Occurrence And Biotransformation Of Androgens,Progestogens,and Glucocorticoids In The Environment

As an important class of endocrine disruptors,steroid hormones have attracted increasing attention in recent years because they can cause abnormal development and reproductive disorders of organisms at lower concentrations.There are natural and synthetic steroid hormones.Natural steroid hormones are mainly derived from the excretion of vertebrates including humans,while the synthetic steroid hormones are mainly derived from the use of synthetic hormonal drugs in daily life.Human-derived steroid hormones mainly enter sewage treatment systems.Due to the limited processing capacity of existing wastewater treatment systems,incompletely removed steroid hormones and their metabolites will enter the receiving waters with the effluent from the wastewater treatment plants and pose potential threats to aquatic organisms in the environment.However,current research on steroids in wastewater treatment plants is mainly focused on estrogenic substances,related research on the other typical endocrine disruptor androgens,is very limited.In addition to wastewater treatment plants,farms with animal feeding are the other main sources of steroid hormones in the environment.However,studies on androgens,progesterones,and glucocorticoids other than estrogens in farm wastewater and feces are few,especially for the animal breeding superpower like China.Animal farming could generate huge amounts of animal manures,which usually contain endogenous steroids and some synthetic steroids used as growth promoters each year.Therefore,good manure management measures must be taken to avoid the drawbacks of manure application to the environment.However,the fate of steroid androgens,progesterones,and glucocorticoids during a common manure management program-aerobic composting is still unknown.It is necessary to understand the occurrence,dissipation,fate and potential risks of steroid hormones in different environmental media.Based on the above points,this paper mainly carried out the following research:(1)Investigated the occurrence,removal,and fate of fourteen natural and synthetic androgens in ten WWTPs in Guangdong province,south China,and performed risk assessments on several androgens detected in the receiving rivers.The results showed detection of ten androgens were detected in the influents of the ten WWTPs,with concentrations up to 4,650 ng/L(androsta-1,4-diene-3,17-dione).However,only three androgens:androsta-1,4-diene-3,17-dione,4-androstene-3,17-dione and 17?-boldenone were detected in the final effluents of the ten WWTPs.Meanwhile,six androgens:androsta-1,4-diene-3,17-dione(N.D.-43.0 ng/g),4-andro stene-3,17-dione(2.06-42.7 ng/g),epi-andro sterone(N.D.-506ng/g),testosterone(0.29-4.24 ng/g),17?-boldenone(N.D.-2.05 ng/g)and methyltestosterone(N.D.-0.70 ng/g)were found in activated sludges.The aqueous phase removal rates for most androgens in the WWTPs exceeded 95%except for 4-androstene-3,17-dione,with its removal rate varying between 79.5%and 100%.The removal of androgens in the WWTPs could be attributed mainly to biodegradation,while removal by precipitation,volatilization,sludge absorption and oxidation was very limited.Eight androgens were also found in five receiving rivers.The risk quotients of some androgens(androsta-1,4-diene-3,17-dione,4-androstene-3,17-dione,methyltestosterone,17?-trenbolone)exceeded 1 in the receiving rivers,showing high risks to aquatic organisms.Further studies are needed to understand the origin of these high-risk androgens and their ecological effects.(2)The sources,distribution and removal of steroid androgens,progestogens,and glucocorticoids were studied in the wastewater treatment systems of two large-scale swine farms with relatively completed wastewater treatment systems in South China.Thirty-one target steroid hormones were detected in wastewater samples from LC and ST pig farms with concentrations ranging from 0.12±0.05 ng/L(medroxyprogesterone acetate,MPA)to 2,900±201 ng/L(5?-dihydroprogesterone,5?-DHP)(LC)and 0.12±0.03 ng/L(MPA)to 11,200±1,300 ng/L(5?-DHP)(ST).A total of 22 target steroid hormones were detected in fecal samples,of which 19 and 17 were detected in LC and ST pig farms,respectively.Most of the detected hormones were synthetic steroid hormones.The analysis of the sources of these synthetic progestogens revealed that the majority of them came from exogenous additions from the farm feedings.The estimated emissions of steroid hormones such as androstenedione(41.5 ?g/d),epiandrosterone(268 ?g/d),progesterone(661 ?g/d)and 5a-dihydroprogesterone(982 ?g/d)from swine farms were higher than the same substances emitted through human bodies,which should be paid attention to.The removal efficiency of detected steroid hormones was evaluated in different treatment systems of two pig farms.Both treating processes can remove steroid hormones efficiently.In comparison,the biogas tank-A2/O-oxidation pond process possesses better performance on steroid hormone removal than the upflow anaerobic sludge reaction bed(UASB)-Two stage series A/O-oxidation pond process(3)The fate of androgens,progestogens,and glucocorticoids during animal manure aerobic composting was investigated and their residues in compost-applied soils was evaluated.The results showed the presence of 16 steroid hormones in the initial compost with concentrations ranging from 3.26 ng/g DW(cortisol)to 2,520 ng/g DW(5a-dihydroprogesterone).Steroids such as hydroxyprogesterone caproate,melengestrol acetate,and methyltestosterone were not found in the initial compost but later detected during the composting process.After 171 days of composting,only 40.4%of detected steroid hormones was removed,and the total concentration of detected steroids was remained as high as 3,210 ng/g DW.The removal rates of some target compounds were negative,especially for the natural androgen androsta-1,4-diene-3,17-dione and the synthetic androgen 17?-boldenone whose concentrations significantly increased by the end of composting,indicating conversion from their conjugates or transformation from other steroids.The steroid hormones were mainly eliminated in the first three weeks and prolonged composting time did not obviously promote further removal.The variations in steroid concentration were related to the changes in compost properties such as pH and temperature during the composting process.The dissipation of steroid hormones was also linked to the changes of microbial communities in the compost to some extent Twelve steroids were detected in the compost-treated soils of a kailyard,while 26 steroid hormones were detected in the roots of Chinese cabbages grown on the soil The results suggest that the application of manure compost products can lead to soil contamination and plant uptake of steroid hormones(4)A single strain of hormone degrading bacterium was screened from bacteria isolated from farm wastewater and used to treat three typical synthetic progestogens with relatively high detected concentrations and frequency.The degradation kinetics of the target compounds were analyzed,and their possible degradation products and transformation pathways were considered.The kinetic results showed that the strain performed well on degradation and conversion of target progestogens,and can utilize the target progestogens as carbon sources directly.The degradation curves of medroxyprogesterone acetate(MPA)and drospirenone(DPN)in the MH broth cultural medium fitted well with first-order reaction kinetic,while levonorgestrel(LNGT)exhibited a zero-order reaction kinetic.The degradation half-life of three target progestogens in MH broth was 1.4 h,3.7 h,and 3.66 h,respectively.The degradation curves of MPA,DPN,and LNGT in the inorganic salt medium were all consistent with the first-order reaction kinetics,and their degradation half-life was 0.94 h,27.5 h,and 19.6 h,respectively.In MH broth,6,2,and 3 degradation products were inferred for MPA,DPN,and LNGT,respectively.7,3,and 4 degradation products of MPA,DPN,and LNGT were inferred in the inorganic salt medium.The strain mainly undergoes oxidation reactions during the degradation processes,and trends to open the ring in C9-10.Besides,the single strain MPA3 in this study also had the ability to degrade and transform a variety of steroid hormones,which means it has a good application value.