Availability Of Cu Research Articles

Hydroxyapatite self-doped biochar with MgO modification immobilizes heavy metal and alters soil microbial community

Functionalized biochars are highly effective in the remediation of heavy metals and the improvement of soil properties. In this study, we prepared a hydroxyapatite self-doped biochar (FB) using fish scales as raw material, and impreged FB with MgCl2 following by pyrolysis to obtain MgO-loaded FB (MFB). A soil incubation experiment was conducted to explore the influence of MFB on the immobilization of Cu, Cd, and Pb, alongside the impact on the soil properties and bacterial community. The results demonstrated that the nano-hydroxyapatite components and MgO micro-nanoparticles on MFB promoted the immobilization of heavy metals in soils through dissolution-precipitation and ion-exchange. The availability of Cu, Cd, and Pb in soils amended with MFB was significantly decreased by 69.1 %, 63.5 %, and 53.7 %, respectively, compared to CK. Furthermore, the MFB amendment significantly increased soil organic carbon and available P, as well as enhanced enzyme activities related to the C-, N-, and P-cycles. Notably, the MgO loaded on biochar played a crucial role in altering the diversity and composition of soil bacterial communities. The complexity and stability of the co-occurrence networks of bacterial communities increased following MgO-loaded biochar addition, and there were more frequent positive interactions among bacterial taxa within the network. The effects of MFB on immobilizing heavy metals and shaping bacterial communities were conducive to the restoration of soil ecological functions. These findings provide a promising strategy for the remediation of heavy metal contaminated soils.

Cationic micronutrient fractions in some tropical Alfisols and Inceptisols as affected by organic amendments and simulated moisture regimes: an incubation study

Cultivation of rice is severely jeopardized by the intangible behavior of micronutrients under variable moisture and organics leading to its inconsistent availability. The present study has been conducted to determine the effect of organic amendments and moisture regimes on cationic micronutrients like zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). Controlled situation incubation study using thrice replicated factorial randomized design with (3 organic amendments × 2 moisture regimes × 2 incubation periods) levels was conducted. Continuous submergence (CS), 50 g kg−1 rice straw and 150 days of incubation (DOI) restored higher soluble and Exchangeable (SE) manganese and iron; while SE-Cu was facilitated under alternate wetting and drying (AWD) condition. SE-Zn was found higher under AWD, no organic administration and 60 DOI. Again AWD, 50 g kg−1 rice straw and 60 DOI recovered higher Mn, Cu, Fe and Zn in organically bound fractions. The adoption of CS, 50 g kg−1 rice straw and 150 DOI recovered higher Mn, Cu, Fe and Zn in manganese and amorphous iron oxide bound fractions; while AWD, no rice straw administration and 60 DOI recovered higher Mn, Cu, Fe and Zn in crystalline iron oxide bound fractions. Substantial change in all the studies fraction resulted into alteration in plant availability of Mn, Cu, Fe and Zn. Under the scenario of global increasing water demands, AWD apart from saving 30-40% moisture improves availability of Cu and Zn which is further accentuated by organic matter, sustaining soil productivity and ensuring food security.

Dietary phytase effects on copper requirements of broilers.

Information on the availability of Cu from plant feedstuffs for broilers in the presence of phytase is scarce. The present research has been conducted with the objective of evaluating the Cu requirements of broilers when fed corn-soy diets with or without phytase. A total of 640 one-day-old male Cobb x Cobb 500, allocated into 80 battery cages with 8 chicks in each, were fed a low Cu content diet (formulated with 8.58 ± 0.21 mg/kg Cu) without phytase from placement to day 7. Starting on day 8, battery cages were distributed into a 2 × 5 factorial arrangement (phytase-added diets X 5 with graded increases of supplemental Cu) until day 28. Feeding treatments (feeds added or not with phytase and 5 graded increases of Cu) were randomly distributed with 8 cages of 8 chicks. The basal non-supplemented feeds were formulated with corn and soybean meal (SBM) without any other significant Cu contributors. Supplemental Cu was from laboratory-grade Cu sulfate pentahydrate (CuSO5H20) which was increasingly added to the feeds. Phytase was added in excess to the producer recommendation (2,500 FYT) and had average analyzed values of 2,768 ± 135.2 FYT/kg whereas analyzed Cu values were: 8.05 ± 0.25, 11.25 ± 0.15, 14.20 ± 0.40, 16.55 ± 0.05, and 19.45 ± 0.45 mg/kg. Statistics were conducted using linear and quadratic polynomial regression models. No interactions occurred between dietary Cu and phytase (p > 0.05) for any response and no effects were found for the individual factors (phytase or dietary Cu) for Ht, Hb, varus, valgus, rotated tibia, and tibia breaking strength, as well as for Cu contents in breast, gastrocnemius tendon, and kidney (p > 0.05). However, the phytase-added diets led to higher BWG, lower FCR, and increased ileal digestible Cu (p < 0.05). The gradual increase in dietary Cu produced linear increases in Cu content in livers, as well as in excreta and retention (p < 0.05). Supplementing phytase at levels expected to maximize phytate degradation was demonstrated to improve BWG and FCR; however, no effects were observed when dietary Cu was increased to a maximum of 19.45 mg/kg. An increase of 8.8% in ileal digestible Cu was observed when birds were fed phytase.

