Zhenhua Yan

Occurrence, bioaccumulation, and trophic magnification of pharmaceutically active compounds in Taihu Lake, China.

The occurrence, bioaccumulation, and trophic magnification of pharmaceutically active compounds, (PhACs) including antibiotics (roxithromycin and erythromycin), non-steroidal anti-inflammatory drugs (ibuprofen and diclofenac), a non-selective β-adrenoceptor blocker (propranolol), an antiepileptic drug (carbamazepine), and steroid estrogens (17β-estradiol and 17α-ethynylestradiol), were investigated in Taihu Lake, China. All eight PhACs were widely detected in surface water and sediment samples with maximal concentrations in the range of 8.74-118 ng L(-1) and 0.78-42.5 ng g(-1) dry weight (dw), respectively. The investigated organisms in the natural freshwater food web in Taihu Lake included phytoplankton, zooplankton, zoobenthos, and fish, and the maximal concentrations of target compounds in these biota samples ranged from 0.65 to 132 ng g(-1) dw. Bioaccumulation factors (BAFs) for all target PhACs were lower than 1000 L kg(-1), suggesting their low bioaccumulation potential in aquatic organisms from Taihu Lake. Trophic magnification factors (TMFs) were estimated at 1.11 for roxithromycin, 0.31 for propranolol, and 1.06 for diclofenac, indicating none of these PhACs underwent trophic magnification in this freshwater food web.

Assessment of in vivo estrogenic response and the identification of environmental estrogens in the Yangtze River (Nanjing section).

Environmental estrogens in the aquatic environment have been shown to be responsible for the feminization of fish. The estrogenic content of the Yangtze River (Nanjing section--referred to as the studied area herein) was assessed using a combination of bioassay and chemical analysis. The in vivo bioassay was conducted by exposing adult male goldfish (Carassius auratus) to different concentrations of river water (25%, 50% and 100%) sampled from three representative sections of the studied area. Chemical analysis of estrogens in water from the three representative sections was conducted using solid phase extraction-gas chromatograph (SPE-GC) detection. The assay showed significant serum vitellogenin (VTG) and 17beta-estradiol (E2) induction and gonad atrophy in the treated fish. The strength of in vivo estrogenic responses in the three representative sections is in the order of Jiangxinzhou section>Daqiao section>Sanchahe section. The result is consistent with the levels of water estrogens determined from the chemical analysis. Steroidal estrogens were the major causal agents responsible for the estrogenic responses in the Jiangxinzhou and Daqiao sections, while phenolic estrogens were the main contributors in the Sanchahe section. The results of these in vivo bioassay and chemical analysis demonstrate that fish in the Yangtze River are exposed to environmental estrogens and are at a risk of feminization.

Assessment of estrogenic contamination and biological effects in Lake Taihu

Lake Taihu is the third largest freshwater lake in China and is contaminated with xenoestrogens associated with high population density, intensive livestock and aquatic breeding activities. A field study in Lake Taihu was conducted using the goldfish (Carassius auratus) as an indicator organism. Several biological markers were selected to assess the extent of estrogenic contamination. Changes in serum vitellogenin (VTG), and gill 7-Ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and reduced glutathione (GSH) were measured in caged juvenile goldfish for 28xa0days in seven locations in northern Lake Taihu. Bioassay showed VTG increased 0.64–2.42 folds over time in goldfish collected from five stations and GSH decreased in samples from all seven stations after 7xa0days of exposure. EROD levels increased continually in fish collected at all the seven stations and the highest concentrations occurred at day 21. GST activity increased significantly at 7xa0days. The concentration of the target estrogens estrone (E1), 17β-estradiol (E2), ethinylestradiol (EE2), octylphenol (OP), diethylstilbestrol (DES), nonylphenol (NP) and bisphenol A (BPA) were determined in lake water at the sampling stations. Each individual estrogen concentration measured was multiplied by its relative potency to gain the estrdiol equivalent (EEQ). There was an obvious correlation between the concentration of VTG and the total EEQ for all seven locations (Pxa0<xa00.001). The biomarker VTG, EROD, GST and GSH assays and chemical analysis might be used to illustrate the potential risk in Lake Taihu.

Bioaccumulation and trophic transfer of pharmaceuticals in food webs from a large freshwater lake

Pharmaceuticals are increasingly detected in environmental matrices, but information on their trophic transfer in aquatic food webs is insufficient. This study investigated the bioaccumulation and trophic transfer of 23 pharmaceuticals in Taihu Lake, China. Pharmaceutical concentrations were analyzed in surface water, sediments and 14 aquatic species, including plankton, invertebrates and fish collected from the lake. The median concentrations of the detected pharmaceuticals ranged from not detected (ND) to 49xa0ng/L in water, ND to 49xa0ng/g dry weight (dw) in sediments, and from ND to 130xa0ng/g dw in biota. Higher concentrations of pharmaceuticals were found in zoobenthos relative to plankton, shrimp and fish muscle. In fish tissues, the observed pharmaceutical contents in the liver and brain were generally higher than those in the gills and muscle. Both bioaccumulation factors (median BAFs: 19-2008xa0L/kg) and biota-sediment accumulation factors (median BSAFs: 0.0010-0.037) indicated a low bioaccumulation potential for the target pharmaceuticals. For eight of the most frequently detected pharmaceuticals in food webs, the trophic magnification factors (TMFs) were analyzed from two different regions of Taihu Lake. The TMFs for roxithromycin, propranolol, diclofenac, ibuprofen, ofloxacin, norfloxacin, ciprofloxacin and tetracycline in the two food webs ranged from 0.28 to 1.25, suggesting that none of these pharmaceuticals experienced trophic magnification. In addition, the pharmaceutical TMFs did not differ significantly between the two regions in Taihu Lake.

