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Microbial community, as the decomposers of constructed wetland (CW), plays crucial role in biodegradation and biotransformation of pollutants, nutrient cycling and the maintenance of ecosystem balance. In this study, 9 water samples, 6 sediment samples, and 8 plant samples were collected in Annan CW, which has the functions of water treatment and wetland culture park. The characteristics of microbial community structure in different media were illustrated by using of high-throughput sequencing-based metagenomics approach and statistical analysis. Meanwhile, this study identified and classified human pathogens in CW to avoid potential risks to human health. The results showed that dominant bacteria phyla in CW include Proteobacteria, Bacteroides, Actinobacteria, Firmicutes and Verrucomicrobia. The distribution of microorganisms in three media is different, but not significant. And the pH and DO profoundly affected microbe abundance, followed by water temperature. The microbial diversity in sediments is the highest, which is similar with the detection of human pathogens in sediments. Moreover, compared with Calamus, Lythrum salicaria and Reed, Scirpus tabernaemontani has fewer pathogenic microorganisms. The distribution of microorganisms in the CW is complex, and a variety of human pathogens are detected, which is more prone to create potential risks to human health and should receive additional attention. [Display omitted] • The dominant phyla in CW include Proteobacteria, Bacteroides and Actinobacia. • The microbial diversity in sediments is the highest, the same with human pathogens. • The pH and DO profoundly affect microbe abundance, followed by water temperature. • The proportion of HPs in the surface wetland is highest. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) have become a major type of persistent organic pollutant (POPs) in the world. To well understand the occurrence, spatial distribution and source apportionment of 16 PAHs in different media in Beijing, a comprehensive study was conducted based on 337 obtained and subsequently selected samples in four specific media, including soil, road dust, surface water and atmosphere covering sampling time spanning from 2005 to 2014. Mean concentrations of Σ16 PAHs in soils (878.5 μg/kg) decreased from inner city to exterior areas with different land uses decreased in the order of industrial estate (2510 μg/kg)>educational area (1331 μg/kg)>Park (783 μg/kg)>cultivated (650 μg/kg)>roadside (583 μg/kg)>residential (568 μg/kg)>green area (478 μg/kg)>forest area (125 μg/kg). Meanwhile, PAHs concentrations in branch roads were slightly higher than trunk roads and mainly concentrated in urban areas (1136 μg/kg). Affected by industrial and residential areas, PAHs concentrations in downstream surface rivers were much higher than upstream surface rivers (475 ng/L). Due to strong mobility, PAHs concentrations in atmosphere were not equally distributed around the study area (157.59 ng/m3). The result of source apportionment determined by diagnostic ratios method indicated PAHs in multiple media in Beijing are mainly from coal and biomass combustion. [ABSTRACT FROM PUBLISHER]

Understanding the exposure risks of trace metals in contamination soils and apportioning their sources are the basic preconditions for soil pollution prevention and control. In this study, a detailed investigation was conducted to assess the health risks of trace metals in surface soils of Beijing which is one of the most populated cities in the world and to apportion their potential sources. The data set of metals for 12 elements in 240 soil samples was collected. Pollution index and enrichment factor were used to identify the general contamination characteristic of soil metals. The probabilistic risk model was employed for health risk assessment, and a chemometrics technique, multivariate curve resolution-weighted alternating least squares (MCR-WALS), was applied to apportion sources. Results suggested that the soils in Beijing metropolitan region were contaminated by Hg, Cd, Cu, As, and Pb in varying degree, lying in the moderate pollution level. As a whole, the health risks posed by soil metals were acceptable or close to tolerable. Comparatively speaking, children and adult females were the relatively vulnerable populations for the non-carcinogenic and carcinogenic risks, respectively. Atmospheric deposition, fertilizers and agrochemicals, and natural source were apportioned as the potential sources determining the contents of trace metals in soils of Beijing area with contributions of 15.5%–16.4%, 5.9%–7.7% and 76.0%–78.6%, respectively. [ABSTRACT FROM AUTHOR]

