Study on Safe Usage of Agricultural Land in Typical Karst Areas Based on Cd in Soil and Maize: A Case Study of Northwestern Guizhou, China

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