Mobility Of Zn Research Articles

Mobility, Speciation and Bioavailability of Zn and Pb in Artificially Polluted Soils by Magnetic Biochars from Siraitia Grosvenorii Residues

Mobility, Speciation and Bioavailability of Zn and Pb in Artificially Polluted Soils by Magnetic Biochars from Siraitia Grosvenorii Residues

Assessing the mobility of Zn, Pb and Ni during the weathering of Nkana smelter copper slag, Zambia

Mine slag dumps could be point-sources of possible pollutants to the surrounding water and soils. The purpose of this study was to investigate the leaching behavior of zinc, lead and nickel from Nkana copper slag dump of Kitwe in Zambia. To assess the toxicity and hazardous nature of the slag, Bath Leaching EN 12,457–2:2002, Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) were employed. The results from these techniques revealed that the copper slag was inert in the open or natural environment. Sequential extraction analysis was conducted to analyze the fractionation of the zinc, lead and nickel using a seven-step procedure. The sequential extraction analysis showed that the 3 metals were predominantly present in the residual fraction. The risk assessment code (RAC) showed that zinc and lead's mobility could pose an environmental risk categorized as low risk, with RAC values of 1.31 % and 1.50 %, respectively. Nickel's mobility fell within the no-risk category with a RAC of 0.32 %. Additionally, the effect of pH, particle size and contact time on the release of the 3 metals were investigated. The results showed that the highest concentrations of zinc and nickel were observed for longer period of exposure (>33 days), in acidic environments (pH 2.2 and pH 3.0), for particle size distribution (<75 μm). However, lead leaching was not affected by the variation of pH or particle size distribution but mostly by duration of exposure. X-ray diffraction (XRD) analysis revealed that diopside (CaMgSi2O6) and quartz (SiO2) constitute the primary phases within the sample. It is recommended to limit the exposure of slag material to acidic environments and minimize the fragmentation of the slag into finer particles as these conditions would promote increased release of zinc, lead and nickel to the surrounding environment.

Влияние минеральных удобрений на содержание микроэлементов в агрочерноземе при использовании технологии No-till

The article presents the results of studies on the effect of mineral fertilizers on the content of Zn, Cu in the soil and winter wheat plants using the No-till technology. In the field experiment, ammonium nitrate (N12P52) and potassium magnesium oxide (K32Mg12S20) were applied during sowing against the background of two additional fertilizing with ammonium nitrate (N34) - N30 at the tillering stage, N70 - at the tube emergence stage. Low content of mobile Zn and Cu compounds was found in the agrochernozem of the southern zone of the Rostov region. The application of ammonium nitrate, ammophos, potassium magnesium oxide does not replenish the reserves of biomicroelements in the soil. The balance of Zn and Cu for all experimental variants was negative: Zn - 115–154 g/ha; Cu - 39.0–56.0 g/ha. The obtained results indicate a violation of the microelement cycle in winter wheat agrocenoses and prove the need to use micronutrient fertilizers to obtain stable grain yields of good quality. Keywords: AGROCHERNOZEM, ZINC, COPPER, WINTER WHEAT, FERTILIZERS, NO-TILL TECHNOLOGY

Влияние минеральных удобрений на содержание микроэлементов в агрочерноземе при использовании технологии No-till

The article presents the results of studies on the effect of mineral fertilizers on the content of Zn, Cu in the soil and winter wheat plants using the No-till technology. In the field experiment, ammonium nitrate (N12P52) and potassium magnesium oxide (K32Mg12S20) were applied during sowing against the background of two additional fertilizing with ammonium nitrate (N34) - N30 at the tillering stage, N70 - at the tube emergence stage. Low content of mobile Zn and Cu compounds was found in the agrochernozem of the southern zone of the Rostov region. The application of ammonium nitrate, ammophos, potassium magnesium oxide does not replenish the reserves of biomicroelements in the soil. The balance of Zn and Cu for all experimental variants was negative: Zn - 115–154 g/ha; Cu - 39.0–56.0 g/ha. The obtained results indicate a violation of the microelement cycle in winter wheat agrocenoses and prove the need to use micronutrient fertilizers to obtain stable grain yields of good quality. Keywords: AGROCHERNOZEM, ZINC, COPPER, WINTER WHEAT, FERTILIZERS, NO-TILL TECHNOLOGY

Effect of long-term application of pig slurry and NPK fertilizers on trace metal content in the soil.

