Laboratório de Microbiologia e Toxicologia, PPG em Biologia, Universidade do Vale do Rio dos Sinos, UNISINOS, C.P. 275, CEP 93001-970, São Leopoldo, Rio Grande do Sul, Brazil.
Environ Monit Assess. 2013 Mar;185(3):2767-75. doi: 10.1007/s10661-012-2747-1. Epub 2012 Jul 3.
In this study, we evaluate spatial and temporal variations of the water's quality used in rice fields. Every 15 days during the different phases of cultivation of the rice-vegetative, reproductive, and maturity-samples were collected from the main irrigation channel, from the surface water in the field, and from the excess-water drainage channel. The differences in the values of 13 variables were analyzed by the analysis of variance system and by the Principal Component Analysis (PCA) technique. The results demonstrate that the values observed for the presence of total coliforms, heat-tolerant coliforms, and pH were higher in the irrigation water and that the calcium and magnesium components were greater in the drainage water. The PCA results indicate that three groups of variance exist and that these three account for 77 % of the observed variances. The first principal component, (39 % of the variances), includes the variables pH, phosphorus, potassium, carbon, and turbidity; the second (28.1 %), calcium, magnesium, and conductivity; while the third accounts for only 9.9 % of the variation and incorporates the variable biological thermotolerant coliforms. The spatial pattern resulting from the distribution of the sampling locations as regards the first two principal components indicates a difference between the irrigation and drainage waters. The variables of the first and third items (except for the turbidity in the second component) reach higher values in the irrigation water, while the variables associated with the second component have higher values in the drainage water. The information provided is important for the analysis of the influence exercised by plantation management decisions on the microbiological, physical, and chemical quality of the water. The results confirm the ability of paddy rice field to filter out some of the chemicals and coliforms from the irrigation water as it passes through the agro ecosystem.
本研究评估了稻田用水的时空水质变化。在水稻生长的不同阶段，每隔 15 天，从主要灌溉渠道、田间地表水和过量排水渠采集水样。通过方差分析系统和主成分分析（PCA）技术分析了 13 个变量值的差异。结果表明，灌溉水中总大肠菌群、耐热大肠菌群和 pH 值的含量较高，而排水水中钙镁成分较高。PCA 结果表明存在三组方差，这三组方差占观测方差的 77%。第一主成分（39%的方差）包括 pH 值、磷、钾、碳和浊度；第二主成分（28.1%）包括钙、镁和电导率；而第三主成分仅占 9.9%的变异，包含生物耐热大肠菌群这一变量。采样位置的空间分布模式对前两个主成分的差异表明，灌溉水和排水水之间存在差异。第一和第三个项目的变量（第二主成分中的浊度除外）在灌溉水中的数值较高，而与第二主成分相关的变量在排水水中的数值较高。这些信息对于分析种植管理决策对水的微生物、物理和化学质量的影响具有重要意义。结果证实了水稻田在通过农业生态系统时，能够过滤掉一些灌溉水中的化学物质和大肠菌群。
