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Contamination of agricultural soils with lead (Pb) is a widespread problem which is mainly due to anthropogenic activities. The present study investigated the effect of organic and inorganic amendments on wheat growth and reducing Pb concentration in the plant. A greenhouse experiment was conducted on Pb spiked soil (500 mg kg -1 of soil) with the application of farmyard manure, poultry manure, gypsum and di-ammonium phosphate (DAP). Plants were harvested after 120 days of growth and analyzed for Pb concentration in different plant parts. Under Pb stress, amendments significantly (p < 0.05) increased grain yield and root dry weights compared to the control. Grain yield and dry weights of shoots and roots were maximum with DAP compared to the control and other amendments. Amendments increased transpiration rate, stomatal conductance, chlorophyll contents and photosynthetic rate. The lowest Pb concentration was found in DAP treated plants which were about 88%, 84%, and 85% lower in root, shoots and grains than control respectively. DAP fertilizer was the most effective in improving these parameters than control and other amendments and can be used to reduce Pb concentration in wheat and probably other crops.

A pot study was used to examine the effects of amendments such as EDTA and elemental sulfur on the growth potential, gas exchange features, uptake and mobilization of Pb by wheat (Triticum aestivum L.) in two texturally different contaminated soils at three levels of EDTA (2, 4, 8 mmol kg(-1) dry soil) and two levels of elemental sulfur (100, 200 mmol kg(-1) dry soil). EDTA resulted in more solubilization of Pb than elemental sulfur in both soils. Application of EDTA and elemental sulfur increased shoot dry matter in the loamy sand soil, whereas in the sandy clay loam soil EDTA treated plants produced lower shoot dry matter compared to that observed with elemental sulfur. Application of EDTA 10d prior to harvest increased the amount of Pb accumulated into wheat shoots with more Pb accumulated by plants from the loamy sand than from the sandy clay loam soil. However, evaluation of the relative extraction efficiency expressed as the percentage of solubilized Pb that is subsequently also effectively accumulated by the plant shoots reveals that the relatively low efficiency does not warrant the massive mobilization induced by the environmentally persistent EDTA chelator. More modest mobilization of Pb induced by elemental sulfur and the higher relative extraction of mobilized Pb therefore deserves further attention in future research. In particular, attention needs to be paid to determining soil types in which elemental sulfur can induce significant impact on soil pH and metal mobility after application of a practically realistic dosage., (2010. Published by Elsevier Ltd.)

Excessive lead (Pb) in industrial dust increases serious concerns about its potential impact on human health and environment. Urban trees, as a green and cost-effective alternative, are now considered an eco-sustainable tool used to monitor and mitigate this environmental pollution. The present study investigated the effect of dust particles and lead deposition on plant functioning and micromorphology of two common roadside plants, Eucalyptus camaldulensis and Conocarpus lancifolius, in an industrial city, Faisalabad, Pakistan. Tree leaf samples were collected from 20 sites varying in dust exposure intensity. These samples were analyzed for antioxidant enzymes such as superoxidase dismutase (SOD), peroxidases (POD), and catalases (CAT), as well as for proline and protein contents. An increased leave of reactive oxygen species and proline contents in response to increasing dust load and lead tissue lead concentrations across the tested locations suggested the sensitivity of plants to urban dust. This study suggested that C. lancifolius leaves accumulated relatively higher dust particles and lead contents than E. camaldulensis. However, this excessive dust deposition and lead uptake inhibited carbon and protein synthesis in E. camaldulensis and C. lancifolius, as evidenced by relatively lower leaf photosynthesis and protein contents. We also found that the concentration of CAT (4.90 nmol min–1 g–1 protein), SOD (38.42 U mg–1 protein), and POD (2.64 µmol min–1 g–1 protein) were higher in E. camaldulensis. The results provide experimental support for the hypothesis that genetically rich populations are better adapted to changing conditions and suggest that C. lancifolius is less sensitive to dust load and lead uptake in terms of growth reduction. Regarding lead uptake and dust removal, C. lancifolius performed better as compared to E. camaldulensis. The above findings are helpful in the quantification of services, assessing the diversity, and identification of eco-friendly trees in urban areas. Furthermore, this study will be helpful for the formulation of future tree-planting policies in urban areas. [ABSTRACT FROM AUTHOR]

