Accumulation Of Trace Elements In Soils Research Articles

Development and use of a mass‐balance model to calculate the likely effects of agrichemicals on trace element accumulation in soils supporting palm oil production

AbstractTrace elements (TEs) can reduce both the quantity and quality of agricultural produce when essential trace elements are deficient or when any trace element accumulates beyond threshold concentrations in soil. Therefore, TEs in agricultural systems should be managed to ensure that soil concentrations are kept within guideline levels and do not affect production. Oil palm agriculture in Indonesia occurs on weathered, acidic soils that require substantial fertilizer inputs to maintain production. To understand whether TE accumulation in soils resulting from fertilizer and pesticide use may affect production in the future, we have developed a mass‐balance model to calculate likely concentrations of TEs in soils after given time periods under production conditions. Our model was developed to simulate processes which occur in the soil–plant system and involve the transport of TEs. It was developed to be rationally convenient, that is, parsimonious, working at environmentally relevant concentrations and able to be applied at the hectare scale to large agricultural systems. The model uses the mass‐balance equation and uses the critical parameters of rainfall, evaporation, erosion, soil adsorption coefficient, initial plant and soil contaminant concentrations, as well as soil‐ and‐crop specific parameters. We validated our model using a data set from a 64‐year fertilizer trial, which had known inputs and application rates of fluorine (F), cadmium (Cd) and uranium (U). We applied the validated model to a smallholder oil palm plantation in Indonesia, modelling accumulation of copper (Cu), F, Cd and U under recommended production conditions, to determine which TEs might limit production and the likely timeframes for this. Our results indicate that topsoil concentrations of Cu and F were likely to reach phytotoxic concentrations in soils (289 and 719 mg kg−1, respectively), within 50 years under these conditions. The future feasibility of intensive oil palm production on weathered, low fertility soils such as those in Indonesia should be assessed to avoid long‐term negative impacts on soil quality.

Potential accumulation of toxic trace elements in soils during enhanced rock weathering

AbstractTerrestrial enhanced rock weathering (ERW) is a carbon dioxide removal technology that aims at accelerating one of the most powerful negative feedbacks on Earth's climate, the chemical weathering of silicates. To achieve this, ERW proposes to spread ground silicate rock on agricultural soils. According to many models, global application rates of 40 tonnes of ground basaltic rock per hectare and per year would be necessary to sequester a significant amount of CO2, representing up to 24% of the current net annual increase in atmospheric CO2. When assessing the viability of ERW as a global geo‐engineering strategy, a pivotal but overlooked question to address is whether ERW may lead to toxic trace element accumulation in soils at unauthorized and potentially harmful levels. This study evaluates the legal sustainability of ERW with regard to trace element contents in soils. We compare different trace element accumulation scenarios considering a range of rock sources, application rates and national regulatory limits. The results indicate that, at the suggested annual application rate of 40 tonnes per hectare, the first regulatory limits would be exceeded after 6 and 10 years for copper and nickel, respectively. This study argues in favour of close tailoring of ERW deployment to local conditions in order to tap into its climate mitigation potential while preserving long‐term soil uses.Highlights Terrestrial enhanced rock weathering (ERW) is a carbon sequestration technology that consists in applying rock powder to soils. This study evaluates whether rock powder application can lead to trace metals accumulation in soils beyond regulatory limits. ERW can lead to the overrun of some environmental regulatory limits within less than a decade. Specific site and rock selection will be necessary for this method to preserve long‐term soil uses.

The content and distribution of trace elements and polycyclic aromatic hydrocarbons in soils of Maritime Antarctica.