One of the goals of sustainable agricultural production is to avoid soil contamination by elements defined as trace metals (TMs). The aim of this study was to assess the long-term impact of the use of pig slurry (PS) and NPK mineral fertilizers on the soil content of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn). In a 9-year crop rotation, PS was used three times only before root crops. The same four levels of NPK doses (N0P0K0, N1P1K1, N3P2K2, N4P2K2) were applied to both plots with and without PS. Soil samples were collected in early spring from topsoil (0-0.3m) and subsoil (0.3-0.6m). Three forms of TMs were determined in the soil: pseudo-total (Aqua regia); bioavailable (Mehlich 3 method) and readily bioavailable (mobile) forms (1M NH4NO3). The tested factors did not have a significant impact on the Cd, Cu and Pb content, regardless of the form analyzed and the soil depth. PS application significantly increased the content of bioavailable forms of Zn regardless of the year, and the content of pseudo-total Zn only in the sugar beet year, i.e. after manure application. Increasing NPK doses increased the content of mobile Zn in the topsoil, especially in PS plots. A tendency to accumulate mobile forms of Cd and Pb was also observed on NPK-fertilized plots. Thus, long-term application of high NPK doses may increase the risk of contamination of the food chain with these metals. The content of mobile Cd and Zn was positively related to the content of total nitrogen in the soil and negatively related to pH.

Glyphosate application may influence the transfer of trace elements from soils to both soil solutions and plants

Trace elements dynamics in the soil-plant system depends on multiple parameters, including chelating organic compounds from natural or synthetic organic matters. In this study, we evaluated the influence of one of the most common pesticides—glyphosate—on the mobility of trace elements considering contrasted soils (uncontaminated, anthropogenically contaminated, and naturally-enriched) in a greenhouse experiment. Four modalities have been tested: one control without any application, two with different glyphosate doses (1 and 3 times the authorised field dose), and one with compost addition to evaluate its potential ability to mitigate the impact of glyphosate on trace element mobility. Both, trace element and glyphosate concentrations were measured in the soil solutions and trace element contents were determined in plants at the end of the experiment. The results showed that, although glyphosate concentrations rapidly decreased in soil solutions, glyphosate application still influenced the transfer of trace elements to both soil solution (up to 12-times higher) and plant (up to 5.2-times higher). This influence was highly dependent on both the specific elements and the type of soils considered. For instance, in uncontaminated soils, glyphosate especially increased the mobilization of Mn, Co, Zn, Mo, and Pb to soil solution. This effect diminished of 2.5 times on average with increasing soil contamination. A similar trend was observed for the transfer of trace elements from soil to plant (i.e., on average 2.2-times lower in the most contaminated compared to the uncontaminated soil). However, in the naturally-enriched soil, opposing trends were noted between soil solutions and plants. The impact of compost addition on the transfer of trace elements to plants remains unclear: compost enhanced the transfer of trace elements to soil solution in uncontaminated and naturally-enriched soils likely due to trace element input through the compost, but decreased the transfer in anthropogenically-contaminated soils likely due to adsorption processes. Therefore, glyphosate could potentially increase the exposure of trace elements through food consumption and their transfer to the ecosystem, particularly in uncontaminated and weakly contaminated soils. In highly contaminated soils, compost could mitigate the glyphosate-induced enhancement of trace element mobility to soil solutions.

