Soil management using fertilizers can modify soil chemical, biochemical and biological properties, including the concentration of trace-elements as cadmium (Cd), chromium (Cd) and nickel (Ni). ...Bacterial isolates from Cd, Cr, and Ni-contaminated soil were evaluated for some characteristics for their use in bioremediation. Isolates (592) were obtained from soil samples (19) of three areas used in three maize cultivation systems: no-tillage and conventional tillage with the application of mineral fertilizers; minimum tillage with the application of sewage sludge. Four isolates were resistant to Cr3+ (3.06 mmol dm−3) and Cd2+ (2.92 mmol dm−3). One isolate was resistant to the three metals at 0.95 mmol dm−3. All isolates developed in a medium of Cd2+, Cr3+ and Ni2+ at 0.5 mmol dm−3, and removed Cd2+ (17–33%) and Cr6+ (60–70%). They were identified by sequencing of the gene 16S rRNA, as bacteria of the genera Paenibacillus, Burkholderia, Ensifer, and two Cupriavidus. One of the Cupriavidus isolate was able to remove 60% of Cr6+ from the culture medium and showed high indole acetic acid production capacity. We evaluated it in a microbe-plant system that could potentially be deployed in bioremediation by removing toxic metals from contaminated soil.
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•Bacterial isolates (592) were obtained from Cd, Cr, and Ni contaminated soil.•Several isolates showed resistance to more than 2 mmol dm−3 of Cd2+, Cr3+, and Ni2+.•One isolate was simultaneously resistant to about 1 mmol dm−3 Cd2+, Cr3+, and Ni2+.•Cupriavidus sp. removed 60% of Cr6+ from the culture medium.•Cupriavidus sp. produces IAA in the culture medium and showed potential for use in bioremediation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Snack foods are common and highly advertised to children and serve their natural predispositions for sweet and salty tastes. However, the risk issues of low-cost snacks eaten by 0–6 aged children are ...lack of more concern. To better understand the issue of low-cost snacks this study considered potentially toxic metals (PTMs) impact on children’s health risk, measured PTMs in a collection of 570 collected low-cost snacks contributed by 1342 voluntary participants children aged 0–6 years involved in Xi’an city are conducted. Nine priority PTMs and amounts ranked as Mn > Zn > Cu > Cr > Sb > Pb > Ni > Cd > Co. The Estimated Weekly Intake of PTMs in snacks for children accounted for a proportion of the Provisional Tolerance Weekly Intake. Children’s daily snack ingestion of Cr, Cd and Pb were especially concerning. It was noted that all PTMs in flour products contribute to the total Target Hazard Quotient (THQ>1) were observed having a non-carcinogenic risk compared to the single metals Cr, Co and Cd with carcinogenic risk. The correlations between Cu, Pb, Zn in low-cost snacks and children’s bloods reflected PTMs especially for Pb that transfers into children’s bodies mostly through low-cost foodstuffs ingestion. Also, the elevated blood lead levels (BLLs) depended on readily available, low-quality snacks accessible for children. Therefore, multi-initiatives aimed at improving the quality, increasing awareness, and a PTM monitoring program for low-cost snack food market to young children should be undertaken.
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•The estimated weekly intake and ingestion risks of PTMs in children low-cost snacks are determined.•EWI of PTMs in snacks accountes for a proportion of PTWI, especial Cr, Cd and Pb.•Flour products with non-carcinogenic risk for children compare to Cr, Co and Cd as carcinogenic risk.•Correlations between Cu, Pb, Zn in snacks and children’s bloods reflect they undergo metal exposure of snack source.•Elevated blood lead levels depend on readily available, low-quality snacks accessible for children.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Wastewater treatment plants, the last barrier between ever-increasing human activities and the environment, produce huge amounts, of unwanted semi-solid by-product - waste activated sludge. Anaerobic ...digestion can be used to reduce the amount of sludge. However, the process needs extensive modernisation and refinement to realize its full potential. This can be achieved by using efficient pre-treatment processes that result in high sludge disintegration and solubilization. To this end, we investigated the efficiency of a novel pinned disc rotational generator of hydrodynamic cavitation. The results of physical and chemical evaluation showed a reduction in mean particle size up to 88%, an increase in specific surface area up to 300% and an increase in soluble COD, NH4-N, NO3-N, PO4-P up to 155.8, 126.3, 250 and 29.7%, respectively. Microscopic images confirmed flocs disruption and damage to yeast cells and Epistilys species due to mechanical effects of cavitation such as microjets and shear forces. The observed cell ruptures and cracks were sufficient for the release of small soluble biologically relevant dissolved organic molecules into the bulk liquid, but not for the release of microbial DNA. Cavitation treatment also decreased total Pb concentrations by 70%, which was attributed to the reactions triggered by the chemical effects of cavitation. Additionally, the study confirmed the presence of microplastic particles and fibers of polyethylene, polyethylene terephthalate, polypropylene, and nylon 6 in the waste activated sludge.
