Cu Concentrations In Soils Research Articles

Toxic elements and energy accumulation in topsoil and plants of spruce ecosystems

The objective of this research was to evaluate trends and relationships of energy and toxic elements accumulation in A-horizon (the depth of 0–5 cm) of soils and in selected plants of the hemioligotrophic (Dystric Cambisols) and oligotrophic (Skeletic-Rustic Podzols) spruce ecosystems situated along transect (750–1110 m a.s.l.) in the NP Slovenský raj (Eastern Slovakia). The results showed that EU limit values of risk elements in agricultural soils were exceeded for Cu and Cd at the altitude of 750–760 m a.s.l., and in case of Cd also above 1000 m a.s.l. Relationship between energy and toxic elements in soils revealed that with an increasing amount of energy, contents of Zn and Cu significantly declined with altitude (r > –0.5 or r > –0.9). The background value of Cu was exceeded in all plants, that of Zn for Dryopteris filix-mas and Rubus idaeus. Furthermore, excessive accumulation of Cd was revealed by all plants. Cu contents in soils were dominant in determining Cu uptake for Vaccinium myrtillus (r > 0.5); Zn and Cd for V. myrtillus (r > 0.6), D. filix-mas (r > 0.5 or r > 0.8) and Fagus sylvatica (r > –0.8 or r > –0.5); Zn also for R. idaeus species (r > 0.4). The soil-plant transfer coefficients higher than 1 hinted R. idaeus on the plots at the altitude of 960 m a.s.l. (Cd 1.1, Cu 1.2, Zn 3.1), which appears as an excellent native indicator of forest ecosystem contamination.

Modeling Zinc and Copper Movement in an Oxisol under Long‐Term Pig Slurry Amendments

Core Ideas Eleven years of Zn and Cu movement in an Oxisol amended with pig slurry (PS) was modeled. Root growth and water uptake effects were successfully added in HYDRUS simulations. Concentration profiles of Zn were described better than those of Cu. DOC‐facilitated Cu transport needs to be considered when modeling Cu transport in soils. Zn concentrations will not be a problem during the next 50 yr in PS‐amended soils. Increases in Zn and Cu concentrations in soils amended with pig slurry (PS) can be described using numerical models. Our main objective was to validate that the HYDRUS‐1D model is able to numerically describe profile concentrations and long‐term vertical transport of Zn and Cu in a clay soil (Oxisol) cultivated under annual cropping in a no‐till system and contaminated by successive doses of PS amendments. We first used a modeling approach that had previously been validated for an Alfisol. Then, we additionally also evaluated the effects of root growth and root water uptake on the transport of trace metals (TMs). Finally, we carried out 50‐yr‐long prospective simulations for different doses of PS amendments. Consideration of root growth and root water uptake processes in HYDRUS‐1D simulations improved the description of measured field Zn concentrations. Although the correspondence between simulated and measured Cu concentrations was not as good as for Zn, we performed prospective simulations for both elements. Future scenarios that considered large PS doses showed large increases in concentrations of both TMs in the soil surface layer. The feasibility of using PS amendments on agricultural Oxisols will be limited by Cu because the soil Cu threshold concentration is exceeded in approximately 29 yr. Moreover, the total loads of both TMs allowed on agricultural soils are reached very fast when large rates are used, especially for Cu (19 yr), indicating that the long‐term disposal of PS on agricultural soils should be done at low doses. These conclusions are probably conservative because our model did not consider potential leaching of TMs from the surface soil into deeper soil layers by dissolved organic C facilitated transport.

Improvement of copper stress tolerance in pepper plants (Capsicum annuum L.) by inoculation with arbuscular mycorrhizal fungi

The effect of arbuscular mycorrhizal fungi (AMF) inoculation, on pepper plant growth and physiological parameters in response to increasing soil Cu concentrations was studied. Treatments consisted of inoculation or not with Funneliformis mosseae or Rhizophagus intraradices and the addition of Cu to soil at concentrations of 0, 2, 4 and 8 mM CuSO4. The increase in copper concentration diminished the inoculation in all treatments. The highest experimental concentration of Cu (8 mM) reduced significantly the hyphae viability and ALP activity, regardless of the inocula used. The total dry weight and the leaf area were higher for mycorrhizal plants. The mycorrhizal dependence was 30 and 50% for plants inoculated with F. mosseae and R. intraradices, respectively at 8 mM CuSO4. The electrolyte leakage was higher at higher Cu concentrations, in roots and leaves. Net photosynthetic rates and transpiration were lower in plants treated with Cu, regardless of the inocula. At low Cu concentration in soil no differences were observed in Cu content in the shoots and roots. At 4 mM Cu, Cu content in roots was significantly higher than in shoots. At 8 mM Cu, in non-inoculated plants accumulate more Cu than inoculated plants in the roots, leaves and fruits regardless of the inocula. Beneficial microbial inoculants such as AMF, is an attractive strategy to farmers in the context of sustainable agriculture. Pre-inoculation in transplants could be an adequate practice to alleviate the deleterious effects in stress of pepper plants. However different AMF species can differ in their ability to minimize stress effects and promote plant growth.

