Trace metals in sediments and aquatic plants from the Xiangjiang River, China

Purpose

The metal concentrations and Pb isotopic composition in sediments and plants from the Xiangjiang River, China, were investigated to understand the contamination and potential toxicity of metals in sediments; to determine the accumulation and distribution of metals in plant tissues; and to trace the possible pollution source of Pb in sediments and plants.

Materials and methods

Sediments and plants were collected from 43 sampling sites in the study region. After sediments were air-dried and passed through a 63-??m sieve, they were acid-digested and DTPA-extracted for determination of total and bioavailable metals. The plants were separated into roots, leaves, and stems; dried; cut into pieces; and digested with HNO₃?CH₂O₂. Metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) and Pb isotopic composition were analyzed by inductively coupled plasma-mass spectrometry.

Results and discussion

Maximum As, Cd, Cr, Cu, Ni, Pb, and Zn concentrations in sediments were 47.18, 55.81, 129.5, 161.6, 160.4, 430.7, and 1,098.8?mg?kg^?1, respectively. The bioavailable fractions of As, Cd, Cu, Pb, and Zn had significant linear relationship with their corresponding total contents in sediments while no significant relationship was observed between bioavailable and total contents of Cr and Ni. In general, plant tissues showed higher As, Cd, Cu, Pb, and Zn concentrations and lower Cr and Ni concentrations compared with sediments. The ²⁰⁶Pb/²⁰⁷Pb ratios decreased in the order of total > bioavailable > stems ?? leaves > roots. A strong linear correlation was observed between the ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁷Pb ratios of the plant tissues, sediments, and the possible pollution sources of Pb in the Xiangjiang River.

Conclusions

As, Cd, Cu, Pb, and Zn demonstrated higher contamination levels in sediments and plants compared with Cr and Ni. Cd had highest potential ecological risk. The Pb from anthropogenic sources with low ²⁰⁶Pb/²⁰⁷Pb ratios was preferentially associated with the bioavailable fractions in sediments and accumulated in roots. The Pb in plant tissues is mainly derived from the Pb in sediment and is taken up through the sediment-to-root pathway.     

Estimation method of residual alkylating agents in water treated with chloring-containing oxidant

Concentrations of trace metals in mosses Hylocomium splendens (Hs) and Pleurozium schreberi (Ps) are compared along with wet deposition at 8 sites in Sweden. Cd, Mn, Zn and Cr concentrations were similar in both mosses, while Cu, Fe, Pb, Ni and V levels were 14 to 24% higher in Hs than in Ps. The comparison to wet deposition estimates indicates that concentrations in mosses are also influenced by other factors than the adsorption of precipitation. No correlation was observed between the wet deposition of Mn, Cr and Ni and moss concentrations.     

Influence of EDTA and citric acid on lead-induced oxidative stress to Vicia faba roots

Purpose

In spite of substantial advancement in recent past, the role of metal speciation in assessing biogeochemical behaviour of Pb is still topical. Organic ligands are capable to modify Pb speciation in nutrient/soil solution and in turn its soil–plant transfer and toxicity. In this sense, the main objective of this study was to evaluate the effect of organic ligands on Pb-induced oxidative stress to Vicia faba roots.

Materials and methods

V. faba seedlings grown to controlled hydroponic system were treated with 5 μM Pb as lead nitrate in the presence and absence of organic ligands viz ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) for 1, 4, 8, 12, and 24 h. The chemical speciation of Pb (percent free and chelated Pb) in nutrient solution in the presence and absence of organic ligands was calculated using Visual Minteq speciation model. The effect of chemical speciation on Pb-induced oxidative stress to V. faba roots was investigated using plant enzymatic antioxidative system [superoxide dismutases (SOD), guaiacol peroxidise (GPX), ascorbate peroxidase (APX), glutathione reductase (GR), and catalase (CAT)]. The antioxidant enzymes activities were determined using ultraviolet spectrophotometer.

Results and discussion

The activities of SOD, GPX, APX, and GR significantly increased whereas that of CAT decreased in V. faba roots under Pb alone treatment. Lead-induced increase/decrease in antioxidant enzymes activities was not linear but varies with treatment exposure time. EDTA dose dependently inhibited Pb-induced changes in antioxidant enzymes activities. However, CA did not cause any significant change in Pb-induced variation in antioxidant enzymes activities, but delayed or slightly reduced the Pb effect.

