High-Content Screening Discovers Microplastics Released by Contact Lenses under Sunlight.

The widespread use of plastic products leads to the ubiquity of microplastics in daily life, while the release of microplastics from long-used contact lenses has not been reported due to the limitations of conventional detection methods. Here, we established a new and rapid method to capture and count microplastics by using a high-content screening system. This method can simultaneously measure the diameter, area, and shape of each plastic particle, and the reliability and applicability of this method were verified with commercial microplastics. It is estimated that 90,698 particles of microplastics could be released from a pair of contact lenses during a year of wearing. The microplastics in the leachates were confirmed to be released from the contact lenses by scanning electron microscopy and Fourier transform infrared spectroscopy fingerprint analysis. Our study reveals an undiscovered pathway of microplastic direct exposure to humans, highlighting the urgent need to assess the potential health risks caused by eye exposure to microplastics.

Life history traits of low-toxicity alternative bisphenol S on Daphnia magna with short breeding cycles: A multigenerational study.

Due to relatively lower toxicity, bisphenol S (BPS) has become an alternative to previously used bisphenol A. Nevertheless, the occurrence of BPS and its ecological impact have recently attracted increasing attentions because the toxicology effect of BPS with life cycle or multigenerational exposure on aquatic organisms remains questionable. Herein, Daphnia magna (D. magna) multigenerational bioassays spanning four generations (F0-F3) and single-generation recovery (F1 and F3) in clean water were used to investigate the ecotoxicology of variable chronic BPS exposure. For both assays, four kinds of life-history traits (i.e., survival, reproduction, growth and ecological behavior) were examined for each generation. After an 18-day exposure under concentration of 200 µg/L, the survival rate of D. magna was less than 15 % for the F2 generation, whereas all died for the F3 generation. With continuous exposure of four generations of D. magna at environmentally relevant concentrations of BPS (2 µg/L), inhibition of growth and development, prolonged sexual maturity, decreased offspring production and decreased swimming activity were observed for the F3 generation. In particular, it is difficult for D. magna to return to its normal level through a single-generation recovery in clean water in terms of reproductive function, ecological behavior and population health. Hence, multi-generational exposure to low concentrations of BPS can have adverse effects on population health of aquatic organisms with short breeding cycles, highlighting the necessity to assess the ecotoxicology of chronic BPS exposure for public health.

Occurrence, source apportionment and ecological risk assessment of thirty antibiotics in farmland system.

Antibiotics are widely used in medical care, livestock production, and aquaculture. However, antibiotic pollution has attracted increasing global concerns due to their ecological risks after entering into environmental ecosystem via animal excretion, effulent from industrial and domestic sewage treatment facilities. In this study, 30 antibiotics were investigated in soils and irrigation rivers using ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometer. This study evaluated the occurrence, source apportionment, and ecological risks of these target compounds in soils and irrigation rivers (i.e., sediments and water) of farmland system by using principal component analysis-multivariate linear regression (PCA-MLR) and risk quotients (RQ). The concentration range of antibiotics in soils, sediments, and water was 0.38-689.58 ng/g, 81.99-658.00 ng/g, and 134.45-1547.06 ng/L, respectively. In soils, the most abundant antibiotics were quinolones and antifungals with an average concentration of 30.00 ng/g and 7.69 ng/g, respectively, contributing to 40% of total antibiotics. Macrolides were the most frequently detected antibiotics in soils with an average concentration of 4.94 ng/g. In irrigation rivers, quinolones and tetracyclines, the most abundant antibiotics, accounted for 78% and 65% of antibiotics in water and sediments, respectively. Higher antibiotic contamination of irrigation water was primarily distributed in highly populated urban areas, while increasing antibiotic contamination of sediments and soils was particularly observed in rural areas. PCA-MLR analysis indicated that antibiotic contamination in soils was mainly ascribed to the irrigation of sewage-receiving water body and manure application of livestock and poultry farming, which cumulatively contributed to 76% of antibiotics. According to RQ assessment, quinolones in irrigation rivers posed high risk to algae and daphnia, contributing 85% and 72% to the mixture risk, respectively. In soils, macrolides, quinolones and sulfonamides were responsible for more than 90% to the mixture risk of antibiotics. Ultimately, these findings can improve our fundamental knowledge on contamination characteristics and source pathways towards risk management of antibiotics in farmland system.

