Spatial distribution, receptor modelling and risk assessment of organophosphate esters in surface water from the largest freshwater lake in China.

The occurrence and risk of organophosphate esters (OPEs) has become a global concern in recent years. This study investigated the occurrence, spatial distribution, and potential sources of thirteen OPEs and their associated ecological and human health risks in water samples from the largest freshwater lake, Poyang Lake, together with its five major inflow rivers and the water channel to Yangtze River. The total OPEs concentrations ranged from 38.44 ng/L to 428.94 ng/L, and the largest tributary Ganjiang River was much more polluted than other rivers. Chlorinated OPEs, such as tris (1-chloro­2-propyl) phosphate and tri (2-chloroethyl) phosphate occupied the dominant composition of OPEs in the research area. Principal component analysis with multiple linear regression, positive matrix factorization, and correlation analysis were used to apportion the potential sources of OPEs in surface water. The combined contribution of polyvinyl chloride, polyester resins, and polyurethane foam (68.64%), antifoam agent and hydraulic fluids (21.50%), and the release of decorative materials and electric equipment from indoor (9.86%) were identified as the OPEs sources in the study region. The risk quotients (RQs) showed the ecological risk was negligible, but 2-ethylhexyl diphenyl phosphate exposures posed medium ecological risk to aquatic organisms. The carcinogenic and non-carcinogenic risks of the target OPEs were below the theoretical risk threshold values, however, toddlers were much more sensitive to the OPEs exposure in surface water than teenagers and adults. Oral ingestion was the principal exposure pathway, and the health risk via oral ingestion was 1-2 orders of magnitude higher than dermal contact exposure route.

Tissue-specific accumulation, elimination, and toxicokinetics of illicit drugs in adult zebrafish (Danio rerio).

The abuse of illicit drugs has led to their extensive detection worldwide and subsequently exerted adverse effects upon aquatic organisms and ecosystem. However, less attention has been paid to the uptake, biotransformation, internal distribution, and toxicokinetic processes in the exposed organisms. In this study, zebrafish (Danio rerio) was exposed to methamphetamine (METH) and ketamine (KET) at three different concentrations in a semi-static exposure system. METH and KET, together with their metabolites, amphetamine (AMP) and norketamine (NK), were consistently detected in zebrafish. Over 14-day exposure, the relative magnitude of mean concentrations of illicit drugs in zebrafish generally followed the order of brain > liver > intestine > ovary > muscle. The uptake rate constants (Ku) of METH and KET were in the range of 0.590-1.38 × 103 L/(kg·d), the elimination rate constants (Ke) were in the range of 0.18-6.98 1/d, and the half-lives were in the range of 0.18-6.98 d, respectively. METH and KET demonstrated relatively rapid uptake and elimination kinetics and short half-lives, and concentrations in organs were driven by external concentrations. Illicit drugs were not persistent within zebrafish organs when there were no substantial external contaminant sources. The observed values of bioconcentration factor (BCFo, L/kg) and kinetically-derived bioconcentration factor (BCFk, L/kg) were at the similar level. The ability of different zebrafish organs accumulating target chemicals from the aquatic environment was different, and brain was the target organ of the test illicit drugs.

[Pollution Characteristics and Risk Assessment of Organophosphate Esters in Rivers and Water Body Around Taihu Lake].