Remediation of multi-metal(loid) contaminated soils using Mn-modified biochar: Mechanistic insights and influencing factors

Mn-modified biochar could impact soil quality and metal(loid) migration in contaminated soils. However, the remediation efficiency, mechanism, and influencing factors of Mn-modified biochar on multi-metal(loid) contaminated soils were largely unknown. In this study, three Mn-modified biochar were prepared by using MnCl2-impregnated rubber, tobacco rod, and coconut shell biochar, respectively. The remediation efficiency of Mn-modified biochar on Pb, As, Cd, Cu, and Zn contaminated soil was also compared. Our data revealed that the addition of Mn-modified biochar increased the effective cation exchange capacity (ECEC), organic matter (OM), alkaline hydrolyzed nitrogen (AHN), and the mobility of the nutrient Zn in the soil. Furthermore, Mn-modified rubber biochar and Mn-modified coconut shell biochar reduced acid extractable or Diethylenetriamine Pentaacetic Acid (DTPA) leached Pb, As, Cd, and Cu However, Mn-modified tobacco rod biochar increased the acid extractable or DTPA leached Pb, Cd, and Cu. The study showed that three Mn-modified biochars could effectively improve soil physicochemical properties and significantly increase soil nutrient activity. Mn-modified rubber and coconut shell biochar can effectively immobilize metal(loid)s and reduce their damage to soil. However, the Mn-modified tobacco rod biochar instead increased the mobility of metal(loid)s. The results indicate that feedstock is an important factor influencing the application of Mn-modified biochar and should be considered in the production.

Influence of Spring Burns on the Properties of Humus Horizon of Chernozem in the Southeast of Western Siberia

On the example of soils of the Basic Experimental Complex of the Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences (Tomsk), the influence of spring grass burns on the properties of the upper layer of the humus horizon of Chernozems. In the areas that burned two months ago, 1, 2, 3 and 11 years ago, a total of 56 samples (5–9 replicates) were collected. We found a considerably high stability of the controlled properties of soils (cationic-anionic composition of water extract, content of grain-size fractions and mobile compounds of a wide range of elements, total C and N, organic carbon, pH value, basicity from carbonates) to pyrogenic effects from spring grass fires. Informative indicators reflecting a significant pyrogenic impact over the past 11 years were the content of mobile Ca, Mg and Sr, as well as water-soluble Mg2+ and basicity from carbonates. Their content is higher in the soils of young (0–3 years) burnt areas relative to the old (11 year old) burnt areas and unburnt areas. Among the studied parameters, the pH value, the content of mobile Ba and Sr, and grain-size fractions of 1–5, 5–10, and 10–50 µm, had the low coefficient of variation (20%), and content of water-soluble ammonium and mobile Li and Zn had the high coefficient of variation (70%).

Zinc and Its Impact on the Function of the Testicle and Epididymis.

Zinc (Zn) is an essential trace element; it exhibits a plethora of physiological properties and biochemical functions. It plays a pivotal role in regulating the cell cycle, apoptosis, and DNA organization, as well as in protein, lipid, and carbohydrate metabolism. Among other important processes, Zn plays an essential role in reproductive health. The ZIP and ZnT proteins are responsible for the mobilization of Zn within the cell. Zn is an inert antioxidant through its interaction with a variety of proteins and enzymes to regulate the redox system, including metallothioneins (MTs), metalloenzymes, and gene regulatory proteins. The role of Zn in the reproductive system is of great importance; processes, such as spermatogenesis and sperm maturation that occur in the testicle and epididymis, respectively, depend on this element for their development and function. Zn modulates the synthesis of androgens, such as testosterone, for these reproductive processes, so Zn deficiency is related to alterations in sperm parameters that lead to male infertility.

Application of zinc modified biochars to enhance zinc availability, speciation and bajra growth in Zn-deficient soil

