Singh S, Kumar M
Division of Environmental Sciences, Indian Agricultural Research Institute, New Delhi, 110012, India.
Environ Monit Assess. 2006 Sep;120(1-3):79-91. doi: 10.1007/s10661-005-9050-3. Epub 2006 Aug 3.
Peri-urban lands are often used for production of vegetables for better market accessibility and higher prices. But most of these lands are contaminated with heavy metals through industrial effluents, sewage and sludge, and vehicular emission. Vegetables grown in such lands, therefore, are likely to be contaminated with heavy metals and unsafe for consumption. Samples of vegetables i.e., spinach (Spinacia oleracea L.) and okra (Abelmoschus esculentus L.); soil and irrigation water were collected from 5 peri-urban sites of New Delhi to monitor their heavy metal loads. While heavy metal load of the soils were below the maximum allowable limit prescribed by the World Health Organization (WHO), it was higher in irrigation water and vegetable samples. The spinach and okra samples showed Zn, Pb and Cd levels higher than the WHO limits. The levels of Cu, however, were at their safe limits. Metal contamination was higher in spinach than in okra. Spatial variability of metal contamination was also observed in the study. Bio-availability of metals present in soil showed a positive relationship with their total content and organic matter content of soil but no relationship was observed with soil pH. Washing of vegetables with clean water was a very effective and easy way of decontaminating the metal pollution as it reduced the contamination by 75 to 100%.
城郊土地常被用于蔬菜种植，以便更好地进入市场并获得更高价格。但这些土地大多因工业废水、污水和污泥以及车辆排放而受到重金属污染。因此，在这些土地上种植的蔬菜很可能被重金属污染，食用不安全。从新德里的5个城郊地点采集了蔬菜样本（即菠菜（Spinacia oleracea L.）和秋葵（Abelmoschus esculentus L.））、土壤和灌溉水样本，以监测它们的重金属含量。虽然土壤中的重金属含量低于世界卫生组织（WHO）规定的最大允许限度，但灌溉水和蔬菜样本中的含量更高。菠菜和秋葵样本中的锌、铅和镉含量高于WHO的限值。不过，铜含量处于安全限值。菠菜中的金属污染比秋葵更高。研究中还观察到金属污染的空间变异性。土壤中金属的生物有效性与其总含量和土壤有机质含量呈正相关，但与土壤pH值无关。用清水清洗蔬菜是一种非常有效且简便的去除金属污染的方法，因为它能将污染降低75%至100%。
