Accumulation Of Heavy Metals In Plants Research Articles

Influence of tannery sludge on oil yield, metal uptake and antioxidant activities of Ocimum basilicum L. grown in two different soils

Abstract Application of sludge to soil for increasing crop productivity has become an alternative to chemical fertilizers in many countries. The present study aimed at investigating the effect of tannery sludge (TS) under two soil types viz coarse soil (Set A) and fine soil (Set B) on oil yield, metal uptake and antioxidant activity of Ocimum basilicum. Experimental data showed that increased biomass and oil yield were observed at 50:50 ratio of sludge and soil of both Sets. Cation exchange capacity (CEC) played a major role in metal uptake which was showed by step wise regression model. Superoxide dismutase (SOD) and catalase (CAT) activity went down in 100% TS, however peroxidase (POD), malondialdehyde (MDA) and proline activity was maximum in 100% TS. POD act as a better intrinsic defense tool to resist the heavy metals present in TS. Principal component analysis (PCA) showed that soil properties should be taken into consideration for predicting heavy metal accumulation in plant.

Uptake of cadmium by cress, lettuce and tomato in Cd-contaminated soil

Increasing of water consumption and demand for irrigation water in agriculture has led to an increase in reuse of treated, or even raw, municipal and industrial wastewater in many countries. Heavy metals (HMs) in these unconventional waters are one of the sources of pollution of water, soil and plant. HM toxicity in plants may eventually cause disturbances in plant growth. Accumulation of HMs in plants has health problems for human beings and animals which consume these plants. In this research, uptake of cadmium (Cd) by three vegetables (cress (Lepidium sativum L.), lettuce (Lactuca sativa L.) and tomato (Solanum lycopersicum L.) from a contaminated soil was studied. The experimental design was completely randomized. For each plant, two soil treatments (control soil and contaminated soil by 100 mg/L Cd) and five replications were considered. After planting, growing and harvesting, and preparation of the samples, Cd uptake in roots and shoots was measured. Results showed that mean Cd uptake by all three plants was significantly different from the control treatment. Maximum uptake of Cd belonged to tomato, whereas lettuce had the lowest uptake. Transfer coefficient of Cd from soil into cress, lettuce and tomato was 1.3, 0.33 and 0.65, respectively. Although transfer coefficient of Cd to lettuce is lower than the other two plants, but consumption of lettuce per person is much greater than cress. Hence, irrigation management of polluted wastewater is important.

Analysis of genetic and epigenetic effects of maize seeds in response to heavy metal (Zn) stress.

Conditions of environmental stress are known to lead genetic and epigenetic variability in plants. DNA methylation is one of the important epigenetic mechanisms and plays a critical role in epigenetic control of gene expression. Thus, the aim of the study was to investigate the alteration of genome methylation induced by zinc stress by using coupled restriction enzyme digestion-random amplification (CRED-RA) technique in maize (Zea mays L.) seedlings. In addition, to determine the effect of zinc on mitotic activity and phytohormone level, high-pressure liquid chromatography (HPLC) and mitotic index analysis were utilized. According to the results, mitotic index decreased in all concentrations of zinc except for 5mM dose and chromosome aberrations such as c-mitosis, stickiness, and anaphase bridges were determined. It was also observed that increasing concentrations of zinc caused an increase in methylation patterns and decrease in gibberellic acid (GA), zeatin (ZA), and indole acetic acid (IAA) levels in contrast to abscisic acid (ABA) level. Especially increasing of ABA levels under zinc stress may be a part of the defense system against heavy metal accumulation in plants.