Conclusions

The present study suggested that physiological responses of V. faba roots to Pb toxicity vary with applied Pb form and duration of exposure. EDTA can inhibit Pb-induced toxicity to V. faba seedlings by forming stable Pb-EDTA complexes due to its high binding strength for Pb. However, CA had no effect on Pb-induced toxicity to V. faba roots due to weak complexation with Pb.     

Influence of pH on the release and chemical fractionation of heavy metals in sediment from a suburban drainage stream in an arid mine-based oasis

Purpose

The objectives of this study were to explore the influences of pH on the release of Cu, Zn, Cd, Pb, Ni, and Cr in sediments derived from the upstream, middle, and downstream reaches of Dongdagou stream in Gansu Province, Northwest China, and to examine the fractionation changes of heavy metals in the sediments after reaching their release equilibrium under different pH conditions.

Materials and methods

Sediment samples were obtained using a stainless steel grab sampler to collect the uppermost 10 cm of sediment from the channel bed. The pH-dependent release experiment was conducted in the solid-to-liquid ratio of 1:20 at different pH values (2, 4, 6, 8, 10, and 12) at room temperature. The total Cu, Zn, Cd, Pb, Ni, and Cr concentrations in the sediments were digested using an acid digestion mixture (HNO₃ + HF + HClO₄) in an open system. Metal fractionation of selected sediments was obtained using the Tessier sequential extraction procedure. Heavy metal concentrations in the samples were determined using atomic absorption spectrophotometry.

Results and discussion

The mean concentrations of heavy metals in sediments decreased in the following order: Zn (1676.67 mg kg^?1) > Pb (528.65 mg kg^?1) > Cu (391.34 mg kg^?1) > Cr (53.48 mg kg^?1) > Ni (34.27 mg kg^?1) > Cd (11.53 mg kg^?1). Overall, the solubility of Cu, Zn, Cd, Pb, and Ni decreased with increasing pH, and they were strongly released at pH 2. Moreover, the solubility of Cr increased with increasing pH, and its release was highest at pH 12. After reaching the release equilibrium of heavy metals under different pH conditions, the percentages of organic Cu, Zn, Cd, and Fe-Mn oxyhydroxide Pb decreased, compared to their initial fractions. The residual fractions of Ni and Cr were dominant, regardless of pH.

Conclusions

The average concentrations of Cu, Zn, Cd, and Pb in sediments were highly elevated compared with the soil background values in Gansu Province, China. The results of this pH-dependent release experiment showed that the release behaviors of Cu, Zn, Pb, and Cr followed an asymmetric V-shaped pattern, whereas Cd and Ni followed an irregular L-shaped pattern. The changes in the release of heavy metals in sediments were related to their redistribution between chemical fractionations.

     

Anthropogenic environmental impact in the Mediterranean coastal area of Koper/Capodistria,Slovenia

Purpose

Heavy metal content in soils could be a consequence of geogenic and different anthropogenic sources. In ancient times, soils in the Mediterranean region were affected by agriculture and viticulture, whereas more recently, industry and traffic might contribute more to their pollution. The aim of the study is to determine the extent of multisource heavy metal pollution in soils within the Koper area.

Materials and methods

Along the northern Adriatic Sea coast, around the port city of Koper/Capodistria, 24 topsoil samples were collected; sets of six samples representing four possible pollution sources: intensive agriculture, viticulture, port activities and industry. The parent material of the soil is mainly derived from the Eocene flysch weathered marls and calcarenites and the soil types are eutric. The chemical composition of the samples was determined by ICP-ES for oxides and several minor elements and by ICP-MS for heavy metals. The mineral composition of the selected samples was checked using X-ray powder diffraction. Different statistical analyses were performed on the normally distributed data.

