铀尾矿库中重金属元素的生态迁移风险研究

用ICP-AES方法检测了铀尾矿库内人工修复植被生境与自然修复植被生境覆土中重金属元素镉、铅、铜、锌、锰、铬、镍的含量,同时检测了自然修复植被生境中先锋植物加拿大蓬与鸡眼草茎叶、植食性昆虫蝗虫、蝽与捕食性节肢动物螳螂、蜘蛛体内的镉、铅、铜、锌、锰、铬、镍的含量.结果显示,人工栽植蜈蚣草覆土中镉、铜、锌、锰、铬的含量均显著高于对照土壤、人工栽植苍耳、商陆与自然修复植被覆土中的含量,其中锰、镉、锌与铬的含量分别是对照土壤中的7.6,2.8,1.4,1.8倍.自然修复植被生境覆土中铅的含量显著高于人工栽植苍耳、商陆生境、人工栽植蜈蚣草生境覆土与对照土壤,其锰含量约为对照土壤的2倍.人工栽植苍耳、商陆生境中覆土中锰,铬含量显著高于对照.加拿大蓬与鸡眼草茎、叶中均含有被检测的7种重金属,加拿大蓬茎与鸡眼草茎叶对Zn、鸡眼草叶对Mn具有明显富集作用.蝗虫对铜与铬有一定的富集作用,对镉、铅、锌、锰与镍未表现富集作用.蝽对镉、铅、铜、锌、锰、铬与镍均具有较强的生物放大作用,其中蝽体内Cr的含量是土壤含量的191.26倍.蜘蛛与螳螂体内的重金属含量很高,对7种被检测重金属均具有非常明显的生物放大作用.蜘蛛体内各种重金属的含量显著高于螳螂体内的含量,蜘蛛体内Cd含量是其环境土壤中含量的693.13倍.研究表明,被检测的7种重金属均能从尾矿沙向上层覆土中迁移.且均能沿着"土壤-生产者-初级消费者一次级消费者"生态链迁移.     

Uptake of Uranium by Lettuce (Lactuca sativa L.) in Natural Uranium Contaminated Soils in Order to Assess Chemical Risk for Consumers

Uranium mining activity in Cunha Baixa (Portugal) village has left a legacy of polluted soils and irrigation water. A controlled field experiment was conducted with lettuce (Lactuca sativa L.) in an agricultural area nearby the abandoned mine in order to evaluate uranium uptake and distribution in roots and leaves as well as ascertain levels of uranium intake by the local inhabitants from plant consuming. Two soils with different average uranium content (38 and 106 mg/kg) were irrigated with non-contaminated and uranium contaminated water (<20 and >100 μg/l). A non-contaminated soil irrigated with local tap water (<1 μg/l uranium) was also used as a control. Uranium in lettuce tissues was positively correlated with soil uranium content, but non-significant differences were obtained from contaminated soils irrigated with different water quality. Uranium in plants (dry weight) growing in contaminated soils ranged from 0.95 to 6 mg/kg in roots and 0.32 to 2.6 mg/kg in leaves. Lettuce bioconcentration is more related to available uranium species in water than to its uranium concentration. Translocated uranium to lettuce leaves corresponds to 30% of the uranium uptake whatever the soil or irrigation water quality. A maximum uranium daily intake of 0.06 to 0.12 μg/kg bodyweight day was estimated for an adult assuming 30 to 60 g/day of lettuce is consumed. Although this value accounts for only 10% to 20% of the recommended Tolerable Daily Intake for ingested uranium, it still provides an additional source of the element in the local inhabitants’ diet.     