Effects of chelates on soil microbial properties, plant growth and heavy metal accumulation in plants

Although chelates can enhance remediation efficiency in phytoremediation, they can cause adverse ecosystem effects. The purpose of this research was to investigate the potential effects of chelating agents on plant and soil ecosystems. The effects of ethylene diamine tetraacetic acid (EDTA), ethylene diamine disuccinate (EDDS), and humic acids (HAs) on soil microbial properties, plant biomass, and metal accumulation were investigated in soils contaminated with Cd, Cu, Pb, Zn, and Ni. Four herbaceous plants were used for experimental purposes: Brassica juncea, Brassica campestris, Sorghum bicolor, and Helianthus annuus. EDTA was most effective for heavy metal uptake by plants, but had significant effects on plants and soils. Although EDDS addition can increase metal uptake, its effects are restricted to some plants and metal species. Plant selection can therefore be a more important factor than use of EDDS. HAs had limited influence on increases in heavy metal uptake but had favorable effects on plants and soil. Decreased plant biomass was strongly related to decreased chlorophyll content caused by increased metal concentrations in plant shoots. Results suggest that more efficient chelates may have higher toxicity. Long-term monitoring is therefore necessary to assess soil quality changes after the addition of chelating agents. Furthermore, the effects of the latter on ecosystems, as well as their metal removal efficiency, should be considered when selecting chelating agents for improved phytoremediation.

Study on Heavy Metal Accumulation of Plantsin Gejiu Tin Mining Area

Based on determination of heavy metal contents in soils and plants, understanding pollution of heavy metal in soils and plants, as well as the heavy metal accumulation in plants, in order to provide scientific basis for phytoremediation of heavy metals in mining areas. The determination and analysis on the concent of Zn, Cu, Pb, Cd, Mn was made in Niuba and southern mining area in Gejiu City. The result showed that the soil pollution from Cd is the most serious while the pollution from Zn was relative to minimum in Niuba abandoned mining area. In southern mining area, Pb in soil pollution was the most serious while Cu was relative to minimum Analysis on correlation between the heavy metal content in plants and soils was made based on the 5 plant samples (Pyracantha fortuneana, Zea mays, Acroptilon repens, Equisetum ramosissimum and Cucurbita moschata) collected from Niuba reclamation area and 5 plant samples (Corylus yunnanensis, Alnus nepalensis, Pyracantha fortuneana,Cupressus torulosa,Acacia dealbata) from recovery area of southern mining area. The results show that Pyracantha fortuneana has a better correlation with soil than other plants, Cucurbita moschata and soil have poor correlation, Corylus yunnanensis has better correlation with soil compared to other plants, Acacia dealbata has poor correlation with soil.

Application of biochar from sewage sludge to plant cultivation: Influence of pyrolysis temperature and biochar-to-soil ratio on yield and heavy metal accumulation

Applying biochar products from sewage sludge (SS) pyrolysis as soil amendment for plant cultivation was investigated in this study with special attention paid to heavy metal accumulation in the plants when pyrolysis temperature and biochar-to-soil mass ratio (C:S) were changed. Biochar obtained at four different temperatures were adopted as soil amendment for Allium sativum L. garlic plant cultivation. Experimental results revealed that biochars were rich in nutrient contents and they improved garlic yields. Although contents of heavy metals including As, Zn, Pb, Ni, Cd, Cr and Cu, etc. were elevated in the biochars compared to local soil, they fell within the acceptable limits for land application and SS is a suitable biochar resource, especially biochar produced at 450°C had rich micropores, relatively stable functional groups in structure and rugged surface to contact well with soil, conducive to its usage as a biochar. The garlic grew faster when planted in the biochar-amended soil and had higher final dry matter yields than those planted in the reference soil, especially biochar produced at 450°C corresponding to the highest final yields. The C:S ratio related to the highest garlic yields changed when the pyrolysis temperature was changed and this ratio was 1:4 for the biochar produced at 450°C. General heavy metal accumulation in the garlic occurred only for the most enriched Zn and Cu, and mainly in the roots & bulbs; in addition this bioaccumulation was increasing as leaching from biochar increased but not increasing with C:S ratio. The garlic planted in soil amended with biochar of 450°C contained the lowest level of heavy metals compared to other biochars. Those results indicated that heavy metal accumulation in plants can be inhibited through proper pyrolysis temperature choice and prevention of heavy metal leaching from the SS biochar.