Copper and zinc forms in soil fertilized with pig slurry in the bean crop

ABSTRACT The application of pig slurry may have different influence on copper (Cu) and zinc (Zn) dynamics in the soil compared with mineral fertilization. The aim of this research was to determine the different forms of Cu and Zn in soil and their uptake by bean plants in response to the application of mineral fertilizer and pig slurry (PS). The treatments were: mineral fertilizer (Cu and Zn oxides) and liquid pig slurry, at increasing rates (0/0, 1.7/6.0, 3.4/12.0 and 6.8/24.0 kg ha-1 Cu/Zn, respectively) applied in a Rhodic Kandiudox. PS increased the Cu content in soil in the exchangeable form, Fe oxides and residual, while the mineral fertilizer increased Cu contents in the fraction associated with soil organic matter. Soil Zn contents in the fractions available, exchangeable and SOM were highest under mineral fertilization, while in the soluble fraction the contents were highest under PS. The fertilizers had not impact on Cu and Zn contents associated with Al oxides, and these elements were mostly associated with Fe oxides in the soil. PS promoted the highest biomass production in shoots and roots of the bean plants, reflecting in the highest accumulation of Cu and Zn.

Stress responses and specific metal exclusion on mine soils based on germination and growth studies by Australian golden wattle

We reported the Australian golden wattle as a copper stabilizer in abandoned copper mine soils earlier. Here we investigate to confirm this plant’s suitability to grow on metal contaminated mine soils based on stress indication. The seeds of Acacia pycnantha collected from mining area were germinated after heat and no heat treatment on two types of irrigation. The daily irrigated and heat treated seeds gave up to 85% germination on sandy soil. The A. pycnantha was grown under greenhouse condition in six different soils collected from abandoned copper mine at Kapunda in South Australia. Among the six soil samples, soil-1 with the highest copper concentration produced 2.05mmolg−1 tissue of proline. Proline expression was prominent in more saline soils (1, 5 and 6) having electrical conductivity (EC) 1184, 1364 and 1256μS, respectively. Chlorophyll a, b and carotenoid levels in plants showed a gradually decreasing trend in all the soils as experiment progressed. The plants grown on soil sample-1, containing 4083±103mgkg−1 of copper resulted in 18±2mgkg−1 accumulation in its leaf. The calcium accumulation was significant up to 11648±1209mgkg−1 in leaf. Although pore water samples showed higher Cu concentration in soils, an increased mobility of arsenic and lead was observed in all the soil samples. Our experiment points out the need for proper monitoring of revegetation processes to avoid revegetation and reclamation failure.

English

Ninety nine surface soils and the corresponding rice grain samples from Wenling County in 2011 were used for the spatiotemporal variability investigation and evaluation of Cd, Cu, Ni, Pb and Zn concentrations to compare with values found in 2006. All heavy metals pose potential pollution risks in soil, especially Cd and Cu. The trend of increasing Cd contamination in rice was obvious. There were large percentage increases in Cd and Cu concentrations in soil and Cd and Ni in some rice regions. The regions with increased soil Cd concentrations were located in the north of Wenling with presence of intensive private small E-waste recycling companies. Concentrations of Cu in soil increased mainly in the east. Increases in the concentrations of Cd and Ni were observed for rice in the southwest and significantly different. Redundancy analysis (RDA) was used to provide a survey of variations in soil metal concentrations and then interpreted by consideration of soil properties and socio-economical observations. It was concluded that Zn concentration was related to the rapid development of local industry. The socio-environmental factors explained 43.3% of the variations in metal concentrations in soil. This study demonstrates the situation and accumulating trend of heavy metal concentrations in a soil-rice system caused by intensive human activities in Wenling County. © 2016 Friends Science Publishers