Effects of Nanoplastics and Butyl Methoxydibenzoylmethane on Early Zebrafish Embryos Identified by Single-Cell RNA Sequencing.

Nanoplastics with small particle sizes and high surface area/volume ratios easily absorb environmental pollutants and affect their bioavailability. In this study, polystyrene nanoplastic beads (PS-NPBs) with a particle size of 100 nm and butyl methoxydibenzoylmethane (BMDBM) sunscreen in personal-care products were chosen as target pollutants to study their developmental toxicity and interactive effects on zebrafish embryos. The exposure period was set from 2 to 12 h postfertilization (hpf). BMDBM and PS-NPBs significantly upregulated genes related to antioxidant enzymes and downregulated the gene expression of aromatase and DNA methyltransferases, but the influenced genes were not exactly the same. The combined exposure reduced the adverse effects on the expression of all genes. With the help of the single-cell RNA sequencing technology, neural mid cells were identified as the target cells of both pollutants, and brain development, head development, and the notch signaling pathway were the functions they commonly altered. The key genes and functions that are specifically affected by BMDBM and/or PS-NPBs were identified. BMDBM mainly affects the differentiation and fate of neurons in the central nervous system through the regulation of her5, her6, her11, lfng, pax2a, and fgfr4. The PS-NPBs regulate the expression of olig2, foxg1a, fzd8b, six3a, rx1, lhx2b, nkx2.1a, and sfrp5 to alter nervous system development, retinal development, and stem cell differentiation. The phenotypic responses of zebrafish larvae at 120 hpf were tested, and significant inhibition of locomotor activity was found, indicating that early effects on the central nervous system would have a sustained impact on the behavior of zebrafish.

Occurrence, toxicity and ecological risk of Bisphenol A analogues in aquatic environment - A review.

Bisphenol analogues (BPs) have been widely applied to industry as the substitutes for bisphenol A (BPA), which have been detected frequently in surface water, sediment, sewage and sludge. The presence of BPs in natural environment could pose risks to the aquatic ecosystem and human health. This study outlined the occurrence, toxicity of BPs in aquatic environment and manifested their potential ecological risk to the aquatic ecosystem throughout the world. As for occurrence, BPA was losing its dominance, while BPs were occupying a large part, especially for bisphenol S (BPS), bisphenol F (BPF) and bisphenol AF (BPAF). In some heavily polluted areas, BPs concentration reached µg/L in aquatic environment, which in the effluent of sewage plants was higher than that in the surface water. BPs content in sludge and sediment was more than that in the aqueous phase. All BPs other than BPS and Bisphenol P (BPP) had moderate toxicity. The current data supports that exposure to BPs may have adverse effects on dysfunction of endocrine system such as thyroid hormone concentration, enzyme activity, and even cell dysfunction, gene damage and chromosomal abnormalities. According to the risk quotient (RQ), BPF shows the highest ecological risk in China, Japan and South Korea, followed by BPA and BPS. The occurrence of bisphenols and their neurotoxicity on aquatic organisms merit further investigation.

Biodegradation of 2-ethylhexyl-4-methoxycinnamate in river sediments and its impact on microbial communities.

Numerous studies have evaluated the toxicity and endocrine disrupting properties of organic UV filters for aquatic organisms, but little is known about their biodegradation in river sediments and their impact on microorganisms. We have set up the sterile and microbiological systems in the laboratory, adding 2-ethylhexyl-4-methoxycinnamate (EHMC), one of organic UV filters included in the list of high yield chemicals, at concentrations of 2, 20 and 200 µg/L, and characterized the microbial community composition and diversity in sediments. Monitoring of EHMC degradation within 30 days revealed that the half-life in the microbial system (3.49 days) was much shorter than that in the sterile system (7.55 days). Two potential degradation products, 4-mercaptobenzoic acid and 3-methoxyphenol were identified in the microbial system. Furthermore, high-throughput 16s and 18s rRNA gene sequencing showed that Proteobacteria dominated the sediment bacterial assemblages followed by Chloroflexi, Acidobacteria, Bacteroidetes and Nitrospirae; Eukaryota_uncultured fungus dominated the sediment fungal assemblages. Correlation analysis demonstrated that two bacterium genera (Anaerolineaceae_uncultured and Burkholderiaceae_uncultured) were significantly correlated with the biodegradation of EHMC. These results illustrate the biodegradability of EHMC in river sediments and its potential impact on microbial communities, which can provide useful information for eliminating the pollution of organic UV filters in natural river systems and assessing their potential ecological risks.