Zinc deficiency poses a serious threat to numerous crops and global human populations. Recently, soil biochar amendment has being promoted as a sustainable farming method. However, its consequence on the bioavailability of Zn in cereal crop has not been fully addressed. In the present study, 0.01% Zn-SO4 (w/w) was loaded in fruit waste, farmyard manure and coconut shell pyrolysis at 400 ℃, for 2 h to make fruit waste Zn-modified biochar (FWZn-MBC), farmyard manure Zn-modified biochar (FYZn-MBC) and coconut shell Zn-modified biochar (CSZn-MBC). Except control treatment, all the modified biochars were applied at 1, 2 and 4% doses on zinc availability, speciation, bajra growth and chemical properties in Zn-deficient soil. The obtained results showed that Zn mobility in soil was 70.04% with application of FYZn-MBC 4% as compared with other treatments. The maximum uptake of Zn in shoot and root by bajra plant was observed by 74.02% and 53% with addition of FYZn-MBC 4% as compared with control soil, due to an increase of soil organic matter. The chlorophyll SPAD values in the bajra aerial surface was increased from 30.23 to 39.24 with application FYZn-MBC 4% than control. The exchangeable fraction of Zn was increased from 7.34 to 14.71% with application of FYZn-MBC 4%. The correlation matrix results indicated that CaCO3 was positively correlated with soil pH. Soil organic matter was highly significant correlated with chlorophyll. Overall, future studies must be carried out to examine the long-term impact of FYZn-MBC 4% on Zn phytoavailbility in Zn-deficient soil.

VARIABILITY OF FLUCTUATING ASYMMETRY OF BETULA PENDULA ROTH LEAVES DEPENDING ON GROWING CONDITIONS

In the work, the relationship (FA) of the leaves of the hanging birch Betula pendula Roth with atmospheric pollution, climatic indicators and soil characteristics was determined. We analyzed data obtained from 10 sites located in the main geographical directions from the city of Ukhta (Komi Republic, Russia). FA was based on 5 morphological parameters (n=100). In the soil, we determined the pH (water and salt extracts), the content of organic matter and mobile forms of metals. Information on air pollution and climate parameters was obtained from open sources. We established high FA of B. pendula at all sites (0.064-0.076). It was shown that this is not related to the geographical location of the birch growing area. There was no excess of standards of pollutants in the air and soil at the sites. Correlation analysis showed that FA increases in response to a decrease in the proportion of organic matter in the soil and an increase in soil acidity (r is -0.49 and -0.42, respectively). Also, the increase in FA is associated with the content of mobile forms of Pb, Mn, Cu (r is 0.6, 0.36, 0.35, respectively). We found no effect of the content of mobile Zn, Fe, Cd in the soil on the FA level of the leaves. Thus, it is shown that soil characteristics affect the asymmetry of the bioindicator plant, including within environmental regulations. This fact should be taken into account when interpreting the results of the assessment of the ecological state of the territories.

Natural metal contents and influence of salinization in deep Canadian Shield groundwater: Base level versus mineral deposit enrichment halos

Groundwater interacts with mineral deposits, making this secondary environment a medium of choice for geochemical exploration. With increasing depth, groundwater in Precambrian shields typically matures and increases in salinity through prolonged water–rock interactions and mixing with geologically old saline fluids. As the focus of mineral exploration is gradually shifting toward deeper targets, the influence of salinity on pathfinder background levels and anomalous thresholds must be considered. We compiled a deep background database (Deep Abitibi Groundwater database; DAGW) containing groundwater samples between depths of 0 m and 690 m from barren exploration boreholes in the Abitibi subprovince, Quebec, to evaluate the natural elemental levels at depth. The DAGW provides valuable knowledge of the base levels of a wide spectrum of elements and of the changes in these base levels along with the increasing salinity in bedrock aquifers of the deep Canadian Shield. This can serve to estimate background values during hydrogeochemical exploration campaigns. The regional Abitibi base level for Zn (median of 7.5 μg/L), a key pathfinder for VMS mineralization, is unaffected by the increasing salinity levels down to depths of 690 m. Hence, down to this depth, the Zn concentrations measured may be used directly for mineral exploration, and no further correction for the effects of salinization is necessary. We conducted a case study near an undisturbed VMS-type deposit (Daniel 25) and a Zn enrichment halo was observed. Within the halo, Zn concentrations increased with depth, indicating that Zn mobility was positively affected by the geochemical conditions of the deeper aquifer. Anomalous Zn thresholds representing the proximal (50–600 m from the mineralization) and direct contact (within 50 m of the mineralization) footprints of the Daniel 25 deposit were estimated at 50 μg/L and 380 μg/L, respectively. An anomalous threshold was also estimated for Co, a secondary pathfinder, at 0.5 μg/L. Unlike Zn, several other elements, which could be used to trace mineral deposits, are affected by salinization. As a final step, we applied a correction to the Daniel 25 data, based on elemental baseline trends observed in the DAGW. The aim was to remove the effects of salinity and enhance the statistical correlations caused by the presence of the mineralized body. This correction led to the emergence of new spatial correlations, notably with Na and Sr, that are coherent with the increasing hydrothermal alteration in proximity to the ore.