HEAVY METALS (Cd, Pb, Zn, and Cu) UPTAKE BY SPRING BARLEY IN POLLUTED SOILS

<p>Accumulation of Cd, Pb, Zn, Cu (HM) by spring barley (Hordeum vulgare L.) from sod podzolic sandy loam and chernozem soils, impacted by heavy metals pollution in the soils, is studied in the article. The aim of study has been to determine spring barley bioaccumulation capacity impacted by the HM pollution with the high level of Cd, Pb, Zn, Cu concentration in soils. The HM concentration diapason caused biomass reduction – the scope of toxic tolerance was obtained. The range of contaminants concentration in soil, which caused the plant biomass reduction, from the beginning to plants death – the scope of toxic tolerance, is the index of a species reaction on selected xenobiotic. It shows: “threshold” concentration of a contaminant that caused a plant biomass inhibition; toxic process development and the correlation between contaminants concentration in soil and/or plant and the plants inhibition; the concentration that caused the plant death. Spring barley accumulation indexes of the studied metals were calculated. Relevant scopes of the plant-uptake index for each metal were calculated. Dynamics of the toxic process development of spring barley as impacted by the pollution in the break-down by studied metals were observed on two different soils. Toxic process dynamic evaluation gives the possibility to simulate concentration of the trace metal in plants, concentration of available forms of these elements in soils, and also contamination level (content of metals) that caused plants height and plant weight reduction by 10%, 50% and 90%.</p><p> </p><p>Celem pracy było określenie wpływu zanieczyszczenia gleb piaszczysto-gliniastych bielicowych i czarnoziemów przez matale ciężkie (Cd, Pb, Zn, Cu) na biakumulację tych pierwiastków w jęczmieniu jarym (Hordeum vulgare L.). Podwyższone stężenie metali ciężkich spowodowało spadek plonu biomasy (od 10 do 90%). Stwierdzono, że im wyższe stężenie pierwiastków w glebie tym reakcja negatywna roślin była większa, aż do zamierania roślin. Wyliczono wskaźniki akumulacji dla każdego z pierwiastków metali. Ocena dynamiki procesu zanieczyszczenia gleb przez metale ciężkie (na podstawie wskaźników akumulacji) daje możliwość stymulowania stężenia tych pierwiastków w glebie. </p>

Comparison on Copper (II) Desorption from Loess Soil with and without Biochars Derived from Flax and Rape Straws

It has been reported that biochar is capable of adsorbing and immobilizingheavy metals in soils due to its prominent properties, such as the porous structure,large and charged surface, and functional groups on surface. The desorption of Cu (II)(Cu) from loess soil was studied and compared using batch washing method, with andwithout biochars derived from flax and rape straws. The effects of contact time, initial pHvalue of solution, temperature, initial concentration of Cu in soil, and co-existing Ca2+ ondesorptions were investigated. The pseudo-second-order kinetic model could be usedto describe the desorbing process well. The leaching ability (η) of Cu from solid phaseincreased in overly acidic solutions. Increasing temperature improved desorption of Cufrom loess soil. When the initial concentration of Cu in soil increased, the η values ofCu decreased. Slight effect of Ca2+ on the η value of Cu was found. No significant immobilizationof Cu by biochars was found because loess soil is much capable of holdingCu, possibly due to high content of carbonates. The results could provide references forimmobilization remediation of loess soils contaminated with heavy metals using biocharsas amendment.

PREDICTING THE VARIABILITY OF COPPER AND ZINC IN LEAF AND SOIL OF OIL PALM PLANTED ON A 12 HA LAND USING GEOSPATIAL INFORMATION SYSTEM TECHNOLOGY

Oil palm (Elaeis guineensis) is an important economic tree crops in the tropic. However, more than 95 % of oil palms grown in Southeast Asia are on acid, low fertility and highly weathered soils. Optimum value of micronutrients in the soil was required to enhance the efficiency of use of macro-nutrients. Hence, to observe and predict the fertility status of the oil palm plantation area, a 12 hectare study site was used and a total of 60 geo-referenced soil and leaf samples were collected for determinations of pH and selected micronutrients of Cu and Zn content. The data were explored and mapped using geostatistic and Geographic Information System (GIS). The study area had acidic type of soil with pH ranged from 3.25-5.85. The analysis showed that almost 78% of the study area had high content of Cu in soil, while another 22% of area was low to moderate in Cu. However, Cu content in leaf were categorized as insufficient as 100% of the area was observed to have Cu less than 3 ppm. About 80% of the study area showed a low to moderate content of Zn in soil, while another 20% of area showed a high content of Zn. Zinc content in leaf ranged from optimum to high categories. However, this value did not reach the excess level of Zn (50 ppm). These results suggest that, this plantation area need a site specific management approach in order to increase its crop productivity in regards to nutrient management. As a preliminary recommendation, a zone management practice would be applied in future as it is beneficial in term of protecting the environment from excessive fertilizer.

