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1.
Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria have re-ceived more and more attention. This article paper reviews some recent advances in effect and significance of rhizobacteria in phytoremediation of heavy metal contaminated soils. There is also a need to improve our understanding of the mechanisms in-volved in the transfer and mobilization of heavy metals by rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes. 相似文献
2.
Oil spills may considerably damage sensitive coastal wetlands. The phytoremediation potential and restoration of a dominant coastal marsh plant, Cyperus rotundus, for diesel pollutant and its phytoremediation effectiveness were investigated in this open-air pot experiment. Cyperus rotundus was transplanted into soil contaminated with diesel at concentrations of 1 000, 5 000, 10 000, 15 000, 20 000 mg/kg. In order to better elucidate the biochemical and physiological responses to diesel pollutants, activity of the antioxidant enzymes peroxidase （POD）, catalase （CAT） and ascorbic acid oxidase （AAO） were determined in the plant tissue after 50 d treatment at the levels mentioned above. The results showed that CAT and AAO of stem and leaf exhibited peak enzyme activities on 15 000 mg/kg soil and 10 000 mg/kg soil respectively, and declined at higher concentrations. Additionally, the increment of biomass and the content of soluble protein, as well as chlorophyll content were affected by diesel. The highest restoration effectiveness appeared at the level of 5 000 mg/kg. Collectively, Cyperus rotundus is a potential plant which can be used for restoring the diesel-contaminated soil. 相似文献
3.
INTRODUCTION Nitrate and heavy metals commonly found ingroundwater pollutants constitute significant healthrisk to humans and a burden on the environment.Mixtures of these compounds often exist in soils andgroundwater at numerous contaminated sites. Highnitrate (NO3 ) levels in drinking water supplies sig- ?nificantly endanger human health, as they are directlyresponsible for methemoglobinemia in infants (bluebaby syndrome) and may play a role in the develop-ment of som… 相似文献
4.
《天津大学学报(英文版)》2015,(5)
In order to investigate the effect of plant density of Potamogeton crispus L. on the remediation of sedi ments contaminated by polycyclic aromatic hydrocarbons, a 54-day experiment with four plant densities(6421,604, 2,567 and 3,530 plants/m2)was conducted. The results showed higher plant density with slower plant growth rate. Surface area per plant was the most sensitive root parameter to plant density. At the end of the 54-day experi ment, planting P. crispus enhanced the dissipation ratios of phenanthrene and pyrene in sediments by 6.5%—26.2%and 0.95%—13.6%, respectively. The dissipation increment increased with increasing plant density. Plant uptake accounted for only a small portion of the dissipation increments. Furthermore, P. crispus could evidently improve sediment redox potentials, and strong positive correlations between root surface area and the redox potential as wel as between the redox potentials and the dissipation ratios of phenanthrene and pyrene were obtained, indicating tha the oxygen released by the roots of P. crispus might be the main mechanism by which P. crispus enhanced the dis sipation of PAHs in sediments. 相似文献
5.
《商丘师范学院学报》2013,(12)
Over the past 15 years there has been much effort invested in microorganisms of glacial snow and ice on the Tibetan Plateau.These studies include: phenotypic characteristics of recovered isolates; factors ( dust, temperature, altitude) influencing microbial abundance , diversity and community in one glacier; distribution of bacterial number , diversity, community along ice core depth;similarities and differences of regionally distributed ice core isolates; seasonal variation of bacterial abundance and diversity . The following need further study .Better methods for more information about the diversity , survival mechanism of glacial microorganism;more research about archaea and fungi; microbial resources; relation of glacial microorganisms with biogeochemical cycle and mass balance;research on altitude distribution . 相似文献
6.
Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops 总被引：3，自引：0，他引：3
Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely： inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil （total or bioavailable concentration） that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include： soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity. 相似文献
7.
