Identification and Risk Assessment of Priority Control Organic Pollutants in Groundwater in the Junggar Basin in Xinjiang, P.R. China

1,2-Dichloroethane causes anxiety and cognitive dysfunction in mice by disturbing GABA metabolism and inhibiting the cAMP-PKA-CREB signaling pathway

1,2-Dichloroethane (1,2-DCE) is a powerfully toxic neurotoxin, which is a common environmental pollutant. Studies have indicated that 1,2-DCE long-term exposure can result in adverse effects. Nevertheless, the precise mechanism remains unknown. In this study, behavioral results revealed that 1,2-DCE long-term exposure could cause anxiety and learning and memory ability impairment in mice. The contents of γ-aminobutyric acid (GABA) and glutamine (Gln) in mice's prefrontal cortex decreased, whereas that of glutamate (Glu) increased. With the increase in dose, the activities of glutamate decarboxylase (GAD) decreased and those of GABA transaminase (GABA-T) increased. The protein and mRNA expressions of GABA transporter-3 (GAT-3), vesicular GABA transporter (VGAT), GABA A receptor α2 (GABAARα2), GABAARγ2, K-Cl cotransporter isoform 2 (KCC2), GABA B receptor 1 (GABABR1), GABABR2, protein kinase A (PKA), cAMP-response element binding protein (CREB), p-CREB, brain-derived neurotrophic factor (BDNF), c-fos, c-Jun and the protein of glutamate dehydrogenase (GDH) and PKA-C were decreased, while the expression levels of GABA transporter-1 (GAT-1) and Na-K-2Cl cotransporter isoform 1 (NKCC1) were increased. However, there was no significant change in the protein content of succinic semialdehyde dehydrogenase (SSADH). The expressions of adenylate cyclase (AC) and cyclic adenosine monophosphate (cAMP) contents were also reduced. In conclusion, the results of this study show that exposure to 1,2-DCE could lead to anxiety and cognitive impairment in mice, which may be related to the disturbance of GABA metabolism and its receptors along with the cAMP-PKA-CREB pathway.

Prioritization of organic contaminants in China's groundwater based on national-scale monitoring data and their persistence, bioaccumulation, and toxicity

There has been increasing concern regarding the adverse environmental and health effects of organic pollutants. A list of priority control organic pollutants (PCOPs) can provide regulatory frameworks for the use and monitoring of organic compounds in the environment. In this study, 20,010 groundwater samples were collected from 15 "first level" groundwater resource zones in China. Fifty (50) organic compounds were analyzed based on their prevalence, occurrence, and physicochemical properties (persistence, bioaccumulation, and toxicity). Results showed that 16 PCOPs, including 12 pesticides, 3 aromatic hydrocarbons (AHs), and 1 phthalate ester, were recognized. Pesticides and AHs accounted for 75 % and 18.75 % of the high-priority pollutants, respectively. There were significant differences in PCOPs between confined and phreatic groundwater. Higher concentrations of pesticides were mainly detected in phreatic groundwater. PCOPs detected in samples from the 15 groundwater resource zones were mainly pesticides and AHs. The groundwater data indicate that the organic compounds detected in the Yellow River Basin (YRB), Yangtze River Basin (YZB), Liaohe River Basin (LRB), and Songhua River Basin (SRB) are mainly categorized as Q1 (high priority) and Q2 (medium priority) pollutants based on the contaminants ranking system in China. The findings from this study offer a snapshot of the wide distribution of PCOPs in the surveyed regions, and are expected to establishing treatment and prevention measures at both the regional and national levels in China.