Results and discussion

The mean concentrations of all samples are: Cr 215 mg kg^?1, Ni 81 mg kg^?1, Zn 67 mg kg^?1, Cu 44 mg kg^?1 and Pb and Co 18 mg kg^?1. The ANOVA showed significant differences only in CaO, C/TOT, P₂O₅, Co and Pb between those locations within reach of the different contamination sources. The observed average values of heavy metals are well below Slovenia’s Directive limit for Cu, Pb and Zn, close to but not above it for Co and above the action value for Cr and Ni. According to Igeo, soils from all the sampling locations are uncontaminated with Co, Ni and Pb, and uncontaminated to moderately contaminated with Cu and Zn at one port location, and with Cr at all locations.

Conclusions

The very high Cr and Ni levels could still be geogenic because soils developed on Eocene flysch rocks are enriched in both metals. Cr and Ni are not correlated because of their different levels of sorption and retention in carbonate soils. Cr was retained and concentrated in the sand fraction but Ni has been mobilised in solution. The only serious threat to the environment seems to be an illegal waste dumping area near the port.     

Boron stress inhibits beet (Beta vulgaris L.) growth through influencing endogenous hormones and oxidative stress response

Objective: This study aimed to evaluate the pleiotropic effects of boron stress on beet (Beta vulgaris L.) growth.

Methods: Beet seedlings were treated with varying concentrations of H₃BO₃ (0.05, 0.5, 2, and 30 mg/L) for 30 d for evaluation of diverse morphological parameters related to shoot and root growth. Transverse sections of beet leaves were observed under a microscope, and the leaf thickness was measured. Photosynthesis in beet was evaluated by measuring the photosynthetic rate, intercellular carbon dioxide concentration, and chlorophyll content; chloroplast morphology was observed by transmission electron microscopy. In addition, the levels of diverse endogenous hormones, as well as oxidative stress parameters, were also analyzed in beet leaves.

Results: We found that boron accumulated in different beet tissues but was observed mainly in mature leaves, followed by young leaves, mature petioles, young petioles, and roots. Boron stress (boron toxicity, 30 mg/L; boron deficiency, 0.05 mg/L) significantly inhibited beet shoot, root growth, and leaf expansion while promoting leaf thickening. Additionally, the levels of indole-3-acetic acid, gibberellin A3, and zeatin in beet leaves decreased significantly under boron stress, whereas the level of abscisic acid increased. Moreover, the levels of superoxide dismutase, peroxidase, catalase, malondialdehyde, and proline in beet leaves increased significantly under boron stress.

Conclusion: Together, our results indicate that boron stress significantly inhibited normal beet growth via the influence of endogenous hormone levels and oxidative stress responses.     

Geographic Classification of Heavy Metal Concentrations in Mosses and Stream Sediments in the Federal Republic of Germany

The results of the first German moss monitoring programme to estimate heavy metal pollution in the Federal Republic of Germany were combined with other large-scale investigations carried out in Germany and then classified geographically in a new form. Using Monte Carlo assisted factor analysis, six factors indicating sources of pollution were identified from the sets of element data from the moss monitoring project (As, Cd, Cr, Cu, Fe, Ni, Pb, Ti, V, Zn) and the data sets for SO₂ and particulate. The geographic distribution patterns of the factor values showed the regions in which the various sources are to be found. By combining the data the primarily anthropogenic chromium concentrations of the mosses were compared with the mainly geogenic chromium concentrations of the stream sediments in the form of examples. After normalization, the transformed chromium concentrations were transferred to a map of the entire area using inverse distance weighting. Anthropogenic and geogenic influences are being discussed on the basis of the results.     