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•Efficient disintegration and solubilization of WAS with novel PD RGHC were reached.•Microjets and shear forces caused mechanically cracked, torn off and split cells.•Increased soluble COD, NH4-N and NO3-N confirmed release of intracellular DOM.•PTM concentrations (most dominant for Pb) were affected by chemical effects of HC.•PE, PP, PET, and PA-6 microplastics were identified in the sludge sample.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pollution from potentially toxic metals (PTMs) is one of the most pressing global environmental challenge with soaring human health concerns. It is now critical to seek out effective remediation ...technologies to control PTMs in the terrestrial environment. Biochar has piqued the interest of researchers due to its ability to immobilize PTMs, particularly in soil, with the assumption that biochar having unique physico-chemical properties may influence PTM mobility. A meta-analysis was performed using 1503 observations extracted from 80 peer-reviewed articles to determine: (a) the effects of various physico-chemical properties of biochar on the bioavailability of PTMs (As, Cd, Cu, Ni, Pb, Zn) in soil and plants, and (b) the best specification of physico-chemical properties of biochar for effective remediation of these PTMs. The findings revealed that the reduction rate of PTM bioavailability is heavily influenced by the physico-chemical properties of both biochar and soil. The physico-chemical parameters of biochar that have effective response to PTMs immobilization were as; 101–500 m2 g−1 surface area, neutral to alkaline pH, pyrolysis temperature > 500 °C, with best application rate of 1.1–3%. However, overall results indicate that the biochar, with given specification of physico-chemical attributes, can decrease the bioavailability of PTMs by 40% in soil and 22% in plants. Moreover, edaphic factors such as soil pH, texture, and crop type can also influence the biochar mediated PTMs adsorption and transformation under field or pot conditions. Furthermore, research gaps remain to be filled in order to investigate the efficiency, high specificity, and secondary pollution aspects of biochar, particularly on large-scale applications as an amendment for PTM remediation.
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•Eighty peer reviewed publications were used to conduct this meta-analysis.•Biochar addition can reduce PTMs concentration in soil by 40% and in plants by 22%.•Biochar pyrolyzed at >500 °C with 101–500 m2 g−1 surface area showed effective results.•Immobilization of PTMs can be a function of physicochemical properties of biochar.•Criteria should be established for uniform classification of biochar.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study a total of 30 street dusts and 10 surface soils were collected in the central district of Tehran and analyzed for major potentially toxic metals. Street dust was found to be greatly ...enriched in Sb, Pb, Cu and Zn and moderately enriched in Cr, Mn, Mo and Ni. Contamination of Cu, Sb, Pb and Zn was clearly related to anthropogenic sources such as brake wear, tire dust, road abrasion and fossil fuel combustion. Spatial distribution of pollution load index in street dust suggested that industries located south-west of the city intensify street dust pollution. Microscopic studies revealed six dominant group of morphological structures in calculation of the exposurethe street dusts and surface soils, with respect to different geogenic and anthropogenic sources. The BCR (the European Community Bureau of Reference) sequential extraction results showed that Sb, Ni, Mo, As and Cr bonded to silicates and sulfide minerals were highly resistant to dissolution. In contrast, Zn, Cd, and Mn were mostly associated with the exchangeable phase and thus would be easily mobilized in the environment. Cu was the most abundant metal in the reducible fraction, indicating its adsorption to iron and manganese oxy-hydroxides. Pb was equally extracted from exchangeable and reducible fractions. Anthropogenic sources related to traffic apparently play a small role in Cr, Ni and Mo contamination and dispersed them as bioavailable forms but with reduced mobility and bioavailablity due to high potential of complexation and adsorption to organic matter and iron and manganese oxy-hydroxides. Calculated Hazard Index (HI) suggests ingestion as the most important pathway for the majority of PTMs in children and dermal contact as the main exposure route for Cr, Cd and Sb for adults. The HIs and fractionation pattern of elements revealed Pb as the sole element that bears potential health risk in street dust and surface soil.
