锑矿区土壤重金属污染及优势植物对重金属的富集特征

通过野外调查采样,分析了冷水江锑矿区4个采样点土壤和优势植物中重金属含量,以及矿区生长的5种优势植物对Sb、As、Cd、Pb、Cu和Zn的的吸收与富集能力及其富集特性。结果表明,矿区土壤中6种重金属元素的平均含量均超出湖南省土壤背景值和全国土壤背景值,土壤受Sb污染最严重,其次是Cd、As的污染。5种优势植物淡竹叶、苎麻、芒草、狗尾草和白背叶体内Sb、As的含量都超过正常范围,具有修复矿区土壤Sb、As污染的潜力。其中苎麻对Sb的富集系数和转运系数均大于1,满足Sb超富集植物的基本特征,可作为生态恢复的先锋植物;芒草对Cd的富集系数和转运系数都大于1,对重金属有较强的耐性,作为重金属污染的修复植物具有较好的应用前景。     

重金属污染废弃地修复植物种类的筛选与评价

基于修复被重金属污染土壤的优良植物的特征，并结合前人的研究成果，对修复被Cd、Pb、Zn、Cu、Mn污染土壤的植物进行了罗列与分析，筛选出了一些可以应用于修复因重金属污染而废弃土地的、且生态恢复生长快、生物量大、抗逆性强、富集重金属多的植物。     

生活垃圾填埋场封场后种植植物中重金属迁移研究

在上海老港生活垃圾填埋场填埋单元封场的覆盖土中掺混了矿化垃圾种植植物,分析Cd、Pb、Cu、Zn 4种重金属在土壤和植物中的迁移变化,研究表明:(1)覆盖土土质从一般耕作土变成肥沃土壤;覆盖土和种植混合土重金属Cd、Pb、Cu、Zn中Cd、Pb含量相近,但种植土的Cu含量略大于覆盖原土,Zn含量远大于覆盖原土;(2)植物能富集土壤和垃圾中的重金属,木本植物的根部富集重金属的能力强于草本植物,但重金属在草本植物根、茎、叶中的迁移速度大于木本植物;(3)植物根、茎、叶的Cu、Zn含量均远大于未受污染土壤种植植物相应部位的Cu、Zn含量,种植的植物不能供家养动物食用,以免通过食物链作用危及人体安全.     

兰坪铅锌矿区不同污染梯度下优势植物的重金属累积特征

对兰坪铅锌矿区污染程度不同的3个样地(云南松林、魁蒿群落和马桑灌丛)进行植被调查,选择其中9种共有的自然生长的优势草本植物为研究对象,测定了土壤及植物体的重金属含量。结果显示,3个样地土壤Cu、Cd、Pb和Zn等4种重金属含量均表现为马桑灌丛>魁蒿群落>云南松林;植物体内重金属积累呈现出随着土壤污染程度增加而增加的趋势;所选择的9种植物均不符合超富集植物的标准,依据不同的耐性机制将9种植物分为3类,野棉花能较强吸收土壤中重金属,并转移到地上部分,属于富集型植物;西南金丝梅、倒提壶、长籽柳叶菜、魁蒿、翻白叶和四脉金茅吸收的重金属主要积累在根部,属于根部囤积型植物;尼泊尔蓼和中华山蓼体内重金属含量较低,属于规避型植物。讨论了利用这些植物进行矿山治理。     

广州李坑生活垃圾填埋场周围植被现状调查与影响分析

为对垃圾填埋场封场后如何进行生态恢复研究提供基础资料，对超负荷运转中的广州市李坑生活垃圾填埋场周围的植被现状进行了调查，测算了物种量、覆盖度、污染状况等。同时运用植被覆盖度、结构、物种量和相对物种量等级评价以及对Zn、Cd等6种污染物的质量指数进行了评价。结果表明，所调查填埋场场区及灌区内有轻度污染，而场外与灌区外则相对较轻或无污染。     

污泥耐受性草本植物的筛选及其对重金属Cu、Zn的富集

为探索植物修复污泥中重金属污染的可行性,配制不同污泥含量的介质土开展盆栽实验,对从河南、云南和上海等地收集的抗逆性强的19种草本植物进行污泥适应性筛选；研究了植物对污泥的生理响应及其对重金属Cu、Zn的吸收和分布.结果表明,上海市浦东新区白龙港污水处理厂污泥农用是可行的,农用时污泥比例应控制在60％以下；筛选出三叶鬼针草、稗子、荆芥和金叶马兰4种污泥耐受性植物；三叶鬼针草具有修复重金属Cu、Zn污染土壤的潜力；稗子具有修复重金属Zn污染土壤的能力；金叶马兰具有修复重金属Cu、Zn污染土壤的能力.     