Influence of aquatic colloids on the bioaccumulation and biological effects of diclofenac in zebrafish (Danio rerio).

Natural aquatic colloids play an important role in the migration, transformation of pollutants in the environment, but their potential effects are often ignored in ecotoxicology research. In this study, diclofenac (DCF) was selected as a typical drug to study the effects of natural colloids on the bioaccumulation and biotoxicity in juvenile zebrafish (Danio rerio) exposed to an environmentally relevant concentration (1 µg/L) and a high concentration (100 µg/L) of DCF. The results showed that the presence of colloids accelerated and enhanced the accumulation of DCF in zebrafish muscle and viscera, and the effects are greater at the environmentally relevant concentration of DCF. However, the colloids enhanced the burden in the head in the environmentally relevant concentration group, but reduced it in the high concentration group. This observation may be related to the occurrence of variations in the contribution of the adsorption forms of DCF and the colloids depending on different DCF concentrations. At the same time, the presence of colloids can significantly induce AChE activity of DCF in the brain and alter swimming activity and shoaling behaviour of the individuals, however no significant effects on the attack and shock behaviour were observed. These findings indicate that the combination of natural colloids and pollutants may change with pollutant concentrations, thereby altering the bioaccumulation and biological effects in aquatic organisms.

Biological uptake, depuration and biochemical effects of diclofenac and carbamazepine in Carassius carassius.

The uptake and depuration kinetics of diclofenac and carbamazepine alone at an environmentally relevant nominal concentration of 2 µg/L and in combination at a concentration ratio of 1:1 with total concentration of 4 µg/L were evaluated in Carassius carassius after 7 d uptake and depuration. Also, the biochemical effects of both drugs alone at nominal concentrations of 2 and 10 µg/L as well as in combination with total concentrations of 4 and 20 µg/L were investigated in Carassius carassius after 7 d exposure followed by 10 d recovery. In the single treatments, steady-state BCFs measured after the 7 d exposure were 73.05, 49.71, 38.01 and 24.93 L/kg for diclofenac and 9.25, 8.99, 5.29 and 4.11 L/kg for carbamazepine in the liver, brain, gill and muscle of Carassius carassius, respectively. Comparatively lower BCFs were measured in the tissues of Carassius carassius for both drugs in the combined treatments. Acetylcholinesterase activity in the brain was significantly induced by diclofenac while carbamazepine and the mixtures significantly inhibited it during all the exposure days as well as after the 10 d recovery in all treatments. This indicates that Carassius carassius could not recover from the neurotoxic effects caused by carbamazepine unlike the inductive effect caused by diclofenac which was recoverable after 10 days. A significant increase in the activities of 7-ethoxyresorufin O-deethylase and glutathione s-transferase for individual and mixed pharmaceuticals suggest that metabolism and detoxification of both drugs took place in the liver of Carassius carassius. Also, a significant increase in the activities of superoxide dismutase, catalase, glutathione reductase and malondialdehyde contents in the individual and mixture treatments mean that the antioxidant defence system of Carassius carassius was triggered to fight against oxidative stress but lipid peroxidation still occurred. However, Carassius carassius recovered from all these increases (superoxide dismutase, catalase, glutathione reductase and malondialdehyde) after the 10 d recovery, suggesting that oxidative damage is reversible. Our results indicate that both drugs at environmentally relevant concentrations might cause adverse effects in Carassius carassius and other fish species.

Ecological impact assessment of 110 micropollutants in the Yarlung Tsangpo River on the Tibetan Plateau.

