Abstract：
Anthropogenic disturbance of soils can disrupt soil structure, diminish fertility, alter soil chemical properties, and cause erosion. Current remediation practices involve amending degraded urban topsoils lacking in organic matter and nutrition with organic amendments (OA) to enhance vegetative growth. However, the impact of OAs on water quality and structural properties at rates that meet common topsoil organic matter specifications need to be studied and understood. This study tested three commonly available OAs: shredded wood mulch, leaf-based compost, and class A Exceptional Quality stabilized sewage sludge (or biosolids) for nutrient (nitrogen and phosphorus) water quality, soil shear strength, and hydraulic properties, through two greenhouse tub studies. Findings showed that nitrogen losses to leachate were greater in the biosolids amended topsoils compared to leaf-compost, mulch amended topsoils, and control treatments. Steady-state mean total nitrogen (N) concentrations from biosolids treatment exceeded typical highway stormwater concentrations by at least 25 times. Soil total N content combined with the carbon:nitrogen ratio were identified to be the governing properties of N leaching in soils. Study soils, irrespective of the type of amendment, reduced the applied (tap) water phosphorus (P) concentration of ∼0.3 mg-P/L throughout the experiment. Contrary to the effects on N leaching, P was successfully retained by the biosolids amendment, due to the presence of greater active iron contents. A breakthrough mechanism for P was observed in leaf compost amended soil, where the effluent concentrations of P continued to increase with each rainfall application, possibly due to an saturation of soil adsorption sites. The addition of OAs also improved the strength and hydraulic properties of soils. The effective interlocking mechanisms between the soil and OA surfaces could provide soil its required strength and stability, particularly on slopes. OAs also improved soil fertility to promote turf growth. Presence of vegetative root zones can further reinforce the soil and control erosion.
摘要：
人为干扰土壤会破坏土壤结构，减少生育能力，改变土壤化学性质，并造成侵蚀。当前的修复实践涉及使用有机改良剂（OA）修改缺乏有机物和营养的退化的城市表层土壤，以增强营养生长。然而,需要研究和了解OAs对水质和结构特性的影响，以满足常见的表层土壤有机质规格。这项研究测试了三种常见的OAs：切碎的木材覆盖物，叶基堆肥，和A类特殊质量稳定的污水污泥（或生物固体），用于营养（氮和磷）水质，土壤抗剪强度,和水力特性通过两个温室浴缸研究。研究结果表明，与叶堆肥相比，生物固体改良的表层土壤中渗滤液的氮损失更大，覆盖改良的表土，控制治疗。来自生物固体处理的稳态平均总氮（N）浓度超过典型的高速公路雨水浓度至少25倍。土壤总氮含量与碳氮比相结合被确定为土壤氮淋溶的主要特性。研究土壤，无论修订的类型如何，在整个实验过程中，将施加的（自来水）水磷（P）浓度降低至〜0.3mg-P/L。与对N浸出的影响相反，P被生物固体修正案成功保留，由于存在较高的活性铁含量。在叶堆肥改良土壤中观察到了P的突破机制，每次降雨时，P的流出物浓度继续增加，可能是由于土壤吸附位点的过饱和。添加OAs还提高了土壤的强度和水力性能。土壤和OA表面之间的有效互锁机制可以为土壤提供所需的强度和稳定性，尤其是在斜坡上。OAs还提高了土壤肥力以促进草坪生长。植被根区的存在可以进一步增强土壤并控制侵蚀。
