基于Meta分析的污废水灌溉对土壤物理性质的影响研究

A Meta-Analysis of the Effects of Wastewater Irrigation on Soil Physical Properties

摘要: 为探究污废水(如再生水、生活污水等)作为农业灌溉替代水源时，对土壤物理性质的影响效应。本研究采用Meta分析方法，系统评估了污废水灌溉对土壤物理性质(土壤粒径分布、孔隙率、含水量、田间持水量及容重)的影响，旨在明确不同水质参数(如pH、电导率EC、总溶解固体TDS、悬浮固体SS)和污废水类型的影响效应机制。研究整合了来自全球48个试验站点、52篇文献的286组数据，以清水灌溉为对照组，通过随机效应模型计算的响应比(Response Ratio, RR)及亚组分析，探讨水质要素、污废水类型对不同深度土壤物理性质的调节作用。结果表明，采用中性至微碱性范围内以及较高的悬浮固体浓度(>100 mg·L⁻¹)的污废水灌溉条件下，土壤孔隙率和持水能力得到提升。当灌溉水电导率为700~3000 μS·cm⁻¹ 时，对土壤物理性质的整体改善效果更为显著，不仅能增加土壤孔隙率、含水量和田间持水量，还可降低土壤容重。然而，因受样本量所限，总溶解固体对土壤物理性质的量化影响范围尚未明确。除水质参数外，污废水类型亦对土壤物理性质具有显著影响。再生水、市政污水等污染物负荷较低的污废水类型，有助于提高孔隙结构，增强土壤含水能力，降低土壤容重。而生活污水灌溉会对土壤物理性质产生不利影响。此外，污废水灌溉对土壤物理性质的影响具有显著的空间异质性和参数依赖性。总体而言，相对于清水灌溉，污废水灌溉可使表层土壤(0~10 cm)含水量提升12.92%，孔隙率增加2.62%~4.31%，容重降低1.01%；但会使深层土壤(60~70 cm)含水量降低28.01%，田间持水量降低11.68%。通过Meta分析进一步研究表明，采用水质参数为pH 7.0~8.0、EC 1000~2000 μS·cm⁻¹、SS 100~150 mg·L⁻¹的污废水进行灌溉可有效改善土壤物理结构并增强保水能力。上述水质参数范围可为以土壤健康为目标的精准灌溉策略提供依据，并有助于确定相应的灌溉用污废水处理要求。

Abstract: Effects of Alternative Water Sources for Agricultural Irrigation (e.g., Reclaimed Water, Domestic Wastewater) on Soil Physical Properties: A Meta-Analysis. This study employs a Meta-analytical approach to systematically evaluate the impact of wastewater irrigation on key soil physical properties, including soil particle size distribution, porosity, water content, field capacity, and bulk density. The research aims to elucidate the underlying mechanisms of influence associated with different water quality parameters (such as pH, electrical conductivity [EC], total dissolved solids [TDS], and suspended solids [SS]) and types of wastewater. Data from 286 observations across 48 experimental sites worldwide, as reported in 52 publications, were synthesized. Using freshwater irrigation as the control, the response ratio (RR) was calculated via a random-effects model, supplemented by subgroup analysis to examine the regulatory roles of water quality factors and wastewater types on soil physical properties at varying depths. The results indicate that irrigation with wastewater within a neutral to slightly alkaline pH range and with elevated suspended solids concentrations (>100 mg·L⁻¹) enhances soil porosity and water-holding capacity. When the irrigation water electrical conductivity ranges from 700 to 3000 μS·cm⁻¹, the overall improvement in soil physical properties is more pronounced, manifesting as increased soil porosity, water content, and field capacity, alongside a reduction in soil bulk density. However, due to limited sample size, the quantitative impact range of total dissolved solids on soil physical properties remains unclear. Beyond water quality parameters, the type of wastewater also significantly affects soil physical properties. Wastewater with lower pollutant loads, such as reclaimed water and municipal wastewater, contributes to improved pore structure, enhanced soil water retention capacity, and decreased bulk density. In contrast, irrigation with domestic wastewater adversely affects soil physical properties. Furthermore, the impact of wastewater irrigation exhibits significant spatial heterogeneity and parameter dependency. Overall, compared to freshwater irrigation, wastewater irrigation increases the water content of surface soil (0~10 cm) by 12.92%, raises porosity by 2.62% to 4.31%, and reduces bulk density by 1.01%. However, it decreases the water content of deeper soil layers (60~70 cm) by 28.01% and reduces field capacity by 11.68%. Further Meta-analytic research indicates that irrigation utilizing wastewater with specific water quality parameters—namely a pH range of 7.0~8.0, electrical conductivity (EC) of 1000~2000 μS·cm⁻¹, and suspended solids (SS) concentration of 100~150 mg·L⁻¹—can effectively enhance soil physical structure and improve water retention capacity. This defined range of water quality parameters provides a scientific basis for developing precision irrigation strategies aimed at soil health preservation. Furthermore, it offers critical guidance for establishing corresponding treatment standards for wastewater intended for agricultural irrigation use.