Jung M C, Thornton I
Centre for Environmental Technology, Royal School of Mines, Imperial College, London, UK.
Sci Total Environ. 1997 May 30;198(2):105-21. doi: 10.1016/s0048-9697(97)05434-x.
The objective of this study is to investigate the extent and degree of heavy metal contamination of paddy fields influenced by metalliferous mining activity. Paddy soils, rice plants and irrigation waters were sampled along six traverse lines in the vicinity of the mine and nearby control site. Soil samples were taken 30, 80 and 150 days after rice transplanting, to study seasonal variation of their chemical properties and heavy metal concentrations. Sampling of rice plants and irrigation waters was also undertaken with seasons. The analysis of the samples were carried out using ICP-AES for 25 elements including Cd, Cu, Pb and Zn. Physical and chemical properties of soils (pH, loss-on-ignition, cation exchange capacity and texture) and waters (pH, Eh and temperature) were also measured. The properties of soils were similar to the average Korean soils, with the exception of some samples taken in the vicinity of the mine. Concentrations of Cd, Cu, Pb and Zn in paddy soils, rice plants and irrigation waters sampled in the immediate vicinity of the mine were relatively high due to the seepage of metals from mining dump sites. Although there was variation between sampling sites, soil pH values under reducing conditions were on average higher than those under oxidising conditions. Relatively low content of organic matter and low cation exchange capacity of soils were found at 80 days after rice transplanting (P < 0.05). No seasonal variations in metal concentrations were found in paddy soils throughout the period of the rice growing, in which soils ranged from flooded reducing conditions through most of the growing season to drained oxidising conditions before and at harvest. Relatively high metal concentrations were found in the rice stalks and leaves under oxidising conditions. The sequential extraction analysis of selected soil samples confirmed that high proportions of exchangeable fractions of the metals were found under oxidising conditions. It was shown that Cd and Zn concentrations in rice leaves and stalks and rice grain increased with increasing metal concentrations in paddy soils to a greater extent than for Cu and Pb. This difference in uptake is in agreement with the greater proportions of Cd and Zn, compared with Cu and Pb, in the exchangeable soil fraction extracted with MgCl2. Average daily intake from locally grown rice by the residents was estimated to be 121 micrograms Cd and 126 micrograms Pb. Thus, long-term metal exposure by regular consumption of the rice poses potential health problems to residents in the vicinity of the mine, although no adverse health effects have as yet been observed.
本研究的目的是调查受金属矿开采活动影响的稻田重金属污染的范围和程度。在矿山附近和附近对照点沿六条横向线采集了稻田土壤、水稻植株和灌溉水样本。在水稻移栽后30天、80天和150天采集土壤样本，以研究其化学性质和重金属浓度的季节变化。水稻植株和灌溉水的采样也随季节进行。使用电感耦合等离子体发射光谱仪（ICP - AES）对包括镉、铜、铅和锌在内的25种元素的样本进行分析。还测量了土壤（pH值、烧失量、阳离子交换容量和质地）和水（pH值、氧化还原电位和温度）的物理和化学性质。土壤性质与韩国土壤平均水平相似，但矿山附近采集的一些样本除外。由于金属从采矿废渣场渗漏，在矿山紧邻区域采集的稻田土壤、水稻植株和灌溉水中镉、铜、铅和锌的浓度相对较高。尽管采样点之间存在差异，但还原条件下的土壤pH值平均高于氧化条件下的pH值。在水稻移栽80天后发现土壤有机质含量相对较低且阳离子交换容量较低（P < 0.05）。在水稻整个生长期间，稻田土壤中的金属浓度未发现季节变化，在此期间，土壤从生长季节大部分时间的淹水还原条件到收获前及收获时的排水氧化条件。在氧化条件下，水稻秸秆和叶片中发现相对较高的金属浓度。对选定土壤样本的连续提取分析证实，在氧化条件下发现金属的可交换部分比例较高。结果表明，与铜和铅相比，水稻叶片、秸秆和稻谷中的镉和锌浓度随稻田土壤中金属浓度的增加而增加的幅度更大。这种吸收差异与用氯化镁提取的可交换土壤部分中镉和锌的比例高于铜和铅一致。估计当地居民从本地种植的水稻中的平均每日摄入量为121微克镉和126微克铅。因此，尽管尚未观察到不良健康影响，但长期定期食用这种水稻会使矿山附近居民面临潜在的健康问题。
