Chen Su, Sun Lina, Sun Tieheng, Chao Lei, Guo Guanlin
Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
Environ Geochem Health. 2007 Oct;29(5):435-46. doi: 10.1007/s10653-007-9088-y. Epub 2007 Apr 3.
A pot experiment was conducted to examine the influence of potassium (K) fertilizer (K(2)SO(4)) application on the phytoavailability and speciation distribution of cadmium (Cd) and lead (Pb) in soil. Spring wheat (Triticum aestivum L.) was selected as the test plant. There were seven treatments including single and combined contamination of Cd and Pb. CdCl(2).2.5 H(2)O and Pb(NO(3))(2) were added to the soil at the following dosages: Cd + Pb = 0.00 + 0.00, 5.00 + 0.00, 25.0 + 0.00, 0.00 + 500, 0.00 + 1000, 5.00 + 500 and 25.0 + 1000 mg kg(-1), denoted by CK, T1, T2, T3, T4, T5 and T6, respectively. The K fertilizer had five levels: 0.00, 50.0, 100, 200 and 400 mg K(2)O kg(-1) soil, denoted by K0, K1, K2, K3 and K4, respectively. The results showed that the K fertilizer promoted the dry weight (DW) of wheat in all treatments and alleviated the contamination by Cd and Pb. The application of K(2)SO(4) reduced the uptake of Cd in different parts including roots, haulms and grains of wheat; the optimum dosage was the K2 level. K supply resulted in a significant (P < 0.05) decrease in the soluble plus exchangeable (SE) fraction of Cd and there was a negative correlation (not significant, P > 0.05) between the levels of K and the SE fraction of Cd in soil. The application of the K fertilizer could obviously restrain the uptake of Pb by wheat and there were significant (P < 0.05) negative correlations between the concentrations of Pb in grains and the levels of K in soil. K supply resulted in a decrease in the SE fraction of Pb (except the K1 level) from the K0 to K4 levels. At the same time, the application of the K fertilizer induced a significant (P < 0.05) decrease in the weakly specifically adsorbed (WSA) fraction of Pb and a significant (P < 0.05) increase in the bound to Fe-Mn oxides (OX) fraction of Pb. At different K levels, the concentration of Pb in the roots, haulms and grains had a positive correlation with the SE (not significant, P > 0.05) and WSA (significant, P < 0.05) fractions of Pb in the soil. All the K application levels in this experiment reduced the phytoavailability of Cd and Pb. Thus, it is feasible to apply K fertilizer (K(2)SO(4)) to alleviate contamination by Cd and/or Pb in soil. Moreover, the level of K application should be considered to obtain an optimal effect with the minimum dosage.
进行了一项盆栽试验，以研究施用钾肥（硫酸钾）对土壤中镉（Cd）和铅（Pb）的植物有效性及形态分布的影响。选用春小麦（普通小麦）作为试验植物。试验设置了包括Cd和Pb单一及复合污染在内的7种处理。以如下剂量向土壤中添加氯化镉（CdCl₂·2.5H₂O）和硝酸铅（Pb(NO₃)₂）：Cd + Pb = 0.00 + 0.00、5.00 + 0.00、25.0 + 0.00、0.00 + 500、0.00 + 1000、5.00 + 500和25.0 + 1000 mg kg⁻¹，分别记为CK、T1、T2、T3、T4、T5和T6。钾肥设置了5个水平：0.00、50.0、100、200和400 mg K₂O kg⁻¹土壤，分别记为K0、K1、K2、K3和K4。结果表明，钾肥在所有处理中均促进了小麦的干重，并减轻了Cd和Pb的污染。施用硫酸钾降低了小麦不同部位（包括根、茎和籽粒）对Cd的吸收；最佳施用量为K2水平。钾供应导致土壤中Cd的可溶性加可交换态（SE）组分显著（P < 0.05）降低，且土壤中钾水平与Cd的SE组分之间存在负相关（不显著，P > 0.05）。施用钾肥可明显抑制小麦对Pb的吸收，籽粒中Pb浓度与土壤中钾水平之间存在显著（P < 0.05）负相关。从K0到K4水平，钾供应导致Pb的SE组分降低（K1水平除外）。同时，施用钾肥使Pb的弱专性吸附（WSA）组分显著（P < 0.05）降低，使Pb的铁锰氧化物结合态（OX）组分显著（P < 0.05）增加。在不同钾水平下，根、茎和籽粒中Pb的浓度与土壤中Pb的SE（不显著，P > 0.05）和WSA（显著，P < 0.05）组分呈正相关。本试验中所有钾肥施用量水平均降低了Cd和Pb的植物有效性。因此，施用钾肥（硫酸钾）缓解土壤中Cd和/或Pb污染是可行的。此外，应考虑钾肥施用量，以用最小剂量获得最佳效果。