In this study, the occurrences of 110 micropollutants in the surface waters and sediments collected at eight sampling sites along the middle reaches of the Yarlung Tsangpo River were investigated in winter. A total of 47 and 45 micropollutants were detected in at least one water or sediment sample, respectively, and their total concentrations reached 790.2 ng/L and 186.5 ng/g on a dry weight basis, respectively. Their composition profiles demonstrated that the majority of micropollutants were polycyclic aromatic hydrocarbons (PAHs) and UV filters. The mixture risk quotient (MRQ) values of the detected micropollutants regularly exceeded 1 for aquatic organisms at all sampling sites, and fish and invertebrates are the more sensitive organisms. The diversity and evenness of the zooplankton levels had a clear negative correlation with the micropollutant occurrences in water. The top 10 mixture components belonging to the UV filter and PAH categories explained more than 80% and 95% of the mixture risk for chronic and acute toxicology, respectively. This study is the first investigation of the presence and risk assessment of 110 micropollutants in the Yarlung Tsangpo River Basin and offers new insights into the ecological security of the water resources of the Tibetan Plateau.

Integrated Proteomics, Biological Functional Assessments, and Metabolomics Reveal Toosendanin-Induced Hepatic Energy Metabolic Disorders.

Toosendanin (TSN), a compound from Melia toosendan, exhibits severe hepatotoxicity, which restricts its clinical application. However, the mechanism is not clear. Our previous research found that covalent modification of TSN for proteins might be a possible reason using human liver microsomes, and the glycolytic enzymes, triosephosphate isomerase 1 (TPIS) and α-enolase (ENOA), were responsible for the hepatotoxicity. In this study, we tried to prove these findings in cell and animal models by integration of proteomics, metabolomics, and biological methods. Proteomics analysis in rats showed that TPIS and ENOA were covalently modified by TSN reactive metabolites. The biological functional assessments revealed that the modifications inhibited the activity of TPIS and induced the activity of ENOA, in vitro and in vivo, followed by an increase in the level of cellular methylglyoxal, advanced glycation end products, and reactive oxygen species/superoxide, and the induction of mitochondrial dysfunction, which further inhibited oxidative phosphorylation and stimulated glycolysis. Furthermore, metabolomics demonstrated the decrease in the level of metabolites in the tricarboxylic acid cycle, fatty acid ß-oxidation, and amino acid metabolism; i.e., TSN induced hepatocyte energy metabolism disorder. In conclusion, these data suggest novel mechanistic insights into TSN-induced liver injury on the upstream level and provide valuable proteins and energy metabolic targets for diagnosis and therapy in the clinic.

Bioconcentration of the antiepileptic drug carbamazepine and its physiological and biochemical effects on Daphnia magna.

Owing to its persistence, carbamazepine an antiepileptic drug is regularly detected in the aquatic environment. The motive for our research was to assess the bioconcentration, physiological and biochemical effects of carbamazepine in Daphnia magna. A 48 h aqueous exposure of carbamazepine yielded bioconcentration factors of 202.56 and 19.95 in Daphnia magna for the respective nominal treatments of 5 and 100 µg/L. Apparently, the inhibition of the capability of Daphnia magna to obtain food attributable to carbamazepine exposure will reduce their fitness to reproduce as well as to grow. Also, a significant alteration in the phototactic behaviour of Daphnia magna exposed to carbamazepine is maladaptive since it will increase their chance of being preyed upon in the surface water during daylight. Again, a significant decline in the acetylcholinesterase activity observed herein brings to light the neurotoxicity of carbamazepine to Daphnia magna. Moreover, significant inhibition of the superoxide dismutase, catalase and glutathione reductase activities coupled with the simultaneous induction of the malondialdehyde content imply that carbamazepine evoked a life-threatening oxidative stress that overpowered the antioxidant defence system of Daphnia magna. These observations confirm that carbamazepine can accumulate and consequently cause negative physiological and biochemical changes to wild Daphnia magna populations.

Comparison of the accumulation and metabolite of fluoxetine in zebrafish larva under different environmental conditions with or without carbon nanotubes.