Liang Yuqi Liao Min Fang Zhiping Guo Jiawen Xie Xiaomei Xu Changxu 《Journal of Zhejiang University. Science. B》2021,22(7):521-532
In order to reveal the mechanism of silicon(Si) fertilizer in improving nitrogen(N) and phosphorus(P) nutrient availability in paddy soil, we designed a series of soil culture experiments by combining application of varying Si fertilizer concentrations with fixed N and P fertilizer concentrations. Following the recommendations of fertilizer manufacturers and local farmers, we applied Si in concentrations of 0, 5.2, 10.4, 15.6, and 20.8 μg/kg. At each concentration of added Si, the availability of soil N and P nutrients, soil microbial activity, numbers of ammonia-oxidizing bacteria and P-decomposing bacteria which means that the organic P is decomposed into inorganic nutrients which can be absorbed and utilized by plants, and urease and phosphatase activity first increased, and then decreased, as Si was added to the soil. These indicators reached their highest levels with a Si application rate of 15.6 μg/kg, showing values respectively 19.78%, 105.09%, 8.34%, 73.12%, 130.36%, 28.12%,and 20.15% higher than those of the controls. Appropriate Si application(10.4 to 15.6 μg/kg) could significantly increase the richness of the soil microbial community involved in cycling of N and P nutrients in the soil. When the Si application rate was15.6 μg/kg, parameters for characterizing microbial abundance such as sequence numbers, operational taxonomic unit(OTU)number, and correlation indices of microbial community richness such as Chao1 index, the adaptive coherence estimator(ACE)index, Shannon index, and Simpson index all reached maximum values, with amounts increased by 14.46%, 10.01%, 23.80%,30.54%, 0.18%, and 2.64%, respectively, compared with the control group. There is also a good correlation between N and P mineralization and addition of Si fertilizer. The correlation coefficients between the ratio of available P/total P(AP/TP) and the number of ammonia-oxidizing bacteria, AP/TP and acid phosphatase activity(AcPA), AP/TP and the Shannon index, the ratio of available N/total amount of N(AN/TN) and the number of ammoniated bacteria, and AN/TN and AcPA were 0.9290, 0.9508,0.9202, 0.9140, and 0.9366, respectively. In summary, these results revealed that enhancement of soil microbial community structure diversity and soil microbial activity by appropriate application of Si is the key ecological mechanism by which application of Si fertilizer improves N and P nutrient availability. 相似文献
8.
Copper accumulation and intracellular distribution in Elsholtzia splendens, a native Chinese Cu-tolerant and accumulating plant species, was investigated by transmission electron microscope (TEM) and gradient centrifugation techniques.Copper concentrations in roots, stems and leaves of E. splendens increased with increasing Cu levels in solution. After exposure to 500 μmol/L Cu for 8 d, about 1000 mg/kg Cu were accumulated in the stem and 250 mg/kg Cu in the leaf of E. splendens. At 50μmol/L Cu, no significant toxicity was observed in the chloroplast and mitochondrion within its leaf cells, but separation appeared at the cytoplasm and the cell wall within the root cells. At ＞250 μmol/L Cu, both root and leaf organelles in E. splendens were damaged heavily by excessive Cu in vivo. Copper subcellular localization in the plant leaf after 8 days' exposure to 500 μmol/L Cu using gradient centrifugation techniques was found to be decreased in the order: chloroplast＞cell wall＞soluble fraction＞other organelles. The plant root cell wall was found to be the site of highest Cu localization. Increase of Cu exposure time from 8 d to 16d, increased slightly Cu concentration in cell wall fraction in roots and leaves, while that in the chloroplast fraction decreased in leaves of the plants grown in both 0.25 μmol/L and 500 μmol/L Cu. TEM confirmed that much more Cu localized in cell walls of E. splendens roots and leaves, but also more Cu localized in E. splendens' chloroplast when the plant is exposed to Cu levels＞250μmol/L, as compared to those in the plant grown in 0.25 μmol/L Cu. Copper treatment at levels＞250 μmol/L caused pronounced damage in the leaf chloroplast and root organelles. Copper localization in cell walls and chloroplasts could mainly account for the high detoxification of Cu in E. splendens. 相似文献
9.