Mobility of Zn and Cu in Bentonites: Implications for Environmental Remediation.

The aim of this study was to evaluate the mobility of copper (Cu) and zinc (Zn) and their impact on the properties of bentonites and unfrozen water content. Limited research in this area necessitates further analysis to prevent the negative effects of metal interactions on bentonite effectiveness. Tests involved American (SWy-3, Stx-1b) and Slovak (BSvk) bentonite samples with Zn or Cu ion exchange. Sequential extraction was performed using the Community Bureau of Reference (BCR) method. Elemental content was analyzed via inductively coupled plasma optical emission spectrometry (ICP-OES). Unfrozen water content was measured using nuclear magnetic resonance (1H-NMR) and differential scanning calorimetry (DSC). Results showed a significant influence of the main cation (Zn or Cu) on ion mobility, with toxic metal concentrations increasing mobility and decreasing residual fractions. Mobile Zn fractions increased with larger particle diameters, lower clay content, and shorter interplanar spacing, while the opposite was observed for Cu. Zn likely accumulated in larger clay pores, while Cu was immobilized in the bentonite complex. The stability of Zn or Cu ions increased with higher clay content or specific surface area. Residual Zn or Cu fractions were highest in uncontaminated bentonites with higher unfrozen water content, suggesting the potential formation of concentrated solutions in sub-zero temperatures, posing a threat to the clay-water environment, especially in cold regions.

Integrating HYDRUS-2D and Bayesian Networks for simulating long-term sludge land application: Uncovering heavy metal mobility and pollution risk in the soil-groundwater environment

The release of sludge-derived heavy metals (HMs) to soil and their subsequent migration into groundwater poses a significant challenge for safe and low-carbon sludge land application. This study developed a predictive framework to simulate 60-year sludge land application, evaluating the risk of HMs pollution in the soil-groundwater environment and assessing the influence of soil and water properties. HYDRUS-2D simulations revealed that highly mobile Cu, Ni, and Zn penetrated a 10 m soil layer over a 60-year period, contributing to groundwater pollution. In contrast, Cr was easily sequestered within the topsoil layer after 5-years continuous operation. The non-equilibrium parameter α could serve as an indicator for assessing their potential risk. Furthermore, the limited soil adsorption sites for Pb (f = 0.02772) led to short-term (1-year) groundwater pollution at a 0.5 m-depth. Bayesian Networks model outcomes indicated that humic-like organics crucially influenced HMs transformation, enhancing the desorption of Cd, Cu, Ni, Pb, and Zn, while inhibiting the desorption for Cr. Additionally, electrical conductivity promoted the release of most HMs, in contrast to the Mn mineralogy in soil. This study bridges the gap between the macro-level HMs migration trends and the micro-level adsorption-desorption characteristics, providing guidance for the safe land application of sewage sludge. Environmental ImplicationThis study introduces a framework integrating HYDRUS-2D simulations with Bayesian Networks to assess the risks of groundwater pollution by heavy metals (HMs) over a 60-year sludge application. Sludge-derived Cu, Ni, and Zn are found to penetrate soil up to 10 m and exceed safety limits, with the non-equilibrium parameter α serving as an indicator for pollution risk. The importance of nutrients from sludge-amended soil for the transformation of HMs in the subsurface environment highlights the need for enhanced sludge management, specifically through more detailed regulation of nutrient composition. These findings contribute to developing precise strategies for the long-term sludge land application.