Mudflat soil amendment by sewage sludge: Soil physicochemical properties, perennial ryegrass growth, and metal uptake

The fast pace of cropland loss in China is causing alarm over food security and China’s ability to remain self-reliant in crop production. Mudflats after organic amendment can be an important alternative cropland in China. Land application of sewage sludge has become a popular organic amendment to croplands in many countries. Nevertheless, the land application of sludge to mudflats has received little attention. Therefore, the objective of the present work was to investigate the impact of sewage sludge amendment (SSA) at 0, 30, 75, 150 and 300 t ha−1 rates on soil physicochemical properties, perennial ryegrass (Lolium perenne L.) growth and heavy metal accumulation in mudflat soil. The results showed that the application of sewage sludge increased organic matter (OM) content by 3.5-fold while reducing salinity by 76.3% at the 300 t ha−1 rate as compared to unamended soil. The SSA reduced pH, electric conductivity (EC) and bulk density in mudflat soil, increased porosity, cation exchange capacity (CEC) and contents of nitrogen (N), phosphorus (P), exchangeable potassium ions (K+), sodium ions (Na+), calcium ions (Ca2+) and magnesium ions (Mg2+) in comparison to unamended soil. There were 98.0, 146.6, 291.4 and 429.2% increases in fresh weight and 92.5, 132.4, 258.6 and 418.9% increases in dry weight of perennial ryegrass at 30, 75, 150, and 300 t ha−1, respectively, relative to unamended soil. The SSA increased metal concentrations of aboveground and root parts of perennial ryegrass (p < 0.05). The metal concentrations in perennial ryegrass were Zn > Cr > Mn > Cu > Cd > Ni, and the metal concentrations in roots were significantly higher than aboveground parts. The metal accumulation in perennial ryegrass correlated positively with sludge application rates and available metal concentrations in mudflat soil. Land application of sewage sludge was proved to be an effective soil amendment that improved soil fertility and promoted perennial ryegrass growth in mudflat soil. However, heavy metal accumulation in plants may cause food safety concern.

Determining the Heavy Metal Concentrations in Plants Exposed to Exhaust Gases Alongside the Sanliurfa Highway

In this study, the aim was to determine the heavy metal accumulation in plants that grow alongside the highways connecting Sanliurfa with neighboring cities that are exposed to exhaust gases. Thus, the lead, copper, iron, cadmium, nickel, and zinc concentration in plants were analyzed. Moreover, these were assessed by determining the parameters such as chlorophyll, malondialdehyde and proline to indicate to what extent the plants were affected by the heavy metal stress. The findings of the study revealed that the heavy metal accumulation in plants varied depending on the distance between the plant and the highway, on density of vehicles, on climate changes, and on air and environmental conditions. It was also determined that there is a clear increase in the heavy metal accumulation in summer. Furthermore, it was revealed that the stress caused by the heavy metal accumulation reduced the chlorophyll ratio and increased the malondialdehyde and proline concentrations, which is an indication of exhaust gases' heavily affecting the environment. The fact that vegetation is seriously affected by exhaust gases means that humans are also

Accumulation of heavy metals in Medicago sativa L. and Trifolium pratense L. at the contaminated fluvisol

Recently, heavy metals concentrations increased in some agricultural areas due to the consequences of anthropogenic impacts. The aim of this study was to determine the level of heavy metals (As, Cr, Ni and Pb) in Medicago sativa L. and Trifolium pratense L. grown on fluvisol, in order to obtain information on safety of these nutrients. The total content of Pb, As, Cr and Ni in the samples of fluvisol was above the maximum allowable amount. The content of heavy metals in Medicago sativa L. and Trifolium pratense L. was below the critical and toxic concentrations in all samples originating from contaminated soil. It was concluded that the accumulation of heavy metals in plants did not depend only on the total content in soil, but also the affinity of the plant, and individual and interactive effects of various soil properties. No statistically significant differences in the accumulation of heavy metals between Medicago sativa L. and Trifolium pratense L were observed. It is necessary to further control of heavy metals in the investigated area, in order to prevent their entry into the food chain and provide healthy food.