Bioconcentration, metabolism and effects of diphenhydramine on behavioral and biochemical markers in crucian carp (Carassius auratus).

Diphenhydramine (DPH), an antihistamine used to alleviate human allergies, is widespread in aquatic environments. However, little is known about the biochemical and behavioral effects of DPH on non-target aquatic animals. In the present study, the tissue distribution, bioconcentration, metabolism, biochemical and behavioral effects were investigated in crucian carp (Carassius auratus) exposed to various concentrations of DPH (0.84, 4.23, 21.7 and 112 μg L(-1)) for 7d. DPH can accumulate in crucian carp, and high concentrations have been observed in the liver and brain with maximum bioconcentration factors of 148 and 81.6, respectively. A portion of the absorbed DPH was metabolized by the crucian carp to N-demethyl DPH and N,N-didemethyl DPH via N-demethylation. Direct fluorimetric assay was employed to assess metabolic activity, while oxidative stress and neurotransmission biomarkers were determined by Diagnostic Reagent Kits. DPH was found to increase hepatic 7-ethoxyresorufin O-deethylase activity in crucian carp with maximal induction of 119%. Concerning the oxidative stress status, DPH significantly inhibited superoxide dismutase (SOD, 37-58%) and glutathione S-transferase (GST, 43-65%) activities and led to a significant increase in malondialdehyde (MDA, 67-140%) levels and catalase (CAT, 38-143%) and glutathione peroxidase (GPx, 39-189%) activities in fish liver. Brain acetylcholinesterase activity was also induced in DPH-exposed crucian carp with maximal induction of 174%. In addition, shoaling was significantly enhanced, while swimming activity and feeding rates were markedly suppressed at DPH concentrations equal to or higher than 21.7 μg L(-1). Furthermore, significant correlations were found between oxidative stress biomarkers (SOD, CAT, GPx, GST and MDA) and behavioral parameters. Collectively, our results confirmed that DPH can accumulate and be metabolized in fish and exert a negative effect at different levels of biological organization.

Long-term effects of antibiotics, norfloxacin, and sulfamethoxazole, in a partial life-cycle study with zebrafish ( Danio rerio ): effects on growth, development, and reproduction

A partial life-cycle study with zebrafish (Danio rerio) was conducted to evaluate the long-term effects of antibiotics, norfloxacin (NOR) and sulfamethoxazole (SMX). A series of bio-endpoints correlated to the growth, development, and reproduction was assessed. The results showed that the body weight and the condition factor were depressed by SMX at 200xa0μg/L during the growth period. Meanwhile, the activities of metabolic enzyme (ethoxyresorufin O-deethylase, EROD) and antioxidant enzymes (superoxide dismutase, SOD and catalase, CAT) were stimulated in all cases. The consequences of parental exposure to antibiotics for the next generation were also examined. The egg production of parents were depressed by the 200xa0μg/L NOR and SMX alone or in combination. Similarly, decreased hatching, survival, and enhanced development abnormality of the next generation also occurred after parental exposure to SMX at the highest concentration. The heartbeat however was not altered in all cases. Furthermore, there was no significant difference in the bio-endpoints between the combined and individual treatment in most cases, with the exception of lower EROD activity and egg production in the co-treatment. The results suggest that long-term exposure to NOR and SMX at environmentally relevant concentrations, individually and in a mixture, may not significantly pose a threat to the growth, development, and reproduction of zebrafish, and an adverse effect may be expected at high concentration.

Bioconcentration and metabolism of ketoconazole and effects on multi-biomarkers in crucian carp (Carassius auratus).

The tissue distribution, bioconcentration, metabolism and biological effects of the antifungal medication ketoconazole were investigated in fish, crucian carp (Carassius auratus) were exposed to a series of nominal concentrations (0.2, 2 and 20xa0μg/L) for 14 days. The ultra-high performance liquid chromatography tandem triple quadrupole mass spectroscopy (UPLC/MS/MS) analysis was used to determine the bioconcentration of ketoconazole and its metabolites in fish. The highest tissue concentration of ketoconazole was observed in the liver with the bioconcentration factor of 257.2, which is lower than the estimated BCF value. The ability of crucian carp to metabolize ketoconazole was confirmed and the results pointed out the existence of seven metabolites likely formed via oxidation of imidazole ring and the metabolic alteration of the piperazine rings. In addition, acetylcholinesterase, 7-ethoxyresorufin O-deethylase, superoxide dismutase and glutathione S-transferase changed significantly after 3, 7 and 14 days of exposure (Pxa0<xa00.05), which indicated that the accumulation and metabolism of ketoconazole in fish tissues may account for the biological effects.

