Heavy Metal Contamination in Phrynops geoffroanus (Schweigger, 1812) (Testudines: Chelidae) in a River Basin, So Paulo, Brazil

The Piracicaba River basin is considered the most disturbed river basin in the state of So Paulo. Considerable amounts of agricultural residues are seasonally drained into the river, and the region is also highly urbanized and industrialized with an incipient sewage treatment system. The presence of heavy metals has been previously reported for the water and riverbed in Piracicaba river basin. In this study we evaluated 13 heavy metals in the blood of 37 Geoffroy`s side-necked turtles, Phrynops geoffroanus, from Piracicaba River and Piracicamirim Creek, one of its tributaries. Blood levels of As, Co, Cr, Se and Pb varied among sites, whereas Sn varied between males and females. However, no obvious pathology was detected. Serum level of Cu (2,194 ng g(-1)) and Pb (1,150 ng g(-1)) found in this study are the highest ever described for any reptile; however, no clinical symptoms have been detected in the present study. There is no information about the time scale of such contamination, which could be currently subclinical and yet lead to a breakdown in the population reproductive success in a few years. Based on the present study, legal enforcement is urged in order to locate and extirpate heavy metal sources in the Piracicaba River basin. In addition, monitoring should include humans and commercial fish consumed in local markets.

Heavy metal contamination in seafood and consumer exposure in the Gulf Cooperation Council

Dissertação para obtenção do Grau de Mestre em Tecnologia e Segurança Alimentar

Dual augmentation for aerobic bioremediation of MTBE and TCE pollution in heavy metal-contaminated soil

In this work we isolated from soil and characterized several bacterial strains capable of either resisting high concentrations of heavy metals (Cd2+ or Hg2+ or Pb2+) or degrading the common soil and groundwater pollutants MTBE (methyl-tertbutyl ether) or TCE (trichloroethylene). We then used soil microcosms exposed to MTBE (50 mg/l) or TCE (50 mg/l) in the presence of one heavy metal (Cd 10 ppm or Hg 5 ppm or Pb 50 or 100 ppm) and two bacterial isolates at a time, a degrader plus a metalresistant strain. Some of these two-membered consortia showed degradation efficiencies well higher (49–182% higher) than those expected under the conditions employed, demonstrating the occurrence of a synergetic relationship between the strains used. Our results show the efficacy of the dual augmentation strategy for MTBE and TCE bioremediation in the presence of heavy metals.

Enhanced phytoextraction: II. Effect of EDTA and citric acid on heavy metal uptake by Helianthus annuus from a calcareous soil

High biomass producing plant species, such as Helianthus annuus, have potential for removing large amounts of trace metals by harvesting the aboveground biomass if sufficient metal concentrations in their biomass can be achieved. However, the low bioavailability of heavy metals in soils and the limited translocation of heavy metals to the shoots by mosthigh biomass producing plant species limit the efficiency of the phytoextraction process. Amendment of a contaminated soil with ethylene diamine letraacetic acid (EDTA) or citric acid increases soluble heavy metal concentrations, potentially rendering them more available for plant uptake. This article discusses the effects of EDTA and citric acid on the uptake of heavy metals and translocation to aboveground harvestable plant parts in Helianthus annuus. EDTA was included in the research for comparison purposes in our quest for less persistent alternatives, suitable for enhanced phytoextraction. Plants were grown in a calcareous soil moderately contaminated with Cu, Pb, Zn, and Cd and treated with increasing concentrations of EDTA (0. 1, 1, 3, 5, 7, and 10 mmol kg(-1) soil) or citric acid (0. 01, 0. 05, 0.25, 0.442, and 0.5 mol kg(-1) soil). Heavy metal concentrations in harvested shoots increased with EDTA concentration but the actual amount of phytoextracted heavy metals decreased at high EDTA concentrations, due to severe growth depression. Helianthus annuus suffered heavy metal stress due to the significantly increased bioavailable metal fraction in the soil. The rapid mineralization of citric acid and the high buffering capacity of the soil made citric acid inefficient in increasing the phytoextracted amounts of heavy metals. Treatments that did not exceed the buffering capacity of the soil (< 0.442 mol kg(-1) soil) did not result in any significant increase in shoot heavy metal concentrations. Treatments with high concentrations resulted in a dissolution of the carbonates and compaction of the soil. These physicochemical changes caused growth depression of Helianthus annuus. EDTA and citric acid added before sowing of Helianthus annuus did not appear to be efficient amendments when phytoextraction of heavy metals from calcareous soils is considered.