Improved Stability of Copper Nanowires with Solution-Grown NiO Shells as Protective Coating

The fast degradation of copper in ambient conditions hinders the practical application of copper nanowires (Cu NWs) in flexible electronics. Here, we describe a simple yet effective solution method for growing NiO shells on the surface of Cu NWs, which enables the protection of the Cu NW network against oxidation without degrading the optical and electrical properties. The corresponding values (for example, before coating: 13.6 Ω/sq at 84.4%, after coating: 14.9 Ω/sq at 84.8%) show that the deposition of NiO shell enables the preservation of high transparency and conductivity of Cu. In contrast to the massive degradation of Cu NW networks including a significant reduction in conductivity in a range of harsh environments (strong oxidation, high temperature, heat and humidity conditions), the Cu NW@NiO networks can survive structurally and maintain conductivity. Finally, a flexible alternating current electroluminescent device employing the Cu NW@NiO networks as the transparent electrodes is realized to demonstrate the availability of Cu NW@NiO networks.

Environmental risks of organic fertilizer with increased heavy metals (Cu and Zn) to aquatic ecosystems adjacent to farmland in the northern biosphere of Japan

In Abashiri, Hokkaido, northern Japan, composted sewage sludge (CSS) containing a large amount of zinc (Zn) and copper (Cu) is used as fertilizer in agriculture. The local environmental risks of Cu and Zn from such organic fertilizers were studied. The study area, especially the brackish lakes located near the farmlands, is important for inland fisheries. The risks posed by heavy metals to the brackish-water bivalve, Corbicula japonica, was therefore investigated as an example. First, the long-term effect of CSS application in agricultural fields was monitored. Second, using pot cultivation, factors influencing Cu and Zn availability in the presence of organic fertilizers were evaluated under different scenarios of SOM content. In addition, the mobility and availability of Cu and Zn in organic fertilizers were evaluated in a field experiment. In the pot cultivation, both organic and chemical fertilizers increased the availability of Cu and Zn with a decrease in pH, possibly caused by nitrification. However, this decrease in pH was inhibited by higher SOM content, i.e. SOM mitigated the heavy metal risk from organic fertilizer. In the field experiment, potato (Solanum tuberosum L.) was cultivated using CSS and pig manure (PM). As observed in the pot cultivation, the applied chemical and organic fertilizers increased the soil-soluble and 0.1 N HCl-extractable Zn with increased nitrate. Considering the habitat and the LC50 values of C. japonica that were lower than the concentration of Cu and Zn in the soil solution phase, there is no significant risk from heavy metals in the organic fertilizers. However, the Kd values for Zn were significantly lower for CSS or the PM-applied plot in the field experiment soil, indicating a higher Zn desorption rate from organically fertilized soil particles. The potential risk of heavy metals from agricultural lands under changing climate conditions must therefore be monitored carefully.

Combined approach for assessing metal(loid)s leaching, mobility and accumulation in a specific near-neutral (pH) environment of a former Cu-smelting area in the Old Copper Basin, Poland

