北方典型设施蔬菜种植区地下水水质特征

Analysis of the Characteristics of Groundwater Quality in a Typical Vegetable Field,Northern China

为探究设施农业对地下水环境质量的影响,以我国华北平原典型设施蔬菜种植区为研究对象,采用常规理化分析、紫外-可见吸收光谱及荧光光谱技术,结合平行因子分析、主成分分析和二维相关光谱分析方法,对种植区地下水中无机盐、重金属及有机物的来源、组成、赋存分布及可能成因进行了研究.结果表明,设施蔬菜种植区地下水水化学特征为Cl-SO_4型水,硬度高,三氮含量严重超出国家地下水V类质量标准(GB/T 14848-93),重金属含量低于国家生活饮用水卫生标准(GB 5749-2006).氮素中NH_4^+-N的大量累积与较浅的地下水埋深度和强还原环境引起的硝化过程受阻有关,部分有毒亲硫重金属元素含量较高为农药和化肥的施用所致.地下水中溶解性有机物来源相似,由微生物代谢淋溶进入地下水的有机粪肥中组分新近产生为主,其主要成分为小分子易降解的类蛋白物质,同时含有部分与类蛋白物质结合的类富里酸物质.种植区地下水中类富里酸物质在地下水中含量稳定,而类蛋白物质含量受耕作过程有机粪肥的使用影响较大.设施蔬菜种植过程中应科学分配有机粪肥的施用,同时水质电导率、硬度及紫外区UVA波段应作为该种植区日后在线监管的主要指标.

This study explores the impact of facility farming on the origin and composition of groundwater and on the distribution characteristics of inorganic salts,heavy metals,and dissolved organic matter in groundwater in a typical greenhouse vegetable planting area in North China plains. The methods used include conventional analysis,UV-Visible,and fluorescence spectroscopy combined with parallel factor analysis,principle components analysis,and two-dimensional（ 2D） hetero-spectral correlation spectra techniques. The results showed that the hydrochemistry type of groundwater in the facility vegetable field was Cl-SO4,the nitrogen content was higher than the National Groundwater V Class Quality Standard（ GB/T14848-93）,and the heavy metal content was lower than the National Drinking Water Standard（ GB5749-2006）. The nitrification process was blocked due to a strongly reducing atmosphere and shallow depth in groundwater,which caused high concentrations of NH4^＋-N. Part of the toxic sulfur-containing metal content increased after the application of inorganic fertilizers. The sources of dissolved organic matter in groundwater were similar; the organic manure components which leach into groundwater were recently produced by microbial metabolism. The main components of dissolved organic matter were small-molecule-biodegradable protein-like substances and the fulvic-like content binding to them. The fulvic-like content that bound to protein-like content in vegetable planting groundwater was stable,while the protein-like content was greatly influenced by the cultivation process of the organic manure application. In the process of vegetable planting,organic manure should be applied scientifically and the supervision of the planting area is crucial.