Antarctica is considered as one of the most pristine areas on Earth. However, increasing intensity of human presence on the sixth continent (scientific operations, functioning of the numerous scientific stations, tourism activities) makes it crucial to investigate the level of environmental pollution within the vulnerable ecosystem of Antarctica. Soils play a significant role in processes of accumulation, mobilization, redistribution of chemical elements within landscapes, and ecosystems. The aim of this work was to analyze the levels of 17 polycyclic aromatic hydrocarbons and eight trace elements in soils of King George and Ardley islands, Western Antarctica. Moreover, our work was aimed to determine the trends and reasons of anthropogenic pollution of Antarctic soils and characterization of accumulation levels of trace elements and PAHs. Results showed the predominance of light PAHs in all studied sites. The content of benzo(a)pyrene does not exceed the threshold concentration (adopted by different national environmental legislation systems). At the same time, the content of benzo(a)pyrene, which is a marker of anthropogenic contamination, is relatively low or equal to 0 in soils of reference landscapes. Cu and Zn were found as most abundant elements in all studied soils. The highest lead concentration content has been described in soil from Bellingshausen station. In general term, obtained Igeo values for trace elements in all samples were under or slightly above the 0 level, indicating low to moderate pollution of the studied soils. This study also contributes new data on trace element accumulation in soils strongly influenced by ornithogenic factor. Principal component analysis allowed to estimate the probable sources of specific trace metals and their relationship with soil variables. Ornithogenic factor has been also revealed as a driver for some trace element accumulation especially in breeding penguin colonies. High contents of organic matter in ornithogenic habitats could increase trace metal mobility, environmental risks for surrounding terrestrial environments should be considered.

Dust-mediated loading of trace and major elements to Wasatch Mountain snowpack

Depth-integrated snow columns were collected at 12 sites across the central Wasatch Mountains, Utah, during March and April 2010 to determine concentrations of trace elements, major anions and cations, and pH. Sample collection was conducted at or near maximum snow accumulation prior to the onset of melt, and included spring dust events driven by southerly pre-frontal winds. Snow samples were melted in the laboratory and subsampled for analyses on filtered (0.45μm) and unfiltered fractions. All measured elements (Al, As, Ba, Ca, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Sr, Ti, Tl, U, V, and Zn) and major anions (Cl, NO3, and SO4) displayed significant increases in concentration (for example, factor of 2 to 5 increases for As, Cr, Hg, and Pb) between the six sites sampled in March (prior to dust events) and the six sites sampled in April (after dust events). Acid neutralizing capacity and pH were also elevated in April relative to March snowpack. Comparison of elemental concentration in the particulate (>0.45μm; difference between unfiltered and filtered concentration) and soluble (<0.45μm; filtered concentration) fractions shows that the concentration increase between March and April snowpack for the trace elements is primarily a result of association with dust particles >0.45μm. The results suggest that the majority of trace element loading to the Wasatch snowpack occurs via dust deposition. The major elements were primarily loaded in the <0.45μm fraction, suggesting deposition of soluble dust particles. The overall findings of this paper are similar to other studies regarding the role of dust on nutrient and trace element accumulation in soils and lake sediments, but to our knowledge this is the first study that compares trace element chemistry of seasonal snowpack before and after dust deposition events.

Solid/liquid partition coefficients to model trace element critical loads for agricultural soils in Canada

Canadian consumers are demanding a sustainable agricultural industry as well as products delivered under Best Management Practices (BMPs). Trace element accumulation in soils may influence crop productivity, food quality and ecosystem and human health. Canada’s feed and foodstuff export industry has already faced cases of penalties for high trace element content [cadmium (Cd) in durum wheat]. Thus, it is imperative to be able to estimate the accumulation and potential short- and long-term impacts of trace elements in soil. A national-level Trace Element Indicator (TEI) based on present loadings of trace elements to agricultural land is in progress. An Expert Panel including Canadian, American and Australian experts guided the assembly of a proposed methodology for this TEI. The proposed TEI, described briefly here, is a critical load approach with a single expression of the risk of impact from single or multiple trace elements from multiple sources (manures, biosolids, effluents and fertilizers and natural processes), invoked in a stochastic manner. Two key data requirements are the current background levels of trace elements in soil, and the leachability of these trace elements. A survey of total and soluble concentrations of 54 elements in up to 112 soils was completed. Although preliminary in scope, these represent key soil series in Canada. From this, a database of the solid/liquid partition coefficient, Kd, was computed. These Kd values will be used to characterize the leachability of the trace elements. Key words: Cadmium, copper, zinc, lead, nickel, uranium, metals, Kd, distribution coefficient