•Anthropogenic PTMs are not necessarily extracted from bioavailable fractions.•Applying bioavailable/bioaccessible fraction of PTMs in calculating hazard indices is proposed.•Lead is the sole element in Tehran street dust and surface soil that pose potential health risk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Phytoremediation is regarded as one of the most cost-effective and environmentally friendly strategies for potentially toxical metals (PTMs) contaminated soil remediation. Despite that, continuous ...studies are conducting to explore the potential plant species in order to achieve enhanced remediation efficiencies. Therefore, in this study, a field investigation was conducted to screen the potential phytoremediation plants from a contaminated site in the surrounding area of a Zn smelter in Feng Country, China. Results indicated that soils in the studied area were severely contaminated with Cd and Zn, while the contents of other metals (Cu, Pb, and Ni) were below the allowanced threshold. Moreover, the contamination was more serious in areas closer to the smelter. The elevated level of contamination had great impacts on plant diversity and abundance. Fifty-nine plant species belonging to 28 families were identified in the studied area, of which plants from the Asteraceae family and herbs were most frequently observed. Plants demonstrated differentiated potential on metal accumulation and translocation, and the total Cd, Cu, Pb, and Zn contents in the aerial parts of plants ranged from 5.57 to 268.5, 14.34 to 140.90, 10.43 to 570.3, and 110.3 to 1350 mg kg−1, respectively. Symphytum officinale Linn. distinguished itself from the various plants as a promising plant candidate for soil remediation, due to its great capacities for absorbing Cd, Pb, and Zn. Specifically, an individual Symphytum officinale Linn. plant can accumulate up to 5.54, 21.0, and 52.9 mg Cd, Pb, and Zn in its aboveground parts (20.67 g dry weight). Results from this study can provide a reference for the phytoremediation of PTMs contaminated soil in this area or other places with similar soil and climate conditions.
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•Cd and Zn were the prime pollutants in soils surrounding the Zn smelter.•Plants from Asteraceae family and herbs were most frequently observed in the studied area.•Symphytum officinale Linn. demonstrated high accumulation capacities for Cd, Pb, and Zn.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Pollution of potentially toxic metals (PTMs) in road dust (RD) is becoming an important threat to the urban environmental quality and human health. The chemical speciation of PTMs is an important ...index charactering the risks, which may also closely relate to the pollution level and source but it was poorly understood. In this study, the chemical speciation of Cd, Cr, Cu, Ni, Pb and Zn in the RD of a megacity (Nanjing), China was determined following an optimized BCR (proposed by the European Community Bureau of Reference) sequential extraction procedure to assess their pollution and potential eco-risk and to explore the variations of metal chemical speciation with the pollution levels and sources. Total concentrations of the PTMs in the RD were enriched 1.4- to 123-fold relative to the subsoil with median contamination factors (CF) of 6.7 (Pb), 6.0 (Cu), 5.5 (Cd), 4.0 (Zn), 2.0 (Cr) and 1.9 (Ni). Pollution of the PTMs should be mainly from industrial and traffic emissions and showed high CF values in the northern industrial zone. Whereas, the chemical percentages of each metal showed relatively narrow spatial variations and were not statistically correlated with the pollution levels (p = 0.05). Comparing of similar studies indicates that no regular patterns existed in chemical percentages for each metal in RD polluted by the traffic and/or both the industrial and traffic sources. In the RD of Nanjing, Pb was mostly associated with reducible phase, Cd and Zn were mainly present in acid-soluble phase, Cu was mostly concentrated in oxidizable phase, while Cr and Ni were predominantly present in residual phase. As the typical pollutants, anthropogenic Cd, Cu, Pb and Zn were mostly associated with the potential mobile phases but also with the residual phase in the RD of Nanjing, causing 1.4- to 3.0-fold increase in the mobility. Combining the assessments from eco-risk index, risk assessment code and sediment quality guidelines with the pollution levels and chemical speciation, we deduced that Cd, Cu, Pb and Zn may pose certain eco-risk upon transport into the aquatic system and soil, and Cd should be primarily concerned.
•Cd, Cu, Pb and Zn were typical pollutants with considerable to very high pollution.•Anthropogenic metals were present in both extractable and residual phases.•Each metal showed similar spatial chemical percentage across degrees of pollution.•Chemical percentage of metals was not necessarily associated with pollutant sources.•The ecological risk of metals was considerable to very high, mainly due to Cd.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This paper is focused on evaluating the quality of bottom sediments and water in the watershed of the Delňa creek, where gold, antimony and mercury were mined in the past. The results showed that the ...biggest source of pollution was a heap of mining material, where the limit values of Sb, As, Hg and Pb concentrations in the sediments were exceeded. Other sources of pollution in the river basin were the right-hand tributaries. A comparison of the dependencies of the concentrations of potentially toxic metals in the water and sediments shows that while the concentrations of pollutants in the waters react to the current state of water quality in the basin and tributaries (pH, concentration, discharge), the sediments exhibit a stable concentration character.