Topsoils, soil profiles, water, and stream sediments as well as slags and rocks were analyzed to assess the extent and severity of environmental pollution resulting from historical Cu mining and smelting in the vicinity of Leszczyna, Old Copper Basin, SW Poland. Numerous tailings, smelting wastes, and Cu-rich rocks were disposed in the study area, causing long-term leaching and accumulation of various metal(loid)s. Surrounding the anthropogenically impacted area, two types of geochemical background are distinguished, one of which is associated with rocks and soils that are naturally enriched in metal(loid)s and the second one is free of them. The presence of significant anthropogenic changes combined with natural enrichment creates a highly complex environmental situation with regard to different sources of metal(loid)s. Additionally, the ore-hosting carbonate rocks are responsible for specific near-neutral (pH) conditions. With a focus on numerous elements (Cu, Zn, Pb, Ni, As, Cd, Co, Ba, and Cr) we studied spatial and vertical metal(loid)s distributions in soils to determine elements fate under near-neutral conditions. We applied the Synthetic Precipitation Leaching Procedure (SPLP) to evaluate the leaching potential of geogenic and anthropogenic materials and the Acid Neutralization Potential (ANP) test to measure the impact of slags on the pH of local soils. The EDTA extraction indicated high (bio)availability of Cu, Cd, Pb, and Zn, and suggested that metals from Cu-rich rocks are substantially more mobile than these of metallurgical origin. Our data indicate significant metal(loid)s mobility from surface-deposited wastes, especially into soils and stream sediments. The study proves that in the near-neutral conditions wastes are mainly subjected to short-time, rainfall-associated leaching, which is responsible for mobilization of labile metal(loid)s fractions (especially Cu, Pb, Zn, and Cd).

Cover crop response to increased concentrations of copper in vineyard soils: Implications for copper phytoextraction

The use of cover crops (CCs) in viticulture is threatened by the contamination of vineyard soils by copper (Cu). This study investigated the response of CCs to increased concentrations of Cu in soil as a way to assess their sensitivity to Cu and their Cu phytoextraction ability. Our first experiment used microplots to compare the effect of increasing soil Cu content from 90 to 204 mg kg−1 on the growth, Cu accumulation level, and elemental profile of six CC species (Brassicaceae, Fabaceae and Poaceae) commonly sown in vineyard inter-row. The second experiment quantified the amount of Cu exported by a mixture of CCs in vineyards with contrasted soil characteristics. Experiment 1 showed that increasing the soil Cu content from 90 to 204 mg kg−1 was detrimental to the growth of Brassicaceae and faba bean. The elemental composition of plant tissues was specific to each CC and almost no change in composition resulted from the increase in soil Cu content. Crimson clover was the most promising CC for Cu phytoextraction as it produced the most aboveground biomass, and, along with faba bean, accumulated the highest concentration of Cu in its shoots. Experiment 2 showed that the amount of Cu extracted by CCs depended on the availability of Cu in the topsoil and CC growth in the vineyard, and ranged from 25 to 166 g per hectare. Taken together, these results emphasize the fact that the use of CCs in vineyards may be jeopardised by the contamination of soils by Cu, and that the amount of Cu exported by CCs is not sufficiently high to offset the amount of Cu supplied by Cu-based fungicides. Recommendations are provided for maximizing the environmental benefits provided by CCs in Cu-contaminated vineyard soils.

Soil aggregate structure, stability, and stoichiometric characteristics in a smelter-impacted soil under phytoremediation

Smelter-impacted soils often result in soil degradation and the destruction of the soil structure. Although soil aggregate typically plays a crucial role in soil structure, the influence of phytoremediation on soil aggregate structure stability and stoichiometric characteristics remains unclear. To study the influence of phytoremediation on soil aggregate structure, stability and stoichiometric characteristics, a 3-year in situ experiment was conducted. After hydroxyapatite was applied, Elsholtzia splendens, Sedum plumbizincicola, and Pennisetum sp. were planted in a smelter-impacted soil. After 3 years, the soil aggregate structure, stability, and stoichiometric of chemical elements were analyzed. The results showed that the three phytoremediation treatments increased the content of &amp;gt;0.25 mm mechanically-stable (DR0.25) and water-stable (WR0.25) aggregates by 6.6%–10.4% and 13.3%–17.5%, respectively. Aggregate mean weight diameter (MWD), geometric mean diameter, and aggregate stability rate (AR, %) were significantly increased, and the soil mechanically stable aggregate fractal dimension (D) was significantly reduced after the 3-year remediation. Soil total nitrogen and phosphorus in aggregates with different particle sizes were significantly increased by 11.4%–46.4% and 107%–236% after different plant treatments. For the stoichiometric characteristics of the aggregates, the combined remediation only significantly reduced the value of N:P and C:P in different particle size aggregates and had no significant effect on the C:N in all particle size aggregates. Meanwhile, the combined remediation of hydroxyapatite and Elsholtzia splendens, Sedum plumbizincicola, and Pennisetum sp. in heavy metal heavily contaminated soil could reduce the availability of Cu and Cd by 54.1%–72.3% and 20.3%–47.2% during the 3 years, respectively. In summary, this combined remediation method can be used for the remediation of farmland that is contaminated by heavy metals.