In this study, continuous monitoring of PM was carried out for 1 year period at one of the largest residential areas in Beijing. Annual mean of PM during sampling period was 100.4 µg/m. The seasonal variation trend of PM was winter > spring > autumn and summer. The total mass concentrations of metals in PM ranged from 0.4 to 13.2 μg/m. There were significant ( p < 0.05) seasonal variations for concentrations of Ca, Al, Mn, As, Rb, Cr, Ni, Cd and Co, seasonal variations in PM-associated metals were not necessarily the same as the seasonal variation in PM, related to differing seasonal trends in source types. The impact of meteorological factors (e.g., wind speed) on metals levels of PM was found to be significant by regression models. The EFs value of Ag, Ca, Cd, Pb, Zn, As, Cu, and Cr were higher than ten, suggesting that those elements were primarily contributed by anthropogenic sources. Seasonal characteristic of EFs were found for As, Cr, Ca and Ag, which indicating the seasonal pollution sources types for those metals. Overall, these findings indicated that the pollution control of ambient PM should not be negligible in residential area in Beijing and the local government should pertinent and accurate prevent and control of air pollution as well as protect human health. [ABSTRACT FROM AUTHOR]

The aquifer in the Beijing Plain is intensively used as a primary source to meet the growing needs of the various sectors (drinking, agricultural, and industrial purposes). The analysis of groundwater chemical characteristics provides much important information useful in water resources management. To characterize the groundwater chemistry, reveal its spatial and seasonal variability, and determine its quality suitability for domestic and agricultural uses, a total of 200 groundwater samples were collected in June and October 2012 from 100 exploited wells in Daxing District, Beijing, China. All of the indices (39 items) listed in the Quality Standard for Groundwater of China (QSGC) as well as eight additional common parameters were tested and analyzed for all samples, based on which research target was achieved. The seasonal effect on the groundwater chemistry and quality was very slight, whereas the spatial changes were very obvious. The aquifer is mainly dominated by HCO-Ca·Mg-type water. Of the 39 quality indices listed in QSGC, 28 indices of all of the samples for the 2 months can be classified into the excellent level, whereas the remaining 11 indices can be classified into different levels with the total hardness, NO, NO, and Fe being the worst, mainly distributed in the residential and industrial land. According to the general quality index, the groundwater can be classified from good to a relatively poor level, mainly from southeast to northwest. Furthermore, the relatively poor-level area in the northwest expands to the southeast more than in the past years, to which people should pay attention because this reverse spatial distribution relative to the natural law indicates an obvious, anthropogenic impact on the groundwater. In addition, the groundwater in this area is generally very suitable for irrigation year-round. Nevertheless, we recommend performing agricultural water-saving measures for the sustainable development of water and urbanization, groundwater recovery, and ecological safety. [ABSTRACT FROM AUTHOR]

A physical, hydrochemical and isotopic evaluation of springs in Beijing was conducted in 2009 to reveal apparent changes in the properties of those springs. The results showed that most of the 2nd class springs and more than 50 % of the 1st class springs recorded in the early 1980s were depleted, while the discharges of existing springs have also decreased sharply. In addition, the majority of springs were of the HCO-Ca-Mg type and good water quality, with the quality indices changing slightly compared to those recorded 30 years ago. The abundances of H, O, and H in the springs indicated that most of the springs were of meteoric origin with a relatively close connection to modern atmospheric precipitation. As a result, the springs have a relatively strong renewability within a shallow circulation. [ABSTRACT FROM AUTHOR]

