Divisional water quality management-based pollution source control in China's watersheds: an analysis by introducing economic factors.

Divisional water quality management (DWQM) is widely adopted in watershed pollution control. During 2011-2015, China zoned 708 priority controlled areas (PCAs) and 774 non-priority controlled areas (NPCAs) for key watersheds. DWQM at watershed level provides guidance on pollution source control (PSC) at local (provincial, city, and county) level. To identify the consistency between DWQM and PSC, a total of 29,688 enterprise-level data from China was analyzed with the difference-in-difference model. The economic factors that affect both are adopted to identify the causes of the disparities between them. The results show that PCAs were more effective than NPCAs and non-controlled areas (NCAs) in reducing COD emissions, thus better achieving divisional water quality goals. NPCAs were no more effective in reducing COD emissions than NCAs. Local government administration and potential subsidies are key to COD emission reductions, but they do not encourage technological progress. Lesser COD emission reductions were achieved in China's national key ecological function zones (NKEFZs) and upstream areas than in other areas. Current DWQM potentially aimed at relatively short-term economic benefits, which led to inconsistency with PSC particularly in NPCAs. To improve the coordination between them, ecological integrity should be the focus. Market-based watershed funding mechanism, especially watershed ecological compensation, transforms the short-term economic welfare from pollution control into long-term watershed ecological benefits.

Top-runner incentive scheme in China: a theoretical and empirical study for industrial pollution control.

Pollution control policies have achieved remarkable results in China. However, industrial firms still lack enthusiasm for technological innovation to reduce pollution and endogenous motivation for controlling pollution, which pose severe obstacles to industrial pollution control. The top-runner scheme can stimulate the pollution control behaviors of firms to a certain extent. Therefore, the top-runner scheme is combined with economic incentive policies to design an appropriate incentive scheme in this paper, theoretical research is conducted on the selection standards and incentive methods, and four industries mainly responsible for pollution in a developed province of China are investigated as case studies. The results show that (1) the selection standard that stipulates the rewarded quotas instead of the discharge amount achieved higher emission reduction efficiency; (2) tax cuts are the best incentive for top-runners, and (3) the top-runner incentive scheme achieves a greater reduction effect in high-pollution industries than low-pollution industries. Value-added tax exemption for the top-runner, as determined by the rewarded quotas, contributes to increasing the enthusiasm from firms to participate in and improve pollution control measures.

Acute oral methylmercury exposure perturbs the gut microbiome and alters gut-brain axis related metabolites in rats.

Environmental pollutants like methylmercury (MeHg) can bring devastating neurotoxicity to animals and human beings. Gut microbiota has been found to demethylate MeHg and promote the excretion of Hg through feces. However, the impacts of MeHg on gut microbiota and metabolites related to gut-brain interactions were less studied in mammals. The object of this study was to investigate the impacts of acute MeHg exposure on gut microbiome and metabolites together with its impact on gut integrity and related biological responses in rats. Rats were exposed to MeHg through oral administration and were sacrificed after 24 h 16 S rRNA gene sequencing was used to study the perturbance to gut microbiome and liquid chromatography mass spectrometry (LC-MS) was used for metabolomics profiling. It was found that gut was one of the target tissues of MeHg. MeHg induce the changes of intestinal microbial community structure and induce the regulating neuron activity change of intestinal neurotransmitters and metabolites on intestinal neurotransmitters and metabolites regulating the neuron activity. This was supported by the increased BDNF level. These findings may suggest a potential new mechanism regarding the neurotoxicity of MeHg. The protocols used in this study may also be applied to understand the neurotoxicity of other environmental neurotoxins like Pb, Mn, polychlorinated biphenyls, and pesticides, etc and to screen the neurotoxicity of emerging environmental contaminants.