Cessna Allan J, Elliott Jane A
Agriculture and Agri-Food Canada, Research Centre, Lethbridge, AB, Canada T1J 4B1.
J Environ Qual. 2004 Jan-Feb;33(1):302-15. doi: 10.2134/jeq2004.3020.
Prairie farm dugouts are frequently constructed for use as potable water sources. Consequently, cumulative pesticide inputs via atmospheric deposition and surface runoff may constitute a risk to human health. Since, relative to other pesticides, herbicides are used in greatest amount on the Canadian prairies, herbicide concentrations were intensively monitored in three dugouts over three growing seasons. Herbicides were detected in the water of all three dugouts each growing season which may reflect cumulative inputs from atmospheric and surface processes over the lifetimes of the dugouts, which varied from 11 to 22 yr. Detections, which were not continuous, tended to be seasonal in nature. During the 3-yr study, detections were most frequent during the spring application period and late fall following dugout turnover. Between these periods, herbicide concentrations generally decreased to below detection limits. The reappearance of herbicides in the dugout water during fall turnover and in concentrations generally greater than those present during the spring application period suggest that, under appropriate environmental conditions, the bottom sediments may act as a source of herbicides to the water column. In general, herbicide inputs due to deposition of application drift did not result in detectable concentrations of herbicides in the dugouts. In the only year that winter samples were monitored, herbicides were also detected during ice cover. On the basis of monthly sampling over each growing season, median concentrations of 9 of the 10 herbicides monitored were less than 0.05 microg L(-1). The exception, 2,4-D, which has been used extensively on the Canadian prairies for more than 50 yr and in greatest amounts, was the most frequently detected herbicide. In no case did herbicide concentrations exceed Canadian drinking water guidelines; however, on occasion maximum herbicide concentrations did exceed aquatic life and irrigation water guidelines.
草原农场的地洞常常被用作饮用水源。因此，通过大气沉降和地表径流累积的农药输入可能对人类健康构成风险。由于相对于其他农药，除草剂在加拿大大草原上的使用量最大，因此在三个生长季节对三个地洞中的除草剂浓度进行了密集监测。在每个生长季节，所有三个地洞的水中都检测到了除草剂，这可能反映了在地洞长达11至22年的使用期限内，大气和地表过程的累积输入。检测结果并非连续，且往往具有季节性。在为期三年的研究中，春季施药期和地洞换水后的深秋期间检测最为频繁。在这些时期之间，除草剂浓度通常降至检测限以下。秋季换水时地洞水中除草剂再次出现，且浓度通常高于春季施药期，这表明在适当的环境条件下，底部沉积物可能成为水柱中除草剂的来源。一般来说，施药漂移沉降导致的除草剂输入并未使地洞中的除草剂浓度达到可检测水平。在唯一监测冬季样本的年份，冰盖期间也检测到了除草剂。根据每个生长季节的月度采样，所监测的10种除草剂中有9种的中位浓度低于0.05微克/升。例外的是2,4-滴，它在加拿大大草原上广泛使用了50多年，且使用量最大，是检测最频繁的除草剂。除草剂浓度从未超过加拿大饮用水标准；然而，最高除草剂浓度偶尔会超过水生生物和灌溉用水标准。
