Lambert Raphaël, Grant Cynthia, Sauvé Sébastien
Environmental Chemistry Laboratory, Department of Chemistry, Université de Montréal, PO 6128 Centre-ville, Montreal, QC, Canada H3C 3J7.
Sci Total Environ. 2007 Jun 1;378(3):293-305. doi: 10.1016/j.scitotenv.2007.02.008. Epub 2007 Apr 2.
This study investigated the solubility of cadmium and zinc in soils after the application of phosphate fertilizers containing those two metals. The solubility of cadmium and zinc was assessed by measuring their concentration in soil water extracts. Three monoammonium phosphate fertilizers containing various amounts of metals were applied on cultivated fields for 3 years at three different rates. In order to investigate the effects of long-term applications of fertilizers on the solubility of Cd and Zn, a similar design was used to apply contaminated fertilizers to soils in a laboratory experiment using a single fertilizer addition equivalent to 15 years of application. Phosphate fertilizers increased the concentration of Cd in soil extracts compared to control in 87% and 80% of the treatments in field and laboratory experiments respectively. Both increasing the rate of application and using fertilizer containing more Cd lead to higher Cd concentrations in extracts for the field and the laboratory experiments. The addition of the equivalent of 15 years of fertilizer application in the laboratory results in higher Cd concentration in extracts compared to the field experiment. For Zn, the fertilizer treatments enhanced the metal solution concentration in 83% of field treatments, but no significant correlations could be found between Zn inputs and its concentration in solution. In the laboratory, fertilizer additions increase the Zn concentrations in 53% of the treatments and decrease it in most of the other treatments. The decrease in Zn concentrations in the laboratory trial is attributed to the higher phosphate concentrations in the soil solution; which is presumed to have contributed to the precipitation of Zn-phosphates. For both trials, the metal concentrations in soil extracts cannot be related to the Zn concentration in the fertilizer or the rate of application. The high Zn to Cd ratio is presumably responsible for the Cd increase in the soil extracts due to competitive displacement by Zn. Finally, the observed acidification of soils with fertilizer application will also contribute to metal solubilisation.
本研究调查了施用含镉和锌的磷肥后，镉和锌在土壤中的溶解度。通过测量土壤水提取物中镉和锌的浓度来评估其溶解度。三种含有不同金属量的磷酸一铵肥料以三种不同施用量在耕地上施用了3年。为了研究长期施肥对镉和锌溶解度的影响，在实验室实验中采用了类似的设计，向土壤中施用受污染的肥料，单次施肥量相当于15年的施用量。在田间和实验室实验中，分别有87%和80%的处理中，与对照相比，磷肥提高了土壤提取物中镉的浓度。无论是增加施用量还是使用含镉量更高的肥料，在田间和实验室实验中，提取物中的镉浓度都会更高。与田间实验相比，在实验室中施用相当于15年施肥量的肥料会导致提取物中镉浓度更高。对于锌，83%的田间处理中肥料处理提高了金属溶液浓度，但锌输入量与其溶液浓度之间未发现显著相关性。在实验室中，53%的处理中施肥增加了锌浓度，而在大多数其他处理中则降低了锌浓度。实验室试验中锌浓度的降低归因于土壤溶液中较高的磷酸盐浓度；据推测这导致了锌磷酸盐的沉淀。对于这两个试验，土壤提取物中的金属浓度与肥料中的锌浓度或施用量均无关联。锌与镉的高比例可能是由于锌的竞争性置换导致土壤提取物中镉增加的原因。最后，观察到施肥导致的土壤酸化也会促进金属的溶解。
