| Endocrine disrupting chemicals?EDCs? are defined as exogenous agents that disturb the normal function of endocrine system in human and other organisms.Due to the affection of artificial factor,the pollution of the EDCs are widely existed in rivers,lakes and other surface waters.To our knowledge,trace amount of those chemicals could cause adverse effect on ecological environment,aquatic life and human bodies,the pollution status of EDCs in water environment have attracted a great many of scientific and public attention.In order to study the occurrence and distribution of EDCs in River water,we investigate the seven EDCs of Bahe River surface water by using gas chromatography-mass spectrometry?GC-MS?technology,in November of 2016 and July of 2017.And the hazard quotient?HQ?in the upper,middle and lower reaches of Bahe River were calculated.The target compounds were the typical representatives of phenolic and steroidal EDCs,including 4-t-octylphenol?4-t-OP?,bisphenol?BPA?,nonylphenol?NP?,estrone?E1?,17?-estradiol?E2?,estriol?E3?and 17?-ethynylestradiol?EE2?.Currently,the most toxicity researches of EDCs to fish were restricted to the controlled exposure experiment in laboratory,the complexity of river matrix often limits the application of laboratory test data in the assessment of biological effects of EDCs.Hence,the Sharpbelly?Hemiculter leucisculus?,an indigenous fish in Bahe River,was chosen as the model fish to study the contamination of EDCs in wild environment.The bioaccumulation of these steroidal and phenols EDCs were detected in muscle tissue of Sharpbelly,and the bioaccumulation factor?BAF?,condition factor?CF?,hepatosomatic index?HSI?and gonadosomatic index?GSI?were calculated.The liver histopathological condition and development status of testis and ovary were analysed with hematoxylin-eosin staining technique.In addition,the quantitative real-time PCR?qRT-PCR?method was applied to analyze the mRNA expressions of vtg in liver and several target genes in hypothalamic-pituitary-gonad?HPG?axis.The main results are shown as following.?1?The concentration of the 4-t-OP,NP,BPA,E1,E2,EE2 and E3 up to 126.0,634.8,1573.1,55.9,23.9,31.5 and 5.2 ng L-1 in surface water,and up to 126.0,634.8,1573.1,55.9,23.9,31.5 and 5.2 ng L-1 in fish tissue.Obvious spatial and seasonal variations in concentrations of the seven compounds were observed in the surface water and fish.In November?dry season?,the level of the target compounds were generally higher than these in July?wet season?.The most contaminated area of EDCs in surface water and fish was at the midstream,the pollution level of which was worse than the downstream water,but the upper river was less polluted by these EDCs.The EE2 that carried by the stream of Chanhe River,and the BPA,NP,4-t-OP that flowed from the Fifth Waste Water Treatment Plant of Xi'an were the major contamination of the target EDCs.?2?The maximum field BAF value of phenols and steroidal EDCs was 376.6 and 567.6respectively for the fish.According the HQ values we calculated,the existence of significantly potential for adverse effects were found at lower and middle reaches of the river.And in November,the HQ values were generally higher than in July.The GSI and CF values of the fish,that collected from the lower and middle reaches of the river,were generally higher than the upper stream,but the HSI values were exactly opposed.It was concluded that fish lived in the lower and middle reaches have a better growth condition and worse development of gonad when compared with the fish in upstream water.?3?More histopathological conditions,like hepatocyte vacuolation,nuclear atrophy,proliferation or swelling of sinusoids,hepatocyte amplification and nuclear pleomorphisms were found at middle and lower reaches of the river.The results showed that great harmful to fish were found at the seriously EDCs contaminated areas of the river.In November and July,there were no obvious difference of oocytes development among all these sites.In July,there were obvious suppression of spermatogenesis found in fish from the midstream,the sperm counts and percentages of males have declined at midstream.The results indicated that heavily EDCs polluted areas have effects on fertility of the male fishes.?4?In November and July,the relative expression of vtg,lh?and cyp19a1b mRNA in male fishes were obviously up-regulated at midstream of the river,while the expression of StAR and cyp19a1a were significantly down-regulated at the same sites in males.In November,The expression of fsh?,StAR and cyp19a1a mRNA in female fish were obviously down-regulated,while lh?and cyp19a1b were up-regulated at middles reaches.However,the expression of all target genes in females were not significantly different among the whole sites in July.The results suggest that the expression of vtg?lh?and StAR genes in males may be a sensitive indicator of EDCs pollution,these genes could been used as a potential biomarker for water environment monitoring.As one of the most important water source to the residents of eastern Xi'an,Bahe River is also a bank of fishery genetic resources.At the period of investigation,the risks of ecological safety were found relative to the EDCs pollution,and some degrees of toxic effect on fish were found in Bahe River.Biological effects and environmental risks of EDCs on fish in Bahe River were comprehensively examined by combing the experiments of environmental analytical chemistry and toxicological exposure.The research results would provide scientific basis for supervision and control of EDCs pollution in Bahe River. |
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