To explore the pollution characteristics, potential sources, and ecological and health risk of organophosphate eaters (OPEs) in the surface water of Taihu Lake, water samples from 18 surrounding rivers were collected, as well as 11 water samples from Taihu Lake. The concentrations of 13 OPEs in the water were determined using UPLC-MS/MS, and the spatial distribution of the OPEs in surface water of Taihu Lake basin was further analyzed. The results indicate that, in addition to tripropyl phosphate (TPrP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP), ten OPEs were detected in all the water samples, the total concentration (ΣOPEs) ranged from 152.5 ng·L-1 to 2524 ng·L-1, and the concentration median value was 519.2 ng·L-1. Tri(chloropropyl) phosphate (TCPP) and tri(2-chloroethyl) phosphate (TCEP) were the dominant OPEs, with the concentration ranges of 73.7-1753.9 ng·L-1 (medium value:204.6 ng·L-1) and 43.9-313.5 ng·L-1 (medium value:131.3 ng·L-1), respectively. The ΣOPEs decreased from the northwest region to the southeast, which corresponds to the economic and industrial development. The results of the source identification reveal that the wastewater discharge from electronics and textile enterprises, construction materials, and vehicular and marine traffic emissions may be the principal sources of the OPEs in Taihu Lake. The ecological risk assessment results indicate that only TCPP, tri(dichloropropyl) phosphate (TDCP), and triphenyl phosphate (TPhP) in some sites had a low risk. The health risk assessment reveals that there were no risks based on water intake, but the long-term risk of OPEs to the aquatic ecosystem and surrounding residents still need attention.

[Organ-Specific Accumulation and Toxicokinetics of Ephedrine in Adult Zebrafish (Danio rerio)].

Ephedrine (EPH) is an alkaloid commonly used to relieve nasal congestion caused by colds, allergic rhinitis, rhinitis, and sinusitis, and to control bronchial asthma. It is also be used as a raw material in the manufacture of methamphetamine. Although the distribution of EPH in surface waters has been widely studied, its uptake, internal distribution, and toxicokinetic processing in exposed organisms have not been well investigated. In this study, we investigated the uptake, disposition, and toxicokinetics of EPH in zebrafish (Danio rerio) in a semi-static exposure system. EPH was consistently detected in zebrafish biological samples, with the highest concentrations of 84.97 ng·g-1 detected in the brain tissue of fish in the high treatment group. Over the 14-d exposure period, the relative abundance of mean concentrations of EPH in biological samples generally followed the order of brain > ovary > liver > intestine > muscle. The uptake rate constants (Ku), elimination rate constants (Ke), and half-lives of EPH in the biological tissues were in the ranges 0.23-570.31 L·(kg·d)-1, 1.22-6.11 d-1, and 0.12-0.57 d, respectively. The observed bioconcentration factor (BCFo) and kinetically-derived bioconcentration factor (BCFk) were similar, ranging 0.24-337.33 L·kg-1 and 0.13-316.43 L·kg-1, respectively. These results are helpful for understanding the behavior of psychoactive substances in aquatic organisms and have directive significance for studying their toxicity and ecological risks to aquatic organisms.

Interactions between stepwise-eluted sub-fractions of fulvic acids and protons revealed by fluorescence titration combined with EEM-PARAFAC.

In aquatic environments, pH can control environmental behaviors of fulvic acid (FA) via regulating hydrolysis of functional groups. Sub-fractions of FA, eluted using pyrophosphate buffers with initial pHs of 3.0 (FA3), 5.0 (FA5), 7.0 (FA7), 9.0 (FA9) and 13.0 (FA13), were used to explore interactions between the various, operationally defined, FA fractions and protons, by use of EEM-PARAFAC analysis. Splitting of peaks (FA3 and FA13), merging of peaks (FA7), disappearance of peaks (FA9 and FA13), and red/blue-shifting of peaks were observed during fluorescence titration. Fulvic-like components were identified from FA3-FA13, and protein-like components were observed in fractions FA9 and FA13. There primary compounds (carboxylic-like, phenolic-like, and protein-like chromophores) in PARAFAC components were distinguished based on acid-base properties. Dissociation constants (pKa) for fulvic-like components with proton ranged from 2.43 to 4.13 in an acidic pH and from 9.95 to 11.27 at basic pH. These results might be due to protonation of di-carboxylate and phenolic functional groups. At basic pH, pKa values of protein-like components (9.77-10.13) were similar to those of amino acids. However, at acidic pH, pKa values of protein-like components, which ranged from 3.33 to 4.22, were 1-2units greater than those of amino acids. Results presented here, will benefit understanding of environmental behaviors of FA, as well as interactions of FA with environmental contaminants.