Impacts of urbanization on the distribution of heavy metals in soils along the Huangpu River, the drinking water source for Shanghai

We investigated the horizontal and vertical distribution of heavy metals (Hg, Pb, Zn, Cu, Cd, As, Ni, and Cr) in soils in the water source protection zone for Shanghai to study the origins of these metals, their connections with urbanization, and their potential risk posed on the ecosystem. Determination of metal concentrations in 50 topsoil samples and nine soil profiles indicated that Hg, Pb, Zn, and Cu were present in significantly higher concentrations in topsoil than in deep soil layers. The spatial distributions of Hg, Pb, Zn, and Cu and contamination hotspots for these metals in the study area were similar to those near heavy industries and urban built-up areas. Emissions from automobiles resulted in increased soil concentrations of Cu, Pb, and Zn along roadsides, while high concentrations of Hg in the soil resulted from recent atmospheric deposition. Calculation of the potential ecological risk indicated that the integrative risk of these heavy metals in most areas was low, but a few sites surrounding high density of factories showed moderate risks.

Effect of simulated climate warming on the morphological and physiological traits of Elsholtzia haichowensis in copper contaminated soil

ABSTRACTThe aim of this study was to investigate the effects of temperature and Cu on the morphological and physiological traits of Elsholtzia haichowensis grown in soils amended with four Cu concentrations (0, 50, 500, and 1000 mg kg−1) under ambient temperature and slight warming. At the same Cu concentration, the height, shoot dry weight, total plant dry weight, and root morphological parameters such as length, surface area and tip number of E. haichowensis increased due to the slight warming. The net photosynthetic rate, stomatal conductance, transpiration, light use efficiency were also higher under the slight warming than under ambient temperature. The increased Cu concentrations, total Cu uptake, bioaccumulation factors and tolerance indexes of shoots and roots were also observed at the slight warming. The shoot dry weight, root dry weight, total plant dry weight and the bioaccumulation factors of shoots and roots at 50 mg Cu kg−1 were significantly higher than those at 500 and 1000 mg Cu kg−1 under the slight warming. Therefore, the climate warming may improve the ability of E. haichowensis to phytoremediate Cu-contaminated soil, and the ability improvement greatly depended on the Cu concentrations in soils.

Thresholds of arsenic toxicity to Eisenia fetida in field-collected agricultural soils exposed to copper mining activities in Chile

Several previous studies highlighted the importance of using field-collected soils—and not artificially-contaminated soils—for ecotoxicity tests. However, the use of field-collected soils presents several difficulties for interpretation of results, due to the presence of various contaminants and unavoidable differences in the physicochemical properties of the tested soils. The objective of this study was to estimate thresholds of metal toxicity in topsoils of 24 agricultural areas historically contaminated by mining activities in Chile. We performed standardized earthworm reproduction tests (OECD 222 and ISO 11268-2) with Eisenia fetida. Total soil concentrations of Cu, As, Zn, and Pb were in the ranges of 82–1295mgkg−1, 7–41mgkg−1, 86–345mgkg−1, and 25–97mgkg−1, respectively. In order to differentiate between the effects of different metals, we used regression analysis between soil metal concentrations and earthworm responses, as well as between metal concentrations in earthworm tissues and earthworm responses. Based on regression analysis, we concluded that As was a metal of prime concern for Eisenia fetida in soils affected by Cu mining activities, while Cu exhibited a secondary effect. In contrast, the effects of Zn and Pb were not significant. Soil electrical conductivity was another significant contributor to reproduction toxicity in the studied soils, forcing its integration in the interpretation of the results. By using soils with electrical conductivity ≤0.29dSm−1 (which corresponds to EC50 of salt toxicity to Eisenia fetida), it was possible to isolate the effect of soil salinity on earthworm reproduction. Despite the confounding effects of Cu, it was possible to determine EC10, EC25 and EC50 values for total soil As at 8mgkg−1, 14mgkg−1 and 22mgkg−1, respectively, for the response of the cocoon production. However, it was not possible to determine these threshold values for juvenile production. Likewise, we were able to determine EC10, EC25 and EC50 of earthworm tissue As of 38mgkg−1, 47mgkg−1, and 57mgkg−1, respectively, for the response of the cocoon production. Finally, we determined the no-observed effect concentration of tissue As in E. fetida of 24mgkg−1. Thus, earthworm reproduction test is applicable for assessment of metal toxicity in field-collected soils with low electrical conductivity, while it might have a limited applicability in soils with high electrical conductivity because the salinity-induced toxicity will hinder the interpretation of the results.

