环境污染及其防治 土壤污染及其防治

X53200701690典型污灌区土壤中多环芳烃的垂直分布特征/肖汝(北京科技大学土木与环境工程学院)…∥环境科学研究/中国环科院.-2006,19(6).-49~53环图X-6研究了有污水灌溉历史的沈抚灌区、浑浦灌区和清原对照点3个土壤剖面多环芳烃(PAHs)含量的分布特征.结果表明,在美国EPA优先控制的16种PAHs中,沈抚灌区土壤剖面中检测出10种,浑浦灌区检出12种,清原检出8种.PAHs总含量峰值随着土壤深度的增加呈下降趋势,但最高值均未出现在0~2cm土层,而是分布在2~5和5~10cm土层.各剖面单组分分布以4~5环PAHs为主,主要污染物是荧蒽、苯并[a]蒽和苯并[k…     

浑河沿岸污灌区地下水中PAHs分布特征研究

在浑河沿岸沈抚、浑蒲污灌区采集23个地下水样,采用固相萃取-气相色谱/氢火焰检测器(SPE-GC/FID)方法,对美国环境保护局(USEPA)优先控制的16种多环芳烃(PAHs)进行定量分析.结果表明,该区域地下水受到PAHs严重污染,苯并[a]蒽(BaA)、苯并[k]荧蒽(BkF)检出率分别为100%和82.6%.土壤剖面研究结果表明,BaA和BkF在土壤中的垂直分布比较均匀,显示其在土壤中具有很强的迁移能力.研究发现其原因在于BaA和BkF的沉积物-水分配系数(Koc)较大,其对数值lg Koc分别为5.30和5.74,在土壤-地下水粗分散系统中,容易吸附于大颗粒胶体有机质上,形成悬浮液、乳浊液或者泡沫等,并在布朗运动力推动之下发生迁移.     

污灌区土壤中多环芳烃的垂直分布及可能来源

用气相色谱-质谱联用(GC/MS)的方法分析太原市小店污灌区9个土壤剖面中16种多环芳烃(PAHs)含量及垂直分布特征.结果表明,小店污灌区表层土(0～10 cm)中PAHs平均含量变化趋势为背景区<沼泽区<清灌区<污灌区;大部分剖面土中PAHs含量随土层深度增加呈减少趋势,PAHs含量变化幅度较大的位置集中在地表以下0～40 cm范围内;高环(4～6环)PAHs大量富集在距地表0～50 cm土壤内,清灌区土壤对4～6环PAHs的富集能力强于污灌区;不同环数PAHs与TOC和砂粒呈正相关关系(rmax=0.791,P=0;rmax=0.882,P=0),与pH呈负相关关系(rmin=-0.1,P=0.702);距地表0～40cm范围内的土壤中PAHs的主要污染来源为小店区煤的燃烧;燃烧产生PAHs的污染途径一是直接沉降至土壤中,二是沉降至水体中,吸附在固体颗粒表面,随着灌溉污水流动而在土壤中大量富集.     

某油泥堆放场地中多环芳烃的污染及其垂向分布特征

通过采集某油田油泥堆放场地及其周边24个表层土壤样品和2个剖面土壤样品,采用超声波萃取-气相色谱/氢火焰离子化检测分析方法,对美国环境保护局(USEPA)优控的16种多环芳烃(PAHs)进行定量分析.结果表明:该研究区域的PAHs污染已较为严重,污染场地内16种PAHs的检出率为100%,w(PAHs)平均值为7 770.7 ng/g;周边土壤的16种多环芳烃的检出率为58.3%～100%,二苯并[a,h]蒽及茚并[1,2,3-cd]芘的检出率相对较低,w(PAHs)平均值为2 038.8 ng/g.研究区域内主要污染物为萘、苊、二氢苊、芴、菲、蒽、荧蒽、(苊)、芘、苯并[a]蒽和苯并[a]芘.从母体PAHs与污染物来源的关系和单组分比值可以看出,污染场地内及周边土壤的污染源是石油源和燃烧源的混合源.w(PAHs)在土壤剖面中的峰值出现在40～60及20～40 cm处,不同组分的PAHs在土壤剖面中的迁移能力表现为2～3环PAHs＞4环PAHs＞5～6环PAHs.     

