Pollution Characteristics And Source Analysis Of Dioxins In The Soil Around Typical Industrial Areas In Northwest My Country

Polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/F s),polychlorinated naphthalenes(PCNs)and polychlorinated biphenyls(PCBs)have received much attention because of their persistence,bioaccumulation,and toxicity(teratogenic,carcinogenic and mutagenesis).These three compounds can be called dioxin-like compounds.The pollution characteristics of PCDD/Fs,PCNs and PCBs have been widely studied in the surroundings environment of the municipal waste incinerators that are identified as major dioxin-like compounds contributors.However,there have been very few studies about pollution characteristics of dioxin-like compounds in the surroundings environment of the cement kilns co-processing municipal waste.The pollution characteristics of dioxin compounds in the surrounding environment of the industrial area have received extensive attention.To the best of our knowledge,few studies have investigated these compounds in industrial areas in the northwestern region of China.In this study,we chose a cement kilns co-processing municipal waste and two typical industrial areas(a comprehensive industrial area and a ferromanganese circular economy industrial area)in Northwestern China as subjects to determined the concentrations distribution of PCDD/Fs,PCBs and PCNs in soil,and identify sources of these compounds.Meanwhile,we identified the relative contribution of individual sources in industrial area to dioxin-like compounds,and assessed the potential risks to human health.The results are the following.1.The levels and pollution characteristics of dioxin-like compounds in soil in the surroundings environment of the cement kilns co-processing municipal waste were determined.The results showed that the PCDD/Fs,PCNs,and PCBs concentration ranges were 2.50-5.95 pg/g,132-1290 pg/g,and 10.8-59.5 pg/g,respectively.The PCDD/Fs and PCBs level in this study were lower than those found in soil around the municipal waste incinerators in previous studies.The source analysis results show that the cement kilns co-processing municipal waste have no fundamental impact on PCDD/Fs in the soil of this study area.Principal component analysis(PCA)showed that the PCNs concentration in soil in the study area was affected by the cement kilns co-processing municipal waste and the historical use of Halowax 1014.The no-carcinogenic risks(no-CR)and carcinogenic risks for children and adults were lower than the reference value(no-CR=1,CR=10-6),while the ingestion gave the highest risks.2.The pollution characteristics and source of dioxin compounds in soil around a comprehensive industrial area in Northwest China were studies.The results of PCA and positive matrix factorization(PMF)show that the local iron and steel plant was the main source of PCDD/Fs concentration in soil in the study area,which contributed more than 90%of the total PCDD/Fs concentration.In addition to the steel smelter,the cement kilns and historical use of industrial products have also made a major contribution to the PCNs concentration in soil surrounding the industrial area.PMF show that iron and steel plant,cement kilns,and Halowax 1051 contribute 32.2%,38.5%,and 22.3%to the concentration of PCNs in soil,respectively.CB-209 was an important contributor to total PCBs in the study area,and likely originated from the phthalocyanine-type pigments used in a local recycled paper mill.Samples S10,S1,S17,and S6 had high ?TEQ(PCDD/Fs+PCNs+PCBs)concentrations,and the carcinogenic risks of PCDD/Fs,PCNs,and PCBs for workers from these samples were 4.87×10-7,2.34×10-7,2.30×10-7,and 2.10×10-7,respectively.According to our results,the health risks of PCDD/Fs,PCNs,and PCBs for workers in this area should be given more attention.3.The pollution characteristics of dioxin compounds in soil around a ferromanganese circular economy industrial area in Northwest China were studies.The PCDD/F,PCN,and PCB concentration ranges were 3.60-156 pg/g,141-832 pg/g and 13.2-1240 pg/g,respectively.The main PCB homologs were CB-209,with an average contribution of about 85%to the total PCBs concentration.Source analysis indicates that the unintentional emissions from dye and paper workshops were responsible for CB-209 concentration in soil in the industrial area.PCA and PMF results show that iron and steel plant was the main source of PCDD/Fs concentration in soil in the study area.PCNs in soil was mainly from the local biomass power plant(54.9%)and iron and steel plant(25.6%),with additional contributions from the historical use of Halowax 1051.The levels of dioxin-like compounds exhibited low carcinogenic risks to workers.With the consideration of the short contamination time and the accumulation of dioxin-like compounds in soil,the carcinogenic risks to workers in the industrial areas should draw serious attention.