Adverse effects in Daphnia magna exposed to e-waste leachate: Assessment based on life trait changes and responses of detoxification-related genes.

The sharp increase in e-waste derived from great consumption of electronic products has become a potential global environmental challenge. Limited information is available about the potential detrimental impact of e-waste on aquatic organisms. The present study investigated the expression of detoxification-related genes and life-history parameter changes in Daphnia magna exposed to e-waste leachate, simultaneously integrating with the chemical analysis of typical pollutants from e-waste leachate. The study aims at assessing impacts of e-waste to aquatic invertebrates and providing insights into its toxic mechanisms. The results showed high concentration of heavy metals like Cu (1657.14 ± 259.3 µg g-1, DW) and persistent organic compounds like polybrominated diphenyl ethers (7831.32 ± 1273.86 ng g-1, DW) in stream sediments near e-waste dismantling areas. Chronic exposure to these pollutants can affect the growth and reproduction of D. magna, resulting in significant development retardation, decreased total egg production per female, and even smaller body size. Expression of some detoxification and reproduction-related genes including DappuHR96, CYP360a, P-gp, EcR, CYP314 and Vtg exhibited different response patterns depending on the e-waste leachate concentration. E-waste leachate may affect the expression of detoxification-related and growth and reproduction-related genes and disrupt the growth and reproduction processes of D. magna.

Assessment of oxidative stress of paracetamol to Daphnia magna via determination of Nrf1 and genes related to antioxidant system.

Paracetamol (APAP) is one of the most widely used anti-inflammatory and analgesic drugs in human being health care and has been universally detected in various aquatic environments. However, its potential adverse effects and toxic mechanisms on freshwater invertebrates still remain unclear. In the present study, the effects of APAP on the expressions of Nrf1 and the antioxidant related genes including GCLC, GST, GPX, CAT, TRX, TrxR and Prx1 in Daphnia magna (D. magna) were evaluated after 24, 48 and 96 h, and the changes of GPX, GST and CAT enzyme activities, as well as the GSH and MDA content under APAP exposure for 48 h were also determined. Results showed that paracetamol affected the expressions of Nrf1 and antioxidant related genes in D. magna, which were related to the exposure time and concentration of APAP. Nrf1 was inhibited at 48 h, but induced at 96 h under the APAP exposure, being about two fold of the control in 5.0 µg/L. CAT were significantly induced in all treatments. But Prx decreased in an concentration-dependent manner in all treatments. In comparison with the mRNA expression, antioxidant enzymes activity displayed less changes in D. magna. Overall, APAP exposure altered the expression of Nrf1 and genes related to antioxidant system and disturbed the redox homeostasis of D. magna.

Toxic assessment of the leachates of paddy soils and river sediments from e-waste dismantling sites to microalga, Pseudokirchneriella subcapitata.

The potential adverse effects of e-waste recycling activity on environment are getting increasing concern. In this work, a model alga, Pseudokirchneriella subcapitata, was employed to assess the toxic effects of the leachates of paddy soils and river sediments collected from e-waste dismantling sites. Chemical analysis of the paddy soils and river sediments and their leachates were carried out and the growth rate, chlorophyll a fluorescence and anti-oxidative systems of the alga were measured. Results showed that two leachates decreased the amount of PSII active reaction centers and affected photosynthesis performance, interfered with chlorophyll synthesis and inhibited algal growth. Some chemical pollutants in the sediments and soils such as polybrominated diphenyl ethers (PBDEs) and metals derived from e-waste recycling activity may impose oxidative stress on algae and affect the activity of anti-oxidative enzymes such as GST, SOD, CAT and APX. The leachates of both river sediments and paddy soils are potentially toxic to the primary producers, P. subcapitata and the leachate from sediments was more deleterious than that from soils.

[Residues and health risk assessment of sulfonamides in sediment and fish from typical marine aquaculture regions of Guangdong Province, China].

Concentrations of sulfonamides including sulfadiazine (SDZ), sulfadimidin (SM2) and sulfamethoxazole (SMX) in sediments, muscle and liver tissues of 7 kinds of fish species collected from two marine aquaculture regions along the coast of Guangdong Provice were determined by high performance liquid chromatography (HPLC) equipped with a ultraviolet detector. Assessment of the health risks were conducted based on the values of maximum residue limits (MRL) and acceptable daily intake (ADI). The results showed that sulfonamides were found in all the sediment samples. The concentrations (dry wet) ranged from 2.1 - 35.2 ng x g(-1), the detected frequency of the 3 sulfonamide antibiotics ranked as SDZ (85.7%) > SM2 (71.4%) > SMX (28.6%). The detection rate of sulfonamides in samples from Daya Bay was higher than that from Hailing Island. Higher concentrations were detected in liver tissues rather than in muscle tissues (P < 0.05). The residues of SDZ, SM2 and SMX in fish muscle tissues (wet weight) ranged from 11.6-37.9, 16.3-27.8 and 4.9-20.0 ng x g(-1), respectively. The calculated daily intakes of sulfonamides in the present study ranged from 3.37-36.72 ng x kg(-1), which accounted for 0.007% -0.073% of the ADI (50 microg x kg(-1)). Health risks to human body were negligible as the estimated intake was less than 1% ADI, therefore the security of dietary was high.

Advanced oxidation kinetics and mechanism of preservative propylparaben degradation in aqueous suspension of TiO2 and risk assessment of its degradation products.

