Ecological Risk Assessment of Heavy Metals at Township Scale in the High Background of Heavy Metals, Southwestern, China
(2.Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang, China 065000)
(3.Key Laboratory of Geochemical Cycling of Carbon and Mercury in the Earth’s Critical Zone, China Geological Survey, Langfang, China 065000)
(4.College of Earth Sciences, Chengdu University of Technology, Chengdu, China 610059)
(5.Yunnan Institute of Geological Survey, Kunming, China 650216)
【Abstract】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.
【Keywords】 soil heavy metal; ecological risk assessment; positive matrix factorization; source apportionment; high background area;
 Drobnik T, Greiner L, Keller A, et al. Soil quality indicators-from soil functions to ecosystem services [J]. Ecological Indicators, 2018, 94: 151–169.
 Zhu L, Liu J W, Xu S G, et al. Deposition behavior, risk assessment and source identification of heavy metals in reservoir sediments of Northeast China [J]. Ecotoxicology and Environmental Safety, 2017, 142: 454–463.
 Hu W Y, Zhang Y X, Huang B, et al. Soil environmental quality in greenhouse vegetable production systems in eastern China: current status and management strategies [J]. Chemosphere, 2017, 170: 183–195.
 Liu M, Zhang A B, Liao Y J, et al. The environment quality of heavy metals in sediments from the central Bohai Sea [J]. Marine Pollution Bulletin, 2015, 100 (1): 534–543.
 Liang J, Feng C T, Zeng G M, et al. Spatial distribution and source identification of heavy metals in surface soils in a typical coal mine city, Lianyuan, China [J]. Environmental Pollution, 2017, 225: 681–690.
 Mwesigye A R, Young S D, Bailey E H, et al. Population exposure to trace elements in the Kilembe copper mine area, Western Uganda: a pilot study [J]. Science of the Total Environment, 2016, 573: 366–375.
 Cheng S P. Heavy metal pollution in China: origin, pattern and control [J]. Environmental Science and Pollution Research, 2003, 10 (3): 192–198.
 Rodrigues S M, Cruz N, Coelho C, et al. Risk assessment for Cd, Cu, Pb and Zn in urban soils: chemical availability as the central concept [J]. Environmental Pollution, 2013, 183: 234–242.
 Cheng H X, Li M, Xie X J, et al. Exploring China: environment and resources [J]. Journal of Geochemical Exploration, 2014, 139: 1–3.
 Chen H Y, Teng Y G, Lu S J, et al. Contamination features and health risk of soil heavy metals in China [J]. Science of the Total Environment, 2015, 512–513: 143–153.
 Kowalska J, Mazurek R, Gasiorek M, et al. Soil pollution indices conditioned by medieval metallurgical activity- a case study from Krakow (Poland) [J]. Environmental Pollution, 2016, 218: 1023–1036.
 Shi Y H, Huang J H, Zeng G M, et al. Evaluation of soluble microbial products (SMP) on membrane fouling in membrane bioreactors (MBRs) at the fractional and overall level: a review [J]. Reviews in Environmental Science and Bio/Technology, 2018, 17 (1): 71–85.
 Chen H M, Zheng C R, Tu C, et al. Heavy metal pollution in soils in China: status and countermeasures [J]. Ambio, 1999, 28 (2): 130–134.
 Wang Q R, Dong Y, Cui Y, et al. Instances of soil and crop heavy metal contamination in China [J]. Soil and Sediment Contamination: An International Journal, 2001, 10 (5): 497–510.
 Teng Y G, Ni S J, Wang J S, et al. A geochemical survey of trace elements in agricultural and non-agricultural topsoil in Dexing area, China [J]. Journal of Geochemical Exploration, 2010, 104 (3): 118–127.
 China Geological Survey, Ministry of Land and Resources. Geochemical Survey of Cultivated Land in China (2015) [EB/OL]. http: //www.cgs.gov.cn/upload/201506/20150626/gdbg.pdf, 2015–06–25.
