中国滨海湿地土壤汞空间分布及影响因素

通过对7个典型滨海湿地土壤（0～20cm）中总汞含量及土壤理化性质、气候以及社会经济因素的测定收集,研究了滨海湿地土壤中汞的空间分布规律和影响因子之间的关系,并对不同介质环境内汞含量进行分析.结果表明:我国滨海湿地土壤总汞的含量范围是1.26～169.94ng/g,平均值为（33.82±3.09） ng/g;滨海湿地土壤汞含量差异是由土壤理化性质、社会经济以及气候因素共同影响的结果,其中土壤理化性质中pH值、有机质、总铁、总氮为关键影响因素;在汞的输入途径中,河流输送对中国滨海湿地土壤总汞含量的影响要高于大气输送.     

Effect of vehicle exhaust on the quantity of polycyclic aromatic hydrocarbons (PAHs) in soil

PAHs are formed during the incomplete combustion of organic substances containing carbon and hydrogen and are one of the first atmospheric pollutants identified as carcinogens. Most of the PAH environmental burden is found in the soil (95%). Soil samples collected from different roadsides were analyzed for seven polycyclic aromatic hydrocarbons (PAHs). The quantitative and qualitative analysis was carried out by UV Spectrophotometer. The individual PAH value ranged from 0.1 to 18.0 mg/kg. Phenenthrene and Pyrene were found to be the most abundant compounds. Vehicle emissions are the principal source of PAH in the Roadside soils. The highest concentration was found at site S2 (Hasthtnagri Roadside) which shows the highest traffic density.     

湖南省农田土壤中HCH和DDT残留状况研究

2009年6月采集了湖南省农田土壤中的160个样品,采用ASE萃取技术,用GC-MS方法测定了样品中的六六六(HCH)、滴滴涕(DDT)。结果表明:HCH和DDT的检出率为100%,说明湖南省农田土壤中有机氯农药残留现象普遍存在。HCH和DDT的平均含量分别为8.03和36.26μg/kg,范围分别在0.20～17.89μg/kg和5.05～45.96μg/kg。与国内不同区域的同类研究相比,湖南省农田土壤的有机氯残留水平处于中等水平。在不同类型土壤中,有机氯残留状况有所差异,HCH在水稻土中残留量最高,而DDT在棉花田最高。     

Migration and biological effect of natural heavy radionuclides on plants

A complex radioecological study of technogenic landscapes of southern Yakutia showed that the main factor responsible for their contamination with uranium and radium is radionuclide dispersal by air with products of rock weathering. Coefficients of biological absorption by plants decrease with an increase in the contamination level, which is explained by the fact that strongly fixed forms of uranium and radium prevail in the contaminated areas. In addition, the root barrier plays an important role. Radiation load is mainly determined by background gamma-radiation. The contribution of internal irradiation accounted for by incorporated radionuclides does not exceed 16% and decreases with an increase in the level of soil contamination. Manchurian alder seeds produced under conditions of enhanced background radiation are more viable than those from the control area. It is shown that seed generations of plants growing under conditions of chronic irradiation are highly resistant to the radiation factor.     

Sugarcane straw management and soil attributes on alachlor and diuron sorption in highly weathered tropical soils

This research evaluated the effects of the new sugarcane harvesting system (without straw burning) and soil attributes on the organic carbon (OC) accumulation and sorption of alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide) and diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) in highly weathered Brazilian soils. Alachlor was more likely to leach (K _d,app = 1.0–7.0 L kg^?1 and mean K _oc,app = 174 L kg^?1) than diuron (K _d,app = 6.2–116.3 L kg^?1 and mean K _oc,app = 1789 L kg^?1). The sorption coefficient (K _d,app) values correlated better with soil OC contents, but the Fe-oxides also played an important role in these highly weathered soils. Sorption was enhanced in the areas without straw burning mostly due to OC accumulation that was higher in the clayey soils, but it was not enough to change their mobility classification.     

Degradation kinetics of forchlorfenuron in typical grapevine soils of India and its influence on specific soil enzyme activities

The rate of degradation of forchlorfenuron, a cytokinin-based plant growth regulator (PGR) was explored in typical grapevine soils of India with simultaneous evaluation of its effect on biochemical attributes of the test soils in terms of the activities of specific soil microbial enzymes. In all the test soils, namely clay, sandy-loam and silty-clay, the dissipation rate was faster at the beginning, which slowed down with time, indicating a non-linear pattern of degradation. Degradation in soils could best be explained by two-compartment 1st + 1st order kinetics with half-life ranging between 4–10 days. The results suggest that organic matter might be playing a major role in influencing the rate of degradation of forchlorfenuron in soil. The rate of degradation in sandy-loam soil was fastest followed by clay and silty-clay soils, respectively. Comparison of the rate of degradation in natural against sterilized soils suggests that microbial degradation might be the major pathway of residue dissipation. Changes in soil enzyme activities as a consequence of forchlorfenuron treatment were studied for extra-cellular enzymes namely acid phosphatase, alkaline phosphatase and β -glucosidase and intracellular enzyme-dehydrogenase. Although small changes in enzyme activities were observed, forchlorfenuron did not have any significant deleterious effect on the enzymatic activity of the test soils. Simple correlation studies between degradation percentage and individual enzyme activities did not establish any significant relationships. The pattern and change of enzyme activity was primarily the effect of the incubation period rather than the effect of forchlorfenuron itself.     

