EDTA Supported Phytoextraction of Cd from Contaminated Soil by Four Different Ornamental Plant Species

In this study, some ornamental plant species such as Althaea rosea Cavan, Lonicera japonica Thunb, Salvia virgata Jacq. (Lamiaceae), and Dahlia hybrida growing in the natural vegetation of Black Sea Region (Turkey) were investigated for their phytoextraction potential of cadmium (Cd) from artificially contaminated soil of 10, 25, 50, and 100 mg/kg concentration under pot conditions. Effect of ethylenediaminetetracetic acid (EDTA) on this removal has also been studied. To evaluate the removal efficiency of the studied plants, the bioconcentration factor (BCF) and translocation factor (TF) values were also calculated. Higher BCF and TF values obtained from stems and leaves of A. rosea Cavan, L. japonica Thunb, and S. virgata Jacq. (Lamiaceae) show that those plants might be cultivated and used as hyperaccumulators in the removal of Cd from the contaminated soils. EDTA enhanced the Cd phytoextraction in plants; however, at the same time it resulted in a slight decrease in the dry matter.     

Fatty acid changes in Althaea rosea tissues during growth

Lipids were isolated from roots, stems, leaves, buds, flowers seeds of Althaea rosea plants at different stages of growth. The lipid contents of al     

Study of Zn,Cu and Pb content in plants and contaminated soils in Sardinia

Trace elements in soils exist as components of several different fractions. We have analyzed the correlation between total and extractable (EDTA, calcium chloride and deionized water) Zn, Pb and Cu concentrations in soils and the concentration of these elements in plant leaves. Soil and plant samples have been taken from Sulcis-Iglesiente (Sardinia), an area rich in mining tailings. This has made that the concentrations of the trace element under study in soils were varied. Three plants have been studied: Dittrichia viscosa, Cistus salviifolius, and Euphorbia pithyusa subsp. cupanii. Soil samples beneath each of them at depths of 0–30 and 30–60 cm have been considered. The highest concentration of trace elements in the leaves of the studied species has been found for Zn. The calcium carbonate content and the crystalline and amorphous forms of iron in the soil have determined the concentration of metal in plant leaves. The soil concentrations that have been found with the extraction methods are uncorrelated with Pb and Cu concentrations in plants, but Zn is correlated with the fraction extracted with EDTA and calcium chloride. The concentrations of trace metals in plants are most closely related to the soil contents of CaCO₃, electrical conductivity, Fe_ox, and Fe_dc.     

Accumulation and tolerance characteristics of lead in <Emphasis Type="Italic">Althaea rosea</Emphasis> Cav. and <Emphasis Type="Italic">Malva crispa</Emphasis> L.

Two ornamental plants of Althaea rosea Cav. and Malva crispa L. were exposed to various concentrations of lead (Pb) (0, 50, 100, 200 and 500 mg·kg^?1) for 70 days to evaluate the accumulating potential and the tolerance characteristics. The results showed that both plant species grown normally under Pb stress, and A. rosea had a higher tolerance than M. crispa, while M. crispa had a higher ability in Pb accumulation than A. rosea. Besides, lower Pb concentration (50 mg·kg^?1) stimulated the shoot biomass in both plant species. Pb accumulation in plants was consistent with the increase of Pb levels, and the main accumulation sites were the roots and the older leaves. In addition, the photosynthetic pigments content and chlorophyll fluorescence parameters were influenced by Pb stress. In such case, both of the plants could improve the activities of antioxidant enzymes of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and the contents of the total soluble sugar and soluble protein, which reached the highest value at Pb 100 mg·kg^?1, as well as the accumulation of the total thiols (T-SH) and non-protein thiols (NP-SH) to adapt to Pb stress. Thus, it provides the theoretical basis and possibility for ornamental plants of A. rosea and M. crispa in phytoremediation of Pb contaminated areas.     

Differential mobilization and metal uptake versus leaching in multimetal soil columns using EDTA and three metal bioaccumulators

Tannery waste is a major environmental concern that needs proper management. Tannery solid waste (TSW) can be added to the soil as an organic amendment but needs metal removal. Chelant-assisted phytoremediation hastens the process of metal removal but also poses risk of leaching at the same time. This research evaluates Ethylenediaminetetraacetic acid (EDTA)-assisted phytoextraction and associated leaching hazard using metal-tolerant plants. Greenhouse trials were carried out with sunflower, spinach, and marigold using columns of uniform diameter packed with field soil and multimetal contamination of TSW (5% and 10%) with four EDTA doses. The amounts of metal absorbed or leached conformed to amounts in the soil amendment and the dose of EDTA. The mobilization of metals by EDTA was however metal-specific. The metals that were extracted in greater amounts by the plants were leached less compared to Cr and Cu. A significant amount of other metals was leached down and thus less amount was phytoextracted by the plants e.g. Cd and Ni. A high correlation was observed between the amount of metal absorbed by the plant and the amount in leachate except for Cr in all the plants. Antioxidant activities like SOD and catalase were also found to be high in sunflower and spinach.     