Rapid population growth and increased economic activity impose an urgent challenge on the sustainability of water resources in Beijing. Understanding the spatial and temporal variability of precipitation is of the upmost importance in order to sustain the region's water resources. Two time series, one long term (1724-2010) from a single meteorological station and a shorter time series (1980-2010) from 20 different meteorological stations within the Beijing area, were analysed using Linear Regression, Moving Average, Mann-Kendall, Rescaled Range and Spatial Interpolation methods. Results from both the long- and short-term meteorological data show a mean annual precipitation rate of 600 mm and 540 mm respectively. Annual precipitation rates have decreased during the 21st century by an estimated 100 mm or 16% in comparison to the 1990s. The 1980-2010 data show an increase in precipitation during the early 1990s followed by a sharp decrease during the subsequent years. The change of annual precipitation with time is more random and diverse in comparison to space. The main local impact factors (terrain, urbanization and elevation) and how they work on the local precipitation especially the spatial diversity are identified qualitatively. Generally speaking, (1) the annual precipitation of the plain area is more than that of the mountainous area (terrain effect), (2) the annual precipitation of the urban area in the plain area is obviously more than that of the surrounding suburb area (urbanization effect) and (3) the annual precipitation of the lower location is approximately more than that of the higher location (elevation effect). Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

An investigation was conducted in Beijing to identify the groundwater evolution and recharge in the quaternary aquifers. Water samples were collected from precipitation, rivers, wells, and springs for hydrochemical and isotopic measurements. The recharge and the origin of groundwater and its residence time were further studied. The groundwater in the upper aquifer is characterized by Ca-Mg-HCO type in the upstream area and Na-HCO type in the downstream area of the groundwater flow field. The groundwater in the lower aquifer is mainly characterized by Ca-Mg-HCO type in the upstream area and Ca-Na-Mg-HCO and Na-Ca-Mg-HCO type in the downstream area. The δ D and δO in precipitation are linearly correlated, which is similar to WMWL. The δ D and δO values of river, well and spring water are within the same ranges as those found in the alluvial fan zone, and lay slightly above or below LMWL. The δ D and δO values have a decreasing trend generally following the precipitation → surface water → shallow groundwater → spring water → deep groundwater direction. There is evidence of enrichment of heavy isotopes in groundwater due to evaporation. Tritium values of unconfined groundwater give evidence for ongoing recharge in modern times with mean residence times <50 a. It shows a clear renewal evolution along the groundwater flow paths and represents modern recharge locally from precipitation and surface water to the shallow aquifers (<150 m). In contrast, according to C ages in the confined aquifers and residence time of groundwater flow lines, the deep groundwater is approximately or older than 10 ka, and was recharged during a period when the climate was wetter and colder mainly from the piedmont surrounding the plain. The groundwater exploitation is considered to be 'mined unsustainably' because more water is withdrawn than it is replenished. [ABSTRACT FROM AUTHOR]

Researchers are paying more and more attention to the adsorption and transport of heavy metals in soil in this study, laboratory, experiments were performed to investigate the characteristics of adsorption and transport of mercury in soils of different locations in the western suburb of Belling. To characterize the adsorption mechanism of mercury in soil, adsorption isotherms were determined through a batch experiment. Soil column experiments were performed in saturated soil under steady-state flow at a specific water head. The breakthrough curves (BTC) for the tracer (bromine) and mercury were obtained after continuous input. Moreover, two solute transport models [convection-dispersion equation model (CDE) and two-site non-equilibrium model (TSN)] were used to simulate heavy metal movement in soil on a laboratory column scale. According to the simulating results, we explored which model is more adapted to simulate the movement of heavy metals in saturated soil in the western suburb of Belling. [ABSTRACT FROM AUTHOR]

In this study, we developed a screening method for highly accurate and sensitive analysis of 12 illicit drugs and metabolites in fish tissues. The approach was based on ultrasonic-assisted extraction and solid phase extraction, followed by ultra-performance liquid chromatography-tandem mass spectrometry analysis. The homogenized samples were ultrasonic-assisted extracted with 1% acetic acid in methanol followed by SPE cleanup with Oasis MCX cartridge. The method was validated in accordance with the European Medicines Agency guidelines by evaluating the following required parameters: the limits of detection and limits of quantification, linearity, accuracy, repeatability, recovery of extraction, and matrix effect. For the tissues involved in this study, the recoveries ranged from 60% to 127%, and the matrix effect ranged from −19% to 83% with the inter- and intra-day variability below 12%. The method has been successfully applied to wild fish caught from six sampling sites of four urban rivers in Beijing, China. The analysis showed that the target compounds, including amphetamine, 3,4-methylenedioxyamphetamine, codeine and heroin were detected with high detection frequencies. Codeine exhibited the highest bioaccumulation factor (up to 73,986) in the muscle of Crucian carp, while ketamine tended to accumulate in the skin, 3,4-methylenedioxyamphetamine and heroin tended to accumulate in gastrointestinal tract, respectively. • A method for sensitive analysis of 12 illicit drugs in fish tissues was established. • Recoveries from 61 to 127% were obtained in different fish tissues. • The uptake of 12 illicit drugs in fish of 4 urban rivers in Beijing was studied. • Bioaccumulation of illicit drugs was tissue specific. [ABSTRACT FROM AUTHOR]