工业废弃地多金属污染土壤组合淋洗修复技术研究

采用批量淋洗实验方法,对比了采用人工螯合剂乙二胺四乙酸二钠盐(EDTA-Na2)和天然有机酸草酸(oxalic acid,OX)对工业废弃地污染土壤中重金属的去除效果,并采用不同浓度草酸和EDTA组合的两步淋洗法研究多金属污染土壤的最佳淋洗方式。结果表明,EDTA淋洗剂对土壤中Zn、Pb、Cu、Ni去除效果较好,而对Cr去除效果较差,实验条件下,EDTA对金属的去除率并未随着浓度增加而增加;相反,草酸对Cr去除效果较好,且去除率随着淋洗剂浓度的增加而增加,而对Zn、Cu、Ni的去除效果随着淋洗剂浓度增加而降低,对Pb的去除率非常低;采用先以0.20 mol L-1草酸提取2 h,再以0.01 mol L-1EDTA提取2 h的两步淋洗法可以达到对多金属同时去除,且对Zn、Cu、Cr、Ni的去除率明显高于单用草酸和EDTA,总去除率分别为Zn 75.21%、Pb 21.30%、Cu 59.81%、Cr 60.72%和Ni 62.10%,更为有意义的是两步淋洗法对非残渣态金属去除效果分别高达Zn 91.93%、Pb 57.75%、Cu 75.33%、Cr 73.94%、Ni 77.99%。利用不同化学淋洗剂对金属去除能力的差异进行组合的多步淋洗法是一种较为高效的去除工业废弃地污染土壤中重金属的化学淋洗修复方法。     

Fractionation of chromium in tannery sludge-amended soil and its availability to fenugreek plants

Purpose

Fenugreek (Trigonella foenum-graecum L.) is a medicinal plant with antidiabetic effects. Chromium has been related to better glucose tolerance in humans. The objective of this study was to determine whether tannery sludge could be used for Cr biofortification of fenugreek.

Materials and methods

Soil was mixed with tannery sludge containing 6.03 g Cr kg^?1. All Cr was in the form of Cr(III). Three treatments were disposed: control without sludge, and two treatments with 10 and 20 g sludge kg^?1, respectively. Control and the 10 g sludge kg^?1 treatments received NPK fertilizer to adjust the concentrations of major mineral nutrients to similar levels in all treatments. Soils were potted and planted with fenugreek. Plants harvested at the initial flowering stage were analysed for total Cr, Fe, Zn and Pb. Sequential soil extraction was applied to obtain operationally defined soil Cr fractions.

Results and discussion

Total Cr in all treatments was below or within the allowable range for agricultural soils (100–150 mg kg^?1). In control soils, most Cr was in the residual fraction (HF/HClO₄ digest). Tannery sludge-amended soils incorporated most Cr into the moderately reducible fraction (oxalic acid/ammonium oxalate extract). In fenugreek shoots, Cr concentrations reached 3.2 mg Cr kg^?1, a higher concentration than that reported for other leafy vegetables. Lead concentrations in plant shoots from this treatment were enhanced but hardly exceeded 1 mg Pb kg^?1.

Conclusions

Tannery sludge-amended soils containing Cr within the range of permissible concentrations can increase shoot Cr in fenugreek. Only sludge with low Pb concentrations should be used for Cr biofortification of fenugreek.     

Contents and chemical forms of heavy metals in school and roadside topsoils and road-surface dust of Beijing

Purpose

The concentration of human activities in urban systems generally leads to urban environmental contamination. Beijing is one of ancient and biggest cities on the world. However, information is limited on Beijing’s soil contamination, especially for roadside and campus soils. Thus, the aims of this study were to investigate the contents and chemical forms of toxic heavy metals Cd, Cr, Cu, Ni, Pb, and Zn in the road-surface dust, roadside soils, and school campus soils of Beijing. In addition, enrichment and spatial variation of these toxic heavy metals in the soils and dust were assessed.

Materials and methods

Topsoil samples were collected from the schools and roadside adjacent to main ring roads, and dust samples were collected from the surface of the main ring roads of Beijing. These samples were analyzed for total contents and chemical forms of Cd, Cr, Cu, Ni, Pb, Sc, Zn, Al, and Fe. Enrichment factors (EFs, relative to the background content) were calculated to evaluate the effect of human activities on the toxic heavy metals in soils.