Laboratory Investigation of the Geochemical Behavior of Metals in Paddy Soils Contaminated with Mine Tailings

The geochemical behavior of metals, including Fe, Mn, Pb and Zn, in contaminated paddy soils was investigated during the cultivation of rice crops through laboratory microcosm experiments. From the two paddy fields contaminated by mine tailings, Siheung and Deokeum in Korea, paddy soils were collected and analyzed for their geochemical characteristics. The Siheung paddy soil showed higher levels of heavy metals, whereas the higher potential for the release of metals was anticipated due to the extremely acidic conditions at Deokeum. In microcosm experiments of flooded paddy soils over 18 weeks, Fe and Mn were released in subsurface pore waters by reductive dissolution, and Pb and Zn were dissolved in high amounts at the surface by oxidation of sulfides. Although amorphous Fe oxide-rich layers were formed at the surface of both paddy soils, the release of Pb and Zn were controlled at the surface by these layers only under slightly alkaline conditions at Siheung. Lead and Zn were associated with the reducible and carbonate fractions at the surface paddy soil of Siheung from the sequential extraction on core samples collected during the flooded period. In the acidic conditions at Deokeum, Pb and Zn were continuously released until the late stage of flooding. A great increase in the exchangeable fraction of metals was observed after the soils had drained. The bioavailability of metals for rice crops would be high under acidic conditions at Deokeum, despite the lower levels of heavy metal contamination.     

模拟降雨条件下污染土壤中重金属元素径流迁移特征

探明污染土壤中重金属元素随地表径流迁移特征,对于防控重金属污染物的迁移扩散具有重要意义。通过室内模拟降雨试验,研究不同降雨强度下(55,100,120mm/h)污染土壤中Cd、Pb和Cr随地表径流迁移的特征。结果表明:径流中3种重金属元素总量在产流的前20min内逐渐降低,随后趋于稳定;产流初期(产流10min内)颗粒态重金属占径流重金属总量的比例均在80%以上;随产流时间延长,颗粒态Cd和Cr对径流重金属的贡献率快速降低,其颗粒态/溶解态的比值范围分别为47.0～0.4和12.9～0.4,而Pb则主要以颗粒态的形式存在,溶解态Pb对其随径流迁移的贡献率可忽略不计;随降雨强度增大,径流中总Cd和Pb含量显著降低,而径流中总Cr含量以及溶解态重金属含量无明显变化规律。     

有机物料对污染土壤上水稻重金属吸收的调控效应

采用重金属污染水稻土开展盆栽试验,研究施用有机碳源、菜籽饼和猪粪对不同水稻(汕优63,简称“SY63”;中浙优1号,简称“ZZY1”)重金属吸收的调控效应.结果表明,在重金属污染土壤上ZZY1具有一定的耐性,相同处理时ZZY1糙米、砻糠、秸秆中重金属含量均低于SY63品种,糙米中Cd含量较SY63低57.5％ ～ 83.8％,Cu含量低37.8％ ～ 69.1％,Zn含量低0.88％ ～ 31.7％,食物链风险较SY63品种低.3种有机物料中,施用菜籽饼使两水稻品种糙米中重金属含量明显低于其他处理;与对照相比,施用菜籽饼使SY63糙米中Cd、Cu和Zn含量降低73.5％、52.6％和32.1％,ZZY1糙米Cd含量降低30.5％.在供试重金属污染土壤上可选择具有一定重金属耐性的水稻品种ZZY1进行粮食生产,同时施用适量的菜籽饼以增强其抵御重金属毒害的能力,降低糙米中Cd、Cu和Zn含量及其食物链污染风险.     

