Spatial distribution, source identification, and potential risks of 14 bisphenol analogues in soil under different land uses in the megacity of Chengdu, China.

This study explored the levels, distribution, potential sources, ecological risks and estrogenic activities of 14 bisphenol analogues (BPs) in soil under eight land-use types in the megacity of Chengdu, China. Eleven BPs were detected in the soil samples and the total concentrations ranged from 32.3-570 ng/g d.w. Levels of bisphenol BP (BPBP) in the soil (up to 208 ng/g d.w.) only second to the most dominant compound bisphenol A (BPA) were found. Relatively higher Σ14BP accumulation in the soil was observed in the commercial and residential areas (median: 136 ng/g d.w. and 131 ng/g d.w.) compared with agricultural area (median: 67.5 ng/g d.w.). Source identification indicated the role of atmospheric particulate deposition and consecutive anthropogenic activities in BP emission. The ecotoxicity assessment implied that BPA, bisphenol S (BPS), bisphenol F (BPF) and bisphenol PH (BPPH) might pose low to medium risk to the ecosystem due to their extensive use and biological effects. The calculated 17ß-estradiol equivalents of BPs were in the range of 0.501-7.74 pg E2/g d.w, and the estrogenic activities were inferior to those contributed by natural estrogens in the soil.

Photodegradation of anthelmintic drugs under natural sunlight and simulated irradiation: kinetics, mechanisms, transformation products, and toxicity.

Albendazole (ALB) and bithionol (BIT) are two anthelmintic drugs (ADs) with high consumption from benzimidazole group and diphenylsulfide group, respectively. However, information on the transformation of the two anthelmintics under environmental condition is scare. Therefore, in the present study, we investigated the natural attenuation of the two ADs in the aquatic environment, including biodegradation, hydrolysis, and direct and indirect photodegradation. The direct photodegradation occupied a vast portion among other degradation pathways of the two ADs in natural water, with near-surface summer half-lives of 0.272-0.387 h and 0.110-0.520 h for ALB and BIT, respectively. Suspended particles in water were found to facilitate the photodegradation of the two ADs. Study on the indirect photodegradation demonstrated the positive roles of singlet oxygen (1O2) and excited triplet dissolved organic matter (3DOM*) in the photolysis of the two ADs, whereas the hydroxyl radical (•OH) affected little on the overall photodegradation procedures of ALB due to the scavenging effect of HCO3-. Dual effects of DO, DOM, HCO3-, NO3-, and NO2- on the photodegradation of ALB and BIT were perceived. Transformation intermediates (TIs) of the two ADs during photodegradation were analyzed by UHPLC-QTOF-MS. Six TIs of ALB were identified, including a broad-spectrum fungicide carbendazim and another common AD ricobendazole. Two TIs of BIT yielded from dechlorination were also detected. Probable transformation mechanism and predicted aquatic ecotoxicity based on the identified TIs were unveiled.

Organophosphorus flame retardants and their metabolites in paired human blood and urine.

Organophosphorus flame retardants (OPFRs) have been shown to be carcinogenic, neurotoxic, and endocrine disruptive, so it is important to understand the levels of OPFRs in human body as well as the modes of external exposure. In this study, we investigated the levels of 13 OPFRs and 7 phosphodiester metabolites in paired human blood and urine, as well as the influencing factors (region, age and gender), and studied the relationship between OPFRs and oxidative stress by urinary metabolites. We found that the concentrations of triphenyl phosphate (TPhP) and tris-(2-ethylhexyl) phosphate (TEHP) in the blood of urban populations were higher than those of rural populations, and that younger populations suffered higher TPhP and 2-ethylhexyl diphenyl phosphate (EHDPP) exposures than older populations. In addition, we found that tris-(2-chloroethyl) phosphate (TCEP), tributyl phosphate (TnBP), TPhP and EHDPP exposure induced oxidative stress. The results of the internal load principal component analysis indicated that dust ingestion, skin exposure, respiration and dietary intake may be the most important sources of TCEP, tris(2-butoxyethyl) phosphate (TBOEP), tri(2-chloroisopropyl) phosphate (TCIPP) and TEHP, respectively, and dust ingestion and skin exposure may be the main sources of TPhP for humans.

Occurrence, distribution and environmental risk of 19 anthelmintic drugs in river water and sediment from the Jinjiang River, China.

This study explored the occurrence and distribution of 19 anthelmintic drugs (ADs) including the benzimidazole group, salicylanilide group, imidazothiazole group, tetrahydropyrimidine group, diphenylsulfide group, macrocyclic lactone group and hexahydropyrazine group in river water and sediment of the Jinjiang River in Sichuan, China, during summer and winter seasons. All targets were detected in river water (up to 74.64 ng L-1) and sediment (up to 1701 ng g-1) samples. The predominant ADs were benzimidazoles regardless of seasons and matrices, accounting for 43-82% of the total anthelmintic abundance. Obvious seasonal variation of AD concentrations in the two matrices was observed, which could be attributed to the seasonality of human and veterinary uses of ADs. Evident spatial variation (urban and rural areas) of ADs in winter was indicative of the influence of anthropogenic activities on the environmental concentration of ADs. Though benzimidazoles accumulated in the water and sediment with the highest concentration among all the ADs, macrocyclic lactones were of the highest risk to non-target organisms through ecological risk assessment, with an RQEcotox value up to 2713. This work contributes to comprehensively assessing the contamination level, ecological level and transmission characteristics of ADs in the environment.

Effects of electroflocculation/oxidation pretreatment on the fouling characteristics of ultrafiltration membranes.

In order to reduce the membrane pollution of ultrafiltration caused by natural organic matter and improve the treatment efficiency, electroflocculation/oxidation is used as the premembrane treatment method. The membrane specific flux attenuation characteristics was compared and analyzed under the conditions of direct ultrafiltration and electroflocculation/oxidation-ultrafiltration. Combined with the analysis of the reversibility of membrane fouling, the mechanism of electroflocculation/oxidation pretreatment to alleviate ultrafiltration membrane fouling was evaluated, and the membrane pore clogging model was used to fit the fouling law. The results show that, in the continuously fed filtration experiment, the electroflocculation/oxidation process involved in the pretreatment and the direct ultrafiltration membrane filtration decreased the ultrafiltration membrane flux to 79.1% and 28.5%, respectively. The reversible resistance generated by ultrafiltration and electroflocculation/oxidation-ultrafiltration processes accounted for 37.70% and 62.26% of their total pollution resistance, whereas the irreversible resistance generated accounted for 47.30% and 12.40%, respectively. Meanwhile, the direct correlation between the the flux dropped and complete clogging became less than that of the ultrafiltration process. The pretreatment significantly strengthened irreversible fouling resistance of the membrane pores. The membrane permeation flux was significantly increased after the electroflocculation/oxidation pretreatment.