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Abstract The groundwater is an important route of human exposure to kinds of contaminants. This study was carried out to investigate the occurrence and spatial distribution of groundwater arsenic in the Jinghui irrigation district in Shaanxi Province, China. The water contamination was assessed for drinking purposes by comparing it to national guidelines, and the impacts of arsenic on human health were quantified using the health risk assessment model recommended by the USEPA. The results show that the concentration of groundwater arsenic ranges from 0.0012 to 0.0190 mg/L (average 0.0054 mg/L), and 2.58% of groundwater exceed the national guidelines of 0.01 mg/L for drinking. The carcinogenic risk of arsenic affecting adults has reached 3.50 × 10−4, significantly exceeding the national guideline (1.00 × 10−4.) The health risks resulting from oral exposure are higher than those of dermal exposure. The carcinogenic risk for adults is higher than that for children, while the non-carcinogenic risk for children is higher than that for adults. The area ratio of the carcinogenic risk is 42.82%, and the area of the non-carcinogenic risk is 69.19%. Groundwater arsenic mainly originates from the discharge of industrial wastewater and the slowly release of natural sediments. The results of this study can help to set up suitable management strategies to guarantee water supply and health safety for local residents. Highlights • The concentration of groundwater arsenic exceeds the national guideline. • The carcinogenic risk for adults is higher than that for children. • Risks resulting from oral exposure are higher than those of dermal exposure. • The area of the non-carcinogenic risk is greater than that of carcinogenic risk. • Arsenic mainly originates from the industrial wastewater and the natural sediments. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate the hydrogeochemistry and spatial distribution of groundwater fluoride in Jinghuiqu irrigation district of China and to identify the hydrogeochemical processes and factors that control fluoride concentration. Water quality was assessed by comparing with the Chinese national groundwater quality guidelines and World Health Organization (WHO) guidelines for drinking water quality. Human health risks of fluoride were also quantified based on the US Environmental Protection of Agency (USEPA) model. The results show that groundwater in the study area is hard and slightly alkaline. The groundwater quality is generally very poor with excessive TDS, TH, Na+, SO42− and F− at some locations. The fluoride concentration in the groundwater samples ranges from 0.34 to 2.55 mg/L with an average of 1.08 mg/L, and 15.2% of the samples containing fluoride exceed the WHO guidelines of 1.5 mg/L for drinking water. High-fluoride groundwater mainly distributes in the southeast of the study area. The trend of fluoride concentration is consistent with the flow direction of groundwater. Groundwater fluoride mainly originates from natural sources and is controlled by hydrogeochemical factors such as alkaline environment, ion exchange, dissolution and precipitation of minerals. Health risk assessment results show that the non-carcinogenic risk for children is higher than that for adults and the health impact on adults is ignorable. The results of this study may help to set up suitable management strategies to guarantee water supply and health safety for local residents. [ABSTRACT FROM AUTHOR]

The air quality in the subway metro indoor microenvironment has been of particular public concern. With specific reference to the growing demand of green transportation and sustainable development, subway metro systems have been rapidly developed worldwide in last decades. The number of metro commuters has continuously increased over recent years in metropolitan cities. In some cities, metro system has become the primary public transportation mode. Although commuters typically spend only 30–40 min in metros, the air pollutants emitted from various interior components of metro system as well as air pollutants carried by ventilation supply air are significant sources of harmful air pollutants that could lead to unhealthy human exposure. Commuters' exposure to various air pollutants in metro carriages may cause perceivable health risk as reported by many environmental health studies. This review summarizes significant findings in the literature on air quality inside metro indoor environment, including pollutant concentration levels, chemical species, related sources and health risk assessment. More than 160 relevant studies performed across over 20 countries were carefully reviewed. These comprised more than 2000 individual measurement trips. Particulate matters, aromatic hydrocarbons, carbonyls and airborne bacteria have been identified as the primary air pollutants inside metro system. On this basis, future work could focus on investigating the chronic health risks of exposure to various air pollutants other than PM, and/or further developing advanced air purification unit to improve metro in-station air quality. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate the hydrogeochemical characteristics, processes, and factors that control the groundwater chemistry in Jinghui canal irrigation district of China. Water quality was assessed by comparing with the Chinese national guidelines and World Health Organization (WHO) guidelines for drinking and irrigation. Impacts of Cr6+ on human health were also quantified using the health risk assessment model. The results show that groundwater in the study area is brackish, hard and slightly alkaline. The groundwater quality is generally very poor with excessive Na+, SO42−, Cl−, total dissolved solids, and total hardness in most samples. Of the groundwater samples, 72.3% are unsuitable for drinking with excessive NO3−-N comparing the WHO guidelines. The non-carcinogenic risks caused by Cr6+ through drinking-water intake are low and acceptable for children and adults in most parts of the study area, while, both children and adults face unacceptable carcinogenic risks of Cr6+ in the whole study area. Over 80% of the sampling sites are not permissible to irrigate by groundwater due to the alkalinity hazard. Long-term groundwater irrigation in the study area will result in the formation of saline, alkaline soil and the decreasing of crop yield. The results of this study may help to set up the suitable management strategies to guarantee water supply and health safety for local residents. [ABSTRACT FROM AUTHOR]