COS-OGA Applications in Organic Vineyard Manage Major Airborne Diseases and Maintain Postharvest Quality of Wine Grapes.

In most wine-growing countries of the world the interest for organic viticulture and eco-friendly grape production processes increased significantly in the last decade. Organic viticulture is currently dependent on the availability of Cu and S compounds, but their massive use over time has led to negative effects on environment health. Consequently, the purpose of this study was to evaluate the effectiveness of alternative and sustainable treatments against powdery mildew, gray mold and sour rot under the field conditions on Nero d’Avola and Inzolia Sicilian cultivars. In detail, the efficacy of COS-OGA, composed by a complex of oligochitosans and oligopectates, and its effects in combination with arbuscular mycorrhizal fungi (AMF) were evaluated to reduce airborne disease infections of grape. COS-OGA combined with AMF induced a significant reduction in powdery mildew severity both on Nero d’Avola and Inzolia with a mean percentage decrease of about 15% and 33%, respectively. Moreover, COS-OGA alone and combined with AMF gave a good protection against gray mold and sour rot with results similar to the Cu–S complex (performance in disease reduction ranging from 65 to 100%) on tested cultivars. Similarly, the COS-OGA and AMF integration provided good performances in enhancing average yield and did not negatively impact quality and microbial communities of wine grape. Overall, COS-OGA alone and in combination could be proposed as a valid and safer option for the sustainable management of the main grapevine pathogens in organic agroecosystems.

Remediation of Cu and As contaminated water and soil utilizing biochar supported layered double hydroxide: Mechanisms and soil environment altering

Preparing materials for simultaneous remediation of anionic and cationic heavy metals contamination has always been the focus of research. Herein a biochar supported FeMnMg layered double hydroxide (LDH) composites (LB) for simultaneous remediation of copper and arsenic contamination in water and soil has been assembled by a facile co-precipitation approach. Both adsorption isotherm and kinetics studies of heavy metals removal by LB were applied to look into the adsorption performance of adsorbents in water. Moreover, the adsorption mechanisms of Cu and As by LB were investigated, showing that Cu in aqueous solution was removed by the isomorphic substitution, precipitation and electrostatic adsorption while As was removed by complexation. In addition, the availability of Cu and As in the soil incubation experiments was reduced by 35.54%–63.00% and 8.39%–29.04%, respectively by using LB. Meanwhile, the addition of LB increased the activities of urease and sucrase by 93.78%–374.35% and 84.35%–520.04%, respectively, of which 1% of the dosage was the best. A phenomenon was found that the richness and structure of microbial community became vigorous within 1% dosage of LB, which indirectly enhanced the passivation and stabilization of heavy metals. These results indicated that the soil environment was significantly improved by LB. This research demonstrates that LB would be an imaginably forceful material for the remediation of anionic and cationic heavy metals in contaminated water and soil.

Properties of Modified Nano Black Carbon and Its Effects on Soil Enzyme Activities

Black Carbon (BC) is a solid material obtainable from the remnants of incomplete burning of biological organisms or fossil fuels, which benefits pollution alleviation and soil amendment. In this study MBC was prepared using acidic potassium permanganate for inactivating heavy metal in soils. The specific surface area and pore volume of BC and MBC were measured by nitrogen adsorption and the space around the black carbon particles was observed by Scanning Electron Microscopy (SEM). The contents of carboxyl, ester and phenol hydroxyl group on their surface have been determined. The effect on availability of Cu in soils and soil enzyme activity of MBC was also investigated. Scanning electron microscopy analysis of MBC demonstrated large micropores with looser aggregate structure. MBC featured a higher surface area (956.88m2·g-1), larger average pore size and pore volume than BC, which can improve its excellent adsorption ability. Using as a soil heavy metal passivator, MBC reduced the available content of copper in three soils significantly and MBC has the best passivation effect on copper in cinnamon soil. Comparison of the enzyme activities in three soils amended with MBC under constant moisture conditions revealed that MBC increased the activities of catalase, urease in different degrees and inhibited the activities of dehydrogenase in three soils. These findings suggest that MBC has a strong passivation ability to Cu and would be applied to the remediation of copper contaminated soil.