Mucorales de solo contaminado com metais pesados na região do pólo cerâmico de Santa Gertrudes, SP: ocorrência e capacidade de biossorção de chumbo e zinco

Pós-graduação em Ciências Biológicas (Microbiologia Aplicada) - IBRC

Heavy metal toxicity in rice and soybean plants cultivated in contaminated soil

Heavy metals can accumulate in soil and cause phytotoxicity in plants with some specific symptoms. The present study evaluated the specific symptoms on rice and soybeans plants caused by excess of heavy metals in soil. Rice and soybean were grown in pots containing soil with different levels of heavy metals. A completely randomized design was used, with four replications, using two crop species and seven sample soils with different contamination levels. Rice and soybean exhibited different responses to the high concentrations of heavy metals in the soil. Rice plants accumulated higher Cu, Mn, Pb and Zn concentrations and were more sensitive to high concentrations of these elements in the soil, absorbing them more easily compared to the soybean plants. However, high available Zn concentrations in the soil caused phytotoxicity symptoms in rice and soybean, mainly chlorosis and inhibited plant growth. Further, high Zn concentrations in the soil reduced the Fe concentration in the shoots of soybean and rice plants to levels considered deficient.

Radionuclides and heavy metal contents in phosphogypsum samples in comparison to cerrado soils

Phosphogysum (PG) or agricultural gypsum, a solid waste from the phosphate fertilizer industry, is used as soil amendment, especially on soils in the Cerrado region, in Brazil. This material may however contain natural radionuclides and metals which can be transferred to soils, plants and water sources. This paper presents and discusses the results of physical and chemical analyses that characterized samples of PG and compares them to the results found in two typical soils of the Cerrado, a clayey and sandy one. These analyses included: solid waste classification, evaluation of organic matter content and of P, K, Ca, Mg, and Al concentrations and of the mineralogical composition. Natural radionuclides and metal concentrations in PG and soil samples were also measured. Phosphogypsum was classified as Class II A - Not Dangerous, Not Inert, Not Corrosive and Not Reactive. The organic matter content in the soil samples was low and potential acidity high. In the mean, the specific 226Ra activity in the phosphogypsum samples (252 Bq kg-1) was below the maximum level recommended by USEPA, which is 370 Bq kg-1 for agricultural use. In addition, this study verified that natural radionuclides and metals concentrations in PG were lower than in the clayey Oxisol of Sete Lagoas, Minas Gerais, Brazil. These results indicated that the application of phosphogypsum as soil amendment in agriculture would not cause a significant impact on the environment.

Heavy-metal pollution and remediation of forest soil around the Harjavalta Cu-Ni smelter, in SW Finland

Abstract

Heavy metal tolerance patterns of total heterotrophic bacteria isolated from the soils of Mahatma Gandhi University campus, Kottayam, Kerala