Results and discussion

Heavy metal contents in the road dust ranged from 0.16 to 0.80, 52.2 to 180.7, 18.4 to 182.8, 11.9 to 47.4, 23.0 to 268.3, and 85.7 to 980.9 mg kg^?1 for Cd, Cr, Cu, Ni, Pb, and Zn, respectively. In the roadside soil and school soil, Cd, Cr, Cu, Ni, Pb, and Zn contents ranged from 0.13 to 0.42, 46.1 to 82.4, 22.7 to 71.6, 20.7 to 29.2, 23.2 to 180.7, and 64.5 to 217.3 mg kg^?1, respectively. The average EF values of these metals were significantly higher in the dust than in the soils. In addition, the average EF values of Cd, Cu, Pb, and Zn in the soils near second ring road were significantly higher than those near third, fourth, and fifth ring roads. Anthropogenic Cd, Pb, and Zn were mainly bound to the carbonates and soil organic matter, while anthropogenic Cu was mainly bound to oxides. The mobility and bioavailability of these metals in the urban soils of Beijing generally decreased in the following order: Cd?>?Zn?>?Pb?>?Cu?>?Ni?>?Cr; while in the dust, they decreased in the following order: Zn, Cu, and Cd?>?Pb?>?Ni?>?Cr.

Conclusions

Both EF and chemical forms documented that Cr and Ni in the soils and dust mainly originated from native sources, while Cd, Cu, Pb, and Zn partially originated from anthropogenic sources. In overall, Beijing’s road dust was significantly contaminated by Cd and Cu and moderately contaminated by Cr, Pb, and Zn, while Beijing’s roadside soil and school soil were moderately contaminated by Cd and Pb. However, the maximal hazard quotients (HQs) for individual Cd, Cr, Cu, Ni, Pb, and Zn and comprehensive hazard index (HI) of these metals in the dust and soil were less than 1, indicating that the heavy metals in the dust and soil generally do not pose potential health effects to children, sensitive population.     

The Influence of Glutathione on Physiological Effects of Lead and its Accumulation in Moss Sphagnum Squarrosum

An attempt has been made to study the physiological andbiochemical responses and to evaluate the bioaccumulationpotential of moss Sphagnum to environmental lead. Supply of0.1 to 100 mM lead acetate caused a loss in chlorophyll andnitrogen content of moss and in nitrate reductase activity in themoss, although the peroxidase activity was increased. Partialrecovery in the above parameters was recorded upon simultaneoustreatment with glutathione. Results also indicate that treatmentwith glutathione increased the bioaccumulation potential bylowering the lead toxicity, which could be the result of inductionof metal binding capabilities of cells as the heavy metal alsoinduced the synthesis of phytochelatins. The moss accumulated asignificant amounts of Pb under both experimental and fieldconditions. The heavy metal accumulated by moss was positivelycorrelated to the soil metal content. The experiments demonstratethat Sphagnum is able to accumulate and tolerate higheramounts of Pb and therefore, it can be used as a bioindicator andphytoremediator of lead contaminated environment.     

不同种类重金属胁迫对两种小麦产量及构成因素的影响

以当前农业研究的热点领域——重金属污染为切入点,研究了大田Cd、Pb、As、Hg、Cr5种重金属胁迫对小麦（郑麦9023、小偃22）籽粒产量及构成因素的影响。结果表明重金属胁迫下,cd、Pb、As、№、cr重金属对产量三要素中单位面积群体穗数的影响最大,其次为穗粒数,对千粒重的影响最小;单位面积群体穗数对重金属Cr、Pb最为敏感,在旱田偏碱性的土壤上,Cr、Pb胁迫对小麦单位面积的群体穗数影响的临界含量分别约为187．5mg·kg^-1和175mg·kg^-1。对两个小麦品种的籽粒产量影响不同,郑麦9023籽粒产量依次为Cr2〈Crl〈CK〈Cd2〈Hgl〈As2〈Asl〈Hg2〈Pbl〈Cdl〈Pb2;小偃22籽粒产量依次为Cr2〈Crl〈CK〈Hgl〈As2〈Hg2〈Cdl〈Cd2〈Pb2〈Asl〈Pb1。重金属Cr对小麦的产量表现为抑制效应,Cd、Hg、Pb、As对小麦产量的影响表现为增产效应;不同种类重金属胁迫对小麦产量影响作用依次为Hg〈Cd〈As〈Pb〈Cr。     

Lead accumulation from non-saline and saline environment by Tamarix smyrnensis Bunge

