College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, PR China.
College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, PR China.
Sci Total Environ. 2024 Jan 10;907:167941. doi: 10.1016/j.scitotenv.2023.167941. Epub 2023 Oct 18.
Cadmium (Cd) contamination in rice threats food safety and human health. Control of Cd pollution has become an urgent need. Most existing studies on heavy metal pollution control have focused on industrial wastewater and few on irrigation water. Some researchers have found ecological ditches, plant ponds and constructed wetlands have the potential of treating heavy metal contaminated irrigation water, but they examined only one of the methods and the validity needs to be verified by field studies. Our study has filled the gap by combining the methods and using field experiments. We examined efficiencies of removal of Cadmium from irrigation water by 14 different combinations of ecological ditches, plant ponds, and constructed wetlands using field experiments. The effects of the purification on Cd concentration in paddy soil and rice grains were also examined. Results showed that there were significant differences among efficiencies of purification of Cd contaminated irrigation water using different systems and that pH, chemical form of Cd in irrigation water, vegetation coverage and biomass of aquatic plants significantly affect the efficiency. Of the 14 purification systems, seven resulted in the concentration of Cd in the effluent water meeting the National Standard for Irrigation Water Quality (GB5084-2021) for all days of the experiment period. The highest amount and rate of Cd removal were achieved by the combination of two-stage ecological ditch, two-stage plant pond, and one-stage constructed wetland, while the highest removal amount and rate per 100 m was achieved by the combination of one-stage plant pond and one-stage constructed wetland. Considering purification efficiency, area of coverage, and cost of construction and maintenance, we suggest that combination of plant pond and constructed wetland be a priority choice for purification of Cd pollution in irrigation water. Compared to the control data collected from rice grain and paddy soil irrigated by unpurified water, Cd concentration in rice grain and paddy soil irrigated by purified water declined by 5.08-19.42 % and 30.93-77.15 % respectively. All results showed that removal of Cd contamination from irrigation water effectively controlled cadmium pollution in rice grain and paddy soil. Our study not only contributes to pollution control practice, but also warrants further investigation of the mechanisms of how the treatment systems work. The most efficient method we identified could be applied locally, regionally and in areas of similar topography, climate, soil, vegetation, agriculture, and heavy metal pollution.
镉（Cd）污染对稻米安全和人类健康构成威胁。控制镉污染已成为当务之急。大多数现有的重金属污染控制研究都集中在工业废水中，而对灌溉水的研究较少。一些研究人员发现生态沟渠、植物池塘和人工湿地具有处理重金属污染灌溉水的潜力，但他们仅检验了其中一种方法，其有效性需要通过现场研究来验证。我们的研究通过结合这些方法并使用现场实验填补了这一空白。我们通过现场实验检验了 14 种不同的生态沟渠、植物池塘和人工湿地组合从灌溉水中去除镉的效率。还检验了净化对稻田土壤和稻米中镉浓度的影响。结果表明，不同系统净化受污染灌溉水的效率存在显著差异，灌溉水中的 pH 值、镉的化学形态、植被覆盖率和水生植物的生物量显著影响效率。在 14 种净化系统中，有 7 种系统在整个实验期间使灌溉水中的镉浓度均符合《农田灌溉水质标准》（GB5084-2021）的要求。两段式生态沟渠、两段式植物池塘和一段式人工湿地组合的镉去除量和去除率最高，而每 100 米去除量和去除率最高的是一段式植物池塘和一段式人工湿地组合。考虑到净化效率、覆盖面积以及建设和维护成本，我们建议植物池塘和人工湿地的组合是净化灌溉水中镉污染的优先选择。与未净化水灌溉的稻米和稻田土壤收集的对照数据相比，净化水灌溉的稻米和稻田土壤中的镉浓度分别下降了 5.08-19.42%和 30.93-77.15%。所有结果表明，从灌溉水中去除镉污染有效地控制了稻米和稻田土壤中的镉污染。我们的研究不仅为污染控制实践做出了贡献，也为进一步研究处理系统的工作机制提供了依据。我们确定的最有效方法可在局部、区域和具有类似地形、气候、土壤、植被、农业和重金属污染的地区应用。