植物吸收对模拟污水净化系统去除氮、磷贡献的研究

采用炉渣、沸石和土壤为基质,黑麦草(Lolium mutliflorum)、水芹(Oenanthe javanica)和香根草(VetiveriaZizanioides)为植被模拟了不同基质人工湿地和无基质的浮床植物净化系统,研究了3种植物在4种净化系统内对生活污水N、P的吸收和去除作用.结果表明:3种植物在各净化系统中均能正常生长,总生物量干重在121.8～557.4g/m2之间,均以黑麦草最高.4种净化系统中,黑麦草、水芹和香根草的地上部N、P平均含量分别为26.33、3.33 mg/g,24.08、2.64 mg/g和12.39、1.41 mg,g;地下部N、P平均含量分别为8.92、1.52 mg/g,19.39、2.55 mg/g和10.85、1.33 mg/g.浮床系统因承受的N、P负荷较高且不存在基质,3种植物的地上部、地下部N、P平均含量几乎均高于各基质人工湿地.4种净化系统中,黑麦草对N、P的吸收能力均明显高于水芹和香根草,3种植物的N、P总吸收量分别为:(黑麦草)5.26～11.73、0.72～131g/m2,(水芹)1.88～8.08、0.18～1.83 g/m2,(香根草)0.86～2.44、0.07～0.79g/m2,各植物的N、P吸收量均以浮床系统最高.植物对N、P的吸收量主要取决于自身的生物量和N、P含量.黑麦草吸收的N、P量分别占4种净化系统N、P去除总量的39.3%～59.4%和88.9%～96.3%,其对N、P的吸收己成为各净化系统去除N、P的主要机制.水芹和香根草对N的吸收仅是各净化系统去N的一个途径,其贡献率分别为;10.2%～37.6%和4.8%～17.7%;水芹和香根草对P的吸收量占浮床系统去P总量的96.4%和83.2%,是系统除P的主要机制,但其对3种基质湿地的去P贡献则很小.     

A Laboratory Study on Revegetation and Metal Uptake in Native Plant Species from Neutral Mine Tailings

Lygeum spartum, Zygophyllum fabago and Piptatherum miliaceum are typical plant species that grow in mine tailings in semiarid Mediterranean areas. The aim of this work was to investigate metal uptake of these species growing on neutral mine tailings under controlled conditions and their response to fertilizer additions. A neutral mine tailing (pH of soil solution of 7.1–7.2) with high total metal concentrations (9,100 and 5,200 mg kg^?1 Zn and Pb, respectively) from Southern Spain was used. Soluble Zn and Pb were low (0.5 and <0.1 mg l^?1, respectively) but the major cations and anions reached relatively high levels (e.g. 2,600 and 1,400 mg l^?1 Cl and Na). Fertilization caused a significant increase of the plant weight for the three species and decreased metal accumulation with the exception of Cd. Roots accumulated much higher metal concentrations for the three plants than shoots, except Cd in L. spartum. Shoot concentrations for the three plants were 3–14 mg kg^?1 Cd, 150–300 mg kg^?1 Zn, 4–11 mg kg^?1 Cu, and 1–10 mg kg^?1 As, and 6–110 mg kg^?1 Pb. The results indicate that neutral pH mine tailings present a suitable substrate for establishment of these native plants species and fertilizer favors this establishment. Metal accumulation in plants is relatively low despite high total soil concentrations.     

Plant Availability and Uptake of Lead, Zinc, and Cadmium in Soils Contaminated with Anti-corrosion Paint from Pylons in Comparison to Heavy Metal Contaminated Urban Soils

Red lead (Pb₃O₄) has been used extensively in the past as an anti-corrosion paint for the protection of steel constructions. Prominent examples being some of the 200,000 high-voltage pylons in Germany which have been treated with red lead anti-corrosion paints until about 1970. Through weathering and maintenance work, paint compounds and particles are deposited on the soils beneath these constructions. In the present study, six such “pylon soils” were investigated in order to characterize the plant availability and plant uptake of Pb, Cd, and Zn. For comparison, three urban soils with similar levels of heavy metal contamination were included. One phase extractions with 1 M NH₄NO₃, sequential extractions (seven steps), and extractions at different soil pH were used to evaluate the heavy metal binding forms in the soil and availability to plants. Greenhouse experiments were conducted to determine heavy metal uptake by Lolium multiflorum and Lactuca sativa var. crispa in untreated and limed red lead paint contaminated soils. Concentrations of Pb and Zn in the pylon soils were elevated with maximum values of 783 mg Pb kg⁻¹ and 635 Zn mg kg⁻¹ while the soil Cd content was similar to nearby reference soils. The pylon soils were characterized by exceptionally high proportions of NH₄NO₃-extractable Pb reaching up to 17% of total Pb. Even if the relatively low pH of the soils is considered (pH 4.3–4.9), this appears to be a specific feature of the red lead contamination since similarly contaminated urban soils have to be acidified to pH 2.5 to achieve a similarly high Pb extractability. The Pb content in L. multiflorum shoots reached maximum values of 73 mg kg⁻¹ after a cultivation time of 4 weeks in pylon soil. Lime amendment reduced the plant uptake of Pb and Zn significantly by up to 91%. But L. sativa var. crispa cultivated on soils limed to neutral pH still contained critical Pb concentrations (up to 0.6 mg kg⁻¹ fresh weight). Possible mechanisms for the exceptionally high plant availability of soil Pb derived from red lead paint are discussed.     