 Cheng H X, Li K, Li M, et al. Geochemical background and baseline value of chemical elements in urban soil in China [J]. Earth Science Frontiers, 2014, 21 (3): 265–306.
 Cheng H X, Li M, Zhao C D, et al. Concentrations of toxic metals and ecological risk assessment for sediments of major freshwater lakes in China [J]. Journal of Geochemical Exploration, 2015, 157: 15–26.
 Li M, Xi X H, Xiao G Y, et al. National multi-purpose regional geochemical survey in China [J]. Journal of Geochemical Exploration, 2014, 139: 21–30.
 Li K, Peng M, Zhao C D, et al. Vicennial implementation of geochemical survey of land quality in China [J]. Earth Science Frontiers, 2019, 26 (6): 128–158.
 Peng M, Zhao C D, Ma H H, et al. Heavy metal and Pb isotopic compositions of soil and maize from a major agricultural area in Northeast China: Contamination assessment and source apportionment [J]. Journal of Geochemical Exploration, 2020, 208: 106403, doi: 10.1016/j.gexplo.2019. 106403.
 Ma H H, Peng M, Liu F, et al. Bioavailability, translocation, and accumulation characteristic of heavy metals in a soil- crop system from a typical carbonate rock Area in Guangxi, China [J]. Environmental Science, 2020, 41 (1): 449– 459.
 Li K, Peng M, Yang Z, et al. Trace metals pollution and health risks for planning area soils of 193 Chinese cities [J]. Environmental Science, 2020, 41 (4): 1825–1837.
 Cheng H X, Peng M, Zhao C D, et al. Epigenetic geochemical dynamics and driving mechanisms of distribution patterns of chemical elements in soil, Southwest China [J]. Earth Science Frontiers, 2019, 26 (6): 159–191.
 Yang Y Z. The geochemistry of anomalous elements in the environment of Guizhou [J]. Guizhou Geology, 1999, 16 (1): 66–72.
 Wu Y F, Liu C Q, Tu C L. Speciation of heavy metals in urban soil at Guiyang [J]. Acta Mineralogica Sinica, 2008, 28 (2): 177–180.
 Tu C L, He T B, Liu C Q, et al. Effects of land use and parent materials on trace elements accumulation in topsoil [J]. Journal of Environmental Quality, 2013, 42 (1): 103–110.
 Zhao Y C, Wang Z G, Sun W X, et al. Spatial interrelations and multi-scale sources of soil heavy metal variability in a typical urban-rural transition area in Yangtze River Delta region of China [J]. Geoderma, 2010, 156 (3–4): 216–227.
 Pan Y P, Wang Y S. Atmospheric wet and dry deposition of trace elements at 10 sites in Northern China [J]. Atmospheric Chemistry and Physics, 2015, 15 (2): 951–972.
 Chai Y, Guo J, Chai S L, et al. Source identification of eight heavy metals in grassland soils by multivariate analysis from the Baicheng-Songyuan area, Jilin province, Northeast China [J]. Chemosphere, 2015, 134: 67–75.
 Li S Y, Zhang Q F. Response of dissolved trace metals to land use/land cover and their source apportionment using a receptor model in a subtropic river, China [J]. Journal of Hazardous Materials, 2011, 190 (1–3): 205–213.
 Huang J H, Cheng W J, Shi Y H, et al. Honeycomb-like carbon nitride through supramolecular preorganization of monomers for high photocatalytic performance under visible light irradiation [J]. Chemosphere, 2018, 211: 324–334.
 Luo X S, Xue Y, Wang Y L, et al. Source identification and apportionment of heavy metals in urban soil profiles [J]. Chemosphere, 2015, 127: 152–157.
 Nanos N, Rodríguez Martín J A. Multiscale analysis of heavy metal contents in soils: spatial variability in the Duero river basin (Spain) [J]. Geoderma, 2012, 189–190: 554–562.
 Huang J H, Li F, Zeng G M, et al. Integrating hierarchical bioavailability and population distribution into potential eco-risk assessment of heavy metals in road dust: a case study in Xiandao District, Changsha City, China [J]. Science of the Total Environment, 2016, 541: 969–976.