Copper availability governs nitrous oxide accumulation in wetland soils and stream sediments

Denitrification is microbially-mediated through enzymes containing metal cofactors. Laboratory studies of pure cultures have highlighted that the availability of Cu, required for the multicopper enzyme nitrous oxide reductase, can limit N2O reduction. However, in natural aquatic systems, such as wetlands and hyporheic zones in stream beds, the role of Cu in controlling denitrification remains incompletely understood. In this study, we collected soils and sediments from three natural environments -- riparian wetlands, marsh wetlands, and a stream -- to investigate their nitrogen species transformation activity at background Cu levels and different supplemented Cu loadings. All of the systems contained solid-phase associated Cu below or around geological levels (40–280 nmol g−1) and exhibited low dissolved Cu (3–50 nM), which made them appropriate sites for evaluating the effect of limited Cu availability on denitrification. In laboratory incubation experiments, high concentrations of N2O accumulated in all microcosms lacking Cu amendment except for one stream sediment sample. With Cu added to provide dissolved concentrations at trace levels (10–300 nM), the reduction rate of N2O to N2 in the wetland soils and stream sediments was enhanced. A kinetic model could account for the trends in nitrogen species by combining the reactions for microbial reduction of NO3− to NO2−/N2O/N2 and abiotic reduction of NO2− to N2. The model revealed that the rate of N2O to N2 conversion increased significantly in the presence of Cu. For riparian wetland soils and stream sediments, the kinetic model also suggested that overall denitrification is driven by abiotic reduction of NO2− in the presence of inorganic electron donors. This study demonstrated that natural aquatic systems containing Cu at concentrations less than or equal to crustal abundances may display incomplete reduction of N2O to N2 that would cause N2O accumulation and release to the atmosphere.

Contrasting effects of siderophores pyoverdine and desferrioxamine B on the mobility of iron, aluminum, and copper in Cu-contaminated soils

Siderophores are biogenic metallophores that can play significant roles in the dynamics of a range of metals, including Cu, in the soil. Understanding the impact of siderophores on the mobility and the availability of metals in soil is required to optimize the efficiency of soil remediation processes such as phytoextraction. This study compared the ability of siderophores desferrioxamine B (DFOB) and pyoverdine (Pvd) to mobilize metals in a series of Cu-contaminated soils, and investigated the extent their metal mobilization efficiency changed over time and with the level of Cu contamination of the soil. Siderophores were supplied (or not) to Cu-contaminated soils and metal mobility was assessed through their total concentration in 0.005 M CaCl2 extract. DFOB selectively mobilized Fe and Al while Pvd also mobilized Cu and Ni, Co, V and As but to a lesser degree. The 1:1 relationship between DFOB in the CaCl2 extract and Fe + Al mobilized from the solid phase suggests that DFOB mobilized metals by ligand-controlled dissolution. The accumulation of Cu in soil enhanced the adsorption of DFOB and Pvd at the surface of soil constituents and the mobilization of Fe to the detriment of Al by the two siderophores. The metal mobilization efficiency of DFOB and to a lesser extent of Pvd decreased over 22 days. According to 15N-Pvd analyses, Pvd degradation at least partly contributed to the progressive reduction in the metal mobilization efficiency of Pvd. The processes behind these results and the relevance of these results for manipulating the availability of Cu (and Fe) in soil are discussed.

Antagonistic effect of copper and zinc in fertilization of spring wheat under low soil phosphorus conditions

Sound micronutrient management requires an understanding of nutrient interactions and transformation processes in soil–plant systems which can regulate bioavailability and plant uptake. A series of studies were conducted under controlled environment and field conditions to evaluate wheat response to Cu and Zn fertilization on P-deficient soils from western Canada. The grain and straw yields of wheat were reduced in two (Waskada and Tisdale) of three soils used in the controlled environment study, while yield was not affected at the Echo field site in 2016 when both Cu and Zn sulfate fertilizer were applied at 5 kg·ha–1 rates. Zinc concentration in soil and plant tissues was increased to apparent toxic levels with fertilizer addition in Waskada soils. An imbalance in tissue P:Zn concentration related to micronutrient fertilization was observed in Waskada and Tisdale soils. The availability of Cu and Zn in post-harvest soils was increased with increasing rate of these fertilizers' addition. Chemical and spectroscopic speciation using sequential extraction and X-ray absorption near edge structure, respectively, revealed that Cu and Zn were mostly speciated as carbonate phases, and complexation of these elements with carbonate and phyllosilicate minerals is likely the process controlling bioavailability in the soils.