浮萍吸收不同形态氮的动力学特性研究

吸收试验结果表明,浮萍(Spirodela oligorrhiza)吸收铵态氮和硝态氮的动力学特性可用M ichaelis-M enten方程来描述。浮萍对铵态氮的亲和力大于对硝态氮的亲和力,证实了浮萍“优先吸收净化铵态氮”的观点。研究还发现,浮萍吸收硝态氮的最大速率大于吸收铵态氮的最大速率,基于浮萍吸收不同形态氮的动力学特性,提出了构建物理作用(增氧工艺)—微生物(硝化作用)—植物(浮萍)复合污水净化体系的见解。     

植物粟对模拟封存CO2泄漏的生理响应

碳捕集与封存（Carbon Capture and Storage,CCS）技术是近年来迅速发展的温室气体减排措施,是以煤为主的中国重要的战略性减排技术之一,减排量巨大。但是,CCS发展备受争议,其泄漏有可能会对周围生态系统尤其是结构单一的农田生态系统造成严重影响。本研究以北方地区主要粮食作物粟为试验对象,自主设计模拟地质封存CO₂泄漏盆栽试验,通过对植物生育期SPAD（叶绿素相对含量）、株高、根系以及产量、穗部特征等指标的观测,分析粟对CCS泄漏的响应。结果表明：（1）受CCS泄漏的影响,植物粟SPAD值显著降低,植株叶片叶绿素含量极显著下降（P＜0.01）。（2）CCS泄漏发生30d后粟的株高显著下降,根分支显著增加,植株受泄漏影响明显。（3）CCS泄漏显著降低了植株地上部干重和鲜重,但是泄漏对地下部鲜重无显著影响,地下部干重较地上部降幅偏小。（4）CCS泄漏影响下,植株粟产量下降34.92%。此外,CCS泄漏下植株穗长、穗粗、总粒重等农艺性状下降显著。     

Indigenous Plant Species with the Potential for the Phytoremediation of Arsenic and Metals Contaminated Soil

Here we present results of a survey conducted to identify and characterize spontaneously growing arsenic-tolerant plant species of the area around the old arsenic/gold mine in ZlotyStok (Poland), with respect of their potential use in phytoremediation. Plants and soil from their rhizosphere were sampled and analyzed for concentrations of As and accompanying Mn, Fe, Mg, Ca, Al, Cu, Zn, Ba, Pb, Ni, Cs, V, Cr, Sr, Rb, Bi, Mo and U. The soil contained primarily very high As, Pb and Al concentrations (up to 7,451, 1,058 and 31,272 mg/kg respectively). The ability of identified species to modify the amount of bioavailable arsenic in their rhizosphere was determined by single extractions of soil samples with the use of water, phosphate buffer, EDTA, and acetic acid. Although As-hyperaccumulators were not found, Calamagrostis arundinaca was identified as a new species which successfully carried out the natural phytoextraction of arsenic. This plant was able to increase substantially the arsenic availability in the soil, and likely due to efficient uptake decreased the total As concentration within the root zone by around 40% relative to the reference soil. Thus, it has high potential for phytoremediation. The lowest amount of available arsenic was found in the rhizosphere of Stachys sylvatica, the species with the lowest As shoot concentration (compared with other plant species). It was proposed as a good candidate for phytostabilization.     