Heavy Metal Accumulation in Plants in the Zinc Smelting Area in North Western GuiZhou Province

By means of AAS analysis method, a study on the concentrations of Pb, Cd in the plants of four different species of plants and soils in the polluted sites by zinc smelting in north-west GuiZhou Province. The fractions of heavy metals in the soils were distinguished by the sequential extraction prcedure as mobile fraction and residual fraction. Heavy metal concentrations in the plant were found linearly increased with their concentrations in soils around plant rhizosphere. The concentrations of Pb and Cd in the four plants followed the order Pb &gt; Cd. Sambucus Chinensis and Ixeris gracilis were proved to have good metal-enriched and transport abilities. These plants would be useful to recover the ecology in these heavy metal polluted regions.

Heavy metals accumulation in plants growing in ex tin mining catchment

The degree of contamination by heavy metals (arsenic, copper, lead, tin and zinc) in soil and transfer to plants has been studied. Specimens of plant species from five locations in an area of 10 x 10 m were sampled with their corresponding soils. Thirty six plant species including two shallow water aquatic plants were identified. Soil and plant specimens were analyzed by using inductively coupled plasma optical emission spectrometry. It was found that metal concentration in soil was highly variable while concentration of metals in plants directly depends on the concentration of metals it was rooted. Roots showed highest metal concentration followed by leaves, shoots and flowers. Bioconcentraion factor and translocation factor were calculated, representing Cyperus rotundus L. as a potential tin-hyperaccumulator plant, previously not reported in literature. Plant Species Imperata cylindrica, Lycopodium cernuum, Melastoma malabathricum, Mimosa pudica Linn, Nelumbo nucifera, Phragmites australis L., Pteris vittata L. and Salvinia molesta, were metal accumulator while Acacia podalyriaefolia G. Don, Bulb Vanisium, Dillenia reticulate King, Eugenia reinwardtiana, Evodia roxburghiania Hk. f. clarke, Gleichenia linearis, Grewia erythrocarpa Ridl., Manihot esculenta Crantz, Paspalum conjugatum Berguis, Passiflora suberosa, Saccharum officinarum, Stenochlaena palustris (Burm.) Bedd. and Vitis trifolia Linn. were tolerated plant species. All other studied plants were excluders. Identified plant species could be useful for revegetation and erosion control in metals contaminated ex-mining sites. Morphological changes such as reduction in size, change in color and deshaping have also been observed in plant species with high metal values.

A comparative study of various grains from the different cities of Pakistan

The fate of trace elements (like Ca, Fe, Al, Pb, K, and Cu) in various pulses (mash, mung, lentils and red kidney beans) of Pakistan has been studied. Samples were collected from two districts (Mansehra and Rawalpindi) and analyzed by wet acid digestion method using atomic absorption spectrophotometry. Experimental results show that the intensity of heavy metal accumulation in plants depends upon the type of the soil, the species of plants, the physicochemical properties of heavy metals, and their content in the soil. The obtained values were compared with the World Health Organization (WHO) standards for food quality. The grains from District Mansehra contained greater amount of trace metals as compared to those collected from District Rawalpindi. However, those values did not exceed the upper limits described by the WHO in nearly all the cases. Based on these findings, the consumption of pulses in larger amounts may easily be recommended.