Sorption and photolysis studies in soil and sediment of the herbicide napropamide

Abstract

The influence of soil and sediment composition on sorption and photodegradation of the herbicide napropamide [N, N‐diethyl‐2‐(1‐naphthyloxy)propionamide] was investigated. Five soils and one sediment were selected for this study and the clay fractions were obtained by sedimentation. Sorption‐desorption was studied by batch equilibration technique and photolysis in a photoreactor emitting within 300–450 nm wavelenght with a maximum at 365 nm. Sorption increased with clay content and was not related to organic matter *content. High irreversibility of sorption was related to the greater montmorillonite content. The presence of soil or sediment reduced photolysis rate due to screen effect and this process did not depend on solid composition but on particle size distribution.     

铅同位素解析技术在工业园污染溯源中的应用

针对土壤中重金属污染溯源及解析不同污染源对土壤中铅的相对贡献率问题,以陕西西部某工业园区为例,采集土壤样品、铅锌冶炼厂矿石混合样、热电厂煤样及焦化厂混合煤样共40个,用ICP-MS测定样品的铅浓度及铅同位素比值(208Pb/204Pb、207Pb/204Pb、206Pb/204Pb).借助于铅同位素比值散点图来对比分析采样点土壤、背景点土壤和可能的污染源样品的铅同位素特征分布,判定其主要污染来源.用混合多元模型计算不同污染区域各污染源的贡献率,结果表明,土壤中的铅同位素比值落在铅锌矿石、炼焦用煤及热电燃煤及背景点的铅同位素比值之间,说明各端元介质均有可能对工业园区土壤中的铅污染有贡献.在铅同位素比值散点图中土壤铅浓度大于60 mg/kg的采样点的铅同位素比值集中落在热电燃煤与炼焦用煤附近.统计定量解析结果可知,对工业园区土壤铅污染的贡献大小依次为热电厂、焦化厂和铅锌冶炼厂.研究表明,铅同位素指纹解析技术用于定性与定量解析工业园区土壤铅污染效果较为理想.     

天津滨海工业区土壤中多环芳烃的污染特征及来源分析

采集天津滨海工业区38个表层土壤样品,利用GC/MS分析技术,研究了土壤中16种优控多环芳烃的含量和组分特征,运用主成分因子载荷方法分析了其污染来源,并初步评价了其风险水平.结果表明,该区域内94.7%土壤已被污染,其中重污染土壤占39.5%,最高污染样点PAHs含量高达5991.7 ng·g-1,平均含量为1148.1 ng·g-1,且城区土壤残留水平明显高于乡村土壤;PAHs的组分特征为以毒性水平较高的高环化合物为主;其污染来源主要是煤、天然气和汽油燃烧组成的混合源.     

Selenium fractions in organic matter from Se-rich soils and weathered stone coal in selenosis areas of China

A high degree of association between Selenium (Se) and organic matter has been demonstrated in natural environments, but Se fractions and speciation in organic matter is unclear. In this study, a method for quantifying organic matter associated with Se (OM-Se) was developed to investigate Se fractions in organic matter in Se-rich soils and weathered stone coal from Enshi, China, where Se poisoning of humans and livestock has been documented. Initially, Se was extracted using water and a phosphate buffer. Subsequently, OM-Se was extracted using NaOH, and then speciated into Se associated with fulvic acids (FA-Se) and humic acids (HA-Se). Both FA-Se and HA-Se were further speciated into the weakly bound and strongly bound fractions using a customized hydride generation reactor. The results show that FA-Se (1.91-479 mg kg⁻¹) is the predominant form of Se in all Se-rich soils and the weathered stone coal samples, accounting for more than 62% of OM-Se (3.07-484 mg kg⁻¹). Weakly bound FA-Se (1.33-450 mg kg⁻¹) was prevalent in the total FA-Se, while weakly bound HA-Se (0.62-26.2 mg kg⁻¹) was variable in the total HA-Se (1.15-32.5 mg kg⁻¹). These data indicate that OM-Se could play a significant source and sink role in the biogeochemical cycling of Se in the supergene environment. Weakly bound FA-Se seems to act as a potential source for bioavailable Se, whereas strongly bound HA-Se is a possible OM-Se sink which is not readily transformed into bioavailable Se.