铀尾矿周边污染土壤微生物群落结构与功能研究

为给铀尾矿周边污染土壤环境监测及生态修复提供科学参考依据,以我国某铀尾矿周边的污染土壤为研究对象,采用常规稀释平板法和Biolog—Eco微平板反应系统研究了高、中、低污染区的土壤微生物群落结构及功能多样性。结果表明,放射性污染从高到低的各级取样点的三类微生物数量大小为细菌〉真菌〉放线菌;与对照相比,各样点的AWCD下降了37．6％~92．0％,AWCD、Shannon指数（H）、Simpson指数（D）与放射性核素的含量基本呈反比关系,而与有机质、全氮、碱解氮显著正相关;不同土壤微生物群落问的代谢特征随着污染程度的变化而变化,主成分分析表明这种变化主要体现在碳水化合物上。     

Plant Growth-Promoting Rhizobacteria (PGPR) and Phosphorus Fertilizer-Assisted Phytoextraction of Toxic Heavy Metals from Contaminated Soils

Phytoremediation is a remediation technique that involves the use of plants to extract, sequester, and/or detoxify pollutants through physical, chemical, and biological processes. The use of phytoremediation is expanding due to its cost-effectiveness compared with conventional methods. This study was conducted to investigate the effects of autumn and spring application of plant growth-promoting rhizobacteria (PGPR, 10⁸ cfu mL^?1 Bacillus megaterium var. phosphaticum sprayed at 250 mL plot^?1) and phosphorus (P) fertilizer (0, 11, 22, 33, 44 kg P ha^?1) on dry matter yield and heavy metal uptake by plants in soils contaminated with heavy metals. Field experiments were conducted using a randomized complete block design with four replications between 2004 and 2007. The results of the study indicated that P fertilization, but not PGPR application, significantly affected dry matter yield. Application of PGPR increased heavy metal availability in soils and the heavy metal uptake of meadow plants. The heavy metal content of the meadow plants resulting from PGPR application was 4–6 times higher for the spring application than the autumn application. Approximately 16, 30, 10, 10, and 3 growing seasons without PGPR are necessary to remove all lead (Pb), nickel (Ni), boron (B), manganese (Mn), and zinc (Zn), respectively, from polluted soil. The time required for Pb, Ni, B, Mn, and Zn removal could be further decreased to approximately 4, 6, 3, 3, and 1 growing seasons, respectively, with 33 kg phosphorus pentoxide (P₂O₅) ha^?1 and 10⁸ cfu mL^?1 PGPR applications at rates of 250 mL plot^?1 in the spring season.     

Invertebrates Minimize Accumulation of Metals and Metalloids in Contaminated Environments

Many studies were conducted measuring the lethal concentration of pollutants by using a contaminated solution or polluted sediments. Considering the impact of polluted food on mortality and uptake quantity of invertebrate shredders in batch cultures, little is known about, e.g. uranium and cadmium. Consequently, we investigated in situ the impact of metal and metalloid polluted food and water on Gammarus pulex L. under nature-like conditions. In contrast to other publications, a very low mortality rate of the invertebrates was found. Furthermore, fixation of elements by G. pulex was shown to be low compared to initial concentrations. Fixation of non essential metals and metalloids is shown to take place mainly on the surface of the invertebrates. This is deduced from easy desorption of a relevant amount of fixed metals and metalloids. It is concluded that the accumulation of metals and metalloids in situ under nature-like conditions within the food web via invertebrate shredders is very low. The invertebrates seem to minimize the uptake of non essential elements in the presence of nutrient-rich food even in habitats with higher contamination levels. Hence, invertebrates seem to be adapted to higher contamination levels in their favourable habitats.     