EDTA enhanced heavy metal phytoextraction: metal accumulation,leaching and toxicity

Synthetic chelates such as ethylene diamine tetraacetic acid (EDTA) have been shown to enhance phytoextraction of some heavy metals from contaminated soil. In a soil column study, we examined the effect of EDTA on the uptake of Pb, Zn and Cd by Chinese cabbage (Brassica rapa), mobilization and leaching of heavy metals and the toxicity effects of EDTA additions on plants. The most effective was a single dose of 10 mmol EDTA kg^–1 soil where we detected Pb, Zn and Cd concentrations that were 104.6, 3.2 and 2.3-times higher in the aboveground plant biomass compared to the control treatments. The same EDTA addition decreased the concentration of Pb, Zn and Cd in roots of tested plants by 41, 71 and 69%, respectively compared to concentrations in the roots of control plants. In columns treated with 10 mmol kg^–1 EDTA, up to 37.9, 10.4 and 56.3% of initial total Pb, Zn and Cd in soil were leached down the soil profile, suggesting high solubility of heavy metals-EDTA complexes. EDTA treatment had a strong phytotoxic effect on the red clover (Trifolium pratense) in bioassay experiment. Moreover, the high dose EDTA additions inhibited the development of arbuscular mycorrhiza. The results of phospholipid fatty acid analyses indicated toxic effects of EDTA on soil fungi and increased environmental stress of soil microfauna.     

Comparative Evaluation of Metal Phytoremediation Potential of Trees,Grasses, and Flowering Plants from Tannery-Wastewater-Contaminated Soil in Relation with Physicochemical Properties

This study reports a comparative account of metal accumulation in the trees, grasses, and flowering plants from agricultural fields contaminated with tannery wastewater. Soil physico-chemical properties along the pollution gradient and soil depth were analyzed. Monitoring and assessment of the plants growing on contaminated sites revealed that the accumulation of Cr in the aboveground part of the trees ranged from 1.87 to 34.44 μg g^?1 dw with maximum concentration in Dendro-calamus strictus (34.44 μg g^?1 dw). Chrysanthemum coronarium and Tagetes erecta showed better accumulation of Cr than other flowering plants. Separate field experiments were conducted on the contaminated area. The shoots of Vetiveria zizanoides (532 mg 4 m^?2) and Cymbopogan winterianus (535.46 mg 4 m^?2) have shown almost similar removal potential of Cr, with maximum removal potential in the roots of C. winterianus (1206.43 mg 4 m^?2). Seasonal flowering plants (i.e., C. coronarium) have shown better accumulation of Cr than T. erecta. The results indicate that the plants of V. zizanoides, C. coronarium, and C. winterianus are suitable for phytoremediation of contaminated sites and trees can successfully be used for phytostabilization.     

Zinc and Copper Bioaccumulation in Brassica napus at Flowering and Maturation

The aim of this research was to investigate the capability of Brassica napus to bioaccumulate zinc and copper from artificially contaminated soil at the flowering and maturation phenological stage. The trial was set up in a greenhouse and the plants were cultivated in pots. The agricultural soil utilized was contaminated with zinc and copper sulfate (300 and 600 mg/kg, respectively). The soil and plant samples were simultaneously collected during the flowering (8 weeks after seeding) and maturation (harvest time, 13 weeks after seeding) stages, and the heavy metal concentrations were then analyzed. The production of vegetable biomass and the length of the roots were measured. The results showed that B. napus accumulated zinc and copper and translocated these elements in different ways in the harvestable parts of the plants. The zinc bioaccumulation was higher than that of copper. At flowering, zinc was mainly accumulated in the shoots (stems + leaves). Copper was particularly accumulated in the roots, during the entire life cycle. Taking into account the biomass production, the highest heavy metal removal by the shoots (above‐ground parts) occurred at the flowering stage for both zinc and copper. The high bioavailability of zinc and copper in the soil did not severely affect the root length and the biomass production.     

