施用猪粪对不同类型土壤中铜的赋存形态及小白菜吸收铜的影响

Effects of Pig Manure Application on Copper Fractions in Different Soils and Copper Accumulation in Chinese Cabbage

【目的】探讨猪粪中铜(Cu)的输入对土壤中Cu的赋存和生物有效性的影响。【方法】将1%和3%的腐熟猪粪(干猪粪∶秸秆=10∶1)添加到黄褐土、红壤、黑土、褐土中,分别老化0、1、2、3、5个月后,进行小白菜盆栽实验。【结果】与对照相比,施用猪粪使黄褐土、红壤、黑土和褐土土壤铜(Cu)全量分别显著增加了20.23%~50.43%、79.87%~142.6%、52.41%~76.43%和41.14%~92.24%。四种土壤中水溶态(F1)、碳酸盐结合态(F3)Cu占比均增加,施用3%猪粪的红壤未老化处理中F1-Cu和黄褐土未老化处理中F3-Cu增幅最大,分别达4.55%和16.47%。土壤铁锰氧化态(F5)、有机结合态(F6)Cu占比增加,残渣态(F7)占比降低。土壤有效态Cu的占比与猪粪老化时间呈显著负相关,3%猪粪老化5个月处理的黄褐土、黑土和褐土土壤有效态Cu占比分别降低12.85%、4.11%和3.68%,而红壤有效态Cu占比随老化时间变化不显著。在黄褐土中,腐殖酸结合态(F4)Cu的占比随猪粪老化时间的延长逐渐增加。施用猪粪显著增加小白菜对Cu的吸收,其中红壤的增幅最大,根系与地上部Cu含量分别显著提高244.5%和381.7%,地上部Cu含量为国家食品中污染物限量标准的1.44~2.56倍。逐步回归分析方程表明小白菜根系Cu的含量与土壤pH、粘粒及腐殖酸结合态(F4)含量呈显著负相关,与猪粪Cu输入量、土壤可溶性有机质含量呈显著正相关。【结论】猪粪的Cu输入显著提高土壤和小白菜的Cu含量。土壤Cu的生物有效性不仅受土壤性质的影响,猪粪本身及在土壤中分解产生的腐殖酸和水溶性有机质对Cu的有效性也有较大的影响。通过比较不同的土壤类型,施用含Cu猪粪在红壤-作物系统中存在相对较高的重金属污染风险。

[Objective] The concentration of heavy metals in pig manure and its impact on the bioavailability of heavy metals in soil has long been a worldwide concern. The manure with copper(Cu) will be added to soils and the Cu fractions will be determined in soils and Chinese cabbage, in order to make sure the Cu accumulation and bioavailability. [Methods] In this study, 1% and 3% of rotten pig manure(dry pig manure∶straw = 10∶1) were added to yellow cinnamon soil, red soil, black soil and cinnamon soil. After aging for 0, 1, 2, 3 and 5 months respectively, a pot experiment of Chinese cabbage was carried out. [Results] The results showed that the total amount of Cu in yellow cinnamon soil, red soil, black soil and cinnamon soil increased significantly by 20.23%-50.43%,79.87%-142.6%, 52.41%-76.43% and 41.14%-92.24% respectively. In four soils, the proportions of water-soluble Cu(F1) and carbonate-bounded form Cu(F3) increased and the increase of F1-Cu in RS-0 with 3% pig manure and F2-Cu in YCS-0 were the most significant, which was 4.55% and 16.47% respectively. The proportion of soil iron manganese oxidation form(F5) and organic-bound form(F6) Cu increased, while the concentration of residual(F7)decreased. The proportion of available Cu in soil was significantly negatively correlated with the aging time of pig manure. The proportion of available Cu in yellow cinnamon soil, black soil and cinnamon soil treated with 3% pig manure for 5 months decreased by 12.85%, 4.11% and 3.68% respectively, while that in red soil did not change significantly with the aging time. In yellow cinnamon soil, the proportion of humic acid-bound form(F4) Cu gradually increased with the extension of pig manure aging time. The application of pig manure significantly increased the Cu accumulation in cabbage, and the most significant increase was observed in red soil. The Cu contents in root and shoot increased significantly by 244.5% and 381.7% respectively, and the Cu content in shoot was 1.44-2.56 times higher than the critical value of the national food pollutant limit standard. According to the results of stepwise regression analysis equation, the contents of Cu in Chinese cabbage root system were significantly negatively correlated with soil p H, clay and F4-Cu content, but significantly positively correlated with pig manure Cu input and soil dissolve organic matter. [Conclusion] The Cu input from pig manure significantly increases the Cu contents in soil and Chinese cabbage. The bioavailability of soil Cu is not only affected by soil properties, but also affected by pig manure itself,humic acid and dissolve organic matter in soil. By comparing different soil types, it can be concluded that the application of pig manure containing Cu stands for a relatively high risk of heavy metal pollution in the soil-crop system, especially in red soil.