Soil and water contamination by potentially toxic metals (PTMs) has exerted adverse environmental impacts, which justifies studies of promising remediation alternatives. This article investigated the ...competitive sorption of cadmium (Cd), lead (Pb), and zinc (Zn) onto peat, compost, and biochar derived from the organic fraction of municipal solid waste (OFMSW), but its main innovation was the post-sorption assessment. The effects of contact time on competition between contaminants were systematically analyzed by batch experiments and the effectiveness of the sorption process was evaluated in desorption tests (H2O, HCl, NaOH, and NaCl) and sequential extraction. Kinetic data were well-fitted to pseudo-first-order (PFO) and pseudo-second-order (PSO) models and the intra-particle diffusion model revealed the existence of multiple linear regions, indicating the sorption process was controlled by a multi-step mechanism. The sorption capacities followed a biochar > compost > peat order, with biochar retaining more than 99% of Cd, Pb, and Zn in all samples. The general order of desorption percentage was peat > compost > biochar, with a below 0.60% biochar release, suggesting the importance of chemical processes. HCl solution (more acid pH) showed the highest release of previously sorbed contaminants and, therefore, can be employed for the reuse of sorbents (sorption/desorption cycles). The only exception was Pb desorption on biochar, with maximum release in NaOH solution. A negative Pearson correlation with F1 (acid-soluble/exchangeable fraction) for Cd and Zn and a positive one with the other steps were reported. Pb exhibited an opposite behavior, showing the highest sorption performances and the lowest desorption rates for all sorbents, justified by positive correlations with F4 (residual fraction) and negative ones with desorption. The findings suggest the evaluated sorbents, especially compost and biochar, can be effective materials in the simultaneous sorption of Cd, Pb, and Zn in wastewater, as well as an amendment for PTMs immobilization in contaminated soils.
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•Compost and biochar are environmentally friendly and innovative sorbents.•The order of sorption capacities was biochar > compost > peat.•Biochar showed an excellent sorption capacity and the lowest desorption rates.•Pb showed the highest sorption and the lowest desorption in multi-metal systems.•Pearson correlations were more similar for Cd and Zn and more different for Pb.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Tree-herb intercropping is a prospective approach for the ecological remediation of soil contaminated with potentially toxic metals (PTMs). In this study, the facilitation and microbial community ...response of woody plant Morus alba L. intercropped with Cd/Zn hyperaccumulator Sedum alfredii H. and pioneer plant Arundo donax L. were carried out in the PTM-contaminated soil. The results indicated that the intercropping system can improve M. alba L. growth, as well as increase its PTMs uptake. The dried biomass of M. alba L. in the intercropping system was increased observably (p < 0.05) by 55.1%. Meanwhile, the contents of chlorophyll in M. alba L. leaves, PTMs contents in M. alba L. roots, and the relative abundance of Rhizobiaceae, Singulisphaera, Isosphaeraceae, and Arthrobacter in the M. alba L. rhizosphere were also notably (p < 0.05) enhanced. Meanwhile, the interactions of microorganisms in the intercropped plants rhizosphere might contribute to improving the biological quality of the contaminated soil. Soil sucrase and acid phosphatase activities in the intercropping system were significantly (p < 0.05) increased by 97.03% and 34.91% relative to the control. Furthermore, in the intercropping system, 93.61%, 61.30%, and 79.18% of Cd, Pb, and Zn were extracted by S. alfredii H., 72.16% of Cu was extracted by A. donax L., and 46.38% of Mn was extracted by M. alba L., which indicated that the extraction amounts of PTMs among the intercropped plants were relatively compensated. The results suggested that the tree-herb intercropping might increase the coexistence of plants and facilitate the adaptability for ecological remediation of PTM-contaminated soils.
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•Growth and photosynthesis of M. alba L. was improved by the intercropping.•Uptake of PTMs in M. alba L. roots was significantly enhanced by the intercropping.•Overall PTMs accumulation amounts were relatively complemented by the intercropped plants.•The intercropping system can enhance the interactions of microorganisms.•The change of microbial community might facilitate the coexistence of intercropped plants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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