Tamarix smyrnensis plants were exposed to Pb(NO₃)₂, with and without addition of salt into soil for 10 weeks. Salt as NaCl was added to water for watering in concentrations 0.5% and 3%. Subsequently, lead uptake was quantified in leaves and roots of the plants by ICP-AES spectrometry. In addition, the influence of Pb on photosynthesis and other physiological parameters was also examined by means of biomass production and shoot length determination. Plant appearance was observed also. The influence of Pb presence in the soil on chlorophyll content was examined. In order to quantify the fate of Pb in the plant, metal excretion by salt glands was investigated as well. It was found that the roots were the main accumulation site of Pb in all plants under all treatments irrespective of salt concentration in soil. Low salinity in soil did not affect Pb accumulation in roots but at high salt concentration Pb accumulation decreased. The opposite was observed in the leaves where more Pb was accumulated at high salt concentration in soil. The toxic effect of Pb was visible only in the group treated with Pb without addition of NaCl into water for watering. The visible toxicity symptoms were connected only with high salinity. No excretion of Pb by salt glands was observed.     

Baseline element concentrations in soils and plants,Bull Island,Cape Romain National Wildlife Refuge,South Carolina,U.S.A.

Baseline element concentrations are given for Spanish moss (Tillandsia usneoides), loblolly pine (Pinus taeda), and associated soils. Baseline and variability data for ash, Al, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Sr, Th, Ti, V, Y, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration among and within 0.5 km grid cells are given for each of the media. In general, only a few elements in Spanish moss showed statistically significant landscape patterns, whereas several elements in loblolly pine and in soils exhibited differences among sampling grids. Significant differences in the concentration of three elements in Spanish moss and eight elements (including total S) in loblolly pine were observed between two sampling dates (November and June); however, the absolute amount of these differences was small. Except for perhaps Ni and Pb concentrations in Spanish moss, element levels in all sample media exhibited ranges that indicate natural rather than anthropogenic additions of trace elements.     

Emerging resistant microbiota from an acidic soil exposed to toxicity of Cr, Cd and Pb is mainly influenced by the bioavailability of these metals

Purpose

The effect of pollutants in soil microorganisms is an important issue in order to understand their toxic effects in the environment, as well as for developing adequate bioremediation strategies. In this sense, the main objective of this study was to assess the involvement of the indigenous microbiota of an acidic forest Mediterranean soil by artificial pollution with heavy metals, and to detect and isolate resistant microorganisms that could be useful for bioremediation.

Materials and methods

Samples from a previously unpolluted acidic forest soil were amended with Cr(VI), Cd(II) or Pb(II) at total amounts ranging from 0.1 to 5,000 mg?kg^?1. These soil microcosms were incubated under controlled laboratory conditions for 28 days. Soluble fractions of metals were determined from aqueous extracts. Both activity and composition of the microbial community were assessed, respectively, by respirometric assays and molecular analysis (polymerase chain reaction denaturing gradient gel electrophoresis). The isolation of metal-resistant microorganisms was attempted by culture plating from microcosms incubated with high concentrations of metals. Isolated strains were tested in cultures with minimal medium to check for their metal resistance and their capacity to reduce the presence of toxic Cr(VI).

Results and discussion

A decrease in the soil respirometric activity and changes in the microbial community composition were detected from 10/100 mg?kg^?1 Cr and 1,000 mg?kg^?1 Cd and Pb. Presumably resistant bacterial and fungal populations developed in most of these polluted microcosms; however, the microbiota was severely impaired at the highest additions of Cr. Even though Cr was the most damaging metal in soil microcosms, if the soluble fractions of metals are considered instead of their total added amounts, the comparison among their toxic effects suggests a similar potential toxicity of Cr and Pb. Isolated multiresistant microorganisms were related mainly to Actinobacteria, Firmicutes and Ascomycota. Some of them showed the capacity to reduce Cr(VI) concentrations between 54 % and 70 % of the initial value. These strains were affiliated to several species of Streptomyces and Bacillus.

Conclusions

The combination of respirometric assays with molecular methods has been useful to assess the effect of metals on the soil microbial community, which can greatly be explained by their differential bioavailability. Cultivation-dependent and -independent approaches have proved the presence and development of multiresistant microorganisms in a previously unpolluted soil. Due to their properties, some of the isolated strains are potentially useful for soil bioremediation.     

