微曝气阻隔技术处理污染场地土壤气中苯的研究

以北京某焦化厂苯精制车间废弃场地为研究对象,挖开10m×10m×4m的污染土基坑作为风险管控区,并进行微曝气阻隔技术处理,以期实现风险管控区的土壤气苯污染管控。结果表明,不曝气时,土壤中微生物主要为厌氧微生物。曝气1次不足以改变深层土壤的厌氧状态,对浅层土壤而言无法达到好氧微生物所需的足够O2,使得苯既不能被厌氧降解也不能被好氧降解,反而因扰动作用加速了苯的逸出,使得苯含量不减反增。再曝气3次后,各土层O2含量均大幅增加,污染土层中苯质量浓度降至0.79mg/m3,而清洁土层中苯质量浓度全部降到了0.22mg/m3以下,能够满足《污染场地挥发性有机物调查与风险评估技术导则》(DB11/T 1278—2015)土壤气中苯的筛选值(3.95mg/m3)。     

高原地区铬渣污染场地污染特性研究

在我国高原地区某铬渣污染场地进行钻孔取样,分析场地工程地质特性,对场地铬的污染状况及空间分布特征进行研究。结果表明:场地地质结构较单一,地下水丰富,土质的渗透性强,渗透系数在1.78×10-3~0.243 cm/s之间;场地铬污染严重,总铬与六价铬的浓度最大值分别为22 485.6 mg/kg和7 495.2 mg/kg,地下水中六价铬的浓度最大值为107.2 mg/L;通过剖面铬浓度分析:铬在纵向上浓度分布受土壤质地的影响,均呈现表层4 m浓度较高,4 m以下浓度较低且变化较小的规律。由Kriging插值法绘的铬浓度分布等值线图可清晰看出场地表层土表现出向沟谷位置迁移趋势,地下水中残留的铬向地下水流场方向迁移。     

搬迁化工企业遗留场地氯苯污染迁移模拟与不确定分析

基于某搬迁化工企业场地污染调查数据,应用跃迁概率地质统计工具(T-progs)建立了溶质迁移地质统计模型,对该场地氯苯污染进行了不确定评估和风险分析。结果表明,研究场地地下水氯苯污染主要集中在场地的北部和南部,模拟初期场地北部污染羽中心氯苯最高质量浓度为1 240mg/L,污染物在地下水中随时间迁移扩散,100年后该污染羽氯苯最高质量浓度降低到1 030mg/L,但污染羽整体迁移速度较慢。地质统计模型不确定评估结果显示,100年后污染羽在最小分布条件下的氯苯最高质量浓度约为540mg/L,最大分布条件下约为1 207mg/L;场地氯苯污染风险集中在场地东北部和西南部区域,与地下水流动方向一致,但受场地非均值影响,氯苯阀值捕获风险区分布呈不规则形状。     

中国铬渣污染场地土壤污染特征

近年来,铬渣堆放引起的环境污染问题已引起国内外的广泛关注。通过收集近20年公开发表的论文和两个铬渣污染场地的取样实测,研究了中国铬渣污染场地土壤污染的特征。结果表明,铬渣污染场地的土壤铬含量高(总铬质量浓度最高达56 000mg/kg),周边地下水被污染,土壤呈碱性,残渣态铬占比较大,以Cr(Ⅲ)为主,呈现出一定的空间分布特征。     

上海市延安高架道路绿地土壤与沿线灰尘中铅的分布特征

对上海市区延安高架道路两旁绿地土壤和沿线灰尘中铅的含量调查发现,延安高架道路沿线绿地土壤中全铅平均质量浓度为93.61 mg/kg,是上海市土壤背景值的3.7倍,沿线灰尘全铅平均质量浓度为324.62 mg/kg,远远超过了绿地土壤中铅的含量.研究区域土壤和灰尘中铅的空间分布差异较大,部分地区出现严重积累.土壤和灰尘中铅的分布规律趋于一致,均表现为延安东路最高,其次是延安中路,延安西路最低.所选区域随着垂直道路水平距离的增加,土壤中铅含量的分布呈现一定的规律性,却易受人为影响而变得复杂多样.     

