宁夏主要枸杞产地土壤环境质量现状与评价

为了摸清宁夏主要枸杞产地土壤环境质量现状,2013年分别在宁夏中宁(n=48)和惠农(n=18)对≤5年、6~10年和≥10年不同树龄枸杞地0~30 cm耕层土壤环境和浅层地下水进行监测,分析评价了枸杞地土壤肥力、土壤重金属含量和浅层地下水水质现状。结果表明,宁夏中宁和惠农不同树龄枸杞地0~30 cm土壤有机质、全氮、有效磷和速效钾含量变幅分别为14.2~16.8 g/kg、0.94~1.16 g/kg、79.1~305.0 mg/kg和183.3~292.3 mg/kg,土壤有机质和全氮含量随着树龄增加而呈增加的趋势。两枸杞产地土壤有机质含量处于二级和三级水平,土壤全氮含量处于一级和二级水平,土壤有效磷和速效钾含量都达到一级标准。不同树龄枸杞0~30 cm耕层土壤有效锌、有效锰、有效铜和有效铁含量分别为0.91~2.55、6.58~7.42、1.32~2.99和16.40~53.90 mg/kg,两枸杞产地土壤有效锌和有效锰已经出现潜在缺乏现象。不同树龄枸杞地0~30 cm土壤铅、镉和砷含量分别在20.6~22.9、0.177~0.304和9.6~12.2 mg/kg之间,均处于安全等级。中宁枸杞地冬灌后浅层地下水(n=9)矿化度、p H值、总氮和总磷平均分别为1.54 g/L、7.59、15.81 mg/L和0.13 mg/L,总氮、总磷含量分别达到地表水劣Ⅴ类和Ⅲ类水标准。因此,两枸杞产地土壤有机质、全氮及锰、锌含量与树龄大小有关,而土壤铅、镉、砷含量与基础环境背景值相关。总体来说,目前宁夏中宁和惠农枸杞产地土壤环境质量尚安全,但浅层地下水已出现不同程度的氮、磷污染。

Evaluation and present situation of soil environmental quality in the major wolfberry production areas of Ningxia

In order to make clear the present situation of soil environmental quality in the major wolfberry production areas of Ningxia, soil sampling from 0~30 cm and shallow groundwater monitoring was conducted in wolfberry fields of ≤5, 6~10, and ≥10 tree years in Zhongning (n=48) and Huinong (n=18) of Ningxia in 2013, and evaluated the situation of soil fer-tility, soil heavy mental content, and shallow groundwater quality in the different tree years wolfberry fields. The results indi-cated that soil organic matter, total N, available P and K contents in topsoil of 0~30 cm were ranged from 14. 2~16. 8 g/kg, 0.94~1.16 g/kg, 79. 1~305.0 mg/kg and 183.3~292. 3 mg/kg in Zhongning and Huinong wolfberry fields, respectively;soil organic matter and total N contents were increased with wolfberry growing years increasing. In these wolfberry fields, soil organic matter content was in the second and third class, soil total N was in the first and second class, and available P, K be-longed to the first class. Soil available Zn, Mn, Cu, and Fe contents in topsoil of 0 ~30 cm were 0.91 ~2. 55, 6.58 ~7.42, 1.32~2. 99 and 16.40~53. 90 mg/kg in different tree years wolfberry fields, respectively; and there was potential de-ficiency of Zn and Mn in topsoil in the studied wolfberry fields. Soil Pb, Cd, and As contents were ranged from 20. 6~22. 9,0.177~0.304 and 9.6~12.2 mg/kg in the topsoil of 0~30 cm in both Zhongning and Huinong wolfberry fields, respective-ly; these heavy mental elements were still in security classification. Degree of mineralization, pH, total N and P in shallow groundwater (n=9) after winter irrigation by the Yellow River water were 1.54 g/L, 7.59, 15.81 mg/L, and 0. 13 mg/L in Zhongning wolfberry fields, respectively; and total N and P content in groundwater reached class ofⅤandⅢ, respective-ly. Therefore, the contents of soil organic matter, total N, and Mn, Zn were related to tree years of wolfberry, but soil Pb, Cd, and As contents were relevant to the background of environmental value. Generally, soil environmental quality was still in security in the major wolfberry production areas of Zhongning and Huinong wolfberry fields in Ningxia, however, shallow groundwater had been more or less polluted by N and P.