Few studies have focused on the influence of environmental conditions on the bioavailability of pollutants interacted with nanomaterials in organisms. In this study, we primarily compared the influence of multiwalled carbon nanotubes (MWCNTs) on the bioavailability of fluoxetine in zebrafish (Danio rerio) larva under different environmental conditions: natural organic matter (NOM) and salinity. The results showed that fluoxetine accumulated in the larvae and then transformed into the metabolite norfluoxetine, with the metabolic rates from 2.8 to 3.5. Following co-exposure to MWCNTs, the accumulation of fluoxetine and norfluoxetine were further enhanced, suggesting a superior carrier of MWCNTs for fluoxetine, especially the functional MWCNTs. The consistent increase in the fluoxetine and norfluoxetine accumulation highlights the bioavailability of absorbed fluoxetine on MWCNTs in zebrafish larvae. The presence of NOM promoted the accumulation of fluoxetine and norfluoxetine in zebrafish, but alleviated the carrier effects of MWCNTs, acting as a natural antidote. Salinity negatively influenced the bioavailability of fluoxetine in the larvae, and further reversed the enhancements caused by MWCNTs. These findings provide a new insight into the influence of environmental conditions on the interactions between nanomaterials and pollutants in organisms.

Recent applications of metal-organic frameworks in sample pretreatment.

Metal-organic frameworks are promising materials in diverse analytical applications especially in sample pretreatment by virtue of their diverse structure topology, tunable pore size, permanent nanoscale porosity, high surface area, and good thermostability. According to hydrostability, metal-organic frameworks are divided into moisture-sensitive and water-stable types. In the actual applications, both kinds of metal-organic frameworks are usually engineered into hybrid composites containing magnetite, silicon dioxide, graphene, or directly carbonized to metal-organic frameworks derived carbon. These metal-organic frameworks based materials show good extraction performance to environmental pollutants. This review provides a critical overview of the applications of metal-organic frameworks and their composites in sample pretreatment modes, that is, solid-phase extraction, magnetic solid-phase extraction, micro-solid-phase extraction, solid-phase microextraction, and stir bar solid extraction.

Single and combined effects of selected haloacetonitriles in a human-derived hepatoma line.

Haloacetonitriles (HANs) are nitrogenous disinfection byproducts (N-DBPs) detected in drinking water that have high toxicity and are a high risk to human health. The cytotoxicity and genotoxicity as well as the oxidative stress of five HANs, namely chloroacetonitrile (CAN), dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), bromoacetonitrile (BAN), and dibromoacetonitrile (DBAN) on a hepatoma cell line (HepG2) were determined by single, binary or ternary exposure. The median effective concentrations, based on cell viability, ranged from 0.8360 mg/L for BAN to 256.9 mg/L for DCAN, with a cytotoxicity order of BAN > DBAN > CAN > TCAN > DCAN. The lowest observed effective concentrations regarding DNA damage were 0.01 mg/L for CAN and DCAN, 0.1 mg/L for DBAN and TCAN, and 1 mg/L for BAN. The DNA damage induced by CAN, DCAN and TCAN was repaired to about 80% in 30 min, and when induced by BAN and DBAN, it was repaired completely in 60 min. The intracellular reactive oxygen species (ROS) levels were significantly increased by the five HANs, and bromo-acetonitrile produced a stronger oxidative stress than chloro-acetonitrile. Co-exposure of DCAN, TCAN and DBAN significantly inhibited cell viability, induced DNA damage and facilitated ROS generation in HepG2 cells. However, the interactive effects were inconsistent for the different endpoints, which seemed to be antagonism for cell viability but synergy for ROS generation.

Investigation of pharmaceutically active compounds in an urban receiving water: Occurrence, fate and environmental risk assessment.