Industrialization of our society has led to an increased production and discharge of both xenobiotic and natural chemical substances. Many of these chemicals will end up in the soil. Pollution of soils with heavy metals is becoming one of the most severe ecological and human health hazards. Elevated levels of heavy metals decrease soil microbial activity and bacteria need to develop different mechanisms to confer resistances to these heavy metals. Bacteria develop heavy-metal resistance mostly for their survivals, especially a significant portion of the resistant phenomena was found in the environmental strains. Therefore, in the present work, we check the multiple metal tolerance patterns of bacterial strains isolated from the soils of MG University campus, Kottayam. A total of 46 bacterial strains were isolated from different locations of the campus and tested for their resistant to 5 common metals in use (lead, zinc, copper, cadmium and nickel) by agar dilution method. The results of the present work revealed that there was a spatial variation of bacterial metal resistance in the soils of MG University campus, this may be due to the difference in metal contamination in different sampling location. All of the isolates showed resistance to one or more heavy metals selected. Tolerance to lead was relatively high followed by zinc, nickel, copper and cadmium. About 33% of the isolates showed very high tolerance (>4000μg/ml) to lead. Tolerance to cadmium (65%) was rather low (<100 μg/ml). Resistance to zinc was in between 100μg/ml - 1000μg/ml and the majority of them shows resistance in between 200μg/ml - 500μg/ml. Nickel resistance was in between 100μg/ml - 1000μg/ml and a good number of them shows resistance in between 300μg/ml - 400μg/ml. Resistance to copper was in between <100μg/ml - 500μg/ml and most of them showed resistance in between 300μg/ml - 400μg/ml. From the results of this study, it was concluded that heavy metal-resistant bacteria are widely distributed in the soils of MG university campus and the tolerance of heavy metals varied among bacteria and between locations

Heavy metal and microbial loads in sewage irrigated vegetables of Kabul, Afghanistan

Little is known about the heavy metal and microbial contamination of vegetables produced in Central Asian cities. We therefore measured the concentration of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) and of faecal pathogens (Coliform bacteria, Salmonella sp., Shigella sp., Ascaris lubricoides, Entamoeba sp. and pinworms [Oxyuris vermicularis syn. Enterobius vermicularis]) in soil, irrigation water, and marketed vegetables of Kabul City, Afghanistan. Leaf Pb and Zn concentrations of leafy vegetables were with 1–5 and 33–160 mg kg^{-1} dry weight (DW) several-fold above respective international thresholds of 0.3 mg Pb kg^{-1} and 50 mg Zn kg^{-1}. The tissue concentration of Cu was below threshold limits in all samples except for spinach in one farm. Above-threshold loads of microbes and parasites on vegetables were found in five out of six gardens with coliforms ranging from 0.5–2 × 10^7 cells 100g^{-1} fresh weight (FW), but no Salmonella and Shigella were found. Contamination with 0.2 × 10^7 eggs 100g^{-1} FW of Ascaris was detected on produce of three farms and critical concentrations of Entamoeba in a single case, while Oxyuris vermicularis, and Enterobius vermicularis were found on produce of three and four farms, respectively. Irrigation water had Ascaris, Coliforms, Salmonella, Shigella, Entamoeba, and Oxyuris vermicularis syn. Enterobius vermicularis ranging from 0.35 × 10^7 to 2 × 10^7 cells l^{-1}. The heavy metal and microbial loads on fresh UPA vegetables are likely the result of contamination from rising traffic, residues of the past decades of war and lacking treatment of sewage which needs urgent attention.

Evidence of heavy metal movement down the profile of a heavily-sludged soil

Two sites in central England where sewage sludge has been deposited for decades were studied to measure the heavy metal distribution in the soil profiles. The first site (S 1) was a field receiving heavy loads sludge from a nearby wastewater treatment plant, and the second (S2) was a farm applying 'normal' sludge rates of 8 t ha(-1) y(-1) of the same sludge. Soil samples were also taken by a near-by untreated control site. In S I the movement of heavy metals was significant even down to 80 cm depth compared to the control. In S2, the concentrations of lead (Pb) and zinc (Zn) and the organic matter content were higher than the control down to 20 cm, while nickel (Ni) moved significantly down to 80 cm. This underlies. the possibility that the metals bound onto organic surfaces moved along with organic matter down to that depth. The movement of metals in S2 points out the potential risks of applying sewage sludge for a long time.