Modified accumulation of selected heavy metals in Bt transgenic rice

Safety assessment of genetically modified crops generally does not take into account the potential hazard of altered patterns of heavy metal accumulation in plants. A pot experiment was conducted under greenhouse conditions to evaluate the impact of heavy metal amendments on the accumulation of Cd, Cu, Pb and Zn in a Bt transgenic rice Ke-Ming-Dao (KMD) and its wild-type Xiushui 11 (Xs11). In control soils, significant difference was only found in contents of Cu (p < 0.01) and Pb (p < 0.05) in straw between KMD and Xs11. At three levels of Cd amendments (5, 10, and 20 mg/kg), the Cd contents in grain and straw of KMD were significantlyhigher than those of Xs11, and all grain Cd contents were significantly higher than the International Criteria (0.2-0.4 mg/kg) as specified by the Codex Alimentarius Commission (CAC). These results implied that it may be unsafe for growing Bt transgenic rice in heavily Cd-polluted areas. No significant difference in Zn was found between the two varieties with the exception of roots at Zn amendment level of 600 mg/kg, while Pb contents in KMD were much higher in the straw at the lead amendment level of 1000 mg/kg and inthe root at 250 mg Pb/kg. Data on the heavy metal accumulation patterns for the genetically modified rice may be used for the selection of growing areas as well as for plant residue management for Bt rice.

The dilemma of controlling heavy metal accumulation in plants

The dilemma of controlling heavy metal accumulation in plants

Concentrations of heavy metals in plants grown on polluted mining soils (Loma Charra mine, Spain)

Evaluation of heavy metal accumulation in plants is of environmental importance due to its toxicity effects in humans and other biota. Soils and plants were sampled in a polluted site around a Pb-Zn(Cd) mine. Total metal contents in the soil indicate a gross degree of pollution in relation to background levels. Soil Cd shows high mobility and availability and consequent high environmental risk. The range of cadmium content in plants (<0.05?3.6 mg/kg) is relatively low, although higher than the reference plant content, and none of the sampled plant species hyperaccumulated Cd, Pb and Zn. Metal concentration in plants exceeds the MLRL (maximum level recommended for livestock), and the barley crop exceeds the EU limit, which indicates a risk of food chain contamination in the studied area.

Effect of biosludge and biofertilizer amendment on growth of Jatropha curcas in heavy metal contaminated soils

The pot experiments were conducted to evaluate the effect of different concentrations of arsenic, chromium and zinc contaminated soils, amended with biosludge and biofertilizer on the growth of Jatropha curcas which is a biodiesel crop. The results further showed that biosludge alone and in combination with biofertilizer significantly improved the survival rates and enhanced the growth of the plant. With the amendments, the plant was able to grow and survive upto 500, 250 and 4,000 mg kg(-1) of As, Cr and Zn contaminated soils, respectively. The results also showed that zinc enhanced the growth of J. curcas more as compared to other metals contaminated soils. The heavy metal accumulation in plant increased with increasing concentrations of heavy metals in soil, where as a significant reduction in the metal uptake in plant was observed, when amended with biosludge and biofertilizer and biosludge alone. It seems that the organic matter present in the biosludge acted as metal chelator thereby reducing the toxicity of metals to the plant. Findings suggest that plantation of J. curcas may be promoted in metal contaminated soils, degraded soils or wasteland suitably after amending with organic waste.

Heavy metals effects on forage crops yields and estimation of elements accumulation in plants as affected by soil

Heavy metals (Cu, Cd, Pb, Zn) effect on the productivity of forage crops (clover and perennial cereal grasses) and their accumulation in plants, depending on the concentration of these elements in a soil, has been studied in micro-field experiments on three types of soil. The principle objective was to determine regularities of heavy metals migration in a soil–plant system aiming the estimation of permissible levels of heavy metals content in soils with the following elaboration of methods, which regulate the toxicants transfer to plants. Methods of field experiments, agrochemical and atomic absorption analysis were used. Results were statistically treated by Statistica 6.0, S-Plus 6. Experimental results have shown that the intensity of heavy metals accumulation in plants depends on the type of the soil, the species of plants, the physicochemical properties of heavy metals and their content in the soil. Logarithmic interdependency of heavy metals concentration in soils and their accumulation in plants is suggested. However, the strong correlation between the different heavy metals concentrations in the various soils and the yield of crops was not observed. Toxicants accumulation in crops decreased in time.