Sources and Ecological Risks of Heavy Metals in Soils Under Different Land Uses in Bangladesh

Soil heavy metal pollution, influenced by both natural and anthropogenic factors, significantly reduces environmental quality. In this study, Cr, Ni, Cu, As, Cd, and Pb in eight different land-use soils from Patuakhali District in Bangladesh were assessed. Concentrations of Cr, Ni, Cu, As, Cd, and Pb in soils were 1-87, 5-271, 4-181, 0-80, 0.2-24.0, and 5-276 mg kg^-1, respectively, measured using an inductively coupled plasma-mass spectrometer. The enrichment factor, pollution load index (PLI), and contamination factor (C_fⁱ) of metal i were used to assess the ecological risk posed by metals in soils. The PLI ranged from 0.78 to 2.66, indicating baseline levels to progressive deterioration of soil due to metal contamination. However, C_fⁱ of Cd ranged from 1.8 to 12.0, which showed that the studied soils were strongly impacted by Cd. Considering the severity of the potential ecological risk of a single metal, the descending order was Cd > As > Pb > Cu > Ni > Cr. Soils under all land uses showed moderate to very high potential ecological risk.     

Application of Organic Wastes in a Soil Polluted with Different Rates of Cr-Pb: Effects on Soil Biological Properties

An experiment was performed to determine the effects of adding municipal solid waste (MSW) and poultry manure (PM) to a soil polluted with chromium (Cr), lead (Pb), and Cr + Pb on the biological parameters of the soil. Soil was mixed with two solutions of Cr(NO₃)₃ and/or Pb(NO₃)₂ to give three concentrations (0, 100, and 250 mg Cr kg^?1 soil and 0, 100, and 250 mg Pb kg^?1 soil) and treated with MSW or PM. When the soil was contaminated with the metals without combining, the greatest adenosine triphosphate (ATP), urease, and phosphatase inhibition percentages occurred for 250 mg Pb kg^?1 soil. When the heavy metals were mixed, the inhibition of the biochemical parameters increased. The application of MSW and PM decreased the inhibition of the biochemical parameters and microbial population in the polluted soils. The inhibition percentage was greater for the soil amended with MSW than with PM, possibly due to the high humic acid concentration.     

不同烤烟品种幼苗形态结构及光合参数对 干旱胁迫响应机制的差异

为了比较不同烤烟品种的苗期耐旱性差异,选用河南烟区主栽烤烟品种‘豫烟6号’、‘豫烟10号’、‘豫烟12号’和‘中烟100’为供试材料,利用浓度为15%的聚乙二醇(PEG-6000)模拟中度干旱环境,研究不同烤烟品种幼苗生物量、根系形态、叶片气孔特征、叶绿体超微结构和光合参数等指标对干旱胁迫响应机制的差异。结果表明:(1)干旱刺激了幼苗根系生长,抑制了地上种幼苗根冠比均显著提高;‘豫烟6号’和‘豫烟12号’幼苗根系生物量、总根长、根系表面积和根系体积均显著增加,但根系平均直径与对照无显著性差异;而‘豫烟10号’和‘中烟100’根系形态指标增加幅度较小,仅有‘豫烟10号’根系表面积显著增加,而根系平均直径均显著下降。(2)干旱引起‘中烟100’叶片气孔总面积比对照显著增加,‘豫烟12号’仅有气孔长度比其对照增加显著。(3)干旱处理后,‘豫烟6号’和‘豫烟12号’叶绿体整体结构变化不大,而‘豫烟10号’和‘中烟100’中叶肉细胞叶绿体被膜分解,与细胞壁分离;其中‘中烟100’叶绿体平均长度、长宽比和面积均显著降低。(4)与对照相比,干旱组叶片光合作用被抑制,其中‘豫烟10号’和‘中烟100’叶片净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均显著下降,而胞间CO2浓度(Ci)显著上升,说明干旱胁迫下烤烟光合速率下降是非气孔因素所致。(5)干旱胁迫后‘豫烟6号’和‘豫烟12号’叶片叶绿素总量显著增加,而‘豫烟10号’和‘中烟100’却呈下降趋势。结果表明,‘豫烟6号’和‘豫烟12号’是耐旱型品种,而‘豫烟10号’和‘中烟100’抗旱性较差,抗旱能力排序为‘豫烟6号’‘豫烟12号’‘豫烟10号’‘中烟100’。     

The transfer of heavy metals to barley plants from soils amended with sewage sludge with different heavy metal burdens

Purpose

Our main aim objective was to evaluate the transfer of Cd, Cr, Cu, Ni, Pb and Zn to barley (Hordeum vulgare) grown in various soils previously amended with two sewage sludges containing different concentrations of heavy metals. This allowed us to examine the transfer of heavv metals to barley roots and shoots and the occurrence of restriction mechanisms as function of soil type and for different heavy metal concentration scenarios.

