RESUMEN
So far little is known about air-soil exchange under any sealed circumstances (e.g., in plastic and glass sheds), which however has huge implications for the soil-air-plant pathways of persistent organic pollutants including organochlorine pesticides (OCPs). A newly designed passive air sampler was tested in a sealed chamber for measuring the vertical concentration profiles of gaseous phase OCPs (hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs)). Air was sampled at 5, 15, and 30 cm above ground level every 10th day during a 60-day period by deploying polyurethane foam cylinders housed in acrylonitrile butadiene styrene-covered cartridges. Concentrations and compositions of OCPs along the vertical sections indicated a clear relationship with proximity to the mixture of HCHs and DDTs which escapes from the soils. In addition, significant positive correlations were found between air temperatures and concentrations of HCHs and DDTs. These results indicated revolatilization and re-deposition being at or close to dynamic pseudo-equilibrium with the overlying air. The sampler used for addressing air-soil exchange of persistent organic pollutants in any sealed conditions is discussed.
Asunto(s)
Contaminantes Atmosféricos/análisis , DDT/análisis , Monitoreo del Ambiente/métodos , Hexaclorociclohexano/análisis , Plaguicidas/análisis , Contaminantes del Suelo/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , TemperaturaRESUMEN
Concentration profiles of polychlorinated biphenyls (PCBs) and toxicity risks of dioxin-like PCBs were investigated in soils collected from a capacitor-burial site. Based on the USEPA model of human health risk assessment, cancer and non-cancer risks for these soils were also estimated when used for residential and industrial purposes. It was observed that the average concentrations of total PCBs (sigma PCBs, 22 congeners) in the soils were 6.23, 19.3, and 1 540 mg x kg(-1) at different depths of 0-30 cm, 30-100 cm, and 200-250 cm, respectively. Tri-CBs and Tetra-CBs were the largest contributors to the total concentrations in the soils, making up 75.7%-94.0%. The toxic equivalent concentration (TEQs) of total PCBs was up to 457 microg x kg(-1), and PCB 126 had the highest contribution. Health risk assessment showed that under residential land uses, children was the most sensitive receptor although cumulative non-carcinogenic risks for both children and adults (0.927-1 760) nearly exceeded the acceptable level, while under industrial land uses except for the topsoil, the total non-carcinogenic risks for workers exceeded the acceptable level. Under residential and industrial land uses, PCBs in the soils had high carcinogenic risks that were more than the acceptable level of carcinogenic risks (10(-6)-10(-5)). Inhalation exposure was the major way subjected to the carcinogenic risk as well as to the non-carcinogenic risk, regardless of children, adults, and workers involved.
Asunto(s)
Dioxinas/análisis , Bifenilos Policlorados/análisis , Contaminantes del Suelo/análisis , Suelo/química , Adulto , Carcinógenos/análisis , Niño , Humanos , Modelos Teóricos , Exposición Profesional , Dibenzodioxinas Policloradas/análisis , Medición de RiesgoRESUMEN
A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.
Asunto(s)
Agricultura , Monitoreo del Ambiente , Metales Pesados/análisis , Contaminantes del Suelo/análisis , Suelo/química , China , Contaminación Ambiental/estadística & datos numéricos , Análisis MultivarianteRESUMEN
The profiles and sources of polycyclic aromatic hydrocarbons (PAHs) were analyzed in 227 agricultural surface soils from the Huanghuai plain, China. The total concentrations of 16 PAHs varied from 15.7 to 1247.6 µg/kg, with an average of 129.5 µg/kg. Compared with pollution level and carcinogenic potential risk in other research, the soil PAH concentrations in this study fell within low to middle level. Unexpectedly, a significant correlation was not observed between the PAH concentration in soils and the corresponding content of the soil organic matter. This is partly interpreted for our sampling sites located in agricultural area where fresh input of organic fertilizers is expected. Principal component analysis-multiple linear regression suggests that low temperature combustion, coal combustion and traffic emissions could be the primary PAH contributors in soils from the Huanghuai plain, accounting for 46.7 percent, 42.1 percent and 11.2 percent of PAH concentrations, respectively.
Asunto(s)
Monitoreo del Ambiente , Contaminación Ambiental/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes del Suelo/análisis , Suelo/química , Agricultura , China , Carbón Mineral , Análisis de Componente Principal , Medición de RiesgoRESUMEN
A high performance liquid chromatographic (HPLC) method was established for the analysis of niclosamide ethanolamine residue in rice and paddy field. The paddy water and plant were extracted with alkaline ethylacetate, while the paddy soil, rice husk and unpolished rice were first extracted with alkaline ethanol, and then with ethylacetate. The extracts were then cleaned-up by a Florisil column and detected by high performance liquid chromatography with an ultraviolet detector (UVD) on a Welchrom C18 column (250 mm x 4.6 mm, 5 microm). The calibration curve showed good linearity from 0.01 mg/L to 10.00 mg/L with the correlation coefficient more than 0. 999 8. The average recoveries of this method were from 93.47% to 100.9% with the relative standard deviations of 1.46% - 5.82% at the spiked levels of 0.01 - 5.00 mg/kg. This method is fast, simple, sensitive, reproducible and practical for the determination of niclosamide ethanolamine residue in paddy fields, and can meet the requirement of the determination of pesticide residues.