Search Results (3)

Arsenic (As), a widely distributed metalloid in the Earth’s crust, constitutes one of the most significant environmental contaminants today. This study was carried out to determine As concentrations in the soils of a Castilla La Mancha (CLM; Spain) benchmark collection that represents all the soil orders (soil taxonomy) in this territory. It also examined vine plant tolerance to As in relation to soil concentration. For this purpose, soils and leaves from vineyards were collected from 10 locations in the CLM community. The bioconcentration factor (BCF) of As in vineyards was assessed. The results of the present study show that As content in soils is widely variable, and is fundamentally related to soil type and parent material. The most surprising point is that, although some vineyards have been treated with As derivatives, the vast majority of them do not accumulate any amount of As. This important finding must be used to enhance the quality of the final obtained product: wine. In other words, CLM wines are not at risk of As contamination and must, therefore, be clean wines. Our results suggest that CLM vineyards are clean of contamination by As because this element in leaves reveals null vine capacity to accumulate As, a process that derives from scarce As in soils and the traditional practices carried out by winegrowers. Full article

Cadmium (Cd) is an unnecessary dietary toxin that is harmful to human health. The Cd translocation in soil-crops system varies greatly depending on different soil matrices; therefore, a valuable method that could accurately evaluate soil Cd thresholds needs to be proposed immediately. In the southwestern part of China, a typical karst mountainous area of east Asia, the results of our survey of 492 soil-maize samples in the region showed high Cd accumulation in the soil, with concentrations ranging from 0.07 to 31.95 mg kg⁻¹. The Cd concentrations in maize kernels planted in those fields, however, were quite low, and only 4 samples exceeded the national standard. A comparative study with nonkarst areas revealed a low bioaccumulation factor for soil Cd. This may be interpreted as the weathering soil-forming process of mineral-bearing rock systems, leading to high accumulation as well as low bioavailability of Cd in karst soils. A total of 172 soil-maize samples were evaluated inaccurately by the national standard evaluation procedure, accounting for 34.96% of the total. Therefore, we proposed the species sensitivity distribution model to address this inaccurate assessment. The results show that the hazardous concentrations of 95% and 5% in maize fields were 2.2 and 85.1 mg kg⁻¹ for soil pH ≤ 5.5, 2.5 and 108.5 mg kg⁻¹ for 5.5 < pH ≤ 6.5, and 3.0 and 161.8 mg kg⁻¹ for 6.5 < pH ≤ 7.5, respectively. The total number of unsuitable samples according to the evaluation results decreased from 172 to 2 after modification. Therefore, this result could be considered a more accurate assessment threshold. Full article

The study of threshold levels of heavy metals in soil is essential for the assessment and management of soil environmental quality. This study reviewed the influencing factors, the derivation, and application aspects of heavy metals’ threshold values comprehensively by a combination of bibliometric analysis and scientific knowledge mapping. A total of 1106 related studies were comprehensively extracted from the Web of Science database during the period from 2001 to 2020. The results showed that the publication output has been growing strongly. An analysis on the subject, journal, country, and institution was carried out to demonstrate the development and evolution of this research branch during the two decades. According to high-frequency keywords analysis, external factors (e.g., soil physicochemical properties) and internal factors (e.g., crop genotype) can affect heavy metal threshold values in the soil–crop system. The current methods mainly include the Point model (e.g., evaluation factor method), the Probability model (e.g., species sensitivity distribution method), and the Empirical model (e.g., ecological environment effect method). A threshold study can be applicable to the risk assessment for soil heavy metal contamination in order to determinate the soil pollution degree and its spatial and temporal distribution characteristics. Moreover, challenges and prospects of the study of heavy metal threshold values are proposed, indicating that research should focus on the relationships between human health risks and the established threshold values of heavy metals in the soil, long-term field trials and bioavailability of heavy metals for the derivation of the thresholds, and the establishment of more scientific and rational soil environmental benchmarks. Full article