Uncertainty assessment of heavy metal soil contamination mapping using spatiotemporal sequential indicator simulation with multi-temporal sampling points.

Mapping the space-time distribution of heavy metals in soils plays a key role in contaminated site classification under conditions of in situ uncertainty, whereas uncertainty assessment is based on the quantification of the specific uncertainties in terms of exceedance probabilities. Geostatistical space-time kriging (STK) is increasingly used to estimate pollutant concentrations in soils. Sequential indicator simulation (SIS) technique is popular in uncertainty assessment of heavy metal contamination of soils. However, these techniques cannot handle multi-temporal data. In this work, spatiotemporal sequential indicator simulation (STSIS) based on an additive space-time semivariogram model (STSIS_A) and on a non-separable space-time semivariogram model (STSIS_NS) was used to assimilate multi-temporal data in the mapping and uncertainty assessment of heavy metal distributions in contaminated soils. Cu concentrations in soils sampled during the period 2010-2014 in the Qingshan district (Wuhan City, Hubei Province, China) were used as the experimental data set. Based on a number of STSIS realizations, we assessed different kinds of mapping uncertainty, including single-location uncertainty during 1 year and during multiple years, multi-location uncertainty during 1 year, and during multiple years. The comparison of the STSIS technique vs. SIS and STK techniques showed that STSIS performs better than both STK and SIS.

Toxicity and bioaccumulation of Cu in an accumulator crop (Lactuca sativa L.) in different Australian agricultural soils

The toxicity and bioaccumulation of Cu in lettuce (Lactuca sativa L. var. Romaine cv. Long Green) grown in different Australian agricultural soils is assessed in this paper. We evaluate the effect of Cu and its interaction with soil properties on biomass production, through the establishment of the effective concentrations of Cu in soil that reduces biomass production by 50% (EC50) and 10% (EC10), and its accumulation in the different parts of the plant. Two biomass assays were conducted in three types of Australian agricultural soils contaminated with different Cu concentrations (no added Cu, 65.9, 659.0, 1977.0, 3295.0 and 6590.0mgCu/kg). Results show that the levels of Cu tested significantly affected plant biomass production in all the soils assayed. No biomass was produced after the second dose (65.9mg/kg) for Soil 1 (a Chromic Luvisol), after the third dose (659mg/kg) for Soil 2 (an Eutric Planosol) and after the fourth dose (1977mg/kg) for Soil 3 (a Pellic Vertisol). Toxicity was greater in soils with low pH and with smaller clay contents. The concentration of Cu in the lettuce leaves never exceeded 10mgCu/kg fresh weight, which is the maximum Cu concentration allowed in the edible part of this crop by Australian legislation. According to the results obtained, lettuce could grow in Cu contaminated Australian agricultural soil having a Cu concentration between those that correspond to their EC50 and the EC10. The specific concentrations lay between 103.96 and 728.88mgCu/kg, and between 49.03 and 443.10mg/kg, respectively, although they are dependent on soil type. At these concentrations, potential yield production would be acceptable and the quality of crops, in terms of Cu concentration in the edible part of the plant, would not be compromised. The results achieved broaden the knowledge on the effect of high Cu concentrations in Australian agricultural soils, which can help when proposing adequate soil quality standards and management strategies in this type of soils.

