酸碱度对山地农村沟渠底泥营养盐动态迁移的影响

  目的  酸碱度是影响沟渠底泥营养盐迁移释放的关键性因子。探究不同pH条件下山地农村沟渠底泥营养盐释放迁移的动态变化，为农村生态环境治理提供理论依据。  方法  采集滇池流域典型山地农村沟渠底泥，通过室内模拟实验测定未灭菌与灭菌处理下不同pH (5.5、7.5、9.5、11.5)条件的底泥、上覆水中营养盐含量，估算底泥-水界面营养盐释放通量。  结果  底泥中总氮质量分数随着pH升高而减少，未灭菌组强碱性(pH 11.5)和酸性(pH 5.5)条件下总氮释放通量分别是对照(pH 7.5)的8和4倍，灭菌组均为对照的2倍。上覆水中溶解性总磷质量浓度和释放通量随pH升高而增加，未灭菌组强碱性(pH 11.5)和弱碱性(pH 9.5)条件下溶解性总磷释放通量分别是对照的12和4倍，灭菌组分别是对照的30和15倍；未灭菌组溶解性总磷释放通量高于灭菌组。冗余分析表明:酸性条件促进底泥中钙结合态磷(Ca-P)的释放，碱性(pH≥9.5)条件促进总氮、总磷和铁铝结合态磷(Fe/Al-P)的释放，中性(pH 7.5)条件对底泥中氮/磷释放影响较小。  结论  碱性(pH≥9.5)和酸性显著促进山地农村沟渠底泥中氮磷营养盐释放，中性条件下释放量最小。底泥灭菌处理降低了不同pH下的微生物活性，阻碍山地农村沟渠底泥中氮磷向上覆水体迁移释放。图6表1参36

Effects of pH on the dynamic migration of nutrient salts in the sediment of ditches in mountain rural areas

  Objective  As pH is a key factor affecting the migration and release of nutrients in the ditch sediment, this study, with an investigation of the dynamic changes of nutrient release and migration in the bottom mud of mountainous rural ditches under different pH conditions, is aimed to provide a theoretical basis for rural ecological environment management.  Method  With the bottom mud of typical mountainous rural ditches in the Dianchi Lake Basin collected, indoor simulation experiments were conducted to determine the nutrient salt content of the bottom mud and the overlying water under different pH (pH 5.5, 7.5, 9.5, 11.5) conditions under non-sterilized and sterilized treatments after which the nutrient release flux at the sediment-water interface was estimated.  Result  The mass fraction of total nitrogen (TN) in the bottom sludge decreased with the increase of pH. The total nitrogen release flux under the strong alkaline (pH 11.5) and acidic (pH 5.5) conditions of the non-sterilized group was 8 and 4 times of the control (pH 7.5), and its release flux in the sterilization group was 2 times of that in the control. The mass concentration and release flux of soluble total phosphorus (DTP) in the overlying water increased with the increase of pH. The release of DTP under the conditions of strong alkaline (pH 11.5) and weak alkaline (pH 9.5) in the non-sterilized group was 12 and 4 times of that in the control, respectively, and its release flux in the sterilized group was 30 and 15 times of that in the control while the non-sterilized group had higher DTP release flux than the sterilized group. RDA shows that acidic conditions promote the release of calcium-bound phosphorus (Ca-P) in sediments, and alkaline (pH≥9.5) conditions promote the release of total nitrogen, total phosphorus and iron-aluminum-bound phosphorus (Fe/Al-P). Neutral (pH 7.5) conditions have little effect on the release of nitrogen or phosphorus in the sediments.  Conclusion  Alkalinity (pH≥9.5) and acidity significantly promote the release of nitrogen and phosphorus nutrients in the bottom mud of mountain rural ditches, and the release amount is the smallest under neutral conditions. Also, the sterilization of the bottom sludge reduces the microbial activity at different pH levels, and prevents the migration and release of nitrogen and phosphorus in the bottom sludge of mountain and rural ditches to the overlying water. Ch, 6 fig. 1 tab. 36 ref.]