Jones K C, Symon C J, Johnston A E
Department of Environmental Science, University of Lancaster, Bailrigg, United Kingdom.
Sci Total Environ. 1987 Nov;67(1):75-89. doi: 10.1016/0048-9697(87)90067-2.
Soil samples collected and stored since the mid-1800s to the present day have been analysed recently for Cd. The samples from long-term experiments under permanent grassland or arable crops at Rothamsted Experimental Station (U.K.) were selected to investigate time trends in elemental composition, due either solely to atmospheric deposition or to a combination of atmospheric deposition and various soil treatments. Increases in soil Cd of 27-55% since the 1850s due to atmospheric deposition were observed. This corresponds to an increase in the soil plough layer Cd concentration of between 0.7 and 1.9 micrograms kg-1 year-1 and is equivalent to an increase of 1.9-5.4 g Cd ha-1 year-1. The changes in soil Cd concentrations since 1846 at one control site corresponded well to predicted increases in the plough layer Cd burden based on assumptions about the temporal trends in atmospheric Cd emissions. In addition, sub-samples of a selection of rock phosphates of known origin and superphosphates, mainly from one supplier, collected and stored in the archive from 1925 onwards were also analysed for Cd. The concentrations ranged from 3.6 to 92 (mean 36) mg Cd kg-1 for rock phosphates and from 3.3 to 40 (9.7) mg kg-1 for superphosphates. On the basis of these data and known application rates the estimated input of Cd to P-treated plots at Rothamsted was 2 g ha-1 year-1, but there was little further increase in soil Cd due to this addition in three long-term arable experiments where soil pH was greater than 6.5. On P-treated plots the mean increase in soil Cd was 1.2 micrograms kg-1 year-1, which is equivalent to an increase in the plough layer burden of 3.1 g Cd ha-1 year-1. By contrast, P-treated soils under permanent grassland with a higher organic matter content and lower pH have increased their Cd content by 7.2 g ha-1 year-1. When permanent grassland soils ranging in pH from 5 to 7 were examined it was found that organic matter had a larger effect on Cd concentration than pH and the effects of pH were not consistent. Farmyard manure applied to some experimental plots at Rothamsted appears to have been a more significant source of Cd than combined atmospheric and phosphate fertiliser inputs.
最近对自19世纪中叶至今采集并保存的土壤样本进行了镉含量分析。选取了英国洛桑试验站长期草地或耕地作物试验的样本，以研究元素组成的时间趋势，这一趋势要么仅由大气沉降导致，要么由大气沉降与各种土壤处理措施共同导致。研究发现，自19世纪50年代以来，由于大气沉降，土壤镉含量增加了27%至55%。这相当于土壤耕作层镉浓度每年增加0.7至1.9微克/千克，等同于每年每公顷土壤镉含量增加1.9至5.4克。自1846年以来，一个对照地点土壤镉浓度的变化与基于大气镉排放时间趋势假设预测的耕作层镉负荷增加情况吻合良好。此外，还对自1925年起收集并保存在档案中的一系列已知来源的磷矿石和主要来自一个供应商的过磷酸钙的子样本进行了镉含量分析。磷矿石的镉浓度范围为3.6至92（平均36）毫克/千克，过磷酸钙的镉浓度范围为3.3至40（9.7）毫克/千克。根据这些数据和已知施用量，估计洛桑试验站磷肥处理地块的镉输入量为每年2克/公顷，但在土壤pH值大于6.5的三个长期耕作试验中，由于这种添加，土壤镉含量几乎没有进一步增加。在磷肥处理地块上，土壤镉的平均增加量为每年1.2微克/千克，这等同于每年每公顷耕作层镉负荷增加3.1克。相比之下，在永久草地中，有机质含量较高且pH值较低的磷肥处理土壤，其镉含量每年增加7.2克/公顷。当对pH值在5至7之间的永久草地土壤进行检测时，发现有机质对镉浓度的影响大于pH值，且pH值的影响并不一致。在洛桑试验站，施用于一些试验地块的农家肥似乎是比大气沉降和磷肥输入总和更重要的镉来源。