Thresholds of copper phytotoxicity in field-collected agricultural soils exposed to copper mining activities in Chile

It has been argued that the identification of the phytotoxic metal thresholds in soil should be based on field-collected soil rather than on artificially-contaminated soils. However, the use of field-collected soils presents several difficulties for interpretation because of mixed contamination and unavoidable covariance of metal contamination with other soil properties that affect plant growth. The objective of this study was to estimate thresholds of copper phytotoxicity in topsoils of 27 agricultural areas historically contaminated by mining activities in Chile. We performed emergence and early growth (21 days) tests (OECD 208 and ISO 11269-2) with perennial ryegrass (Lolium perenne L.). The total Cu content in soils was the best predictor of plant growth and shoot Cu concentrations, while soluble Cu and pCu2+ did not well correlate with these biological responses. The effects of Pb, Zn, and As on plant responses were not significant, suggesting that Cu is a metal of prime concern for plant growth in soils exposed to copper mining activities in Chile. The effects of soil nutrient availability and shoot nutrient concentrations on ryegrass response were not significant. It was possible to determine EC10, EC25 and EC50 of total Cu in the soil of 327mgkg−1, 735mgkg−1 and 1144mgkg−1, respectively, using the shoot length as a response variable. However, the derived 95% confidence intervals for EC10, EC25 and EC50 values of total soil Cu were wide, and thus not allowing a robust assessment of metal toxicity for agricultural crops, based on total soil Cu concentrations. Thus, plant tests might need to be performed for metal toxicity assessment. This study suggests shoot length of ryegrass as a robust response variable for metal toxicity assessment in contaminated soils with different nutrient availability.

Impact of meteorological and environmental factors on the spatial distribution of Fasciola hepatica in beef cattle herds in Sweden.

BackgroundFasciola hepatica is a parasite with a significant impact on ruminant livestock production. Previous studies in north-west Europe have described its geographical distribution and determined potential predictors of fasciolosis using geographical information system (GIS) and regression modelling. In Sweden, however, information about the distribution of fasciolosis is limited. This study examined the geographical distribution of F. hepatica and identified high-risk areas for beef cattle in Sweden and sought to characterise potential predictors. Beef cattle serum samples were collected during winter 2006-2007 from 2135 herds which were examined for F. hepatica antibodies by enzyme-linked immunosorbent assay (ELISA). Fasciolosis distribution maps were created using GIS based on postcode location of seropositive herds. Spatial scan analysis (SaTScan) was performed to determine high-risk areas. Using datasets on animal density, temperature, precipitation and Corine land cover data, including soil type and soil mineral concentrations in Sweden, bivariate and multiple logistic regression analyses were carried out in R software to reveal potential predictors of F. hepatica infection.ResultsOverall herd seroprevalence of F. hepatica in beef cattle was 9.8 % (95 % CI: 8.6-11.1). An irregular spatial distribution of F. hepatica, with two main clusters, was observed in south-west Sweden. The most northerly occurrence of F. hepatica in the world was documented. The final model explained 15.8 % of the variation in F. hepatica distribution in study herds. Absence of coniferous forest was the variable with the highest predictive value. Precipitation in July-September, Dystric Cambisol, Dystric Regosol, and P and Cu concentrations in soil were other negative predictors. Beef cattle herd density, Dystric Leptosol and Fe concentration were positive predictors.ConclusionsThe spatial distribution of F. hepatica in Swedish beef cattle herds is influenced by multi-factorial effects. Interestingly, absence of coniferous forest, herd density, specific soil type and concentration of some soil minerals are more important predictors than climate factors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0447-0) contains supplementary material, which is available to authorized users.

Trace metal/metalloid concentrations in waste rock, soils and spontaneous plants in the surroundings of an abandoned mine in semi-arid NE-Brazil

This study aims to determine the concentrations of trace metals/metalloid in waste rock, soils and plants in three different environments of an abandoned mine in Brazil. Waste rocks (X-ray fluorescence, X-ray diffractometry and SEM–EDS), soils (general characterization and potentially bioavailable nutrients and metals) and plants (total metal contents in shoots) were analyzed. Studied plant species included Bidens pilosa, Pityrogramma calomelanos, Ruellia paniculata, Combretum leprosum, Ziziphus joazeiro, Psidium guajava and Mangifera indica. The results showed that copper is the unique potentially toxic element in waste rocks, with concentrations up to 350,000 mg kg−1 in some rocks. The higher proportion of carbonates relative to sulphides naturally attenuates acidification due to sulphide oxidation, preventing acid drainage and soil acidification. Total Cu concentration in soils exceeded the reference values for soil quality in Brazil by 185, 78 and 18 times in the ore processing, waste rock and border areas, respectively, indicating a high contamination of soils even after 25 years of mine abandonment. Bioavailable Cu was positively correlated with inorganic carbon and phosphorus and negatively correlated with organic carbon in soils. Despite high Cu concentration in soils, the Cu levels in plant shoots were within the usual range, except for Bidens pilosa and Pityrogramma calomelanos, which showed 267 and 46 mg kg−1, respectively. Nevertheless, these concentrations are below the levels required to be considered hyperaccumulator species. This indicates that the ability to immobilize Cu in the roots/rhizosphere should be further studied due to its potential to remediate by immobilization and/or revegetate Cu-contaminated soils.