Biochar produced from the straw of common crops simultaneously stabilizes soil organic matter and heavy metals

The simultaneous stabilization of heavy metals and organic matter in polluted soil has received little research attention. In this study, we studied the immobilization of Cu and Cd and the mineralization of organic matter in the acidic soil amended with biochar produced from rice, wheat, corn, and rape straws through incubation experiments. Compared with that in the control treatment, the availability of Cu and Cd in the biochar amended soils decreased by 17–31% and 3–17%, respectively. The cumulative amount of CO2 released from each treatment in 60 days of incubation followed the order: control treatment (399 mg CO2-C kg−1) > rape straw biochar treatment (388 mg CO2-C kg−1) > rice straw biochar treatment (374 mg CO2-C kg−1) > corn straw biochar treatment (355 mg CO2-C kg−1) > wheat straw biochar treatment (288 mg CO2-C kg−1). The information implied that biochar produced from the straw of common crops can simultaneously stabilize both heavy metals and organic matter in the acidic soil. The transformation of Cu and Cd from acid soluble fraction to residual fraction was the potential mechanism of biochar in facilitating soil heavy metal immobilization. The significant decrease in soil β-glucosidase activity, which controlled the degradation of soil organic matter, was an important potential pathway of biochar in decreasing soil organic matter mineralization. A significant decrease in the content and a substantial increase in the structural complexity of soil dissolved organic matter could further the decrease of wheat straw biochar in soil organic matter mineralization. Thus, biochar produced from the straw of common crops is a promising amendment for simultaneously stabilizing both heavy metals and organic matter in the acidic soil.

Silicon fertilizers, humic acid and their impact on physicochemical properties, availability and distribution of heavy metals in soil and soil aggregates

It has been confirmed that silicon (Si) fertilizer and humic acid (HA) could effectively decrease the heavy metals in soil. Nonetheless, the impact of these additives on soil aggregate characteristics was ignored. Therefore, the effects of Si fertilizer, HA, and their combinations on the physicochemical characteristics, availability of heavy metals (Cu, Cd, Pb, Zn), and fraction changes in soils and soil aggregates were investigated in this research. The results showed that Si fertilizer and HA significantly modified soil properties such as soil pH, electrical conductivity total organic carbon, water-soluble organic carbon, and nitrate‑nitrogen. HA and Si-HA (SHA) supplementation significantly decreased the availability of Cu, Cd, Pd, and Zn. Besides, there was no significant difference in physicochemical properties between soil and soil aggregates. The availability of Cu, Cd, Pd, and Zn in soil aggregates could be significantly inhibited by the addition of HA and SHA, and the content in microaggregates was greater than that in macroaggregates. After the addition of the three additives, the main fractions of heavy metals in different particle sizes were changed and eventually transformed to the residue state. These results indicated that Si fertilizer, HA, and SHA were influential in physicochemical properties and metal availability in soil aggregates. Therefore, it is of great scientific significance to study the impact of heavy metal pollution on the ecological environment in different aggregates, which will provide reference data for future sustainable management of heavy-metal polluted soils.

Fate of copper in soil: effect of agrochemical (nano)formulations and soil properties

Different Cu formulations and soil pre-incubation regime can significantly impact the short-term availability of Cu in soil.

Do DOM optical parameters improve the prediction of copper availability in vineyard soils?

Accumulation of copper (Cu) in soils due to the application of fungicides may be toxic for organisms and hence affect winegrowing sustainability. Soil parameters such as pH and dissolved organic matter (DOM) are known to affect the availability of Cu. In this study, we investigated the contribution of chromophoric and fluorescent DOM properties to the prediction of Cu availability in 18 organic vineyard soils in the Bordeaux winegrowing area (France). The DOM parameters, assessed through absorbance and fluorescence analyses, and proxies for Cu availability (total soluble Cu and free ionic Cu2+) were measured in 0.01 M KCl extracts. Total soluble Cu (CuKCl) varied 23-fold while free ionic Cu2+ varied by a factor of 4600 among the soils. DOC concentrations were similar among the soils, but the samples differed in the quality of DOM as assessed by optical spectroscopy. Multilinear regression models with and without DOM quality parameters were investigated to predict Cu availability. The best model for CuKCl successfully explained 83% of variance and included pH, CuT, and two DOM fluorescence quality indices, the FI fluorescence index, which distinguishes between microbial and higher plant origins, and the HIX humification index. For the prediction of Cu2+, pH alone explained 88% of variance and adding DOM parameters did not improve modelling. The two Cu availability proxies were related to pH. This study confirms the prominent role of pH in Cu availability and underlines the importance of DOM quality to better predict Cu solubility.