Bioaccumulation of mercury,arsenic, cadmium,and lead in plants grown on coal mine soil

Mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) are the major toxic metals released by coal mining activities in the surrounding environment. These metals get accumulated in the soils. The plants grown on the contaminated soil uptake these toxic metals in their roots and aerial parts. This study monitored the bioaccumulation of Hg and other three toxic metals in coal mine soil. The pot study of Hg accumulation in Brassica juncea showed that the extent of Hg uptake by roots and shoots of the plants grown on was high in the mature plant and Hg content in root was higher than the shoot. In the soil of unreclaimed overburden (OB) dump, the toxic metal content was higher than that of reclaimed OB dump which posed high ecological risk in the soil of unreclaimed OB dump. Bioaccumulation coefficient (BAC) value showed that Hg was not accumulated in the leaves of Dalbergia sissoo L., Gmelina arborea, Peltaphorum inerme L., Cassia seamea L, and Acacia mangium L grown on coal mine soil.     

Enhanced uptake of soil Pb and Zn by Indian mustard and winter wheat following combined soil application of elemental sulphur and EDTA

Enhancement of Pb and Zn uptake by Indian mustard (Brassica juncea (L.) Czern.) and winter wheat (Triticum aestivumL.) grown for 50 days in pots of contaminated soil was studied with application of elemental sulphur (S) and EDTA. Sulphur was added to the soil at 5 rates (0–160 mmol kg^?1) before planting, and EDTA was added in solution at 4 rates (0–8 mmol kg^?1) after 40 days of plant growth. Additional pots were established with the same rates of S and EDTA but without plants to monitor soil pH and CaCl₂-extractable heavy metals. The highest application rate of S acidified the soil from pH 7.1 to 6.0. Soil extractable Pb and Zn and shoot uptake of Pb and Zn increased as soil pH decreased. Both S and EDTA increased soil extractable Pb and Zn and shoot Pb and Zn uptake. EDTA was more effective than S in increasing soil extractable Pb and Zn, and the two amendments combined had a synergistic effect, raising extractable Pb to ¿1000 and Zn to ¿6 times their concentrations in unamended control soil. Wheat had higher shoot yields than Indian mustard and increasing application rates of both S and EDTA reduced the shoot dry matter yields of both plant species to as low as about half those of unamended controls. However, Indian mustard hyperaccumulated Pb in all EDTA treatments tested except the treatment with no S applied, and the maximum shoot Pb concentration was 7100 mg kg^?1 under the highest application rates of S and EDTA combined. Wheat showed similar trends, but hyperaccumulation (1095 mg kg^?1) occurred only at the highest rates of S and EDTA combined. Similar trends in shoot Zn were found, but with lower concentrations than Pb and far below hyperaccumulation, with maxima of 777 and 480 mg kg^?1 in Indian mustard and wheat. Despite their lower yields, Indian mustard shoots extracted more Pb and Zn from the soil (up to 4.1 and 0.45 mg pot^?1) than did winter wheat (up to 0.72 and 0.28 mg pot^?1), indicating that the effects of S and EDTA on shoot metal concentration were more important than yield effects in determining rates of metal removal over the growth period of 50 days. Phytoextraction of Pb from this highly contaminated soil would require the growth of Indian mustard for nearly 100 years and is therefore impractical.     

Over-expression of gsh1 in the cytosol affects the photosynthetic apparatus and improves the performance of transgenic poplars on heavy metal-contaminated soil

