Remediation of Agricultural Soils with Long-Term Contamination of Arsenic and Copper in Two Chilean Mediterranean Areas

Abstract

Soil amendments may decrease trace element accumulation in vegetables, improving food security and allowing the recovery of contaminated farmlands. Despite some promising results in the laboratory, validation of soil amendments in field conditions are scarce, especially in aerobic soils. Here, we assessed the effect of different potential soil amendments on arsenic (As) accumulation in lettuces. Then, we compared them in terms of food security and the associated investment (efficacy and efficiency, respectively). We also hypothesized that the soil amendments do not lead to side effects, such as yield decrease, phytotoxicity of Cu, or undesired changes in soil properties. Thereby, we assessed lettuces grown on untreated contaminated soils (C+), treated contaminated soils, and untreated uncontaminated soils (C−) in two contrasting soil types (sandy and loamy soils). The treated contaminated soils consisted of multiple soil amendments. Soil amendments were: diammonium phosphate (DP), iron sulfate (IS), ferrous phosphate (FP), calcium peroxide (CP), and organic matter (OM). We found that phosphate amendments (DP and FP) reduced the As in edible tissues of lettuce in both areas, while CP only reduced As accumulation in the sandy soils area. The As intake through lettuces grown on these amended soils was about 30% lower than on the unamended ones. Cu concentrations in lettuces above 25 mg kg−1 grown in contaminated soils without reducing growth were found, a result that differed from non-field studies.

From risk assessment to land planning. The case of a trace element‐contaminated area in Chile

“…Another 16 studies assessed the biological or ecological impacts of the contaminations, including mainly plants and earthworms (e.g., Mondaca et al, 2017; Vivas et al, 2022), while five studies assessed the human health risks (e.g., Berasaluce et al, 2019). On the other hand, 16 studies focused on remediation alternatives for degraded landscapes (e.g., Pardo et al, 2018) or agricultural uses (Carvajal et al, 2023; Mondaca et al, 2022). Other studies focused on developing chemical methods or social issues.…”

“…Furthermore, the potential use of biological solutions using Trichoderma has also been reported (Carvajal et al, 2023). On the other hand, it has been proven that applying soil amendments can improve food security by decreasing As accumulation in lettuce (Mondaca et al, 2022). Nevertheless, despite validating some low‐cost remediation technologies in the study area, the lack of a scientific study with a broader perspective hampers the land restoration process.…”

Technologies for Environmental Ecological Restoration and Agricultural Sustainability Are the Focus of Future Safeguarded Agriculture Development

“…Mondaca et al (2022) validated the remediation effects of several soil amendments, including diammonium phosphate (DP), iron sulfate (IS), ferrous phosphate (FP), calcium peroxide (CP), and organic matter (OM), in contaminated sandy and loamy soils under field conditions (Figure 2F) [11]. The study found that phosphate amendments (DP and FP) reduced the foliar arsenic (As) concentration in lettuce grown in both areas, while CP only reduced it in the sandy soils.…”

“…(E) Effects of different salt types and salt concentrations (0, 0.5%, 1.0%, 2%, 3%, and 3.5%) on the Cd desorption rates (%) [10]. (F) The geographical location of the studied areas and the main trace element sources: (a) sandy soils area; and (b) loamy soils area [11]. (G) Canonical scores of the first two canonical discriminant functions (Can) of the control and PLB treatments (1, 5, and 10 = 1%, 5%, and 10%) [12].…”

An appraisal of the principal concerns and controlling factors for Arsenic contamination in Chile

“…Also, the role of agricultural activity in accelerating As contamination needs to be investigated, as a significant amount of As could be released from the sediments due to the agriculture activity and contaminate shallow groundwater resources, as in Bengal delta, India 213 . Work on As translocation in rice cultivation and its implication for human health by Bastías and Baldarrian 214 and recent work of Moncada et al 215 dealing with the remediation of agricultural soils with long-term As and Cu contamination are efforts towards filling this gap.…”