观赏植物与驯化污泥联合修复垃圾渗滤液污染土壤

垃圾填埋场渗滤液污染土壤具有重金属-有机物复合污染的特性。研究了观赏植物广东万年青、白掌、孔雀竹芋和经垃圾渗滤液驯化的污泥对该污染土壤的修复效果,结果表明:采用单一植物修复时,广东万年青较白掌和孔雀竹芋对土壤污染物具有更强耐性,能在污染土壤中生长良好,对重金属Cd和Pb的富集能力也更强;驯化污泥能明显提高污染土壤中有机污染物的降解率,并使重金属Cd和Pb稳定态比例分别提高了34.7%和36.6%,降低了重金属的生物有效性。当采用广东万年青和驯化污泥联合修复时,污泥能促进植物的生长,且当污泥添加量为480 mg·kg~(-1)时,联合修复对土壤中Cd、Pb及有机污染物的去除率分别较不加污泥的对照提高了51.7%、25.5%和40.2%。     

潮滩盐沼植物翅碱蓬对常见重金属的累积吸收及其机制

潮滩盐沼植物翅碱蓬对常见重金属(Cu、Zn、Pb和Cd)的累积吸收研究表明,该植物对常见重金属有一定的累积且随潮滩变化不明显,其对Cu、Zn、Pb和Cd的累积吸收系数分别为4. 7、4. 6、3. 1和4. 9,而生物富集吸收系数则分别为0. 97、1. 73、0.41和2.23;植物体内不同部位的分布、迁移规律研究表明,植物的不同部位累积情况存在明显差异,Cu表现为根>茎>叶,Zn表现为叶>根>茎,Pb表现为根>叶>茎,Cd表现为根>茎≈叶。在此基础上初步探讨了翅碱蓬对常见重金属累积吸收机制。     

Cd、Pb复合污染下柠檬酸对龙葵修复效率及抗氧化酶的影响

植物修复土壤重金属被普遍认为是清洁、经济的生物修复方法。为了提高生物修复土壤重金属污染的效率,在室内盆栽实验中添加柠檬酸作为螯合剂促进龙葵对重金属的吸收,并研究其生理活性的变化。结果表明:当添加柠檬酸浓度为10 nmol/kg时,龙葵生物量显著提高(P<0.05),各部分生物量表现为:茎>叶>根;随着柠檬酸浓度的增加,龙葵对重金属Cd的吸收量显著(P<0.05)增加,在10 nmol时总吸收量最大,为229.85μg/g DW;龙葵对Cd、Pb的富集系数均在柠檬酸浓度为5 nmol/kg时达到最大;Pb吸收量随柠檬酸浓度增加表现出先增大后减小的趋势;添加柠檬酸促进了龙葵对Cd的吸收,增强了抗氧化酶活性,而对Pb的吸收效果不明显。     

北京黑石头填埋场治理后期土壤质量评价

为了评价北京黑石头垃圾填埋场在好氧加速降解治理后期表层土壤质量,测定了填埋场表层土壤重金属Cd、Hg、As、Cu、Pb、Cr、Zn、Ni的含量,以及容重、孔隙度、有机质、有效磷、速效钾和碱解氮等理化性质,运用内梅罗污染指数、潜在生态危害指数对土壤重金属污染进行了评价,运用BP神经网络法对土壤宜林性进行了评价。结果表明:土壤重金属含量大多高于北京市土壤背景值,但属于较安全的范畴;容重与通气孔隙度表现良好,但毛管孔隙度与孔隙比低,水气性能不够协调;养分状况总体上属于中上等水平,在17个样点中,养分极高2个,养分高11个,养分中等4个;土壤理化性质能满足一般园林乔灌木和草坪的生长需求,土层浅薄是该填埋场建植绿化的主要限制因素。     

Zinc tolerance and uptake by <Emphasis Type="Italic">Arabidopsis halleri ssp. gemmifera</Emphasis> grown in nutrient solution

Background, aim, and scope  

Zinc is an essential micronutrient element but its concentrations found in contaminated soils frequently exceed those required by the plant and soil organisms, and thus create danger to animal and human health. Phytoremediation is a technique, often employed in remediation of contaminated soils, which aims to remove heavy metals or other contaminants from soils or waters using plants. Arabidopsis (A.) halleri ssp. gemmifera is a plant recently found to be grown vigorously in heavy metal contaminated areas of Japan and it contained remarkably high amount of heavy metals in its shoots. However, the magnitude of Zn accumulation and tolerance in A. halleri ssp. gemmifera need to be investigated for its use as a phytoremediation plant.     