Pharmaceutically active compounds (PhACs) recently have been recognized to constitute a health risk for aquatic ecosystems. The major pathways of PhACs to enter the aquatic environment are excretion and discharge of effluents through sewage treatment plants (STPs). The occurrence, bioaccumulation and risk assessment of lipophilic PhACs, including erythromycin, ketoconazole, indomethacin, diclofenac, gemfibrozil, bezafibrate, propranolol, carbamazepine, sertraline and 17α-ethinylestradiol were investigated in a river that receives effluents from STP. The results indicate that the PhACs were extensively existed in fish, sediment, suspended particulate matter (SPM), colloidal phase (5 kDa to 1 µm) and truly dissolved phase (< 5 kDa) water, with total concentration of ten PhACs (Σ10PhACs) of ND-19.6 ng/g, 7.3-11.2 ng/g, 25.3-101.5 ng/g, 10.1-27.7 ng/L and 67.0-107.6 ng/L, respectively. The Σ10PhACs for particulate and water samples collected from STP's outfall site were higher than those collected from upstream and downstream, indicating that the STP is an important PhACs source of river. However, the Σ10PhACs in sediment showed no significant statistical differences in the sampling area, and which was 3.5-9.5 times lower than those in SPM samples. The colloidal phase contributed 2.5-28.5% of erythromycin, 5.8-45.6% of ketoconazole, 8.4-32.2% of indomethacin, 7.0-21.4% of diclofenac, 11.6-36.9% of gemfibrozil, 10.2-45.9% of bezafibrate, 5.9-16.8% of propranolol, 1.9-11.1% of carbamazepine and 1.1-23.8% of sertraline in the aquatic environment. This suggests that aquatic particulates (e.g., colloids and SPM) maybe an important carrier for PhACs in the aquatic system. In general, the Σ10PhACs in the tissues of fish were in order as follows: kidney > brain > liver > gill > muscle. Based on truly dissolved concentrations of PhACs in the water, bioaccumulation factors were between 3.7 and 2727.3 in the fish tissues, sertraline exhibited bioaccumulation potential. In all the risk assessments, erythromycin could cause most harmful adverse health effects for the most sensitive algae group based on the acute and chronic data. In addition, the risk quotient values for diclofenac toward fish were higher than 1. These results indicate that the PhACs pose a potential risk to the aquatic organisms, especially for chronic risk.

Bioconcentration and effects of hexabromocyclododecane exposure in crucian carp (Carassius auratus).

As a cycloaliphatic brominated flame retardant, hexabromocyclododecane (HBCD) has been widely used in building thermal insulation and fireproof materials. However, there is little information on the bioconcentration as well as effects with respect to HBCD exposure in the aquatic environment. To investigate the bioconcentration of HBCD in tissues (muscle and liver) and its biochemical and behavioural effects, juvenile crucian carp (Carassius auratus) were exposed to different concentrations of technical HBCD (nominal concentrations, 2, 20, 200 µg/L) for 7 days, using a flow-through exposure system. HBCD was found to concentrate in the liver and muscle with a terminal concentration of 0.60 ± 0.22 µg/g lw (lipid weight) and 0.18 ± 0.02 µg/g lw, respectively, at an environmentally-relevant concentration (2 µg/L). The total thyroxine and total triiodothyronine in the fish plasma were lowered as a result of exposure to the HBCD. Acetylcholinesterase activity in the brain was increased, while swimming activity was inhibited and shoaling inclination was enhanced after exposure to 200 µg/L HBCD. Feeding rate was suppressed in the 20 and 200 µg/L treatment groups. In summary, HBCD concentrations 10-100× higher than the current environmentally-relevant exposures induced adverse effects in the fish species tested in this study. These results suggest that increasing environmental concentrations and/or species with higher sensitivity than carp might be adversely affected by HBCD.

Locking plates versus intramedullary nails in the management of displaced proximal humeral fractures: a systematic review and meta-analysis.

PURPOSE: To compare the clinical outcome and complications of locking plates versus intramedullary nails in patients with displaced proximal humeral fractures. Our hypothesis was that there would be no difference between these two implants with regard to clinical outcome and complications. METHODS: We performed a systemic review of PubMed, EMBASE, Clinical Trials Registry, Cochrane Central Register of Controlled Trials and Google Scholar to identify all relevant randomized controlled trials, prospective and retrospective comparative studies on April 26, 2017. The studies of locking plates compared to intramedullary nails in patients with displaced proximal humeral fractures were included. We conducted a meta-analysis of shoulder functional scores, range of motion, pain scores, and complications. RESULTS: This meta-analysis included 13 comparative studies with 958 patients (529 in the locking plate group and 429 in the intramedullary nail group). A significantly greater external rotation (MD = 9.67; 95% CI, 4.22-15.12; P = 0.0005) and a significantly higher penetration rate (RR = 1.75; 95% CI, 1.11-2.77; P = 0.02) were observed in the locking plate group compared with the intramedullary nail group. Constant-Murley scores, DASH scores and total complication rate were comparable between the two groups. Moreover, there were no significant differences in forward elevation, VAS scores, and other complications. CONCLUSIONS: Current evidence indicates that locking plates and intramedullary nails have similar performance in terms of the functional scores and total complication rate. No superior treatment was suggested between locking plates and intramedullary nails for displaced proximal humeral fractures.