In this study, UV‐LED was employed as a novel light source to investigate the degradation of a representative antibiotic compound, chloramphenicol (CAP), in the absence or presence of H2O2. The UV‐LED irradiation showed a higher capability for degradation of CAP than conventional UV‐Hg vapor lamps. Effects of the initial CAP concentration, UV wavelength, and light intensity on the degradation of CAP by UV‐LED were evaluated. Introduction of H2O2 evidently enhanced the degradation efficiency of CAP due to the production of reactive hydroxyl radicals. Results showed that the UV‐LED/H2O2 removed CAP by up to 95% within 60 min at pH 5.0, which was twice as that achieved by the UV‐LED alone. The degradation products were identified to propose plausible degradation pathways. Moreover, the formation potentials of typical carbonaceous disinfection by‐products (C‐DBPs) and nitrogenous disinfection by‐products (N‐DBPs) were assessed for the CAP polluted water treated by the UV‐LED alone and UV‐LED/H2O2 processes. Results indicate unintended formation of certain DBPs, thereby highlighting the importance of health risk assessments before practical application. This study opens a new avenue for developing environment‐friendly and high‐performance UV‐LED photocatalytic reactors for abatement of CAP pollution in water. Practitioner points: UV‐LED bore higher capability to degrade CAP than low‐pressure Hg lamp.The optimal performance to degrade CAP can be achieved at the UV wavelength of 280 nm.The degradation efficiency under UV‐LED/H2O2 process was double of that under UV‐LED process.TCM, DCAN, and TCNM formation were higher under the existence of UV‐LED radiation.The addition of H2O2 had greater influence on the formation of DCAcAm than the introduction of UV‐LED. [ABSTRACT FROM AUTHOR]

Air pollution in transportation cabins has recently become a public concern. However, few studies assessed the exposure levels of suspected air pollutants including Volatile Organic Compounds (VOCs). This paper studied the exposure levels of in-carriage VOCs (benzene, toluene, ethylbenzene, xylene, styrene, formaldehyde, acetaldehyde, acetone and acrolein) in Shanghai, China and estimated the health risk in different conditions. The results indicated that VOCs concentrations in metro carriages varied from different train models, due to the difference in carriage size and ventilation system. The concentrations of aromatic VOCs in old metro carriage were 1–2 times higher than the new ones, as better paintings were used in new trains. Poor air circulation and ventilation in the underground track was likely to be the cause of higher VOCs levels (~ 10%) than the above-ground track. Lower aromatic compounds levels and higher carbonyls levels were observed in metro carriages at suburban areas than those at urban areas, likely due to less aromatic emission sources and more carbonyls emission sources in suburban areas. Acetone and acrolein were found to increase from 7.71 to 26.28 μg/m 3 with number of commuters increasing from 40 to 200 in the carriages. According to the acceptable level proposed by the World Health Organization (1 × 10 − 6 –1 × 10 − 5 ), the life carcinogenic risk of commuters by subway (8.5 × 10 − 6 -4.8 × 10 − 5 ) was little above the acceptable level in Shanghai. Further application of our findings is possible to act as a reference in facilitating regulations for metro systems in other cities around world, so that in-carriage air quality might be improved. [ABSTRACT FROM AUTHOR]

Air quality in transportation microenvironment has received widespread attention. In this study, the exposure levels of volatile organic compounds (VOCs) and particulate matter that have a diameter of less than 2.5 micrometers (PM2.5) in Shanghai metro system were measured simultaneously, and their risks to human health under different driving conditions were then assessed. The results showed that VOCs, PM2.5 concentrations and life cancer risk (LCR) of four VOCs (benzene, formaldehyde, ethylbenzene, and acetaldehyde) in the old metro carriages were about 3 times, 3 times and 2 times higher than those in the new metro carriages, respectively. This difference can be ascribed to the fact that air filtration system in the new metro trains is significantly improved. The VOC levels, PM2.5 concentrations and LCR of VOCs on the above-ground track were slightly higher than those on the underground track. This is due to less outdoor polluted air entering into the carriage on the underground track. Number of passengers also had an effect on VOCs and PM2.5 concentrations in metro carriages. Additionally, the LCR of VOCs inside metro trains should not be ignored (7.69 × 10−6~1.47 × 10−5), especially inside old metro trains with the old ventilation system. [ABSTRACT FROM AUTHOR]