Recent studies of transgenic poplars over‐expressing the genes gsh1 and gsh2 encoding γ‐glutamylcysteine synthetase (γ‐ECS) and glutathione synthetase, respectively, provided detailed information on regulation of GSH synthesis, enzymes activities and mRNA expression. In this experiment, we studied quantitative parameters of leaves, assimilating tissues, cells and chloroplasts, mesophyll resistance for CO₂ diffusion, chlorophyll and carbohydrate content in wild‐type poplar and transgenic plants over‐expressing gsh1 in the cytosol after 3 years of growth in relatively clean (control) or heavy metal‐contaminated soil in the field. Over‐expression of gsh1 in the cytosol led to a twofold increase of intrafoliar GSH concentration and influenced the photosynthetic apparatus at different levels of organisation, i.e., leaves, photosynthetic cells and chloroplasts. At the control site, transgenic poplars had a twofold smaller total leaf area per plant and a 1.6‐fold leaf area per leaf compared to wild‐type controls. Annual aboveground biomass gain was reduced by 50% in the transgenic plants. The reduction of leaf area of the transformants was accompanied by a significant decline in total cell number per leaf, indicating suppression of cell division. Over‐expression of γ‐ECS in the cytosol also caused changes in mesophyll structure, i.e., a 20% decrease in cell and chloroplast number per leaf area, but also an enhanced volume share of chloroplasts and intercellular airspaces in the leaves. Transgenic and wild poplars did not exhibit differences in chlorophyll and carotenoid content of leaves, but transformants had 1.3‐fold fewer soluble carbohydrates. Cultivation on contaminated soil caused a reduction of palisade cell volume and chloroplast number, both per cell and leaf area, in wild‐type plants but not in transformants. Biomass accumulation of wild‐type poplars decreased in contaminated soil by more than 30‐fold, whereas transformants showed a twofold decrease compared to the control site. Thus, poplars over‐expressing γ‐ECS in the cytosol were more tolerant to heavy metal stress under field conditions than wild‐type plants according to the parameters analysed. Correlation analysis revealed strong dependence of cell number per leaf area unit, chloroplast parameters and mesophyll resistance with the GSH level in poplar leaves.     

Cadmium Remediation by Arbuscular Mycorrhizal Fungus–Colonized Celery Plants Supplemented with Ethylenediaminetetraacetic Acid

A pot trial using Glomus mosseae along with EDTA (ethylenediaminetetraacetic acid) was conducted for the phytoextraction of cadmium (Cd) by celery (Apium graveolens Linn.) plants from soil artificially contaminated with Cd under glass house conditions. The experiment is a 2 × 2 × 4 factorial design with two levels of G. mosseae inoculations (G. mosseae inoculated and uninoculated), two EDTA concentrations (without and with 2.5 mmol kg^?1 soil EDTA) and four Cd concentrations (0, 5, 10, and 20 mg kg^?1 soil). The results indicate the formation of an effective symbiosis between G. mosseae and celery in the contaminated soil. However, an increase in Cd input level and EDTA addition showed strong phytotoxic effect on celery plants and G. mosseae, as a considerable decrease in the frequency of root colonization and spore density was noticed. However, the plants were able to withstand the stressed condition due to the benefits provided by G. mosseae through increased P accumulation, chlorophyll content, and plant growth, resulting in an increase in Cd accumulation, which was good enough for the phytoextraction purpose. Thus, celery plants inoculated with G. mosseae and later supplemented with EDTA could be an effective and potentially suitable practice for the remediation of Cd-contaminated sites.     

Suppressive soil against Sclerotinia sclerotiorum as a source of potential biocontrol agents: selection and evaluation of Clonostachys rosea BAFC1646

The fungal diversity structures of soils that are suppressive and non-suppressive to Sclerotinia sclerotiorum were characterised and screened for fungal strains antagonistic to the S. sclerotiorum pathogen. Soil suppressiveness was associated with a particular fungal diversity structure. Principal component analysis showed that antagonism by fungal species in suppressive soils was associated with the occurrence of Fusarium oxysporum, Fusarium solani, Talaromyces flavus var. flavus and Clonostachys rosea f. rosea. In particular, C. rosea f. rosea occurred exclusively in suppressive soil samples, suggesting that this morpho-species plays an important role in suppression of S. sclerotiorum diseases. One strain of C. rosea f. rosea (BAFC1646) was selected for further experiments. Dual-culture assays confirmed the antagonistic behaviour of C. rosea f. rosea BAFC1646 against three different S. sclerotiorum strains. Antifungal activity was corroborated by diffusion assays with metabolite extracts. Greenhouse assays with soybean plants showed that the selected C. rosea f. rosea strain reduced the percentage of dead plants when co-inoculated with S. sclerotiorum. In addition, inclusion of C. rosea f. rosea alone increased shoot lengths significantly. In this work, we established the involvement of fungal species in soil suppressiveness and in further assays confirmed that C. rosea f. rosea BAFC1646 exhibits a bioprotective effect against S. sclerotiorum in soybean plants.     