High mercury leachate containing HgS22- complex ion: Detoxifying solidification and high efficiency Hg extraction.

Clean and efficient treatment of high-mercury leachate produced from remediation of mercury-polluted soil has become a huge challenge for environmental scientists. In this work, cement solidification was firstly adopted to treat the high-concentration mercury leachate, which had high alkalinity. Different mercury concentrations, namely 3.120mg/L Hg mercury leachate and 9.243mg/L Hg mercury concentrated leachate, were separately solidified by Portland cement. The results indicated that simply using the cement can properly solidify both the leachates to meet the waste landfill standard, with liquid (mL)/solid (g) ratio (L/S ratio) of 4:10-6:10. In order to make full use of mercury in the leachates, a Hg extraction method was subsequently carried out under different experimental parameters, such as temperature and pH value. It was shown that the Hg extraction ratio could reach as high as 99.84% and almost all the mercury in the leachate could be transformed to HgS precipitate; moreover, the Hg concentration in the treated leachate was reduced from 3.120 to 0.005mg/L at pH2.98 and 30°C, which was much less than the limit of the national standard, indicating that the leachate had been completely cleaned and could be discharged freely. Hence, simple cement solidification renders high-mercury leachate nontoxic, and the Hg extraction method can successfully recover the Hg and enable the residual leachate to be discharged safely.

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.

Uptake, depuration, and bioconcentration of two pharmaceuticals, roxithromycin and propranolol, in Daphnia magna.

The objective of the present study was to investigate the uptake, depuration, and bioconcentration of two pharmaceuticals, roxithromycin (ROX) and propranolol (PRP), in Daphnia magna via aqueous exposure. Additionally, dietary and pH effects on the bioconcentration of two pharmaceuticals in daphnia were studied. During the 24-h uptake phase followed by the 24-h depuration phase, the uptake rate constants (k(u)) of ROX for daphnia were 9.21 and 2.77 L kg(-1) h(-1), corresponding to the exposure concentrations of 5 and 100 µg L(-1), respectively; For PRP at the nominal concentrations of 5 and 100 µg L(-1), k(u) were 2.29 and 0.99 L kg(-1) h(-1), respectively. The depuration rate constants (k(d)) of ROX in daphnia, at the exposure concentrations of 5 and 100 µg L(-1), were 0.0985 and 0.207 h(-1), respectively; while those of PRP were 0.0276 and 0.0539 h(-1) for the nominal concentrations of 5 and 100 µg L(-1), respectively. With the decreasing exposure concentrations, the bioconcentration factors (BCFs) in daphnia ranged from 13.4 to 93.5 L kg(-1) for ROX, and 18.4 to 83.0 L kg(-1) for PRP, revealing the considerable accumulation potential of these two pharmaceuticals. Moreover, after 6h exposure, the body burdens of ROX and PRP in dead daphnia were 4.98-6.14 and 7.42-12.9 times higher than those in living daphnia, respectively, implying that body surface sorption dominates the bioconcentration of the two pharmaceuticals in daphnia. In addition, the presence of algal food in the media could significantly elevate the kd values for both ROX and PRP, thereby restraining their bioconcentration in daphnia. A pH-dependent bioconcentration study revealed that the bioconcentration of the two pharmaceuticals in daphnia increased with increasing pH levels, which ranged from 7 to 9. Finally, a model was developed to estimate the relationships between pH and the BCFs of the two pharmaceuticals in zooplankton. The predicted values based on this model were highly consistent with wildlife monitoring data, implying that this model will be useful in identifying the bioaccumulation risks that pharmaceuticals pose to zooplankton.