Enhanced hydroxyl radical generation in the combined ozonation and electrolysis process using carbon nanotubes containing gas diffusion cathode.

Combination of ozone together with electrolysis (ozone-electrolysis) is a promising wastewater treatment technology. This work investigated the potential use of carbon nanotube (CNT)-based gas diffusion cathode (GDC) for ozone-electrolysis process employing hydroxyl radicals (·OH) production as an indicator. Compared with conventional active carbon (AC)-polytetrafluoroethylene (PTFE) and carbon black (CB)-PTFE cathodes, the production of ·OH in the coupled process was improved using CNTs-PTFE GDC. Appropriate addition of acetylene black (AB) and pore-forming agent Na2SO4 could enhance the efficiency of CNTs-PTFE GDC. The optimum GDC composition was obtained by response surface methodology (RSM) analysis and was determined as CNTs 31.2xa0wt%, PTFE 60.6xa0wt%, AB 3.5xa0wt%, and Na2SO4 4.7xa0wt%. Moreover, the optimized CNT-based GDC exhibited much more effective than traditional Ti and graphite cathodes in Acid Orange 7 (AO7) mineralization and possessed the desirable stability without performance decay after ten times reaction. The comparison tests revealed that peroxone reaction was the main pathway of ·OH production in the present system, and cathodic reduction of ozone could significantly promote ·OH generation. These results suggested that application of CNT-based GDC offers considerable advantages in ozone-electrolysis of organic wastewater.

Influence of multi-walled carbon nanotubes on the effects of roxithromycin in crucian carp (Carassius auratus) in the presence of natural organic matter

Carbon nanotubes are increasingly entering the aquatic environment and may interact with other co-existing contaminants, such as antibiotics. However, whether these interactions may affect their bioavailability in aquatic organisms is the subject of considerable debate. The primary objective of this study was to assess the risks arising from the coexistence of roxithromycin (ROX) and multi-walled carbon nanotubes (MWCNTs) in waters containing natural organic matter (NOM), focusing on the distribution and bioaccumulation of ROX in crucian carp (Carassius auratus), and the related biochemical status. There were no significant differences in ROX bioaccumulation in fish following exposure to ROX with and without NOM. However, the further addition of MWCNTs significantly facilitated the bioaccumulation of ROX in the liver (32-80%), gill (15-74%), intestine (51-113%), and bile (15-67%) in different exposure periods. Meanwhile, a 0.3-fold increase in the metabolic enzyme activity and oxidative stress in the liver were markedly accelerated by the co-exposed MWCNTs compared to ROX alone. The findings imply that the ROX adsorbed on MWCNTs may be a higher threat to fish than ROX alone. The high and fast release of ROX from MWCNTs in bile salts and serum albumin may contribute to the enhancement in bioaccumulation and bioactivity of ROX in fish with MWCNTs.

Bioconcentration and multi-biomarkers of organic UV filters (BM-DBM and OD-PABA) in crucian carp

Organic UV filters (OUV-Fs) are increasingly used in sunscreens and personal care products. In the present work, the bioconcentration and multi-biomarker effects of butyl methoxydibenzoylmethane (BM-DBM) and ethylhexyl dimethyl p-aminobenzoate (OD-PABA) were investigated in crucian carp (Carassius auratus). The fish were exposed to various concentrations of BM-DBM (3.88, 35.61, 181.85 and 337.15μg/L), OD-PABA (4.66, 53.83, 264.22 and 459.32μg/L) and their mixture (2.31+2.79, 23.69+26.18, 97.37+134.81 and 193.93+246.08μg/L) for 28 days. The maximal concentrations of two OUV-Fs were detected in the fish liver, followed by the brain, kidney, gill and muscle in most cases. The maximal BCF values of OD-PABA calculated in various exposure concentrations were 0.37 - 101.21 in single exposure groups and 0.11 - 31.09 in mixed exposure groups. Acetylcholinesterase (AChE) activity was significantly inhibited by BM-DBM as well as the mixtures at all of the exposure concentrations and by OD-PABA at higher concentrations (≥264.22μg/L) during 28 days of exposure. The maximal inhibition rates of AChE activity reached 64.04% for BM-DBM, 41.05% for OD-PABA and 61.50% for the mixtures at the highest concentration, which indicated that these two OUV-Fs might damage the central nervous system. Concerning oxidative stress status, BM-DBM and the mixtures significantly increased superoxide dismutase (SOD) and glutathione reductase (GR) activities and inhibited catalase (CAT) activity, while OD-PABA caused a significant increase of GR and CAT activities. AChE and GR activities seemed to be more sensitive biomarkers for BM-DBM and OD-PABA.