Characteristics of Modified Biochars and Their Immobilization Effect on Cu and Cd in Polluted Farmland Soil Around Smelter

Heavy metals in farmland soil are one of the most hazardous pollutants in the environment, owing to their universality and irreversibility. Modified biochar has been widely used in the adsorption and immobilization of heavy metals in soil, and its applicability is mainly determined by the types of heavy metals, pollution levels, and soil environmental conditions. Soil pollution is gradually becoming more complex and diversified, and heavy metal pollutants mostly occur in the form of compound pollution. However, most studies have focused on single heavy metal pollutant or the addition of heavy metal to soil. This study used rice straw as a raw material to prepare biochar, and modified it with K3PO4, KMnO4, and NaOH. The physicochemical and structural characteristics of the modified biochars were detected using a BET accelerated surface area and porosimetry system, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and the biochars were then analyzed for the availability and forms of Cd and Cu in soils contaminated with heavy metals in the mining area. The results showed that the surface roughness of the modified biochar increased to different degrees with increases in specific surface area and pore volume, with the NaOH modified biochar showing the most significant increases from 4.96 m2·g-1 to 60.79 m2·g-1, and from 0.02 cm3·g-1 to 0.12 cm3·g-1, respectively. The pore diameter changed in the opposite direction. The absorption peaks of the functional groups of the modified biochar were all changed, with K3PO4 modified biochar exhibiting the greatest degree of change. The addition of biochar significantly improved the soil pH value (P<0.05), and the pH value of the soil treated with K3PO4 modified biochar exhibited the largest increase. With an application of 20.5% K3PO4 modified biochar, the availability of Cu and Cd in the soil was significantly reduced, by 75.44% and 67.70%, respectively. The immobilization efficiency of Cu was much higher than that of Cd. The best immobilization efficiency of Cu and Cd in soil was achieved with K3PO4 modified biochar. With an addition of 2% K3PO4 modified biochar, the immobilization efficiency of Cu and Cd was 61.06% and 4.12%, respectively. In summary, K3PO4 modified biochar had a better immobilization effect on both Cu and Cd in compound contaminated soil.

HUBUNGAN PERBEDAAN TINGGI MUKA AIR TERHADAP KADAR Cu DAN Zn DAUN SERTA PERTUMBUHAN TANAMAN KELAPA SAWIT (Elaeis guineensis Jacq.) DI LAHAN GAMBUT

Peatland is an important natural resource for human life because it can be used as growth of oil palm plantation. The growth of oil palm plantations in peatlands is strongly influenced by peat water management. This study aims to study the relationship of different water levels to the content of leaf Cu and Zn nutrients and the growth of oil palm plants ( Elaeis guineensis Jacq.) in the peatlands. This research has been carried out on peatland areas in oil palm plantations of PT. Jatimjaya Perkasa Sei Bangko, Kubu District, Rokan Hilir Regency, Riau Province. Analysis of soil samples and plants samples has been carried out at the Soil Laboratory, Faculty of Agriculture, Universitas Riau, Pekanbaru. The research was conducted in December 2017 to January 2018. This research was conducted using a survey method, the determination of the location of the study using a purposive sampling method, determination of sampling location is determined by stratified sampling method, where the strata in this study are grouped according to different peat water levels namely water level 60 cm with oil palm plants at the same age which is six years and the piezometer has been installed properly. The parameters that observed in this study were soil pH, availability of Cu and Zn nutrient, total soil-K, content of Cu, Zn and K leaves and growth of oil palm plants which included plant height, midrib length and leaflet. The observed data were analyzed for variance and tested further by DNMRT at the level of 5%, analyzed by regression to see the relationship between water level and parameters. The results showed that peatland with water level of 40 - 60 cm had a soil pH, K-total soil, Cu leaves, Zn leaves, midrib length and the highest oil palm plantations compared to peat land with a groundwater level 60 cm, and has a different length of leaflets. Key words : Cu and Zn nutrient, Oil palm plantation, Peatlands, Water Level.