Toxicity of cadmium to soil microbial biomass and its activity：Effect of incubation time on Cd ecological dose in a paddy soil 总被引：4，自引：0，他引：4
INTRODUCTION Cadmium (Cd) is ubiquitous in the human en-vironment and has been recognized as one of the mostdeleterious heavy metal pollutants (Robards andWorsfold, 1991; Christine, 1997). It may easily movefrom soil to food plants through root absorption andaccumulate in their tissues (Oliver, 1997). In this way,Cd may enter the food chain and affect human health(Adriano, 1986). Among many heavy metals pollut-ing soil, Cd is of concern because of its potentiallyharmful effects on… 相似文献
10.
ZHANG Ming-kui ZHENG Shun-an 《浙江大学学报(A卷英文版)》2007,8(11):1808-1815
Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas, China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concen- tration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased. The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils. 相似文献
11.
INTRODUCTION Biosphere pollution by heavy metals and nu-cleotides was accelerated dramatically during the last few decades due to mining, smelting, manufacturing, treatment of agricultural soils with agro-chemicals and soil sludge, etc. Problems associated with the contamination of soil and water such as animal wel-fare, health, fatalities and disruptions of natural eco-systems are well documented (He et al., 2005). Heavy metals such as Pb, Cr, As, Cu, Cd, and Hg, being added to our so… 相似文献
12.
Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria have received more and more attention. This article paper reviews some recent advances in effect and significance of rhizobacteria in phytoremediation of heavy metal contaminated soils. There is also a need to improve our understanding of the mechanisms involved in the transfer and mobilization of heavy metals by rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes. 相似文献
13.
重金属的开采和冶炼不仅破坏生态平衡,而且严重威胁人类的健康。以毕节地区2个铅锌矿为研究对象,采用现场采样、室内分析的方法,调查研究了该地区土壤及优势植物中重金属含量。结果表明：研究区土壤主要受到Pb、Zn、Cu、Cd四种重金属污染,其中,Cd污染最为严重,Pb、Zn为轻度污染。优势植物重金属含量测定表明,野艾蒿属于重金属富集型植物,苦苣菜属于规避型植物,马刺蓟属于根部囤积型植物。以上几种优势植物对重金属均具有一定的耐性,可以作为铅锌矿区弃地植物修复的优选物种。 相似文献
14.
INTRODUCTIONPhytoremediation,thatuseofgreenplantstodecontaminateCuandotherheavymetalsinsoils,isanemergingtechniquewithadvantagesofbeinginsitu,cost-effectiveandenvironmentallysus-tainable(Chanyetal.,1997;Cunninghametal.,1997;Saltetal.,1998).Theavailabilityofmetalinthesoilforplantuptakeisoneimportantlimitationforsuccessfulphytoremediation(Blaylocketal.,1997).Forexample,lead(Pb)isoneofthemostimportantenvironmentalpollutants,haslimitedsolubilityinsoils,andisavailableforplantuptakeduetocompl… 相似文献
15.
Phytoremediation is emerging as a potential cost-effective solution for remediation of contaminated soils, and bioavailability of metal in the soil for plant uptake is an important factor for successful phytoremediation. This study aimed at investigating the ability of EDTA and citric acid for enhancing soil bioavailability of Cu and phytoremediation by Elsholtzia splendens in two types of soils contaminated with heavy metals [i.e. mined soil from copper mining area (MS), and paddy soil (PS) polluted by copper refining]. The results showed that addition of 2.5 mmol/kg EDTA significantly increased the H2O extractable Cu concentration from 1.20 to 15.78 mg/kg in MS and from 0.26 to 15.72 mg/kg in PS, and that shoot Cu concentration increased 4-fold and 8-fold as compared to the control. There was no significant difference between the treatment with 5.0 mmol/kg EDTA and that with 2.5 mmol/kg EDTA, probably because that 2.5 mmol/kg EDTA was enough for elevating Cu bioavailability to the maximum level. As compared with the control, citric acid had no marked effect on both soil extractable Cu and shoot Cu concentration or accumulation. The results indicated that EDTA addition can increase the potential and efficiency of Cu phytoextraction by E. splendens in polluted soils. 相似文献
16.