典型氯碱污染场地环境风险评价

以广东某氯碱化工污染场地为研究区域,采集了场地22个土壤及地下水样品,分析了25项污染物在不同区域的分布特征及其来源。监测结果表明,煤炭堆场与锅炉房区土壤受重金属铅、镍污染。六六六、四氯化碳、三氯甲烷、六氯苯、苯是场地的特征污染物,主要分布在危险品仓库、漂洗车间与四氯化碳车间。根据监测结果开展了不同暴露途径致癌风险值及非致癌危害商的计算。结果表明,部分样品表层土壤中上述有机污染物的基于人体健康致癌风险指数均超过10-6,最高达到1.65×10-2,表明风险水平高;非致癌危害在各暴露途径下也超过可接受值1,最高达5.59×104,表明风险水平高。说明对于存在高风险的区域必须进行采取合适的措施进行修复,减缓场地再利用后对人群健康的影响。     

西部某机械加工企业酸洗场地环境调查与污染特征分析

以西北高原地区某铁塔厂酸洗车间为重点区,对场地开展系统的环境调查,结果表明:该场地以重金属锌污染为主要污染因子,场地内土壤Zn浓度范围13.68~68 800 mg·kg-1,局部区域土壤p H异常、土壤Fe含量和Cl-浓度升高现象;土壤Zn污染垂向迁移深,多数点位Zn污染(Zn含量超过200~500 mg·kg-1)深度达10 m以上,少数点位污染深度达15 m以下,其中北区酸池5 m以内、南区酸池3 m以内和下水管道及两侧区域3~10 m深度范围内为重污染;场地土壤p H异常范围与锌污染范围一致,土壤Cl-浓度和Fe浓度与Zn浓度具有相关性,可作为判断土壤锌污染程度和范围的辅助因子;现场速测的Zn含量与实验室总量测定结果一致性强,在p H异常区域的现场速测p H值与实验室测定结果的一致性较好,现场速测结果可作为污染表征的基础依据。推测酸池泄漏、含重金属洗液长期下渗和工业废水的直接排放为场地污染主要原因。     

桂林市表层土壤总汞分布特征研究

为了研究桂林市表层土壤汞污染情况,采集了不同功能区(包括校园区、风景旅游区、交通运输区、居民区、商业区、农业用地区和其他区域)的表层(0~10cm)土壤样品36个,采用硫酸-硝酸混合液浸提、原子荧光方法测定土壤中的总汞。结果表明,桂林市表层土壤的总汞质量浓度在0.136~1.873mg/kg,平均值为0.557mg/kg,中值为0.440mg/kg。各功能区土壤中汞的平均值均超过《土壤环境质量标准》(GB 15618—1995)的一级标准(0.15 mg/kg),以风景旅游区最高,为0.900 mg/kg,其次为商业区,为0.595 mg/kg。进一步对桂林市表层土壤总汞浓度与环境参数的关系进行了研究,结果表明,各采样点土壤的总汞浓度与有机质显著相关,与土壤pH无相关关系。     

土壤中苯并[a]芘和二苯并[a，h]蒽的快速测定及其降解特性研究

建立了加速溶剂萃取-高效液相色谱-二极管阵列检测(ASE-HPLC-PAD)快速测定土壤中苯并[a]芘(BaP)和二苯并[a.h]葸(DBA)的方法.通过提取剂、提取方法的优化,检测波长(BaP、DBA的λmax分别为294.6、295.8 nm)的选择,减少了干扰物的影响,提高了检测灵敏度.土壤中添加BaP、DBA的质量浓度均为0.02～0.50 mg/kg时,其平均回收率均为77.26%～109.56%,相对标准偏差为0.60%～2.74%;土壤中BaP、DBA的最小检测质量浓度分别为2.15、1.10μg/kg.将ASE-HPLC-PAD方法应用于污染场地土壤中BaP与DBA的测定及其降解特性研究表明,BaP与DBA的降解半衰期分别达210、693 d.     