Temporal changes in the mobility of As, Pb, Zn, and Cu due to differences in biochar stability caused by lignin content

Understanding biochar aging is a critical factor in predicting its long-term effects when added to soil. This study explores the complex links between lignin content in biochar feedstock and biochar stability during accelerated aging, including its influence on heavy metal mobility in soil. In this study, nine types of biochar based on fir (F), pine (P), and oak (O) sawdust were produced at 400 °C, and lignin was extracted from them using ammonia after 0, 3, and 7 days (named as 0FB, 3FB, 7FB, 0PB, 3PB, 7PB, 0OB, 3OB, and 7OB). Subsequently, each biochar was subjected to 25 cycles of wet-dry (WD) and freeze–thaw (FT) aging. The aged low-lignin biochars (7FB, 7 PB, and 7OB) released more dissolved organic matter (DOM) and contained more oxygen-containing surface groups on their surfaces than the high-lignin biochars (0FB, 0PB, and 0OB). The low-lignin biochars with high DOM leaching released 37–85 % more anionic arsenic (As) from biochar-amended soil after 25 cycles of aging than the high-lignin biochars. The stabilities of lead (Pb), zinc (Zn), and copper (Cu) were increased due to strong binding to surface functional groups on the low-lignin biochar. The acid-soluble fractions of Pb, Zn, and Cu were converted to organic-bound fractions as biochar aging progressed, with the degree of transformation being inversely proportional to the lignin content of biochar. This research highlights the crucial role of lignin in shaping biochar stability, and reveals how biochar stability impacts soil heavy metals speciation, opening new avenues for effective biochar-based environmental solutions and the promotion of soil health.

Comparative Analysis of Laboratory-Made and Industrial-Made Sewage Sludge Ash: Implications for Effective Management Strategy Development.

In the pursuit of environmentally and economically sustainable sewage sludge ash (SSA) management methods, researchers often employ laboratory-made SSA (L-SSA) as a substitute for industrial-made SSA (I-SSA) produced in fluidized bed furnaces. To check whether L-SSA is a material that imitates I-SSA well, the fractionation of metals whose presence is a significant problem during SSA management was performed. In addition, the grain distribution, specific surface area, and textural properties of the tested materials were examined. Differences in total Pb and Hg content and mobility of Cu, Ni, Mn, and Zn were observed between I-SSA and L-SSA. Larger particle sizes of L-SSA compared to I-SSA were confirmed, while comparable textural properties and specific surface area of both types of materials were maintained. Based on the results, it was concluded that L-SSA is chemically different compared to I-SSA, and that L-SSA should not be used as a reference in research focused on the design of SSA management methods. Moreover, fractionation of metals was performed in disposed fluidized beds (FBs), which are diverted to non-hazardous waste landfills without prior analysis. It has been proven that studied metals are present in FBs as abundantly as in SSA, while Cu, Mn, and Ni may show higher mobility than in I-SSA.

Zinc Nutrition in Rice Based Cropping Systems: A Comprehensive Review

Rice-based cropping systems being the most practiced cropping system in India, it suffers zinc deficiency as majority of the Indian soils are deficient in the Zn micronutrient. Zn is considered the fourth most important yield limiting nutrient of Agricultural crops. Apart from plant nutrition Zn also plays crucial role in human nutrition. Zn plays a vital role in the physiological function of plants and it is associated with phytohormone activity, protein synthesis and carbohydrate metabolism. To understand better zinc nutrition and its associated benefits from optimum nutrition and ways to manage Zn in rice-based cropping systems, the present review critically examines nutrient mobilization and transformation of Zn in rice-based cropping systems of India.

Zinc Biofortification through Biofertilizers, Foliar and Soil Application in Maize (Zea mays L.)

