Effect of LMWOAs on Maize Remediation of Cadmium and Plumbum Pollution in Farmland

Abstract

Plant extraction is a thorough remediation method to remove heavy metals from soil. Chelating agents can enhance the extraction effect of heavy metals from soil by plants. In this study, low molecular weight organic acids (LMWOAs), such as citric acid (CA), tartaric acid (TA) and polyaspartate (PASP), were added to the farmland soil contaminated with Cd and Pb and combined with corn to enhance the absorption and extraction of Cadmium (Cd) and Plumbum (Pb). The effects of LMWOAs on the growth and yield of maize, Cd and Pb concentrations in each part of maize, rhizosphere soil pH, total cadmium and lead content and DTPA-Cd and Pb concentrations were studied. The enrichment, transport and extraction ability of maize were analyzed, and calcium chloride (CaCl2) was compared. The results showed that: (1) Exogenous LMWOAs increased the biomass and yield of maize compared with no material added (CK), and CA increased the yield of maize by 6.33%. (2) Exogenous LMWOAs promoted the uptake of Cd and Pb in all parts of maize, and the distribution of Cd and Pb in all organs was as follows: straws > roots > maize cobs > kernels and roots > straws > maize cobs > kernels. The Cd and Pb concentrations in maize kernels were in line with GB 13078-2017 in China, which could be used as feed maize. (3) Exogenous LMWOAs enhanced the enrichment of Cd and Pb in maize straws and roots. PASP had a good enrichment effect on Cd and Pb. CA and CaCl2 could enhance the transport capacity of Cd and Pb from maize roots to straw. (4) Compared with CK, the total amount of Cd and Pb in rhizosphere soil decreased by 6.93–26.99% and 2.74–6.79%, respectively. LMWOAs could promote the concentration of DTPA-Cd and Pb in rhizosphere soil, and PASP had the most significant increase in DTPA-Cd and Pb in rhizosphere soil. Compared with CK, the soil pH value decreased by 0.03–0.14 units. LMWOAs can enhance the removal of heavy metals from maize, and PASP has the most significant comprehensive effect.

Simulation Study on Risk and Influencing Factors of Cadmium Loss in Contaminated Soil

“…Cadmium (Cd) is a highly toxic heavy metal that severely threatens human health [1]. Exposure to Cd may lead to serious chronic diseases, including lung cancer, gastrointestinal disorders, kidney injury, and liver disease [2,3].…”

Screening for Low-Cadmium Accumulation in Maize Varieties Based on Species Sensitivity Distribution and Research on Soil Environmental Thresholds

“…Soil is the direct carrier of agricultural production, and when it is polluted by heavy metals, the edible parts of crops can have high heavy metal content. These heavy metals can enter the human or animal body through the food chain and accumulate, causing chronic heavy metal poisoning and endangering human health [7,8]. To reduce the transfer of heavy metals to the food chain, two main approaches are currently used: passivating heavy metals in soil through chemical methods or screening for crop varieties that are tolerant to heavy metals and have low accumulation [4].…”