某聚氯乙烯树脂厂退役场地土壤汞污染特征分析

场地重金属污染是工业化进程的产物,污染来源多为原料及副产物的泄漏或不达标排放,给人类和环境造成不同程度的危害。本文以武汉某退役聚氯乙烯(PVC)树脂厂为研究对象,结合氯化汞催化工艺特点,探究场地土壤重金属汞的污染来源及分布特征,为同类型场地土壤重金属汞的污染调查、防治、修复提供案例支撑。研究结果表明:1)参与调查的33个点位中有27.3%已达到相当严重的污染水平,潜在生态风险单项指数Ei值最高达57 900,污染分布范围主要集中于氯化汞催化乙炔生产氯乙烯(VCM)工艺段,水平迁移扩散能力不强;2)重金属汞的垂直迁移受土壤性质影响,粘土对重金属汞的截留效果佳,粘土层中0.8~1.0 m至1.8~2.0 m最大汞浓度衰减量达2 040 mg·(kg·m)~(-1),衰减率达97.2%,而疏松的杂填土则有利于汞的垂直下渗;3)调查区域受重金属汞污染呈现典型点源污染特征。     

Spatial distribution and vertical variation of arsenic in Guangdong soil profiles, China

Total of 260 soil profiles were reported to investigate the arsenic spatial distribution and vertical variation in Guangdong province. The arsenic concentration followed an approximately lognormal distribution. The arsenic geometric mean concentration of 10.4 mg/kg is higher than that of China. An upper baseline concentration of 23.4 mg/kg was estimated for surface soils. The influence of soil properties on arsenic concentration was not important. Arsenic spatial distributions presented similar patterns that high arsenic concentration mainly located in limestone, and sandshale areas, indicating that soil arsenic distribution was dependent on bedrock properties than anthropogenic inputs. Moreover, from A- to C-horizon arsenic geometric mean concentrations had an increasing tendency of 10.4, 10.7 to 11.3 mg/kg. This vertical variation may be related to the lower soil organic matter and soil degradation and erosion. Consequently, the soil arsenic export into surface and groundwaters would reach 1040 t year-1 in the study area.     

Global hexachlorobenzene emissions

Information from a variety of sources has been assembled to give a global picture of hexachlorobenzene (HCB) emissions in the mid 1990s. No single overwhelming source of HCB was identified. The best estimates of global HCB emissions from different categories of sources are as follows: pesticides application - 6500 kg/yr; manufacturing - 9500 kg/yr; combustion - 7000 kg/yr, includes 500 kg from biomass burning. This adds up to total current HCB emissions of approximately 23,000 kg/yr with an estimated range 12,000-92,000 kg/yr. A substantial portion of HCB measured in the atmosphere is thought to come from volatilization of "old" HCB on the soil from past contamination along with unidentified sources. No information on potential sources in developing countries was available.     

非均相UV/Fenton氧化法降解水中六氯苯的研究

采用超声辐照促进浸渍法制备了非均相UV/Fenton催化剂Fe/Al2O3,并对其进行了表征.以制备的催化剂对水中六氯苯进行非均相UV/Fenton法氧化降解.考察了铁的负载量、初始pH、H2O2投加量、催化剂投加量和反应时间对六氯苯降解效果的影响,并探讨了六氯苯的降解动力学规律.结果表明,制备的催化剂表面活性组分分散均匀,对六氯苯具有较高的催化活性和重复利用性.非均相UV/Fenton法降解六氯苯的最佳实验条件为:铁的负载量为2%,废水初始pH为3,H2O2和Fe/Al2O3催化剂的投加量分别为34 mg/L和150 mg/L,反应时间为20 min.在此条件下,浓度为500μg/L的六氯苯降解效率达94.5%.HCB的降解反应动力学规律可用Langmuir-Hinshwood方程很好地描述.六氯苯在催化剂表面的吸附常数为1.962 L/mg,表面反应速率常数为0.08 mg/(L·min).     

Surfactant solubilization of hydrophobic compounds in soil and water

The soil/water partition coefficient (K_d) of hexachlorobenzene (HCB) ranged from 220 1/kg to 1800 1/kg for eight soils having a wide range of physico-chemical properties. K_d normalised to soil organic carbon (K_oc) was found to be 28000 ± 4800 1/kg. Anionic surfactant dodecylsulphate (DS) present at concentrations above the critical micellar concentration (CMC) caused reductions in the apparent soil/water partition coefficient (K_d ^*) in the range of 3–26 times for most soils and up to 36–91 times for sandy soils. Below CMC, at environmentally relevant surfactant concentrations, K_d ^* was reduced by a factor of 1–13. For clay and calcareous soils significant adsorption/complexation/precipitation of DS occurred. At the lowest DS concentration this produced a two-fold increase in K_d ^*. At increasing DS concentrations this effect was shielded by the solubihzing effect from DS. Monomer (K_mn) and micellar (K_mc) surfactant/water partition coefficients for HCB were determined to be, 980 ± 190 1/kg and 21000 ± 1600 1/kg, respectively.     