废旧汽车拆解区土壤中多环芳烃垂向分布特性

研究分析了废旧汽车拆解区土壤剖面的美国EPA优控的16种多环芳烃的纵向分布.结果表明,表层土壤中16种多环芳烃总含量达到了17 323 ng·g-1,其中芘(Pyr)、苯并[a]蒽(BaA)、芴(Flu)含量最高,分别达到11 820、1 234和1 083 ng·g-1.汽车拆解区表面和土壤深度为10 cm的土壤均达到了重度污染级别;深度在50~350 cm之间的土壤为轻度至中度污染,当土壤深度超过400 cm,土壤基本未受到污染.但是,7种致癌性PAHs(Chr、BaA、BbF、BkF、BaP、DahA、IcdP)总量在土壤深度达到850 cm时仍有34.15 ng·g-1.随着土壤深度的增大,多环芳烃含量急剧降低,当土壤深度超过300 cm,三环的菲(Phe)、荧蒽(Fl)和二氢苊(Ace)成为优势组分.土壤剖面菲(Phe)/蒽(Ant)比值和荧蒽(Fla)/芘(Pyr)、Fluo/Pyr、BaA/(BaA+Chr)等参数表明,土壤表面的多环芳烃主要来源于石油污染.     

北京东南郊污灌区PAHs垂向分布规律

采用Eijkelkamp土壤采样器对北京东南郊污灌区进行了3个钻孔剖面采样,分析了土壤样品的理化参数,并且采用气相色谱-质谱联用仪对土壤样品的多环芳烃（PAHs）进行了定量分析,研究了土壤理化参数和16种PAHs从表层到5.5 m深的范围内垂向变化规律.结果表明,污灌区表层土壤中有14种PAHs检出,检出浓度在4～428 μg/kg之间,表层以下PAHs的检出种类显著减少,主要以2环和3环的萘、菲、芴、苊烯、二氢苊、荧蒽6种为主.粘粒含量、粘土矿物总量、阳离子交换容量以及总有机碳4个理化参数相互之间在垂向变化上具有一致性,均在0.05水平上显著相关.表层以下粘粒含量与低环PAHs在垂向含量变化也有较好的一致性,粘粒含量高的层位,PAHs含量也较高.从剖面PAHs含量变化可以判断,低环PAHs较易迁移,它们的迁移性强弱顺序为：二氢苊>芴>萘>菲>苊烯>荧蒽,其它高环PAHs难以迁移,仅在表层土壤中检出,说明在长期污灌条件下,迁移性较好的低环PAHs能够迁移到较深的土层中,有可能导致浅层地下水的污染.     

煤矿区表层土壤中芳香烃组成、分布特征及标志化合物研究

采用GC-MS技术分析了平顶山市石龙区土壤样品中多环芳烃(PAHs)污染物的化学组成及分布特征,共鉴定出78种代表性化合物,包括11种US EPA优控PAHs.结果表明,总体上土壤样品中单体烃菲、荧蒽、芴、芘含量比较高.在不同功能区域芳烃含量差别较大,采矿区及焦化厂区土壤中芳烃含量明显高于污灌区和农业区,而煤矸石山附近土壤中芳烃含量最高.采矿区、焦化厂区和污灌区土壤中低环数PAHs的比例远大于高环数PAHs,农业区反之.通过对(ρ)MP/(ρ)P、MPI1、(ρ)P/(ρ)A、(ρ)FL/(ρ)PY等参数值的分析认为,煤尘、烟灰沉降是石龙区土壤中PAHs积累的主要影响因素.由单体烃与PAHs的相关性分析得知,苊和蒽可作为煤矿区域表层土壤中PAHs的标志性污染物.     

