Cao Xinde, Ma Lena Q
Soil and Water Science Department, University of Florida, Gainesville, FL, USA.
Environ Pollut. 2004 Dec;132(3):435-42. doi: 10.1016/j.envpol.2004.05.019.
Leaching of arsenic (As) from chromated copper arsenate (CCA)-treated wood may elevate soil arsenic levels. Thus, an environmental concern arises regarding accumulation of As in vegetables grown in these soils. In this study, a greenhouse experiment was conducted to evaluate As accumulation by vegetables from the soils adjacent to the CCA-treated utility poles and fences and examine the effects of soil amendments on plant As accumulation. Carrot (Daucus carota L.) and lettuce (Lactuca sativa L.) were grown for ten weeks in the soil with or without compost and phosphate amendments. As expected, elevated As concentrations were observed in the pole soil (43 mg kg(-1)) and in the fence soil (27 mg kg(-1)), resulting in enhanced As accumulation of 44 mg kg(-1) in carrot and 32 mg kg(-1) in lettuce. Addition of phosphate to soils increased As accumulation by 4.56-9.3 times for carrot and 2.45-10.1 for lettuce due to increased soil water-soluble As via replacement of arsenate by phosphate in soil. However, biosolid compost application significantly reduced plant As uptake by 79-86%, relative to the untreated soils. This suppression is possibly because of As adsorbed by biosolid organic mater, which reduced As phytoavailability. Fractionation analysis showed that biosolid decreased As in soil water-soluble, exchangeable, and carbonate fraction by 45%, whereas phosphate increased it up to 2.61 times, compared to the untreated soils. Our results indicate that growing vegetables in soils near CCA-treated wood may pose a risk of As exposure for humans. Compost amendment can reduce such a risk by reducing As accumulation by vegetables and can be an important strategy for remediating CCA-contaminated soils. Caution should be taken for phosphate application since it enhances As accumulation.
铬酸铜砷酸盐（CCA）处理过的木材中砷（As）的浸出可能会提高土壤中的砷含量。因此，人们对这些土壤中生长的蔬菜中砷的积累产生了环境担忧。在本研究中，进行了一项温室实验，以评估蔬菜从与CCA处理过的电线杆和围栏相邻的土壤中积累砷的情况，并研究土壤改良剂对植物砷积累的影响。胡萝卜（Daucus carota L.）和生菜（Lactuca sativa L.）在添加或不添加堆肥和磷酸盐改良剂的土壤中种植了十周。正如预期的那样，在电线杆土壤（43毫克/千克）和围栏土壤（27毫克/千克）中观察到砷浓度升高，导致胡萝卜中砷积累量增加至44毫克/千克，生菜中砷积累量增加至32毫克/千克。向土壤中添加磷酸盐会使胡萝卜的砷积累量增加4.56至9.3倍，使生菜的砷积累量增加2.45至10.1倍，这是因为土壤中磷酸盐取代了砷酸盐，从而增加了土壤水溶性砷的含量。然而，与未处理的土壤相比，施用生物固体堆肥显著降低了植物对砷的吸收，降幅为79%至86%。这种抑制作用可能是由于生物固体有机物吸附了砷，从而降低了砷的植物有效性。分级分析表明，与未处理的土壤相比，生物固体使土壤水溶性、可交换性和碳酸盐态砷含量降低了45%，而磷酸盐则使其增加了2.61倍。我们的研究结果表明，在CCA处理过的木材附近的土壤中种植蔬菜可能会对人类造成砷暴露风险。堆肥改良可以通过减少蔬菜中的砷积累来降低这种风险，并且可以成为修复CCA污染土壤的重要策略。由于磷酸盐会增加砷的积累，因此在施用时应谨慎。