Combined effects of mercury and hexachlorobenzene in the rat

Abstract

The objective of the present study was to assess the potential interactive effects of two Great Lakes chemical contaminants, hexachlorobenzene (HCB) and mercury (HgCl₂). Groups of 10 female Sprague‐Dawley rats were administered by gavage single doses of HCB (400, 600 mg/kg b.w. in corn oil), HgCl₂ (10.0, 12.5 mg/kg b.w. aqueous) or combinations of both followed by observation for clinical signs of toxicity for 14 days. Five animals from treatment groups died before the termination of the study; one animal each in 600 mg HCB, 400 mg HCB + 10 mg HgCl₂, and 600 mg HCB + 10 mg HgCl₂, and two animals in 600 mg HCB + 12.5 mg HgCl₂. The surviving animals were necropsied at the termination of the study, and hematological, clinical chemistry, histopathological and tissue residue analyses were performed. Relative liver weights were increased in both low and high dose groups of HCB but not in animals treated with HgCl₂ alone. Co‐administration of HgCl₂ did not alter the HCB effects on the liver weight of the animals. Serum cholesterol levels were increased in all the groups receiving HCB but not HgCl₂. No interactive effects on other serum parameters were seen in animals administered with both chemicals. Mild to moderate morphological changes occurred in the liver, thyroid, thymus, ovary and bone marrow of rats exposed to HCB or HCB + HgCl₂, and in the kidney of HgCl₂ or HgCl₂ + HCB treated animals. More severe histological changes occurred in the groups receiving both chemicals. The histological effects appeared to be additive. It was concluded that co‐administration with HCB and HgCl₂ resulted in additive effects in some of the endpoints measured but no synergism or antagonism was observed.     

Uptake and accumulation of lead by plants from the Bo Ngam lead mine area in Thailand

A field survey of terrestrial plants growing on Bo Ngam lead mine area, Thailand, was conducted to identify species accumulating exceptionally high concentrations of lead. Plant and soil samples were collected from five areas. Lead concentrations in surface soil ranged from 325 to 142,400 mg/kg. The highest lead concentration in soil was found at the ore dressing plant area and lowest at a natural pond area. In different areas, the concentrations of lead in plants were different when comparing various study sites. A total of 48 plant species belonging to 14 families were collected from five sampling sites. Twenty-six plant species had lead concentrations more than 1000 mg/kg in their shoots. Three species (Microstegium ciliatum, Polygala umbonata, Spermacoce mauritiana) showed extremely high lead concentrations in their shoots (12,200-28,370 mg/kg) and roots (14,580-128,830 mg/kg).     

Comparative tolerance of Pinus radiata and microbial activity to copper and zinc in a soil treated with metal-amended biosolids

A study was conducted to evaluate the effects of elevated concentrations of copper (Cu) and zinc (Zn) in a soil treated with biosolids previously spiked with these metals on Pinus radiata during a 312-day glasshouse pot trial. The total soil metal concentrations in the treatments were 16, 48, 146 and 232 mg Cu/kg or 36, 141, 430 and 668 mg Zn/kg. Increased total soil Cu concentration increased the soil solution Cu concentration (0.03–0.54 mg/L) but had no effect on leaf and root dry matter production. Increased total soil Zn concentration also increased the soil solution Zn concentration (0.9–362 mg/L). Decreased leaf and root dry matter were recorded above the total soil Zn concentration of 141 mg/kg (soil solution Zn concentration, >4.4 mg/L). A lower percentage of Cu in the soil soluble?+?exchangeable fraction (5–12 %) and lower Cu²⁺ concentration in soil solution (0.001–0.06 μM) relative to Zn (soil soluble?+?exchangeable fraction, 12–66 %; soil solution Zn²⁺ concentration, 4.5–4,419 μM) indicated lower bioavailability of Cu. Soil dehydrogenase activity decreased with every successive level of Cu and Zn applied, but the reduction was higher for Zn than for Cu addition. Dehydrogenase activity was reduced by 40 % (EC₄₀) at the total solution-phase and solid-phase soluble?+?exchangeable Cu concentrations of 0.5 mg/L and 14.5 mg/kg, respectively. For Zn the corresponding EC₅₀ were 9 mg/L and 55 mg/kg, respectively. Based on our findings, we propose that current New Zealand soil guidelines values for Cu and Zn (100 mg/kg for Cu; 300 mg/kg for Zn) should be revised downwards based on apparent toxicity to soil biological activity (Cu and Zn) and radiata pine (Zn only) at the threshold concentration.     

