Environment Biogeochemical Characteristics Of Pharmaceutically Active Compounds(PhACs)in The Jiaozhou Bay,North China

In recent years,a variety of novel zoonotic diseases,such as SARS,avian influenza and HFMD(hand-foot-and-mouth disease),have emerged,and the aging of the global population undergoes constant exacerbation.To face this situation,an increasing number of novel pharmaceutically active compounds(PhACs)are involved in accelerating research and development,production and application.As the types and consumption of PhACs increase each year,most drugs inevitably enter the environment.Their strong bioactivity,persistence and bioaccumulation characterize the drugs to be significantly influential on human health and the ecological environment.The impact of PhACs entering oceans on marine ecosystems is immeasurable,and the different impacts of PhACs on marine environments are also increasingly highlighted.For this reason,PhACs are recognized as an important new type of marine organic pollutant.In the meantime,the potential ecological risks in marine environments,especially offshore environments,and the prevention and control of PhAC pollution have been popular topics that have been increasingly investigated by scholars abroad and at home.Therefore,systematic studies on PhACs in marine environments are of great scientific significance and application value.In this study,the seawater,sediment and atmospheric sedimentation(snow)of Jiaozhou Bay(JZB),a model bay that is influenced by both human activities and natural factors,were selected as the primary study objects.By high throughput screening and the combination of the relationships between PhACs and the relevant environmental factors,a systematic exploration was applied to study the occurrence,biogeochemical distribution characteristics,sources,pollution trends,environmental control factors and potential ecological risks of PhACs in the environment of JZB.A series of new results and understandings have been obtained as follows:1.In these three media—seawater,sediments and atmospheric sedimentation(snow)of JZB—PhAC contamination was found to different extents,suggesting a wide presence of PhACs in the environment of JZB.The PhAC distribution in the seawater of JZB is mainly guided by a means of “sources and channels—the hydrodynamic process of seawater”,in addition to the self-degradation factors of the compounds.Namely,the distribution of the compounds is formed by a passive diffusion mode.In contrast,in the sediments,the PhAC distribution is regulated and controlled by the path of “sources and channels—hydrodynamic process of seawater-composition of sediments”;that is,the distribution is shaped by a “passive diffusion-active adsorption”composite pattern.Using high-throughput screening and advanced mass spectrum analysis technology,a total of thirty-six PhACs were detected in seawater,of which seventeen were first reported in seawater;thirty-eight targeted compounds were found in snow,and all of them were disclosed in a scientific journal for the first time,while the study was the first report concerning PhAC contamination in snow;moreover,twenty-five target PhACs were verified in the sediments of JZB,of which ten were discovered for the first time in marine sediments.Among the three environmental media above,the sediments were found to contain the highest PhAC occurrence concentration,with a value of 3.62-21.4 ng/g,followed by snow and seawater,whose PhAC concentrations were 52.8-1616 ng/L and 23.6-217ng/L,respectively.The occurrence of different types of PhACs in the marine environment varies greatly depending on the application range,utilization purpose and physicochemical properties of the drug itself.Of the PhACs remaining in the seawater,the preponderant kinds include tetracycline(7.48 ng/L),carprofen(8.30 ng/L),lincomycin(8.55 ng/L)and amantadine(24.7 ng/L).In the snow,the primary kinds were triamcinolone diacetate(2.84 ng/L),ronidazole(8.79 ng/L),desacetylcefotaxime(17.7 ng/L)and tetracycline(125 ng/L).In the sediments,the major PhACs included roxithromycin(0.97 ng/g),oxytetracycline(1.00 ng/g)and ketoprofen(2.49 ng/g).Despite a significant difference in the composition of PhACs in distinct environmental media,antibiotics and hormones generally dominate in environments because they are frequently used in clinical medical care and livestock and poultry farming in China.This result is overall consistent with the characteristics of PhAC production and utilization in China.The PhAC distribution presents a gradual decrease in density from east to west,where the areas inside the bay have a higher concentration than the areas outside the bay.Meanwhile,the isopleth of the total PhAC concentration appears to be practically parallel to the coastline.In addition,it was noted that the PhAC concentration in western JZB(38.4 ng/L;5.06 ng/g)was obviously lower than that in eastern JZB(116ng/L;14.2 ng/g),where the impact of human activities is severe.Regarding the seawater environment,PhACs are positively correlated with nutrients,and both display a distribution pattern highly similar to each other(the correlation factors r being larger than 0.9).Of the nutrients,phosphates were proven to exhibit a significantly positive correlation with 16 PhACs(P<0.01).This finding indicates that phosphates may harbor similar sources.The content of PhACs is negatively correlated with salinity.Low salinity signifies a high input volume of fresh water,but the PhAC concentration in seawater increases when the fresh water input increases.The correlation indicates the “single-diffusion” passive mode of the PhAC distribution in seawater,which is managed by the “hydrodynamic process”.Regarding the sediments,the PhACs here are significantly positively correlated with TOC(P<0.01,r=0.932).Organic matter plays a vital role in adsorbing PhAC contaminants.Similarly,a significantly positive correlation was noted between PhACs and clay(P<0.01,r=0.896).The smaller the diameter of sediment grains is,the larger the total surface area,and the stronger the adsorption action,which is also more favorable for the enrichment of PhACs.The PhAC distribution in sediments shows an active mode of “diffusion-adsorption”,where it is jointly regulated by the“hydrodynamic process” and “sediment adsorption”.2.Land-based input was identified as the main source of PhACs in the JZB.River input was found to be the major land-based input of the PhACs in this area,which was mainly derived from eastern rivers(the sewage discharge of the Licun River,in particular).Atmospheric sedimentation may also be a non-negligible,important source of the PhACs in JZB.The PhACs were found to harbor potential toxicity risks for some biological groups in JZB.According to the systematic analyses on the relationship between the PhACs in the JZB seawater and key environmental factors,phosphate was considered a potential indicator to prompt the distribution characteristics of PhAC concentrations in JZB seawaters,while coprostanol was considered a possible indicator of the distribution of the concentration of PhACs in the JZB sediments.The input of rivers in the eastern part of the bay,especially the waste discharge from the Licun River,forms the prime source of PhACs in this region.As the bay has been severely contaminated by human excreta,domestic sewage and medical wastewater from the eastern coastal region are likely to be the main sources of the PhACs in JZB.The investigation of the PhAC transmission route suggested that in atmospheric sedimentation,in addition to the PhACs of salbutamol,ronidazole,oxolinic acid and a few other kinds that are from remote transmission,most of the PhACs come from local pollutant emissions.In short,for PhACs,the discharge of local contaminants contributes more than remote transmission.Of the PhACs in snow,drugs for humans only,animals only and both humans and animals account for 40.1%,46.0% and 13.8%,respectively.The high amount of veterinary drugs in the atmosphere may be associated with the persistent landfill deposition of animal droppings.The impacts of PhACs on aquatic organisms such as invertebrates,algae,fishes and plants in JZB were noted to vary greatly.Though unlikely to bring potential risks to fishes and plants(RQ<0.01),the PhACs in seawater,sediments and atmospheric sedimentation present a much less optimistic picture for invertebrates and algae.Tetracycline,ofloxacin,lincomycin,roxithromycin,clindamycin,oxytetracycline,and sulfamethoxazole posed high or medium risks to invertebrates and algae.