 Pan H Y, Lu X W, Lei K. A comprehensive analysis of heavy metals in urban road dust of Xi’an, China: contamination, source apportionment and spatial distribution [J]. Science of the Total Environment, 2017, 609: 1361–1369.
 Huang J H, Peng S Y, Mao X M, et al. Source apportionment and spatial and quantitative ecological risk assessment of heavy metals in soils from a typical Chinese agricultural county [J]. Process Safety and Environmental Protection, 2019, 126: 339–347.
 Alleman L Y, Lamaison L, Perdrix E, et al. PM10metal concentrations and source identification using positive matrix factorization and wind sectoring in a French industrial zone [J]. Atmospheric Research, 2010, 96 (4): 612–625.
 Pekey H, . Application of positive matrix factorisation for the source apportionment of heavy metals in sediments: a comparison with a previous factor analysis study [J]. Microchemical Journal, 2013, 106: 233–237.
 Schaefer K, Einax J W. Source apportionment and geostatistics: an outstanding combination for describing metals distribution in soil [J]. Clean-Soil Air Water, 2016, 44 (7): 877–884.
 Xue J L, Zhi Y Y, Yang L P, et al. Positive matrix factorization as source apportionment of soil lead and cadmium around a battery plant (Changxing County, China) [J]. Environmental Science and Pollution Research, 2014, 21 (12): 7698–7707.
 Zhang J, Chen Z L, Xu S Y, et al. Lead pollution and its assessment in urban street dust of Shanghai [J]. Environmental Science, 2006, 27 (3): 519–523.
 Liu Y L, Zhang L J, Han X F, et al. Spatial variability and evaluation of soil heavy metal contamination in the urban-transect of Shanghai [J]. Environmental Science, 2012, 33 (2): 599–605.
 Dai B, Lü J S, Zhan J C, et al. Assessment of sources, spatial distribution and ecological risk of heavy metals in soils in a typical industry-based city of Shandong province, Eastern China [J]. Environmental Science, 2015, 36 (2): 507–515.
 Li Y M, Ma J H, Liu D X, et al. Assessment of heavy metal pollution and potential ecological risks of urban soils in Kaifeng city, China [J]. Environmental Science, 2015, 36 (3): 1037–1044.
 He B, Zhao H, Wang T Y, et al. Spatial distribution and risk assessment of heavy metals in soils from a typical urbanized area [J]. Environmental Science, 2019, 40 (6): 2869–2876.
 Song B, Wang F P, Zhou L, et al. Cd content characteristics and ecological risk assessment of paddy soil in high cadmium anomaly area of Guangxi [J]. Environmental Science, 2019, 40 (5): 2443–2452.
 Liu Y Z, Xiao T F, Xiong Y, et al. Accumulation of heavy metals in agricultural soils and crops from an area with a high geochemical background of cadmium, Southwestern China [J]. Environmental Science, 2019, 40 (6): 2877–2884.
 DZ/T 0295–2016, Determination of land Quality Geochemical Evaluation [S].
 DD 2005–03, Technical Requirements of Ecological Geochemical Assessment Sample Analysis (Trial) [S].
 Muller G. Index of geoaccumulation in sediments of the Rhine River [J]. Journal of Geology, 1979, 2 (3): 108–118.
 Loska K, Wiechula D, Korus I. Metal contamination of farming soils affected by industry [J]. Environment International, 2004, 30 (2): 159–165.
 China National Environmental Monitoring Center. Soil Background Values of Heavy Metals in China [M]. Beijing: China Environmental Science Press, 1990.
 Hakanson L. An ecological risk index for aquatic pollution control. A sedimentological approach [J]. Water Research, 1980, 14 (8): 975–1001.
 USEPA. EPA positive matrix factorization 5.0 fundamentals and user guide [EB/OL]. https: //www.epa.gov/air-research/epa-positive-matrix-factorization-50-fundamentals-and-user-guide, 2014.
