Heavy metals input with phosphate fertilizers used in Argentina
Abstract
Sustainability of conventional agriculture is based upon a high input of agrochemicals, such as phosphate fertilizers. Conventional inorganic phosphorus fertilizers may cause an inadvertent addition of heavy metals, which are contained as impurities. Fertilizers commonly used in Argentina were analyzed to determine concentrations of chromium, cadmium, copper, zinc, nickel and lead. Rock phosphate contained the highest levels of cadmium and zinc, chromium was enhanced in diammonium phosphate and copper and lead were high in one superphosphate sample. Urea-phosphate contained the lowest levels of heavy metals. Concentrations of heavy metals varied considerably and the levels of Cd and Pb in some analyzed materials were significant relative to those naturally present in soils. Continuous fertilization of soils could increase the heavy metal contents exceeding natural abundances in soils, and transfer of these metals to the human food chain must not be overlooked.
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Recent advances in phyto-combined remediation of heavy metal pollution in soil
2024, Biotechnology AdvancesThe global industrialization and modernization have witnessed a rapid progress made in agricultural production, along with the issue of soil heavy metal (HM) pollution, which has posed severe threats to soil quality, crop yield, and human health. Phytoremediation, as an alternative to physical and chemical methods, offers a more cost-effective, eco-friendly, and aesthetically appealing means for in-situ remediation. Despite its advantages, traditional phytoremediation faces challenges, including variable soil physicochemical properties, the bioavailability of HMs, and the slow growth and limited biomass of plants used for remediation. This study presents a critical overview of the predominant plant-based HM remediation strategies. It expounds upon the mechanisms of plant absorption, translocation, accumulation, and detoxification of HMs. Moreover, the advancements and practical applications of phyto-combined remediation strategies, such as the addition of exogenous substances, genetic modification of plants, enhancement by rhizosphere microorganisms, and intensification of agricultural technologies, are synthesized. In addition, this paper also emphasizes the economic and practical feasibility of some strategies, proposing solutions to extant challenges in traditional phytoremediation. It advocates for the development of cost-effective, minimally polluting, and biocompatible exogenous substances, along with the careful selection and application of hyperaccumulating plants. We further delineate specific future research avenues, such as refining genetic engineering techniques to avoid adverse impacts on plant growth and the ecosystem, and tailoring phyto-combined strategies to diverse soil types and HM pollutants. These proposed directions aim to enhance the practical application of phytoremediation and its integration into a broader remediation framework, thereby addressing the urgent need for sustainable soil decontamination and protection of ecological and human health.
Identifying driving factors of soil heavy metal at the mining area scale: Methods and practice
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Heavy metals in hair of small mammals from the cacao agroforestry and Brazilian Atlantic Forest
2023, Global Ecology and ConservationThe current growing demand for resources, food production, and agricultural crops leads to a drastic reduction in biodiversity and ecosystem services. One of the options to mitigate the recurring effects of land use changes is the adoption of wildlife-friendly systems, such as cacao agroforestry systems, which integrates production with biodiversity conservation. Cacao management involves the frequent use of pesticides, such pesticides are comprised of heavy metals that are considered non-point sources of pollution. Animal hair is considered an excellent cumulative bioindicator of contamination. Small mammals are known as bioindicators of pollution, as they provide a warning of adverse effects on ecosystems. The main objective was to determine the concentrations of six heavy metals (Pb, Ni, Cr, Cd, Mn, and Cu) in hair of small mammals in traditional cacao agroforests and Atlantic Forest fragments in the southern region of Bahia, Brazil. The study covered 12 traditional cacao agroforests and 12 Atlantic Forest fragments. A total of 34 small mammals were captured in the traditional cacao agroforests, representing 12 species, while 18 were captured in the Atlantic Forest fragments, representing 6 species. We found that small mammals in both habitats had similar levels of lead in their hair. Heavy metals concentrations in the hair of small mammals were higher in individuals from traditional cacao agroforests than the Atlantic Forest fragments (Cacao agroforest (mg/Kg): Pb - 26.42 ± 16.42; Ni - 5.31 ± 4.3; Mn - 1.64 ± 2.63; Cu - 1.13 ± 1.15; Cd - 1.42; Atlantic Forest (mg/Kg): Pb - 19.28 ± 14.46; Ni - 0.18; Mn - 0.34 ± 0.40; Cu - 1 ± 2.05). Marsupials exhibited higher lead concentrations compared to rodents (Didelphimorphia (mg/Kg): Pb - 28.66 ± 18.73; Rodentia (mg/Kg): Pb - 18.44 ± 9.85), likely due to their distinct eating habits and habitat use. Body condition of the small mammals did not differ between the two habitat types, and there was no relationship between the bioaccumulation of heavy metals in small mammals and body condition. This is the first study to evaluate heavy metal contamination in small mammals in traditional cacao agroforests and Atlantic Forest fragments, thus providing important data that indicate the presence of heavy metals in the hair of the small mammals sampled, and consequently, the presence of these heavy metals in the environment where these small mammals lived.
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The estimated cost ranged from 8 to 161 euros per tonne, with an additional 230 euros when considering the pruning costs inherent to the crop. These costs fall below the threshold (320 euros per tonne) for the economically viable P reuse at the farm level. Consequently, CPPW, when reduced to powder and loaded with ions, emerges as an affordable adsorbent with good removal performance, offering a promising avenue for direct utilization in agriculture as both soil conditioner and fertiliser.