows:Through the collection,screening and analysis of toxicity data,it was shown that the study of copper toxicology experiments in seawater systems was more inclined to acute experiments,there were few chronic and biological enrichment experiments,and the research scope was insufficient;through the analysis of toxic effects in toxicological experiments,it was found that aquatic animal was more sensitive to copper than hydrophyte,and the invertebrates were generally more sensitive to copper than vertebrates;the criteria maximum concentration（CMC）was 9.44μg/L,and the criteria continuous concentration（CCC）was1.44μg/L based on the toxicity percentile rank（TPR）method;the short-term water quality criteria（SWQC）was 5.18μg/L,and the long-term water quality criteria（LWQC）was 1.19μg/L based on the species sensitivity distribution（SSD）method.Compared with the TPR method,which uses the most sensitive four species for criteria derivation,the SSD method considers all species into the fitting model,and the criteria results obtained are more representative of the Bohai Bay ecosystem.By analyzing the correlation between the four factors of temperature,salinity,p H,dissolved organic carbon（DOC）,and the copper toxicity effect value,it was determined that temperature was the most influential factor among the four main environmental factors in Bohai Bay.On this basis,the SWQCs and LWQCs values of copper in the Bohai Bay under different seasons were derived by using the SSD method and combined with the temperature changes in different seasons in the Bohai Sea.Under the condition that the average water temperature in winter,spring,summer,and autumn were 0.09,15.96,24.87and 17.83℃,the SWQCs were 44.29,4.70,3.33 and 4.31μg/L,and the LWQCs were 18.14,1.93,1.36 and1.77μg/L.The risk of Bohai Bay was assessed by entropy method（HQ）,safety threshold method(MOS₁₀),and joint probability curve method（JPC）,and the result was that the overall ecological risk of copper to Bohai Bay was at a medium-low level,that the water quality of Bohai Bay was generally good;at the same time,combined with the current water quality standards of China,it is suggested that corresponding revisions should be considered to form a future-oriented copper water quality standard to meet the needs of pollution prevention and control under the current environmental situation.