Saha Ganesh Chandra, Ali M Ashraf
Department of Civil Engineering, Dhaka University of Engineering and Technology, Gazipur 1700, Bangladesh.
Sci Total Environ. 2007 Jul 1;379(2-3):180-9. doi: 10.1016/j.scitotenv.2006.08.050. Epub 2006 Oct 24.
Arsenic (As) concentrations in the soil layers of 12 rice fields located in four As affected areas and two unaffected areas in Bangladesh were monitored during 2003. In the unaffected areas, where irrigation water contained little As (<1 microg/L), As concentrations of rice field soils ranged from 1.5 to 3.0 mg/kg and did not vary significantly with either depth or sampling time throughout the irrigation period. In the As affected areas where the irrigation water contained elevated As (79 to 436 microg/L), As concentrations of rice field soils were much higher compared to those in the unaffected areas and varied significantly with both depth and sampling time. For the top 0 to 150 mm of the soil, the As concentration increased significantly at the end of the irrigation season (May-June 2003). About 71% of the As that is applied to the rice field with irrigation water accumulates in the top 0 to 75 mm soil layer by the end of the irrigation season. After the wet season during which the rice fields were inundated with flood/rain water, the As concentrations in the soil layer decreased significantly and were reduced to levels comparable to those found in soil samples collected at the beginning of the irrigation period. The long-term As accumulation in agricultural soil appears to be counteracted by biogeochemical pathways leading to As removal from soil.
2003年期间，对孟加拉国四个砷污染区和两个未受影响区的12个稻田土壤层中的砷（As）浓度进行了监测。在未受影响的地区，灌溉水中砷含量很低（<1微克/升），稻田土壤中的砷浓度在1.5至3.0毫克/千克之间，在整个灌溉期内，砷浓度随深度或采样时间的变化均不显著。在灌溉水中砷含量较高（79至436微克/升）的砷污染区，稻田土壤中的砷浓度比未受影响地区高得多，且随深度和采样时间的变化显著。对于土壤表层0至150毫米，在灌溉季节结束时（2003年5月至6月），砷浓度显著增加。到灌溉季节结束时，通过灌溉水施用于稻田的砷中约71%积累在土壤表层0至75毫米土层中。在稻田被洪水/雨水淹没的雨季过后，土壤层中的砷浓度显著下降，并降至与灌溉期开始时采集的土壤样品中发现的浓度相当的水平。农业土壤中砷的长期积累似乎被导致砷从土壤中去除的生物地球化学途径所抵消。