Classification and identification of metal-accumulating plant species by cluster analysis

Identification and classification of metal-accumulating plant species is essential for phytoextraction. Cluster analysis is used for classifying individuals based on measured characteristics. In this study, classification of plant species for metal accumulation was conducted using cluster analysis based on a practical survey. Forty plant samples belonging to 21 species were collected from an ancient silver-mining site. Five groups such as hyperaccumulator, potential hyperaccumulator, accumulator, potential accumulator, and normal accumulating plant were graded. For Cd accumulation, the ancient silver-mining ecotype of Sedum alfredii was treated as a Cd hyperaccumulator, and the others were normal Cd-accumulating plants. For Zn accumulation, S. alfredii was considered as a potential Zn hyperaccumulator, Conyza canadensis and Artemisia lavandulaefolia were Zn accumulators, and the others were normal Zn-accumulating plants. For Pb accumulation, S. alfredii and Elatostema lineolatum were potential Pb hyperaccumulators, Rubus hunanensis, Ajuga decumbens, and Erigeron annuus were Pb accumulators, C. canadensis and A. lavandulaefolia were potential Pb accumulators, and the others were normal Pb-accumulating plants. Plant species with the potential for phytoextraction were identified such as S. alfredii for Cd and Zn, C. canadensis and A. lavandulaefolia for Zn and Pb, and E. lineolatum, R. hunanensis, A. decumbens, and E. annuus for Pb. Cluster analysis is effective in the classification of plant species for metal accumulation and identification of potential species for phytoextraction.     

Transgenic poplar trees expressing yeast cadmium factor 1 exhibit the characteristics necessary for the phytoremediation of mine tailing soil

Genetic engineering of plants for phytoremediation is thought to be possible based on results using model plants expressing genes involved in heavy metal resistance, which improve the plant’s tolerance of heavy metals and accumulation capacity. The next step of progress in this technology requires the genetic engineering of plants that produce large amounts of biomass and the testing of these transgenic plants in contaminated soils. Thus, we transformed a sterile line of poplar Populus alba X P. tremula var. glandulosa with a heavy metal resistance gene, ScYCF1 (yeast cadmium factor 1), which encodes a transporter that sequesters toxic metal(loid)s into the vacuoles of budding yeast, and tested these transgenic plants in soil taken from a closed mine site contaminated with multiple toxic metal(loid)s under greenhouse and field conditions. The YCF1-expressing transgenic poplar plants exhibited enhanced growth, reduced toxicity symptoms, and increased Cd content in the aerial tissue compared to the non-transgenic plants. Furthermore, the plants accumulated increased amounts of Cd, Zn, and Pb in the root, because they could establish an extensive root system in mine tailing soil. These results suggest that the generation of YCF1-expressing transgenic poplar represents the first step towards producing plants for phytoremediation. The YCF1-expressing poplar may be useful for phytostabilization and phytoattenuation, especially in highly contaminated regions, where wild-type plants cannot survive.     

Influx,transport, and accumulation of cadmium in plant species grown at different Cd2+ activities

Abstract

Cadmium (Cd) has no known essential biological function, but it is toxic to plants, animals, and humans. A promising approach to prevent Cd from entering the food chain would be to select and/or create Cd‐accumulating plants to remediate contaminated soils or to develop Cd‐excluding plants to reduce Cd flow from soils into foods. The present study was undertaken to examine the differences in Cd influx, transport, and accumulation among five plant species in relation to plant tolerance to Cd toxicity. Ryegrass (Lolium perenne L.) had the least reduction in dry matter which may be due to its lowest Cd transport rate (TR) to shoots at all Cd levels among the plant species tested. White‐clover (Trifolium repens L.) was the most sensitive species to Cd toxicity, likely because of its highest Cd influx rate (IR) and high TR when plants were grown at low Cd²⁺ activity (≤8 μM). The high tolerance of cabbage (Brassica oleracea var. capitata L.) to moderate Cd toxicity (≤14 μM) appeared to be mainly due to the detoxification of Cd inside plant tissue since it recorded the highest TR and relatively high IR for Cd among the tested species. At Cd²⁺ activities up to 28 uM, the Cd uptake ratios of shoot/root for ryegrass were, on average, about 50‐fold and 27‐fold lower than that for cabbage and maize (Zea mays L.), respectively. These results showed that Cd could be easily transported into shoots of cabbage and maize, but was mainly confined to roots of ryegrass. We suggest that influx and transport rates, especially transport rate, could be used as plant physiological parameters for screening Cd‐excluding genotypes among monocotyledonous plants.     