Aims: Here is clearly aim of study is to achieve the maximum grain yield and for improve the economic conditions of farmers. Study Design: The experiment was conducted in a split-plot design. Place and duration of study: The field experiment was conducted to study the effect of biofertilizers, foliar and soil application of zinc fertilizers in maize (Zea mays L.) at the research farm of the Khalsa College, Amritsar, Punjab (India) (31o63' N latitude, 74o83' E longitude and 234 m above sea level) during rainy seasons of 2018 and 2019. Methodology: The four levels of biofertilizers and foliar application as main plot [recommended dose of fertilizer (RDF: 150 kg nitrogen: 27.3 kg phosphorus: 25 kg K ha-1), RDF + Zn solubilizing bacteria (ZnSB), RDF + ZnSB + vesicular-arbuscular mycorrhiza (VAM) + 0.5% foliar ZnSO4.7H2O) at silking and early milk stage] and four subplot treatment of soil application of ZnSO4.7H2O @ 12, 25 and 50 kg/ha at the time of sowing along with no soil Zn control were evaluated in three replications. Results: Foliar application of zinc in addition to biofertilizers (ZnSB + VAM) produced significantly higher growth, yield and quality over control treatment. Soil application of zinc sulphate (50 kg ha-1) significantly improved growth, grain yield and Zn harvest index, Zn mobilization efficiency index and recovery efficiency over no Zn control treatment. The grain zinc content, zinc uptake and zinc use efficiencies were significantly maximum with the application of VAM + ZnSB along with 0.5% zinc sulphate foliar at silking and early milk stage than ZnSB, VAM and control treatment. Conclusion: Zn application of soil and foliar improved the growth, yield and quality parameters of maize.

Effect of biochar, zeolite and bentonite on physiological and biochemical parameters and lead and zinc uptake by maize (Zea mays L.) plants grown in contaminated soil

Heavy metals (HMs) are common contaminants with major concern of severe environmental and health problems. This study evaluated the effects of organo-mineral amendments (mesquite biochar (MB), zeolite (ZL) and bentonite (BN) alone and in combination) applied at different rates to promote the maize (Zea mays L.) growth by providing essential nutrient and improving the soil physio-chemical properties under zinc (Zn) and lead (Pb) contamination. Result revealed that the incorporation of organo-mineral amendments had significantly alleviated Pb and Zn contamination by maize plants and improved the physiological and biochemical attributes of plants. Combined application of organo-mineral amendments including BMA-1, BMA-2 and BMA-3 performed excellently in terms of reducing Pb and Zn concentrations in both leaves (19–60%, 43–75%, respectively) and roots (24–59%, 42–68%, respectively) of maize. The amendments decreased the extractable, reducible, oxidisable and residual fractions of metals in soil and significantly reduced the soil DTPA-extractable Pb and Zn. BMA-1 substantially improved antioxidant enzyme activities in metal-stressed plants. This study indicated that combined use of organo-mineral amendments can effectively reduce the bioavailability and mobility of Pb and Zn in co-contaminated soils. Combined application of organo-mineral amendments could be viable remediation technology for immobilization and metal uptake by plants in polluted soils.

Flooding by sea and brackish waters enhances mobility of Cd, Zn and Pb from airborne dusts in coastal soils

Sea level rise and extreme weather conditions caused by climatic changes enhance the frequency and length of submersion events in coastal soils, causing deposited airborne dusts to get in contact with marine salts.The behaviour of Cd, Zn and Pb from pedogenetic minerals and from dusts from mining and smelting activities, added to two soils under different agricultural management (arable and grassland) was examined after soil flooding for 1, 7 and 30 days with waters of increasing salinities (0, 4.37, 8.75, 17.25 and 34.5 g L−1). A rain water event following 1 d flooding released an extra amount of metals. Concentration of potentially toxic elements (PTE), pH, dissolved inorganic and organic C were measured in solutions collected by gravity from soil columns. Speciation distribution of leached metals and oversaturation parameters were calculated by Visual Minteq 3.0 and showed that complexation by chloride ions for Cd and fulvic acids for Pb were the drivers of solubilisation, while Zn interacted with both.Results showed that marine salts enhance up to 300 times leaching of Cd, and several times that of Zn and Pb from contaminated soils and that airborne toxic elements are much more mobilized than pedogenic ones. Smelter exhaust metals, particularly Pb, were made more mobile than those in mine tailings (up to 55 against 0.7 ng μg-1 Pb). Soil management strongly also influence mobilization by saline water: much lower amounts were leached from the grassland soil. Soil organic matter quality (DOC and humification) affects the extent of mobilization. The length of the flooding period did not result in coherent time trend patterns for the three metals, probably because of the multiple changes in solution parameters, but leached metals were always highly linearly correlated negatively with pH and positively with DOC.