Local Adaptation of Metallicolous and Non‐Metallicolous Anthyllis vulneraria Populations: Their Utilization in Soil Restoration

Restoration of metalliferous mine soils requires using plant species tolerant to high metal concentrations and adapted to nutrient‐poor soil. Legumes can increase plant productivity through N₂‐fixation, but they are often scarce in metalliferous sites. We examined survival, growth, and tolerance of four populations of a legume, Anthyllis vulneraria, from two metalliferous (MET) Zn‐Pb mine sites, Avinières (AV) ([Zn‐EDTA] = 26,000 mg/kg) and Eylie (EY) ([Zn‐EDTA] = 4,632 mg/kg), and two non‐metalliferous (NMET) sites located in the south of France with the aim to select the most appropriate populations for restoration of mined soils. In a common garden experiment, plants from each population were reciprocally grown in soil from the provenance of each population. The two NMET populations exhibited high mortality and low growth rates in soil from the mined sites. The AV MET exhibited a high growth rate in metalliferous soils, but showed high mortality in non‐metalliferous soils. The growth of the EY MET was very low in the AV‐contaminated soil, but was the highest of all populations in moderately and non‐metalliferous soils. Plants from the AV MET population showed a high growth and survival in metalliferous soil and would be appropriate in the restoration of metal‐contaminated sites (>30,000 mg Zn kg^?1). The EY MET population would be adapted to the restoration of moderate metal‐contaminated soils (<30,000 mg Zn kg^?1). Taking into account the broad distribution of A. vulneraria, these two populations could be suitable for the restoration of derelict mine sites in mediterranean and temperate regions of Europe and North America.     

The performance of vetivers (Chrysopogon zizaniodes and Chrysopogon nemoralis) on heavy metals phytoremediation: laboratory investigation

Abstract

Phytoremediation with vetiver was investigated in relation to heavy metal contaminated soil in Thailand. The work compared the performance of two species of vetiver named Songkhla 3 (Chrysopogon zizaniodes) and Prachuap Khiri Khan (Chrysopogon nemoralis) in absorbing lead, zinc, and cadmium in contaminated soils. Toxicity Characteristic Leaching Procedure (TCLP), and Allium tests were conducted to determine toxicity of treated soil. Ethylenediaminetetraacetic acid (EDTA) was also used to increase heavy metals concentration in solution in soil, which led to an increase in translocation and bioaccumulation factors. In general, results showed that concentration of heavy metals decreased in soil and increased in both the shoots and roots of vetivers during a 4-month treatment period. TCLP results indicated that the concentration of zinc and cadmium in contaminated soil was reduced over treatment time, and significantly increased after EDTA was applied. To confirm vetiver performance in phytoremediation, Allium testing showed that remained heavy metals in treated soils had no effect on nucleus aberration. Songkhla 3 and Prachuap Khiri Khan showed similar trends in their ability to remediate lead, zinc, and cadmium from contaminated soil. Both species could accumulate higher concentrations of heavy metals in their shoots and roots over time, and with EDTA application.     

Phytoremediation potential of some agricultural plants on heavy metal contaminated mine waste soils,salem district,tamilnadu

The Pot culture experiment performed for phytoextraction potential of selected agricultural plants [millet (Eleusine coracana), mustard (Brassica juncea), jowar (Sorghum bicolor), black gram (Vigna mungo), pumpkin (Telfairia occidentalis)] grown in metal contaminated soils around the Salem region, Tamilnadu, India. Physiochemical characterization of soils, reported as low to medium level of N, P, K was found in test soils. The Cr content higher in mine soils than control and the values are 0.176 mg/L in Dalmia soil and 0.049 mg/L in Burn &; Co soil. The germination rate low in mine soil than control soils (25 to 85%). The content of chlorophyll, carotenoid, carbohydrate and protein decreased in mine soils than control. The morphological parameters and biomass values decreased in experimental plants due to metal accumulation. Proline content increased in test plants and ranged from 0.113 mg g^?1 to 0.858 mg g^?1 which indicate the stress condition due to toxicity of metals. Sorghum and black gram plants reported as metal tolerant capacity. Among the plants, Sorghum produced good results (both biomass and biochemical parameters) which equal to control plant and suggests Sorghum plant is an ideal for remediation of metal contaminated soils.     

The EDTA Amendment in Phytoextraction of 134Cs From Soil by Indian Mustard (Brassica juncea)

Soil contamination with radiocaesium is a significant problem at any countries when a nuclear accident occurred. Recently, phytoextraction technique is developed to remediate the contaminated environment. However, the application is limited by the availability of the contaminant for root uptake. Therefore, a green house trial experiment of soil amendment with ethylene diamine tetraacetic acid (EDTA) has been conducted to examine ¹³⁴Cs availability for root uptake. Two groups of Indian mustard (Brassica juncea) were cultivated in ¹³⁴Cs contaminated soil. The soil in the first group was treated with EDTA amendment, while the other was not. Plant growth was observed gravimetrically and the ¹³⁴Cs concentration in soil as well as plants were determined using gamma spectrometry. The plant uptake capacity was determined as transfer factor (F_v), and the F_v values of 0.22 ± 0.0786 and 0.12 ± 0.039 were obtained for the soil treated with and without EDTA amendment, respectively. The phytoextraction efficiency of the plant cultivated in ¹³⁴Cs contaminated soil both with and without EDTA amendment was low. The EDTA amendment to the soil seems to enhance the ¹³⁴Cs availability for root uptake of Indian mustard and can still be considered to assist the field phytoremediation of contaminated soil.     