Heavy metals in sediments,soils, and aquatic plants from a secondary anabranch of the three gorges reservoir region,China

We investigated the occurrence of cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), Znic (Zn), iron (Fe), manganese (Mn), and magnesium (Mg) in sediments, as well as in related soils and aquatic plants in the Liangtan River, a typical secondary anabranch of the Yangtze River in the Three Gorges Reservoir Region (TGRR) of China. We found that sediments accumulated more metals than soils and aquatic plants. Concentrations of the nine metals in sediments and soils followed the same sequence, while their concentrations in aquatic plants followed a different sequence. Potential adverse effects of contaminated sediments on benthic fauna were evaluated, and the results showed that the toxic effect on benthic organisms followed the sequence Zn?>?Ni?>?Cr?>?Cu?>?Cd?>?Pb. The potential ecological risk index analysis indicated that Cd in sediments had considerable ecological risk, whereas Cr, Cu, Zn, Ni, and Pb had low ecological risk. The potential ecological risk index (RI) of the heavy metals in sediments of the Liangtan River was 174.9, indicating moderate ecological risk. The transfer factor trend of metals for aquatic plants showed that Cd and Ni had the most and least accumulation, respectively. For Cu, Cd, Mg, Pb, and Cr, a significant positive correlation of the metal concentrations was observed between sediments and soils, but no correlations (excluding Cr) were detected between sediments and aquatic plants. Our study indicated that anthropogenic input may be the primary source of metal contamination in the Liangtan River, and that Zn and Cd pollution in the Liangtan River should be further explored.     

Australian native plant species Carpobrotus rossii (Haw.) Schwantes shows the potential of cadmium phytoremediation

Many polluted sites are typically characterized by contamination with multiple heavy metals, drought, salinity, and nutrient deficiencies. Here, an Australian native succulent halophytic plant species, Carpobrotus rossii (Haw.) Schwantes (Aizoaceae) was investigated to assess its tolerance and phytoextraction potential of Cd, Zn, and the combination of Cd and Zn, when plants were grown in soils spiked with various concentrations of Cd (20–320 mg kg^?1 Cd), Zn (150–2,400 mg kg^?1 Zn) or Cd + Zn (20?+?150, 40?+?300, 80?+?600 mg kg^?1). The concentration of Cd in plant parts followed the order of roots > stems > leaves, resulting in Cd translocation factor (TF, concentration ratio of shoots to roots) less than one. In contrast, the concentration of Zn was in order of leaves > stems > roots, with a Zn TF greater than one. However, the amount of Cd and Zn were distributed more in leaves than in stems or roots, which was attributed to higher biomass of leaves than stems or roots. The critical value that causes 10 % shoot biomass reduction was 115 μg g^?1 for Cd and 1,300 μg g^?1 for Zn. The shoot Cd uptake per plant increased with increasing Cd addition while shoot Zn uptake peaked at 600 mg kg^?1 Zn addition. The combined addition of Cd and Zn reduced biomass production more than Cd or Zn alone and significantly increased Cd concentration, but did not affect Zn concentration in plant parts. The results suggest that C. rossii is able to hyperaccumulate Cd and can be a promising candidate for phytoextraction of Cd from polluted soils.     