南京和宜兴市土壤中多环芳烃(PAHs)的纵向分布

采集了江苏省南京和宜兴市的土壤剖面样品,用高效液相色谱分析了16种PAHs在土壤样品中的含量,研究了PAHs在土壤剖面中的纵向分布特征和影响因素。结果表明,在采样点土壤0～10cm的表土中16种PAHs总量最高,为280.8～717.1μg/kg,随着土壤剖面的加深PAHs总量减少,在70～80cm土层中为8.7～97.5μg/kg。不同PAHs组分在土壤中分布的特点不同,低环的PAHs(≤3环)含量在0～80cm土层中都有分布且随土壤深度加深而减少,而高环的PAHs(≥4环)主要分布在0～30cm土层中,30cm以下土层中含量较少甚至检测不到。相关分析表明,在每个土壤剖面中PAHs总量与其土壤有机碳含量显著相关,PAHs在农田土壤剖面中的纵向分布与土壤有机碳含量、PAHs的理化性质有很大的关系。     

多环芳烃在不同灌区土壤剖面的分布特征研究

文章在不同类型灌溉用水的三个典型灌区进行土壤精细剖面钻探采样分析,研究16种优控多环芳烃在土壤剖面的分布特征和不同灌溉条件对土壤质量的影响。结果表明:表土是多环芳烃的主要累积层位,污灌区、再生水灌区、清灌区表土的多环芳烃总量分别为726、200、34μg/kg,说明长期进行污水和再生水灌溉均会造成不同程度的土壤污染;受多环芳烃自身理化性质的影响,低环的多环芳烃容易向土壤剖面的深部迁移,在表土以下的层位占绝对优势分布,高环的多环芳烃迁移性很弱,基本只在表层有检出;通过对各灌区剖面的典型多环芳烃含量和土壤理化指标进行相关分析和回归分析,得出TOC是多环芳烃在土壤剖面垂向迁移的主要影响因素。     

大清河流域表层土壤中多环芳烃的污染特征及来源分析

采集大清河流域72个表层七壤(0～20cm)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,根据多环芳烃分布特征和苯并[a]蒽/(苯并[a]蒽+麓)和荧葸/(荧蒽+芘)比值分析了其污染来源,并初步评价了其污染水平.结果表明,表层土壤中16种多环芳烃含量范围为54.2-3231.6μg·kg-1,均值和中位数分别为405.1和233.2μg·kg-1.多环芳烃组分特征表现出以萘、菲等2-3环多环芳烃为主,其含量占到总含量的49%,4环和5～6环含量分别为31%和20%.大清河流域土壤多环芳烃污染主要来自于燃烧源,并表现出以生物质和煤的燃烧为主要来源的特征.相对于国内外其它地区多环芳烃检测结果和土壤标准,大清河流域土壤多环芳烃处于中等偏低污染水平,Nap和Fla是主要的超标化合物.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

Degradation of 2,4-dichlorophenol(2,4-DCP)was studied in a novel three-electrode photoelectrocatalytic(PEC)integrative oxidation process,and the factors influencing the degradation rate,such as applied current,flow speed of O_2,pH,adscititious voltage and initial 2,4-DCP concentration were investigated and optimized.H_2O_2 was produced nearby cathode and Fe~(2 )continuously generated from Fe anode in solution when current and O_2 were applied,so,main reactions,H_2O_2-assisted TiO_2 PEC oxidation and E-Fenton reaction,occurred during degradation of 2,4-DCP in this integrative system.The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process,while it was only 31% in E-Fenton process and 46% in H_2O_2-assisted TiO_2 PEC process.So,it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect.By the investigation of pH,it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

Effects of arsenic on seed germination and physiological activities in wheat seedlings