Heavy metal accumulation in plants and soil irrigated with wastewater from Mexico city

Analysis by PIXE has been successfully employed in the study of environmental samples since it is possible to detect in a simple and fast way a high number of elements (heavier than Na) with a high sensitivity. In this work the PIXE method has been applied to study the extent of heavy metal contamination in soils and plants from Mixquiahuala, Hidalgo and Tláhuac, D.F. These two agricultural sites have been irrigated with wastewater from Mexico City for more than 50 years. The use of wastewater increased the crop productivity; however, in the areas irrigated for long periods of time, deterioration is now observed and only certain plant species can be grown. In this work, we present the range of variation that was observed for metals such as Fe, Cr, Co, Mn, Ni, Cu, Zn and Pb. Some of these elements were found at concentrations above the potentially hazardous levels in soils; however, they accumulated in plants to a lower extent, probably because of the physical and chemical properties of soils that prevent their translocation to plants.

Heavy metals in plants and phytoremediation.

In some cases, soil, water and food are heavily polluted by heavy metals in China. To use plants to remediate heavy metal pollution would be an effective technique in pollution control. The accumulation of heavy metals in plants and the role of plants in removing pollutants should be understood in order to implement phytoremediation, which makes use of plants to extract, transfer and stabilize heavy metals from soil and water. The information has been compiled from Chinese publications stemming mostly from the last decade, to show the research results on heavy metals in plants and the role of plants in controlling heavy metal pollution, and to provide a general outlook of phytoremediation in China. Related references from scientific journals and university journals are searched and summarized in sections concerning the accumulation of heavy metals in plants, plants for heavy metal purification and phytoremediation techniques. Plants can take up heavy metals by their roots, or even via their stems and leaves, and accumulate them in their organs. Plants take up elements selectively. Accumulation and distribution of heavy metals in the plant depends on the plant species, element species, chemical and bioavailiability, redox, pH, cation exchange capacity, dissolved oxygen, temperature and secretion of roots. Plants are employed in the decontamination of heavy metals from polluted water and have demonstrated high performances in treating mineral tailing water and industrial effluents. The purification capacity of heavy metals by plants are affected by several factors, such as the concentration of the heavy metals, species of elements, plant species, exposure duration, temperature and pH. Phytoremediation, which makes use of vegetation to remove, detoxify, or stabilize persistent pollutants, is a green and environmentally-friendly tool for cleaning polluted soil and water. The advantage of high biomass productive and easy disposal makes plants most useful to remediate heavy metals on site. Based on knowledge of the heavy metal accumulation in plants, it is possible to select those species of crops and pasturage herbs, which accumulate fewer heavy metals, for food cultivation and fodder for animals; and to select those hyperaccumulation species for extracting heavy metals from soil and water. Studies on the mechanisms and application of hyperaccumulation are necessary in China for developing phytoremediation.

Agricultural use of sediments from the Albufera Lake (eastern Spain)

Dredging of the Albufera Lake, a very important natural area of eastern Spain, has been proposed to remediate the silting process, but a very large amount of sediments would be generated. To assess the feasibility of applying these to the sandy agricultural soils surrounding the lake, three rates (180, 360 and 720 t/ha) of four different sediments, corresponding to different degrees and sources of contamination, were tested by mixing with a soil obtained from the area of potential application. The effects on the soil properties and yield and nutrient contents of lettuce ( Lactuca sativa L.) and tomato ( Lycopersicon esculentum Mill.) were studied. As the most relevant changes, sediments improved the soil water-retention and cation exchange capacity of the mixture, but increased its salinity and heavy metal contents. Yield of lettuce increased with parallel to the sediment applications whereas tomato growth and yield remained unaffected. Significant effects were also found on the nutrient contents of the plant tissues, depending on the sediment and application rate used, but no heavy metal accumulation in plants could be detected. According to the results, the application of appropriate rates of sediments to the agricultural soils surrounding the lake seems to be a sound practice to avoid problems arising from the disposal of large amounts of dredged material, and to improve the properties of the sandy soils of the area.