Soil and air pollution caused by heavy metals and limestone dust are prevalent in urban environments and they are an alarming threat to the environment and humans. This study was designed to investigate the changes in morphological and physiological traits of three urban tree species seedlings (Bombax ceiba, Conocarpus lancifolius, and Eucalyptus camaldulensis) under the individual as well as synergetic effects of heavy metal lead (Pb) and limestone dust toxicities. The tree species were grown under controlled environmental conditions with nine treatments consisting of three levels of dust (0, 10, and 20 g) and three levels of Pb contaminated water irrigation (0, 5, and 10 mg L-1). The results depicted that the growth was maximum in T1 and minimum in T9 for all selected tree species. B. ceiba performed better under the same levels of Pb and limestone dust pollution as compared with the other two tree species. The B. ceiba tree species proved to be the most tolerant to Pb and limestone pollution by efficiently demolishing oxidative bursts by triggering SOD, POD, CAT, and proline contents under different levels of lead and dust pollution. The photosynthetic rate, stomatal conductance, evapotranspiration rate, and transpiration rate were negatively influenced in all three tree species in response to different levels of lead and dust applications. The photosynthetic rate was 1.7%, 3.1%, 7.0%, 11.03%, 16.2%, 23.8%, 24.8%, and 30.7%, and the stomatal conductance was 5%, 10.5%, 23.5%, 40%, 50.01%, 61.5%, 75%, and 90.9%, greater in T2, T3, T4, T5, T6, T7, T8, and T9 plants of B. ceiba, respectively, as compared to T1. Based on the findings, among these three tree species, B. ceiba is strongly recommended for planting in heavy metal and limestone dustpolluted areas followed by E. camaldulensis and C. lancifolius due to their better performance and efficient dust and heavy metal-scavenging capability. [ABSTRACT FROM AUTHOR]

Contamination of agricultural soils with lead (Pb) is a widespread problem which is mainly due to anthropogenic activities. The present study investigated the effect of organic and inorganic amendments on wheat growth and reducing Pb concentration in the plant. A greenhouse experiment was conducted on Pb spiked soil (500 mg kg of soil) with the application of farmyard manure, poultry manure, gypsum and di-ammonium phosphate (DAP). Plants were harvested after 120 days of growth and analyzed for Pb concentration in different plant parts. Under Pb stress, amendments significantly ( p < 0.05) increased grain yield and root dry weights compared to the control. Grain yield and dry weights of shoots and roots were maximum with DAP compared to the control and other amendments. Amendments increased transpiration rate, stomatal conductance, chlorophyll contents and photosynthetic rate. The lowest Pb concentration was found in DAP treated plants which were about 88%, 84%, and 85% lower in root, shoots and grains than control respectively. DAP fertilizer was the most effective in improving these parameters than control and other amendments and can be used to reduce Pb concentration in wheat and probably other crops. [ABSTRACT FROM AUTHOR]

Continuous irrigation of soils with untreated effluents can result in the accumulation and translocation of some metals in the soils and plants. Application of farmyard manure (FYM) to such soils may increase or decrease their availability and retention time. Calcareous soils contaminated with 100, 200, and 400mg kg–1Ni, Zn, and Pb as chloride salts were used, and farmyard manure added (40g kg–1for 90 days) with moisture contents at field capacity. Soil samples were drawn at 30 day intervals, and metals extracted with (AB-DTPA) C14H23NO3O10. With FYM application of 400 mg kg–1, Ni availability increased from 179 (day 30) to 240 mg kg–1(day 90); Zn from 163 (day 30) to 230 mg kg–1(day 90), but, Pb decreased from 214 to 161 mg kg–1. FYM forms multi-dentate complex which greatly enhances the Ni and Zn solubility, and organic matter immobilizes Pb in the soil. [ABSTRACT FROM PUBLISHER]

We compared acetic, ascorbic, and oxalic acids with ethylenediaminetetraacetic acid (EDTA) to enhance phytoextraction of nickel (Ni), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), and lead (Pb) by maize. Except ascorbic acid, acids significantly (P< 0.05) decreased shoot dry weight with maximum (5.60 g pot−1) recorded with ascorbic acid and minimum with oxalic acid (4.06 g pot−1). Maximum ammonium bicarbonate–diethylenetriaminepenta acetic acid (AB-DTPA)–extractable nickel (19.94 mg kg−1) was recorded with EDTA and it was minimum (10.57 mg kg−1) with oxalic acid. The EDTA significantly (P< 0.05) increased AB-DTPA-extractable lead while other acids decreased it. Except acetic acid, other acids significantly (P< 0.05) increased Ni and Zn concentration in shoots with maximum Ni (9.22 mg kg−1) and Zn (37.40 mg kg−1) with EDTA. [ABSTRACT FROM AUTHOR]

Lead is a highly toxic heavy metal, but its putative toxicity with respect to its speciation remains to unveil. In this study, Pb-induced toxicity to Vicia faba pigment contents was assessed against Pb speciation and accumulation. After a culture period of three weeks, V. faba seedlings were exposed to 5 μM of lead nitrate alone or chelated by citric acid (CA) or ethylenediaminetetraacetic acid (EDTA). The plants were treated for 1, 4, 8, 12 and 24 h in nutrient solution. Exposure to Pb-5 caused increased production of reactive oxygen species, lipid peroxidation and decrease in V. faba chlorophyll contents during 24 h. Lead-induced oxidative stress and toxicity to chlorophyll contents varied with the speciation of Pb. Addition of EDTA to Pb solution alleviated Pb-induced oxidative stress and toxicity to V. faba pigments by decreasing Pb accumulation in V. faba leaves. However, addition of citric acid to Pb did not affect Pb accumulation or toxicity to V. faba leaves. It is proposed that metal speciation plays an important role in Pb toxicity to V. faba pigment. Moreover, organic ligands vary greatly in terms of their ability to modify Pb phytoaccumulation and toxicity. [ABSTRACT FROM AUTHOR]