Material and methods

A greenhouse experiment was performed to evaluate the transfer of heavy metals to barley grown in 36 agricultural soils from different parts of Spain previously amended with a single dose (equivalent to 50 t dry weight ha^?1) of two sewage sludges with contrasting levels of heavy metals (common and spiked sludge: CS and SS).

Results and discussion

In soils amended with CS, heavy metals were transferred to roots in the order (mean values of the bio-concentration ratio in roots, BCF_Roots, in brackets): Cu (2.4)?~?Ni (2.3)?>?Cd (2.1)?>?Zn (1.8)?>?Cr (0.7)?~?Pb (0.6); similar values were found for the soils amended with SS. The mean values of the soil-to-shoot ratio were: Cd (0.44)?~?Zn (0.39)?~?Cu (0.39)?>?Cr (0.20)?>?Ni (0.09)?>?Pb (0.01) for CS-amended soils; Zn (0.24)?>?Cu (0.15)?~?Cd (0.14)?>?Ni (0.05)?~?Cr (0.03)?>?Pb (0.006) for SS-amended soils. Heavy metals were transferred from roots to shoots in the following order (mean values of the ratio concentration of heavy metals in shoots to roots in brackets): Cr (0.33)?>?Zn (0.24)?~?Cd (0.22)?>?Cu (0.19)?>?Ni (0.04)?>?Pb (0.02) for CS-amended soils; Zn (0.14)?>?Cd (0.09)?~?Cu (0.08)?>?Cr (0.05)?>?Ni (0.02)?~?Pb (0.010) for SS-amended soils.

Conclusions

Soils weakly restricted the mobility of heavy metals to roots, plant physiology restricted the transfer of heavy metals from roots to shoots, observing further restriction at high heavy metal loadings, and the transfer of Cd, Cu and Zn from soils to shoots was greater than for Cr, Ni and Pb. Stepwise multiple linear regressions revealed that soils with high sand content allowed greater soil-plant transfer of Cr, Cu, Pb and Zn. For Cd and Ni, soils with low pH and soil organic C, respectively, posed the highest risk.     

Digestion Methods for Total Heavy Metals in Sediments and Soils

The objectives of this study were to analyze the total contents of Cd, Cr, Cu, Ni, Pb, and Zn in the freshwater sediments and the arable and non-arable soils of Taiwan, and to compare the different digestion methods for their determination. Two hundred and thirty-nine freshwater sediments were collected from the Fei-Tsui Reservoir Watershed (FTRW) in northern Taiwan. Forty-two surface (0–15 cm) and subsurface (15–30 cm) soil samples were likewise collected from 21 representative arable soils derived from various parent materials and with varying weathered degrees in different regions of Taiwan. In addition, one hundred and ninety-four non-arable soils were collected from the different forest regions, industrial parks, resident areas, and commercial areas. Several digestion methods including the aquaregia and different combinations of concentrated acids (HClO₄, HNO₃, H₂SO₄, or HF) were compared. All samples were digested both by the aqua regia method and the Baker and Amacher method for Cd, Cr, Cu, Ni, Pb, and Zn. The Reisenauer method was used for Cr and the Burau method for Pb further. The results indicate that the best digestion methods to analyze the total contents of heavy metals in the sediments and soils were recommended as follows: the Baker and Amacher method for Cd, Cr,Cu, Ni, and Zn; the Reisenauer method for Cr, but for simplicity the Baker and Amacher method is also recommended as the flexible method for the total analysis of Cr; the aqua regia method for Cu, Ni, and Zn; and the Burau method for Pb.