Copper accumulation and changes in soil physical–chemical properties promoted by native plants in ​​an abandoned mine site in northeastern Brazil: Implications for restoration of mine sites

In this study, the copper-accumulating capacity of plants growing spontaneously in copper-contaminated soils in an ​​abandoned mine site in northeastern Brazil was evaluated by calculating enrichment (EF) and translocation (TF) factors. The effects of physical and chemical changes in the rhizosphere soil on copper mobility were determined by using different compounds (Mehlich3/MgCl2) to extract Cu from different types of soil samples (bulk/rhizosphere soil). Finally, the possible implications for the use of these plant species in restoring the area were assessed by calculating the balance between the Cu mobilized in the rhizosphere and the Cu absorbed by the plants. On the basis of the EF and TF values obtained (all <1), none of the species under study (Ruellia paniculata, Bidens pilosa, Pityrogramma calomelanos and Combretum leprosum) were classified as hyperaccumulators. However, consideration of readily bioavailable levels (extracted with MgCl2) and the rhizosphere soils (rather than total levels and bulk soils) yielded higher correlations with the levels of metal in plant tissues. This approach therefore appears more appropriate for determining the capacity of the plants to accumulate copper. The different characteristics of the bulk and rhizosphere soils have direct effects on the concentrations of copper, which were much lower in the rhizosphere soil. In general, each species responded differently to the high concentration of Cu in soils (range 3604–9601mgkg−1). By calculating the balance between the amounts of Cu mobilized in the rhizosphere and uptake by plants, we found that the presence of such plants in the field may have antagonistic effects. Two of the species (B. pilosa and P. calomelanos) contained more Cu in their tissues than mobilized in the rhizosphere. This is a desirable characteristic for restoration purposes, as the plants can reduce the bioavailable Cu content in soils and thus act as facilitators for regeneration of the site. By contrast, the other two species (R. paniculata and C. leprosum) mobilized more Cu in the rhizosphere than they were able to take up, which may led to transfer of bioavailable Cu to the ecosystem, which is undesirable in terms of site restoration.

The effects of soil metals on the composition of oil of Paeonia ostii seeds

Peony seed oil has been known to have a high value for health due to the high content of unsaturated fatty acid. However, few studies have investigated which factors impact the oil quality and composition of seeds in the traditional mining cultivation area. In the present study, the investigation was conducted in 30 cultural field sites. Significantly negative relationships were found between Cu content in soils or leaves and linoleic and unsaturated fatty acids. Further tests revealed that Cu evidently accumulated in leaves. This demonstrated Cu content in soils was the important factor that influenced linoleic acid content and unsaturated fatty acid content. Such proposition must be considered when cultivating groups of plant toward expanding oil production.

Productivity and quality enhancement of rice through micronutrients and soil amendments in acid soils of north-eastern hill region of India

A field experiment was conducted on sandy loam soil at Lamphelpat, Manipur during kharif seasons of 2013 and 2014 to assess the effect of soil amendments and micronutrients fortification on productivity and quality of rice. The experiment was laid outin split plot design with foursoil amendmenttreatments in the main plots and fourmicronutrients fortification treatments in the sub-plots. The results showed that application FYM 5.0 t/ha, lime 200 and 400 kg/ha improved growth attributes and increased yield components of rice over those of the control plots. Use of lime 400 kg/ha recorded highest rice grain (7.16 t/ha) and straw (8.95 t/ha) yields as compared to the other soil amendment practices. It also recorded higher N, P, K, Zn, Fe and Se contents in rice grain, greater returns and higher crop profitability (Rs. 1240/ha/day) than those of control plots, but comparable to the other soil amendment practices. Soil amendments (5 t/ha FYM, 200 and 400 kg/ha lime) significantly increased the available N, P, K, Fe, Zn, Mn and Cu content in soil over those of the control plots. Micronutrient fortification also improved growth, increased productivity and nutrient contents in rice grain and enhanced gross and net returns, returns per rupee invested and crop profitability.