尾矿库尾砂及周边农田土壤重金属形态分布及其生物有效性

采用BCR（community bureau of reference）连续提取法对大宝山矿山槽对坑尾矿库尾砂和周边农田土壤重金属Cd、Pb、Cu和Zn的形态分布及其生物有效性进行了分析。结果表明,尾砂中Cd、Pb、Cu和Zn残渣态占绝对优势,占其总量的百分数均在85%以上。农田土壤中Cd、Cu和Zn都以残渣态为主,分别占其总量的60%、60%和90%以上,Pb以残渣态和可还原态为主,占其总量的93.44%。农田土壤重金属有效性较尾砂大,尾砂和农田土壤重金属生物有效性均以Pb为最高。     

地下部分隔对蚕豆/玉米间作氮素吸收和土壤硝态氮残留影响

利用田间试验,探讨了地下部分隔对蚕豆/玉米间作氮素吸收和土壤硝态氮残留的影响,结果表明:蚕豆/玉米间作,蚕豆不分隔条件下籽粒和秸秆吸氮量比分隔分别增加20 10%,34 43%;玉米不分隔条件下籽粒吸氮量与分隔近似,但秸秆吸氮量比分隔减少13 04%;蚕豆和玉米不分隔条件下土壤硝态氮累积量都高于分隔。蚕豆/空带间作,蚕豆不分隔籽粒吸氮量高于分隔,但土壤硝态氮累积量没有差异。空带/玉米间作,地下部分隔与否,作物吸氮量和土壤硝态氮累积量都没有差异。     

Spatial Relations between Row Crops and Nitrate Contamination in Groundwater

Nitrogen management practices associated with row crops arewidely considered as an important contributor to nitrate pollution in water resources. We studied the relations between row crops and nitrate concentration in groundwater in an agricultural basin of Iowa, U.S.A., from a spatial perspective. Nitrate concentration and row crop area wereanalyzed on a section scale (a square mile, or 2.56 km²)for three different years. Their section values were standardized to remove the effects of precipitation and non-constant sample variances in different years. The between-year differences in individual section values werecollectively analyzed as an indication of changes in the spatial distribution from year to year. Contingency table analysis was applied to test for relations of spatial changesbetween nitrate and row crops. During the study period, thenitrate concentration and row crop area on a per section basischanged considerably from one sampling year to another.However, no significant changes were found in their spatial distributions. As a result, no significant relations betweennitrate and row crops were found in terms of changes in theirspatial distributions.     

Nitrate Dynamics in Shallow Groundwater and the Potential for Transport to Off-Site Water Bodies

Large quantities of the nitrate leaching below the crop root-zone, particularly during the wet season, in the tropical Far North Queensland (FNQ) of Australia, may be entering off and on-site the water bodies. The objectives of this study were to (i) provide quantitative information on NO₃-N in the shallow fluctuating groundwater (GW) that develops during the rainy season (January through May) in the Johnstone River Catchment (JRC) of FNQ and (ii) determine whether this NO₃-N is potentially transportable to creeks/streams. The NO₃-N concentration and GW table heights were monitored, at least at weekly intervals, in 6 piezometers, installed to 8.5–12.0 m depth in 6 different soil types under fertilized sugarcane (Saccharum Officinarum-S) in the JRC during the 1999 rainy season.Depending on the location of piezometers on the landscape and time of water sampling, the GW table fluctuated between from 1.5 to 11.5 m abovethe piezometer bottom. The NO₃-N concentration in the fluctuating GW also showed spatio-temporal dynamics and it ranged from 0.60 to 3.70 mg L^-1. The NO₃-N adsorbed at anion exchanges sites, up to 10 m depth, ranged from 154 to 3956 kg ha^-1, compared with 21 kgha^-1 under rainforest. In the fluctuating GW, the NO₃-N concentration increased with increasing GW table height and the NO₃-N adsorbed at anion exchange sites (R² = 0.96). The NO₃-N load in the GW ranged from 40 to 110 kg ha^-1 and it increased with increasing GW table and GW NO₃-N concentration. The estimated N-load in the GW that was discharged into creeks/streams when the GW receded ranged from 21 to 81 kg ha^-1. The results provide evidence that a(i) a major proportion of the NO₃-N that was leaching below the sugarcane root-zone entered the shallow GW that developed during the rainy season, and (ii) a significant proportion of the NO₃-N inthe GW was transported to creeks/streams when the GW table receded.