The absolute kinetic rate constants of propylparaben (PPB) in water with different free radicals were investigated, and it was found that both hydroxyl radicals (HO(•)) and hydrated electrons could rapidly react with PPB. The advanced oxidation kinetics and mechanisms of PPB were investigated using photocatalytic process as a model technology, and the degradation was found to be a pseudo-first-order model. Oxidative species, particularly HO(•), were the most important reactive oxygen species mediating photocatalytic degradation of PPB, and PPB degradation was found to be significantly affected by pH because it was controlled by the radical reaction mechanism and was postulated to occur primarily via HO(•)-addition or H-abstraction reactions on the basis of pulse radiolysis measurements and observed reaction products. To investigate potential risk of PPB to humans and aqueous organisms, the estrogenic assays and bioassays were performed using 100 µM PPB solution degraded by photocatalysis at specific intervals. The estrogenic activity decreased as PPB was degraded, while the acute toxicity at three trophic levels first increased slowly and then decreased rapidly as the total organic carbon decreased during photocatalytic degradation.

Assessment of toxic effects of triclosan on the swordtail fish (Xiphophorus helleri) by a multi-biomarker approach.

The toxic effects of triclosan (TCS) on the swordtail fish (Xiphophorus helleri) were assessed based on various biomarkers including enzymatic activities of ethoxyresorufin O-deethylase (EROD), erythromycin N-demethylase (ERND) and glutathione-s-transferase (GST) and mRNA expression levels of CYP1A, CYP3A, glutathione S-transferase (GST) and P-glycoprotein (P-gp). The acute toxicity test showed the LC(50) value of 1.47 mg L(-1) for TCS. The mRNA expressions of CYP1A, CYP3A, GST and P-gp showed dose-effect relationships in female swordtail fish when exposed to TCS, These mRNA expression levels were found more sensitive to TCS exposure than the enzymatic activities of EROD, ERND and GST do. In addition, the male fish displayed higher gene expression levels and more dramatic changes in enzyme activities than the females did. Our data further demonstrated that TCS was a typical inducer to Phase I and Phase II metabolism enzymes and genes, suggesting it is a potential ecotoxicological risk to aquatic ecosystems.

Arsenic contamination in the freshwater fish ponds of Pearl River Delta: bioaccumulation and health risk assessment.

This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05-3.01 mg kg(-1) wet weight (w. wt) and 8.41-22.76 mg kg(-1) dry weight (d. wt), respectively. In addition, the As content was positively correlated (p < 0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ (15)N. The slope of the regression (-0.066 and -0.078) of the log transformed As concentrations and δ (15)N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10(-4)) stipulated by the USEPA.

Assessment of typical pollutants in waterborne by combining active biomonitoring and integrated biomarkers response.

Organic pollutants, heavy metals and pharmaceuticals are continuously dispersed into the environment and have become a relevant environmental emerging concern. In this study, a situ assay to assess ecotoxicity of mixed pollutants was carried out in three typical sites with different priority contaminations in Guangzhou, China. Chemical analysis of organic pollutants, metals and quinolones in three exposure sites were determined by GC-ECD/MS, ICP-AES and HPLC, as well as, a combination of biomarkers including: ethoxyresorufin O-deethylase (EROD); aminopyrine N-demethylase (APND); erythromycin N-demethylase (ERND); glutathione S-transferase (GST); malondialdehyde (MDA); CYP1A; and P-glycoprotein (P-gp) mRNA expressions were evaluated in Mugilogobius abei. Results of chemical analysis in sediment samples revealed that the dominant chemicals were organic pollutants and heavy metals in Huadi River while quinolones in the pond. Bioassays indicated that differences among sites were in relation to some specific biomarkers. EROD and GST activities significantly increased after 72 h in situ exposure, but no difference was observed among the exposure sites. APND, ERND and MDA exhibited dissimilar change patterns for different priority pollutants. CYP1A and P-gp mRNA expressions were significantly induced at all exposure sites, whilst P-gp activity was typical for S2 with the highest levels of quinolones. The molecular biomarkers seemed to be more susceptible than enzyme activities. These assays confirmed the usefulness of applying a large array of various combined biomarkers at different levels, in assessing the toxic effects of mixed pollutants in a natural aquatic environment.

Mutagenicity assessment of produced water during photoelectrocatalytic degradation.

Oilfield produced water was treated by photocatalysis, electro-oxidation, and photoelectrocatalysis, respectively. The chemical composition and toxicity of the raw effluent and treated products were assessed by chemical and mutagenicity analysis. The raw effluent exhibited mutagenic activity in both strains of Salmonella typhimurium. The lowest concentration of the dichloromethane extract capable of inducing a positive response in strains TA98 and TA100 were as low as 4 and 5 microg/plate, respectively. All three technologies could detoxify direct-acting mutagenic organic pollutants efficiently, although they could not completely eliminate mutagenicity in the water after 60 min of treatment. At equivalent doses, photoelectrocatalysis exhibited the greatest capability to reduce genotoxicity, whereas photocatalysis was the least effective and did not cause appreciable change in mutagenicity. The gas chromatography-mass spectrometry (GC-MS) analysis revealed that n-alkanes (259.4 ng/L) and phenolic compounds (2,501.4 ng/L) were the main organic constituents in the oilfield produced water. Thus, the results of both biological and chemical analysis indicate that photoelectocatalysis was the most effective technology for degradation of oilfield wastewater.