Distribution, contamination assessment, and sources of heavy metals in surface sediments from the south of the North Yellow Sea, China

This paper reports the contents of six heavy metals and particle sizes in the surface sediments of 120 sampling stations in the southern North Yellow Sea to reveal heavy metal distribution characteristics, contamination assessment, and sources. Cu and Cr enrichments were mainly found in coastal areas with high mud content (silt and clay). However, Zn, Cd, Pb, and Hg were enriched in Weihai Bay and Dongpu Bay, which have denser populations, estuaries, and shipyards. The geoaccumulation index and principal component analysis showed that Cu and Cr contamination was low, and the sources were mainly natural processes. In addition, Zn and Cd pollution in the nearshore area was moderate, and its provenance was natural processes and human activity. However, most areas exhibited Pb and Hg contamination due to waterborne traffic and industries, including shipbuilding and gold mining.

Distribution, contamination and provenance of heavy metals in sediments from the nearshore area of Weihai City, eastern Shandong Peninsula, China

We analyzed eight heavy metals (Cu, Pb, Zn, Cr, Cd, Hg, As, and Ni) in 85 seabed sediments off the coast of Weihai City, eastern Shandong Peninsula, China, to reveal their distributions, enrichment status, and pollutant sources. Cu, Pb, Zn, Cr, As, and Ni were enriched in all bays in both the inner and outer waters. However, Cd and Hg were more abundant in Weihai Bay, followed by Rongcheng Bay and Chaoyang Port, with denser populations and more developed industries near the coast. Most areas exhibited slight contamination with As and Pb, with relatively severe contamination in localized areas. Moreover, Weihai Bay showed slight contamination with Cd, Zn, and Hg. Heavy metals are largely influenced by the discharge of anthropogenic pollutants along the coast. It is recommended to implement strict control measures on the discharge of waste into the sea, and ensure the sustainable development of the marine ecological environment.

Evaluation of water quality at national scale from 2011 to 2021: Advances and challenges

More environmental policies and larger investments in protecting the aquatic environment in China have been made in the last decade than previously. It is important to assess how this will affect river water quality. Here, changes in water quality in China between 2011 and 2021 are assessed. Water bodies meeting class III or better defined in the Chinese Environmental Quality Standards for Surface Water (GB3838-2002) were labeled WQI, water bodies meeting class V or better but below class III were labeled WQII, and water bodies below class V were labeled WQIII. The percentage of WQI water bodies increased from 66.1 % in 2011 to 81.0 % in 2021, and the percentages of WQII and WQIII water bodies decreased between 2011 and 2021. The percentage of WQI water bodies increased more quickly and the percentage WQIII water bodies decreased more quickly after 2017 than between 2011 and 2016. The percentages of WQI water bodies in the Northwest River Basin (RB), Pearl RB, Southeast RB, Southwest RB, and Yangtze RB were >80 %, and were higher than the percentages of WQI water bodies in the other five RBs. The percentages of WQI and WQII water bodies increased but the percentage of WQIII water bodies decreased in the Hai RB. The percentage of WQI water bodies increased but the percentages of WQII and WQIII water bodies decreased in the Huai RB, Liao RB, Yangtze RB, and Yellow RB. The river monitoring capacity increased and pollution sources, particularly point sources, became more controlled, and this improved river water quality. River management in China has passed the first stage of controlling pollution sources after 10 years of centralized management. The next stage should be focused on strengthening control of non-point sources of pollution and rehabilitating ecological systems to improve river health.

Spatial variability and risk assessment of heavy metals in the soil surrounding solid waste from coking plants in Shanxi, China

Heavy metal pollution in the soil surrounding solid wastes from coking plants poses potential threats to human health and has attracted widespread attention. This study is the first to assess the spatial variability and risks of heavy metals in the soil surrounding solid waste from coking plants. The results showed that the concentrations of Cu, Ni, Pb, and Cd in the soil were much higher than the background value of the soil. Solid waste had a clear influence on the contents of Ni, Cd, Mn, Pb, and Cr in the soil. The ecological risk assessment of heavy metal pollution demonstrated that the pollution degree of Cu, Pb, and Cd was more serious than others, and the ecological risk of heavy metals was mainly caused by Cd in the soil. The human health risk assessment showed that adults and children near coking plants might face carcinogenic risk from exposure to Cr. This study can provide a theoretical basis for the prevention and management of soil heavy metal pollution surrounding solid waste in coking plants.

