The Identification Of Water Quality Risks In Gonghu Bay Resources

Gonghu Bay Resources in the northeast direction of Taihu lake, sandwiched between Wuxi and Suzhou, is the important water source of the two cities.In order to reflect the risks better, in this study it researched the surroundings and combined with the current situation of the eutrophication of Gonghu Bay. In the 2013.3-2014.2,after sampling the water source and the surrounding rivers,we tested their physical indicators, nutrient indicators, algal toxins, heavy metals, antibiotics,then comparised them with the corresponding standard(if there is no standard then new standards were set).At last, analysed and evaluated its risks. To provide a scientific basis for reasonable monitoring and management of the Gonghu Bay.(1) Divide the Gonghu Bay into the northern and southern zones. The nitrogen and phosphorus content in the two regions are relatively high, there are all over the nutrition standards(environmental quality standards for surface water). By “area evaluation method” to evaluate the risk of algal blooms in the water, throughout the year they elevated then to reduce and in august and september, the level of risk was highest. The concentration of the entire bay exhibit lower west to east, north to south trend. In the summer,in august and september five levels of risk and four levels of risk accounted for 21.2%, 52.7% and 18.2%, 1.5%, indicating that the water bloom already pose a risk issue.(2) Through the detected, MCs in the low level from March to June, begins to rise sharply in July, reached the highest value(0.22 μg?L-1) in September. with the newly established level of risk of MCs in Gong bay showed that in annual antibiotic content in low-risk status. Through the the US EPA on water environmental health assessment model,and the results showed that throughout the year HI values are less than 1, indicating a small degree of harm to human health.(3) The average content of the measured data heavy metals in soil compare with the environmental quality standard for soils. The Pb, Cd average value is much higher than a standard soil environmental quality, contrast with soil background values showed heavy metals Pb, Cd growth trend obviously in recent years. Heavy metals Pb, Cd has constituted the risk in Gonghu Bay. Heavy metals Cu, Zn and Ni in soil is more than 1.5 times of the background value,and showed a potential risk. According to the potential ecological risk index, the showed that the main ecological risk factors is are element of Pb and Cd in each point in surface sediments,the highest point value appears in N3, achieve the moderate degree of harm. The RI showed that N3 and N4 points are in the middle of ecological harm. Comparison with different metals′ contribution to the value of the potential ecological risk index, it showed the main ecological risk factor is still the Cd t in surface sediments from each poin.(4) Detecting 16 kinds of antibiotics showed that except sulfacetamide(SAAM), sulfamethazine(SDM) and sulfanilamide dimethyl pyrimidine(SDM), the rest of antibiotics were detected. The detectable levels: Oxytetracycline( OTC)> tetracycline( TC)> chlortetracycline(CTC)> sulfamethoxypyridazine(SMP)> ofloxacin(OFL)> norfloxacin(NOR)> trimethoprim(TMP)> enrofloxacin(ENR)> ciprofloxacin(CIP)> roxithromycin(ROX)> sulfamethyldiazine(SMR)> sulfamethoxazole(SMX)> sulfaquinoxaline(SQX). Through the EU’s technical guidance document(TGD) regarding the environmental risk assessment method to evaluate the antibiotic risk status in water, five kinds of antibiotics reached high ecological risk; four kinds of antibiotics reach the moderate risk; the remaining three kinds of antibiotics are low-risk status.