Use of the landfill water pollution index (LWPI) for groundwater quality assessment near the landfill sites

The purpose of the paper is to assess the groundwater quality near the landfill sites using landfill water pollution index (LWPI). In order to investigate the scale of groundwater contamination, three landfills (E, H and S) in different stages of their operation were taken into analysis. Samples of groundwater in the vicinity of studied landfills were collected four times each year in the period from 2004 to 2014. A total of over 300 groundwater samples were analysed for pH, EC, PAH, TOC, Cr, Hg, Zn, Pb, Cd, Cu, as required by the UE legal acts for landfill monitoring system. The calculated values of the LWPI allowed the quantification of the overall water quality near the landfill sites. The obtained results indicated that the most negative impact on groundwater quality is observed near the old Landfill H. Improper location of piezometer at the Landfill S favoured infiltration of run-off from road pavement into the soil-water environment. Deep deposition of the groundwater level at Landfill S area reduced the landfill impact on the water quality. Conducted analyses revealed that the LWPI can be used for evaluation of water pollution near a landfill, for assessment of the variability of water pollution with time and for comparison of water quality from different piezometers, landfills or time periods. The applied WQI (Water Quality Index) can also be an important information tool for landfill policy makers and the public about the groundwater pollution threat from landfill.     

Molybdenum (Mo) increases endogenous phenolics,proline and photosynthetic pigments and the phytoremediation potential of the industrially important plant Ricinus communis L. for removal of cadmium from contaminated soil

Cadmium (Cd) in agricultural soil negatively affects crops yield and compromises food safety. Remediation of polluted soil is necessary for the re-establishment of sustainable agriculture and to prevent hazards to human health and environmental pollution. Phytoremediation is a promising technology for decontamination of polluted soil. The present study investigated the effect of molybdenum (Mo) (0.5, 1.0 and 2.0 ppm) on endogenous production of total phenolics and free proline, plant biomass and photosynthetic pigments in Ricinus communis plants grown in Cd (25, 50 and 100 ppm) contaminated soils and the potential for Cd phytoextraction. Mo was applied via seed soaking, soil addition and foliar spray. Foliar sprays significantly increased plant biomass, Cd accumulation and bioconcentration. Phenolic concentrations showed significantly positive correlations with Cd accumulation in roots (R ² = 0.793, 0.807 and 0.739) and leaves (R ² = 0.707, 721 and 0.866). Similarly, proline was significantly positively correlated with Cd accumulation in roots (R ² = 0.668, 0.694 and 0.673) and leaves (R ² = 0.831, 0.964 and 0.930). Foliar application was found to be the most effective way to deliver Mo in terms of increase in plant growth, Cd accumulation and production of phenolics and proline.

     

Response of antioxidant enzymes in Nicotiana tabacum clones during phytoextraction of heavy metals

Background, aim, and scope  Tobacco, Nicotiana tabacum, is a widely used model plant for growth on heavy-metal-contaminated sites. Its high biomass and deep rooting system make it interesting for phytoextraction. In the present study, we investigated the antioxidative activities and glutathione-dependent enzymes of different tobacco clones optimized for better Cd and Zn accumulation in order to characterize their performance in the field. Main features  The improved heavy metal resistance also makes the investigated tobacco clones interesting for understanding the plant defense enzyme system in general. Freshly harvested plant material (N. tabacum leaves) was used to investigate the antioxidative cascade in plants grown on heavy metal contaminated sites with and without amendments of different ammonium nitrate and ammonium sulfate fertilizers. Materials and methods  Plants were grown on heavily polluted soils in north-east Switzerland. Leaves were harvested at the field site and directly deep frozen in liquid N₂. Studies were concentrated on the antioxidative enzymes of the Halliwell–Asada cycle, and spectrophotometric measurements of catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), superoxide dismutase (SOD, EC 1.15.1.1), glutathione peroxidase (GPX, EC 1.11.1.9), glutathione reductase (GR, EC 1.6.4.2), glutathione S-transferase (GST, EC 2.5.1.18) were performed. Results and discussion  We tried to explain the relationship between fertilizer amendments and the activity of the enzymatic defense systems. When tobacco (N. tabacum) plants originating from different mutants were grown under field conditions with varying fertilizer application, the uptake of cadmium and zinc from soil increased with increasing biomass. Depending on Cd and Zn uptake, several antioxidant enzymes showed significantly different activities. Whereas SOD and CAT were usually elevated, several other enzymes, and isoforms of GST were strongly inhibited. Conclusions  Heavy metal uptake represents severe stress to plants, and specific antioxidative enzymes are induced at the cost of more general reactions of the Halliwell–Asada cycle. In well-supplied plants, the glutathione level remains more or less unchanged. The lack of certain glutathione S-transferases upon exposure to heavy metals might be problematic in cases when organic pollutants coincide with heavy metal pollution. When planning phytoremediation of sites, mixed pollution scenarios have to be foreseen and plants should be selected according to both, their stress resistance and hyperaccumulative capacity.