Impacts of irrigation with Cd-contaminated water from Sugovushan Reservoir, Azerbaijan on total cadmium and its fractions in soils with varied textures

Abstract

Cadmium (Cd) presents a significant environmental threat due to its toxic nature and propensity to accumulate in various organs, posing serious health risks upon human exposure. This study focuses on the Sugovushan reservoir in Azerbaijan, aiming to comprehensively understand Cd behavior in soils subjected to varying water levels, shedding light on the intricate interplay between water quality and soil Cd content. Soil samples with distinct textures were collected from a agricultural area in Azerbaijan and subjected to an incubation experiment. The experiment, conducted at 20±0.5°C for 10 days, involved four water levels (%100, %75, %50, and %25 of field capacity) in a randomized complete block design. Cd-contaminated water from Sugovushan reservoir was applied, and inorganic Cd fractions were determined after incubation. The sequential extraction method, as per Shuman's procedure, was employed to assess Cd distribution in exchangeable (EX-Cd), organic (OM-Cd), Mn oxide (MnO-Cd), amorphous Fe oxide (AFeO-Cd), and crystalline Fe oxide (CFeO-Cd) fractions. The soils exhibited varying textures (Sandy Clay Loam, Silty Loam, and Clay) with alkaline reactions, differing salinity, and low organic matter content. Despite somewhat elevated total Cd levels (1.75–2.66 mg/kg), the soils remained below the 3 mg/kg contamination threshold. Water from Sugovushan reservoir, though alkaline, contained Cd concentrations exceeding agricultural use limits. Incubation with Cd-contaminated water increased total Cd content in all soils, with SaCL exhibiting the highest susceptibility. Notably, the SaCL soil showed a significant increase in the exchangeable Cd fraction, emphasizing its environmental risk. This study underscores the importance of soil texture in influencing Cd mobility, especially in low-clay-content soils. The heightened susceptibility observed in SaCL soil highlights the potential threat to food safety, emphasizing the need for sustainable agricultural practices and water management.