Sponsor(s): Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences(CAS)
12 issues per year
Current Issue: Issue 09, 2020
Environmental Science is supervised by Chinese Academy of Sciences and sponsored by Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS). Launched in 1976, it is a monthly and international public journal. Its scope covers the latest and significant achievements in basic research and applied research, and the theories and techniques for pollution control, clean production and ecological construction. The journal is included in MEDLINE, CA, AJ, BP, IM, JICST, ZR, CSA, CSTPCD, CNKI and CSCD.
Zhao Jingzhu, Hao Jiming, Tian Gang
Ecological Risk Assessment of Heavy Metals at Township Scale in the High Background of Heavy Metals, Southwestern, China
Environmental Science,2020,Vol 41,No. 09
Heavy metals (HMs) are naturally occurring elements that have high natural background levels in the environment. Therefore, it is important to conduct ecological risk assessment and identify potential sources of HMs. In the past, studies were conducted at the regional scale. The accuracy of those studies could not meet the needs of spatial planning and natural resource management. Therefore, it is necessary to conduct ecological risk assessment at the township scale. In this study, 1 092 soil samples (from 0–20 cm depth) were collected in the town of Reshui, an area with high background levels of soil HMs with the parent material of carbonatite, which is commonly found in Southwest China. The town of Reshui is a multi-ecological risk superimposed area where the ecological risk is high. In this study, concentrations of HMs (Cd, Cr, As, Hg, Pb, Cu, Zn, and Ni) in the topsoil were analyzed, and statistical analysis (SA), geographic information system (GIS) modeling, and positive matrix factorization (PMF) analysis were performed. The geoaccumulation index ( Igeo) and potential ecological risk index (PERI) were applied for the ecological risk assessment and quantification of the sources of the soil HMs. The mean values of HM concentrations in the topsoil were 18.1, 1.18, 174.1, 202.2, 0.09, 71.1, 34.9, and 167.2 mg·kg −1 for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively, which were considerably higher than the average background value (ABV) in soils in Yunnan Province except for As and Pb. The average concentrations of Cd, Cr, Cu, and Ni exceeded the screening values specified in the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618–2018) by 5.82, 1.16, 4.04, and 1.02 times, respectively. The Igeo value showed that the major pollutant was Cu in the surface soil of the study area, followed by Cr, and Cd. Speciation analysis of HMs indicated that HMs(Cr, As, Pb, Cu, Zn, and Ni) mainly existed in the residual form, mostly from the geological background with low bioavailability. The potential effective components of Hg had higher levels, but the total amount of Hg and its pollution risk were lower. Cd had a high bioavailability ratio, was easy to enter the soil solution and be absorbed by crops, and was the HM with the highest pollution risk in the study area. The PERI showed that the proportions of low ecological risk, moderate risk, and high risk soil samples were 44.23%, 54.40%, and 1.37% of the total number of samples, respectively. Hg and Cd were the major sources of risk because of their high toxicity coefficient. The PMF analysis indicated that there were four major sources of HMs in the study area: human activity, natural sources, coal mining and traffic emissions, and agricultural sources with the risk contribution ratios of 9.29%, 53.67%, 11.23%, and 25.81%, respectively. The PMF analysis effectively quantified the ecological risk from these sources, providing a reference for further pollution control and prevention measures.
Seasonal Pollution Characteristics and Analysis of the Sources of Atmospheric VOCs in Chengdu Urban Area
Environmental Science,2020,Vol 41,No. 09
To investigate the seasonal variations in the concentrations of atmospheric volatile organic compounds (VOCs) in the urban area of Chengdu, VOC species were monitored from December 2018 to November 2019, and the concentrations, chemical composition, chemical reactivity, and sources of VOCs were analyzed. Average volume fractions of VOCs in spring, summer, autumn, and winter are 32.29 × 10 −9, 36.25 × 10 −9, 40.92 × 10 −9, and 49.48 × 10 −9, respectively. The concentrations in winter are significantly higher than the winter concentrations measured in other areas. There is no significant difference between VOC concentrations in spring and summer, but component concentrations vary from season to season. In winter, alkanes account for the largest proportion of total VOCs owing to vehicle emissions. The proportion of oxygen (nitrogen)-containing VOCs in summer and autumn is much higher than that in spring and winter. Volatile emissions from primary sources and secondary conversions have a great contribution. The average concentration of key components of VOCs in different seasons did not change significantly. C 2–C 4 alkanes, ethylene, acetylene, and dichloromethane concentrations may be significantly affected by vehicle exhaust, oil and gas volatilization, solvent use, and LPG fuel use. ·OH consumption rate and OFP calculations show that key active species are mainly m-/ p-xylene, ethylene, propylene, 1-hexene, toluene, isopentane, and n-butane. Therefore, these species should be given priority in emissions control measures. Since the temperature in spring and summer is higher than in autumn and winter, and the UV rays are more intense, PMF analysis reveals the natural sources and the secondary emission sources as the major sources. The oil and gas volatilization sources contribute 9% to VOC concentrations in summer. The major VOC sources in autumn and winter are vehicle exhaust and combustion sources. Emissions from the combustion sources contribute 25% and emissions from the catering sources in autumn and winter contribute 9% to total VOC levels.