黄土高原半干旱地区尾菜高量还田的环境风险及其成本约束机制

尾菜还田能够培肥低质黄土,但其高量还田是否带来环境二次污染并由此增加处理成本等问题仍不清楚。在黄土高原半干旱区,采用覆土埋压方法设计了3个尾菜高量还田厚度(20 cm、40 cm和60 cm)和3个覆土厚度(10 cm、20 cm和30 cm)随机组合的小区试验,和两个中型试验(尾菜还田厚度350 cm,覆土厚度30 cm),调查了尾菜降解率、土壤表面NH_(3)和H_(2)S排放速率、土壤重金属和农药残留量、盐离子含量以及工程成本等数据。结果显示,所有处理尾菜累积降解率均呈对数增长曲线,其表现先快后慢,第20天和第35天小区和中型试验场尾菜降解率均达70.0%以上,之后趋缓;还田尾菜厚度60 cm、覆土厚度10~30 cm,较对照全菜(60 cm厚尾菜露天堆放)的NH_(3)和H_(2)S排放量分别减少71.0%~86.0%和84.9%~87.9%。覆土表面NH_(3)排放速率时间序列均呈单窄峰值曲线,峰值大小和排放量与还田尾菜厚度呈显著正相关(P<0.05),与覆土厚度呈显著负相关(P<0.05)。小区试验覆土表面H_(2)S排放量与对照全土(翻耕0~30 cm土壤)无显著差异,但中型试验场的H_(2)S排放量明显增加。尾菜还田量越大,污染物排放强度越小;中型试验场尾菜层及其上层和下层土壤重金属、农药残留量、Ca^(2+)含量均与对照全土无显著差异,而Na^(+)向深土层淋洗。中型试验场尾菜还田量与处理成本呈幂律负相关关系,尾菜还田量越大,其处理成本越低,最低成本均值可至25.0±7元∙t^(−1)(鲜重)。因此,在黄土高原半干旱区,采用覆土埋压法高量还田尾菜是一种低成本、简便易行和生态环保的尾菜高效处理方案。

Analysis of the Effect of Combined DesensitizingAcupoints Therapy in Treating 419 Cases of Allergic Rhinitis Accompanied Asthma

Objective: To explore the effect of combined acupoint desensitizing therapy.Methods: A total of 419 cases of allergic rhinitis accompanied with asthma were treated by combined acupoint desensitizing therapy with positive allergen extract on acupoints of head and upper back region.Results: After 3 courses of treatment, skin test repeated with responding allergen extract showed that the scope of redness and swelling of skin were smaller than those before treatment,P < 0.01. The3H-TdR incorporation lymphocyte transformation rate, acidophil count, IgA, IgG level and E-rosette formation rate of acupoint desensitizing group were different significantly from those of the two control groups (the acupoint 0.85% normal saline injection group and the subcutaneous desensitizing group),P < 0.01 orP < 0.05. Follow-up study for over 3 years showed that the markedly effective rate of the acupoint desensitizing group was 68.73%, the effective rate 29.12% and total effective rate, 97.85%. The effect was higher than that of the two control groups, P<0.01.Conclusion: Combined acupoint desensitizing therapy is valuable and worthy of popularizing in treating patients of allergic rhinitis accompanied asthma.