Phytoremediation is emerging as a potential cost-effective solution for remediation of contaminated soils, and bioavailability
of metal in the soil for plant uptake is an important factor for successful phytoremediation. This study aimed at investigating
the ability of EDTA and citric acid for enhancing soil bioavailability of Cu and phytoremediation by Elsholtzia splendens
in two types of soils contaminated with heavy metals [i.e. mined soil from copper mining area (MS), and paddy soil (PS) polluted
by copper refining]. The results showed that addition of 2.5 mmol/kg EDTA significantly increased the H2O extractable Cu concentration from 1.20 to 15.78 mg/kg in MS and from 0.26 to 15.72 mg/kg in PS, and that shoot Cu concentration
increased 4-fold and 8-fold as compared to the control. There was no significant difference between the treatment with 5.0
mmol/kg EDTA and that with 2.5 mmol/kg EDTA, probably because that 2.5 mmol/kg EDTA was enough for elevating Cu bioavailability
to the maximum level. As compared with the control, citric acid had no marked effect on both soil extractable Cu and shoot
Cu concentration or accumulation. The results indicated that EDTA addition can increase the potential and efficiency of Cu
phytoextraction byE. splendens in polluted soils.
Project supported by the National Natural Science Foundation of China (No. 29977017) and the Science and Technology Ministry
of China (No. 2002CB410804) 相似文献
17.
丛枝菌根真菌可以与绝大多数陆生植物共生,它可以吸收铵态氮、硝态氮、一些氨基酸和一些复杂的有机氮素,吸收的氮素在根外菌丝中转化成精氨酸,并以这种形式运输到根内菌丝,在根内菌丝和根细胞界面,精氨酸再进一步转化为NH4^＋后转移到宿主植物体,参与植物氮素代谢,而转移的氮量及对宿主植物氮营养的贡献与宿主植物、真菌以及基质养分和水分条件有关． 相似文献
18.
Jun Zhao Xin Zhao Lei Chao Wei Zhang Tao You Jie Zhang 《Journal of Zhejiang University. Science. B》2014,15(7):670-680
Pollution discharge disturbs the natural functions of water systems. The environmental microbial community composition and diversity are sensitive key indicators to the impact of water pollutant on the microbial ecology system over time. It is meaningful to develop a way to identify the microbial diversity related to heavy metal effects in evaluating river pollution. Water and sediment samples were collected from eight sections along the Tiaozi River where wastewater and sewage were discharged from Siping City in northeastern China. The main pollutants contents and microbial communities were analyzed. As the primary metal pollutants, zinc (Zn) and arsenic (As) were recorded at the maximum concentrations of 420 and 5.72 μg/L in the water, and 1704 and 1.92 mg/kg in the sediment, respectively. These pollutants posed a threat to the microbial community diversity as only a few species of bacteria and eukaryotes with strong resistance were detected through denaturing gradient gel electrophoresis (DGGE). Acinetobacter johnsonii, Clostridium cellulovorans, and Trichococcus pasteurii were the dominant bacteria in the severely polluted areas. The massive reproduction of Limnodrilus hoffmeisteri almost depleted the dissolved oxygen (DO) and resulted in the decline of the aerobic bacteria. It was noted that the pollution reduced the microbial diversity but the L. hoffmeisteri mass increased as the dominant community, which led to the overconsuming of DO and anaerobic stinking water bodies. Water quality, concentrations of heavy metals, and the spatial distribution of microbial populations have obvious consistencies, which mean that the heavy metals in the river pose a serious stress on the microorganisms. 相似文献
19.
A series of laboratory and pot experiments carried out to examine the role of soil microbial biomass in red soils' nitrogen availability and productivity showed that soil available N (NA), dry matter yield (DMY) of ryegrass, and plant uptake of nitrogen were each closely correlated with microbial biomass-C (Cmic) or -N (Nmic), suggesting that soil microbial biomass is a very important nitrogen pool available to plants in red soils. After correction for the substrate effect, the computed turnover of the Nmic in three tested soils ranged from 63 to 250 days. Soils with low Nmic or light texture generally had higher Nmic turnover rate than those with high Nmic or heavy texture. These results showed that soils with low Nmic, microbial biomass could also play an important role in the availability of nitrogen to plants due to these soils' high turnover rate. 相似文献