The effects of arsenic(As)were investigated on seed germination,root and shoot length and their biomass and some other factors to elucidate the toxicity of As.The results showed low concentrations of As(O-1 mg/kg)stimulated seed germination and the growth of root and shoot,however,these factors all decreased gradually at high concentrations of As(5-20 mg/kg).The contents Of O2-,MDA,soluble protein and peroxidase(POD)activity all increased with increasing As concentrations.Soluble sugar content,ascorbate peroxidase(APX),and superoxide dismutase(SOD)activities decreased at low concentrations of As,and increased at high concentrations of As.While acetylsalicylic acid(ASA)and chlorophyll contents,catalase(CAT)activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg,and then decreasing trend.By polyacrylamide gel electrophoresis(PAGE).As induced the expression of POD isozymes of wheat seedlings.As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg.However,As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg.The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.     

Sustainability： A view from the wind-eroded field

This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeo- aeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground （even when they are attached to dust-sized particles）, and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustalnabillty of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas （like China, the Sahel and Norflawestern Europe） generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth （so that wind erosion may even improve the soil）. Finally some remarks are made about environmental change in relation to sustainability.     

Bioconcentration kinetics of PCBs in various parts of the lifecycle of the tadpoles Xenopus laevis

Polychlorinated biphenyls （PCBs） in Xenopus laevis have been reported only for a few congeners. Additionally, there is very little information on the ability of Xenopus laevis to bioconcentrate PCBs. To address these issues, the tadpole Xenopus laevis was exposed to Aroclor 1254 mixtures in water at room temperature for 110 d followed by an additional 110 d of nonspiked PCBs in the water for the control group. During the whole process, bioconcentration factors （BCFs） of PCBs ranged from 1180 to 15670. For most PCB congeners, the highest and lowest bioconcentrations of the kinetic curves were found to be remarkably simultaneous, respectively. All 141 PCB congeners under the same experimental conditions had no linear correlation on the lgBCF versus lgKow relationship. The relationship between lgBCFs and lgKow followed a parabolic pattern indicative of selective bioconcentration, suggesting that the kinetic curves of the PCB congeners observed in the lifecycle of the tadpoles may be concentrated due to the amphibian special species and internal metabolism. In contrast, lgBCFs for PCBs were inversely related to lgKow, suggesting that a metabolism of the higher Kow PCB congeners occurred. These results support the author＇s conclusion that the tadpole Xenopus laevis plays major roles in the bioconcentration of PCB congeners, and demonstrated that the exposure kinetic curves of PCB congeners are complex. Besides the amphibian metamorphous development, the lifecycle of the tadpole Xenopus laevis also may be of importance in determining the bioconcentration of PCB congeners.     

Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

Polymerase chain reaction(PCR)was used to amplify a 600-base pair(bp)sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil(Alfisol)and Red soil(Ultisol),and three different minerals(goethite,kaolinite,montmorillonite). DNA bound on soil colloids,kaolinite,and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted,10- and 20-fold.The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected.DNA bound on goethile was amplified irrespective of whether the complex was used directly,or diluted 10- and 20-fold.The amplification of mineral-bound plasmid DNA by PCR is,therefore,markedly influenced by the type and concentration of minerals used.This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.     

Arsenic uptake and transport of Pteris vittata L. as influenced by phosphate and inorganic arsenic species under sand cu｜ture

In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator, uptake and transport of arsenate (As(Ⅴ)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P. vittata. The reduction in As accumulation was greater in old fronds than in young fronds, and relatively weak in root and rhizome. Moderate increases, from 0.05 to 0.3 mmol/L, in phosphate reduced uptake of As(Ⅲ) more than As(Ⅴ), while the reverse was observed at high concentrations of phosphate (≥ 1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposure to As(Ⅴ); but the suppression of phosphate to As transport in the root or rhizome may be insignificant when P. vittata when exposure to As(Ⅲ) under sand culture conditions. The finding will help to understand the interaction of P and As during their uptake process in P. vittata.