Sources of volatile organic compounds in suburban homes in Shanghai, China, and the impact of air filtration on compound concentrations

Air pollution in China is an ongoing concern, with subsets of the population (e.g., asthmatic children) especially susceptible to the associated health effects. In addition, people spend the majority of their time indoors, where pollutant composition may differ from the better characterized ambient environment. Although volatile organic compounds (VOCs) present health risks and have high concentrations indoors, their sources have not been thoroughly quantified in typical homes in suburban China. Similarly lacking is an understanding of how well a purifier with high efficiency particulate air and activated carbon filters can remove VOCs in a real-world setting in China. In this study, we a) quantified total VOCs (TVOC) and 900 + individual VOCs in 20 homes in China, b) identified potential sources of VOCs, and c) evaluated impacts of filtration. We used non-negative matrix factorization, a variable reduction technique, to identify sources. TVOC and individual compounds had higher concentrations indoors than outdoors (mean [range] indoors, filtration with pre-filter only: 302 [56-793] μg m-3; outdoors, entire study: 92 [26-629] μg m-3), indicating prevalent sources indoors. Many compounds detected have not, to our knowledge, been measured in homes in China. Some compounds (e.g., octanal, heptanal, ⍺-cedrene) were specific to the indoor environment, a few were ubiquitous (e.g., acetaldehyde, formaldehyde), and others were detected infrequently. These compounds may originate from consumer products, solvents, vehicle emissions, a hexane source, wooden products, and cooking. Filtration may improve air quality indoors by lowering concentrations of some VOCs, and, specifically, contributions related to solvents and consumer products.

Concentration, risk assessment, and source identification of heavy metals in surface sediments in Yinghai: A shellfish cultivation zone in Jiaozhou Bay, China

To identify the affection of shellfish cultivation on sediment conditions in Yinghai shellfish cultivation zone in Jiaozhou Bay, the concentration, sources, and the potential ecological risk of heavy metals was identified. Results show the range of Cu, Zn, Pb, Cd, Cr, Hg, As and Mn are 10.15-29.98, 35.95-111.22, 12.44-27.68, 0.08-0.22, 18.03-82.32, 0.04-0.13, 4.02-7.72 and 574.07-839.33mg·kg^-1. Shellfish cultivation influences heavy metal content to some extent. Principal component analysis suggests the accumulation of Zn, Mn, and Cu mainly results from agricultural and industrial actions, Pb from traffic pollution, and Hg from coal combustion. According to the potential ecological index, there is medium and higher ecological risk of contamination by Hg and Cd, which indicates that the study area suffers from varying degrees of heavy metal pollution.

Compositions and pollutant sources of haze in Beijing urban sites

Haze from urban sites in Beijing was collected with a self-assembled electrostatic dust collector. The sizes and morphologies, thermal properties, and compositions of the particles in the haze were characterized by scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and X-ray photoelectric spectroscopy (XPS), respectively. Based on these results, the causes and pollutant sources of the chemicals in the haze were analyzed, and some countermeasures were further advanced to reduce the related pollutant sources. Graphical abstract ᅟ.

The real-time method of assessing the contribution of individual sources on visibility degradation in Taichung

Visibility degradation caused by air pollution has become a serious environmental problem in megacities in Northeast Asia. In general, aerosol chemical compositions are measured by a conventional method of time integrated filter sampling for off-line analysis, which cannot represent temporal and spatial variations in the real atmosphere. The in situ air composition measuring equipment, OCEC carbon aerosol analyzer and a long-path visibility transmissometer-3 were used to collect hourly measurements of the soluble ions, organic/elemental carbon, and ambient visibility, respectively. During the observation, two types of weather conditions were identified: transport and stagnant. Because PM2.5 was identified as the predominant species of light extinction, the sources of PM2.5 were determined and investigated using a positive matrix factorization (PMF) analysis. The PMF outputs characterized the six main emission sources (marine/crustal aerosols, secondary nitrate, secondary sulfate, direct vehicle exhaust, coal/incinerator combustion, and local sewage emission) and reconstructed the PM2.5 mass concentrations of each pollutant source in two weather conditions. In addition, the light extinction (bext) was reconstructed using a multivariate linear regression analysis with hourly-reconstructed PM2.5 mass concentrations to determine the contributions of each source to bext. The primary results showed that the extinction coefficient was proportional to the PM2.5 with high value in stagnant weather conditions. The secondary sulfate was the most abundant source of bext contribution during the sampling period. In addition, the bext contributions of direct vehicle exhaust and coal/incinerator combustion significantly increased in the stagnant weather condition. According to the results of hourly measurements, this work further emphasized that the sources of direct vehicle exhaust and coal/incinerator combustion in PM2.5 were the important sources of visibility degradation in the stagnant weather conditions, which suggests that the pollutants derived from direct vehicle exhaust and coal/incinerator combustion should be controlled first to improve visibility in Taichung.