Isolation of gibberellin A8-glucoside from shoot apices of Althaea rosea

Summary Gibberellin A₈-glucoside has been isolated from shoot apices of Althaea rosea. It showed a weak growth-promoting activity on rice seedlings and oat mesocotyl sections but did not induce germination of lettuce seeds in darkness.     

Root development and heavy metal phytoextraction efficiency: comparison of different plant species in the field

Heavy metal phytoextraction is a soil remediation technique which implies the optimal use of plants to remove contamination from soil. Plants must thus be tolerant to heavy metals, adapted to soil and climate characteristics and able to take up large amounts of heavy metals. Their roots must also fit the spatial distribution of pollution. Their different root systems allow plants to adapt to their environment and be more or less efficient in element uptake. To assess the impact of the root system on phytoextraction efficiency in the field, we have studied the uptake and root systems (root length and root size) of various high biomass plants (Brassica juncea, Nicotiana tabacum, Zea mays and Salix viminalis) and one hyperaccumulator (Thlaspi caerulescens) grown in a Zn, Cu and Cd contaminated soil and compared them with total heavy metal distribution in the soil. Changes from year to year have been studied for an annual (Zea mays) and a perennial plant (Salix viminalis) to assess the impact of the climate on root systems and the evolution of efficiency with time and growth. In spite of a small biomass, T. caerulescens was the most efficient plant for Cd and Zn removal because of very high concentrations in the shoots. The second most efficient were plants combining high metal concentrations and high biomass (willows for Cd and Zn and tobacco for Cu and Cd). A large cumulative root density/aboveground biomass ratio (L_A/B), together with a relative larger proportion of fine roots compared to other plants seemed to be additional favourable characteristics for increased heavy metal uptake by T. caerulescens. In general, for all plants correlations were found between L _A/B and heavy metal concentrations in shoots (r=0.758^***, r=0.594^***, r=0.798^*** (P<0.001) for Cd, Cu and Zn concentrations resp.). Differences between years were significant because of variations in climatic conditions for annual plants or because of growth for perennial plants. The plants exhibited also different root distributions along the soil profile: T. caerulescens had a shallow root system and was thus best suited for shallow contamination (0.2 m) whereas maize and willows were the most efficient in colonising the soil at depth and thus more applicable for deep contamination (0.7 m). In the field situation, no plant was able to fit the contamination properly due to heterogeneity in soil contamination. This points out to the importance and the difficulty of choosing plant species according to depth and heterogeneity of localisation of the pollution.     

卡拉麦里南部工业区梭梭和琵琶柴重金属空间分布及污染评价

对五彩湾工业区周边21个采样点的梭梭(Hadoxylon)和琵琶柴(Reaummuria soongorica)的Zn、Cu、Cr、Pb、As、Hg 6种重金属元素含量测定,运用统计学方法和地统计插值法分析其茎叶和根部重金属含量变化情况和空间分布特征,并综合评价其污染程度和潜在生态危害性。结果表明:梭梭和琵琶柴植株Hg含量的最大值和均值都超出新疆土壤背景值0.017 mg/kg,除梭梭根部的均值0.060 mg/kg未超出国家土壤背景值0.065 mg/kg,在二者其他部位的最大值和均值都已超出;琵琶柴整株中Cr最大值72.62 mg/kg和Zn最大值97.61 mg/kg均超出新疆土壤背景值49.3 mg/kg和国家土壤背景值61 mg/kg,Pb元素未被检出。插值精度方面,Hg、As的RMSE较小,分别为0.263和0.443,预测模型中Hg的R~2为0.72,Cu的R~2为0.67,能较好地估计预测样点的重金属含量,Zn的R~2为0.31,精度较低;插值结果,琵琶柴中的Zn、Cr、As、Hg含量较高的区域均在工业园区内部及周围,受人为扰动程度较大。梭梭和琵琶柴中Hg元素分别为中度污染和重度污染;Hg元素为中等潜在危害程度高于其他4种元素。