 Chavent M, Guégan H, Kuentz V, et al. PCA- and PMF- based methodology for air pollution sources identification and apportionment [J]. Environmetrics, 2009, 20 (8): 928–942.
 Guan Q Y, Wang F F, Xu C Q, et al. Source apportionment of heavy metals in agricultural soil based on PMF: a case study in Hexi Corridor, northwest China [J]. Chemosphere, 2018, 193: 189–197.
 Jang E, Alam M S, Harrison R M. Source apportionment of polycyclic aromatic hydrocarbons in urban air using positive matrix factorization and spatial distribution analysis [J]. Atmospheric Environment, 2013, 79: 271–285.
 GB 15618–2018, Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (Trial) [S].
 Zhao K L, Liu X M, Zhang W W, et al. Spatial dependence and bioavailability of metal fractions in paddy fields on metal concentrations in rice grain at a regional scale [J]. Journal of Soils and Sediments, 2011, 11 (7): 1165–1177.
 Xia W, Wu D M, Yuan Z Y. Study on the migration and transformation law of heavy metals in soil-crop system [J]. Resources Environment & Engineering, 2018, 32 (4): 563–568.
 Kong X Y, Liu T, Yu Z H, et al. Heavy metal bioaccumulation in rice from a high geological background Area in Guizhou province, China [J]. International Journal of Environmental Research and Public Health, 2018, 15 (10): 2281.
 Zhao W F, Song Y X, Guan D X, et al. Pollution status and bioavailability of heavy metals in soils of a typical black shale area [J]. Journal of Agro-Environment Science, 2018, 37 (7): 1332–1341.
 Liu G N, Wang J, Liu X, et al. Partitioning and geochemical fractions of heavy metals from geogenic and anthropogenic sources in various soil particle size fractions [J]. Geoderma, 2018, 312: 104–113.
 Lee J S, Chon H T, Kim K W. Migration and dispersion of trace elements in the rock-soil-plant system in areas underlain by black shales and slates of the Okchon zone, Korea [J]. Journal of Geochemical Exploration, 1998, 65 (1): 61–78.
 Alloway B J. Heavy metals in soils [M]. London: Chapman and Hall, 1995.
 Facchinelli A, Sacchi E, Mallen L. Multivariate statistical and GIS-based approach to identify heavy metal sources in soils [J]. Environmental Pollution, 2001, 114 (3): 313–324.
 Micó C, Recatalá L, Peris M, et al. Assessing heavy metal sources in agricultural soils of an European Mediterranean area by multivariate analysis [J]. Chemosphere, 2006, 65 (5): 863–872.
 Liu R H, Wang Q C, Lu X G, et al. Distribution and speciation of mercury in the peat bog of Xiaoxing’an mountain, Northeastern China [J]. Environmental Pollution, 2003, 124 (1): 39- 46.
 Blake L, Goulding K W T. Effects of atmospheric deposition, soil pH and acidification on heavy metal contents in soils and vegetation of semi-natural ecosystems at Rothamsted Experimental Station, UK [J]. Plant and Soil, 2002, 240 (2): 235–251.
 Chen X D, Lu X W, Yang G. Sources identification of heavy metals in urban topsoil from inside the Xi’an second ring road, NW China using multivariate statistical methods [J]. CATENA, 2012, 98: 73–78.
 Smolders E, Degryse F. Fate and effect of zinc from tire debris in soil [J]. Environmental Science & Technology, 2002, 36 (17): 3706–3710.
 Lv J S, Liu Y, Zhang Z L, et al. Identifying the origins and spatial distributions of heavy metals in soils of Ju country (Eastern China) using multivariate and geostatistical approach [J]. Journal of Soils and Sediments, 2015, 15 (1): 163–178.
 Lu A X, Wang J H, Qin X Y, et al. Multivariate and geostatistical analyses of the spatial distribution and origin of heavy metals in the agricultural soils in Shunyi, Beijing, China [J]. Science of the Total Environment, 2012, 425: 66–74.