Cu污染土壤接种丛枝菌根真菌对旱稻生长的影响

采用盆栽实验的方法,研究了不同Cu处理水平(0、100和200 mg/kg)下,接种丛枝菌根真菌(arbuscular my-corrhizal fungi,AMF)Glomus mosseae对旱稻(Oryzal Sativa L.)生长的影响。结果表明,未添加Cu处理下,旱稻菌根侵染率可达69%,随着土壤中Cu添加量增加,旱稻菌根侵染率显著下降(P<0.05)。与未接种处理相比,接种处理显著提高100mg/kg Cu处理下根系生物量以及200 mg/kg Cu处理下地上部分生物量(P<0.05);接种处理显著降低了100 mg/kg Cu处理下旱稻地下部Cu含量,却显著增加了200 mg/kg Cu处理下旱稻地上部分以及地下部分Cu含量(P<0.05)。     

Distribution and availability of arsenic in soils from the industrialized urban area of Beijing, China

Concentrations of arsenic (As) were determined in soils of 5 industrial sites in an urban area of Beijing, China. Fifty seven typical surface soils were sampled to determine total concentrations of metals, pH and dissolved organic carbon (DOC). One hundred and eight deep soils were submitted to a four-step, sequential extraction to assess the relative mobility and bioavailability of As in the soil profiles. Total concentrations of As in surface soils ranged from 5.7 to 2.3 x 10(1) mg kg(-1), dw with greater concentrations inside the perimeter of the chemical plant which had greater concentrations than did other plants. 75.4% of surface soil samples in the industrial area contained concentrations of As that were greater than was considered to be the background concentration of 7.8 mg kg(-1), dw for the region. The mean concentration (9.9 mg kg(-1), dw) in the industrial soils was greater than that soils from other type of land use. Concentrations of As were significantly and negatively correlated with soil pH and DOC in industrial soils. Although mean concentration of total As in the soils from all sites were less at greater depths, the entire range from 0 to 180 cm (especially 0-80 cm) contained concentrations of As that were greater than background. Sequential extractions of soil indicated that only some surface soils had relatively great amount of extractable fraction of As. Most soils had relatively great amount of residual As. This result suggests that most arsenic in Beijing industrial soils should be immobile and of limited bioavailability.     

Contents and leachability of heavy metals (Pb, Cu, Sb, Zn, As) in soil at the Pantex firing range, Amarillo, Texas.

Pantex firing range soil samples were analyzed for Pb, Cu, Sb, Zn, and As. One hundred ninety-seven samples were collected from the firing range and vicinity area. There was a lack of knowledge about the distribution of Pb in the firing range, so a random sampling with proportional allocation was chosen. Concentration levels of Pb and Cu in the firing range were found to be in the range of 11-4675 and 13-359 mg/kg, respectively. Concentration levels of Sb were found to be in the range of 1-517 mg/kg. However, the Zn and As concentration levels were close to average soil background levels. The Sn concentration level was expected to be higher in the Pantex firing range soil samples. However, it was found to be below the neutron activation analysis (NAA) detection limit of 75 mg/kg. Enrichment factor analysis showed that Pb and Sb were highly enriched in the firing range with average magnitudes of 55 and 90, respectively. Cu was enriched approximately 6 times more than the usual soil concentration levels. Toxicity characteristic leaching procedure (TCLP) was carried out on size-fractionated homogeneous soil samples. The concentration levels of Pb in leachates were found to be approximately 12 times higher than the U.S. Environmental Protection Agency (EPA) regulatory concentration level of 5 mg/L. Sequential extraction (SE) was also performed to characterize Pb and other trace elements into five different fractions. The highest Pb fraction was found with organic matter in the soil.