Abstract: The distribution of 15 phthalate acid esters (PAEs) in water, sediment and suspended particle samples from representative lakes of Beijing was investigated and its relationship with anthropogenic activities was also assessed. The sample preparation and analysis methods for PAEs, using solid-phase extraction or microwave assisted extraction coupled with gas chromatography–mass spectrometry, were developed to achieve the satisfactory detection limits and recoveries. The analysis results indicated occurrences of most target PAEs were widespread in the researched lakes with the total PAE concentrations ranged from 0.386 to 3.184μg/L in water, from 52.6 to 8216.4ng/g dry weight in sediments and from 138.7 to 2052.4μg/g dry weight in suspended particles. Di-(2-ethylhexyl) phthalate and di-butyl phthalate were the predominant PAEs, frequently being detected in all matrices, followed by di-iso-butyl phthalate and butyl benzyl phthalate. It was also found that anthropogenic activities were associated with the spatial distribution of phthalates in sediments considering its relationship with population distribution characteristics of Beijing. [Copyright &y& Elsevier]

Abstract: Precipitation water samples were collected at an urban site in Beijing in a hydrological cycle (July 2008–July 2009), and analyzed for TDS, total alkalinity, total hardness, free CO2, soluble SiO2, bromide, sulfide, phosphate, major ions (K+, Na+, Ca2+, Mg2+, NH4 +, HCO3 −, Cl−, SO4 2−, NO3 −), trace elements (CO3 2−, Mn, Sr2+, Fe2+, Fe3+, Al, F−, NO2 −), stable isotopes (2H and 18O), and radioactive isotope (3H). In addition, available published hydrochemical and isotopic data of precipitation of Beijing in the past were also collected and conjointly analyzed. Most of the parameters of samples tested varied considerably in the hydrological cycle. In general, HCO3 − and SO4 2−, and Ca2+ and NH4 + are the dominant anions and cations, respectively. Using Na+ as an indicator of marine origin, and Al for the terrestrial inputs, the proportions of major elements from sea salt and terrestrial sources were estimated by using the combination of statistical analysis methods and analogy method. More than 70.1% of Cl−, 98.1% of Ca2+, and 93.6% of K+ were non-sea-salt origin, while more than 98.4% of Na+ was from marine sources. The LMWL (Local Meteoric Water Line) was obtained with an equation of δ2H=7.0181δ18O+3.5231 (‰, R2 =0.86, n=36), which was similar to GMWL (Global Meteoric Water Line). δ2H, δ18O and Δ-excess changed radically with month and season, but had no apparent seasonal effect, precipitation amount effect, and temperature effect. The annual mean values of Δ-excess for 1979 (16.5‰) and 1980 (16.3‰) were much bigger than that for 2007 (7.2‰), 2008 (2.1‰) and 2009 (4.5‰). The composition of 2H and 18O was probably intrinsically determined by the sources of water vapor and the physical and chemical processes occurred along the migration paths of water vapor from sources to the aimed precipitation area. Temporal change of 3H was only influenced by the nuclear testing in the early 1960s worldwide and the natural yield of 3H in the upper atmosphere intrinsically. 3H had nearly approached to the natural levels, which would bring difficulty if not invalidation to groundwater dating using 3H technique. [Copyright &y& Elsevier]