Temporal Variability of Faecal Contamination from On-Site Sanitation Systems in the Groundwater of Northern Thailand
Temporal Variability of Faecal Contamination from On-Site Sanitation Systems in the Groundwater of Northern Thailand
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DOI：
10.1007/s00267-018-1016-7
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发表时间：
2018-06-01
影响因子：
3.5
通讯作者：
Ziegler, Alan D.
中科院分区：
文献类型：
--
作者：
Chuah, C. Joon;Ziegler, Alan D.
我们调查了现场卫生系统对当地地下水的影响。在这项为期一年的研究中，我们监测了粪便污染水平对包括降雨量和地下水位在内的水文气候因素的反应。粪便浓度指标--E.每隔7~14d对13对浅井和深井进行大肠埃希菌(ESC)、肠球菌(ENT)、硝酸盐-的检测。所有来自浅井的样本粪便污染检测呈阳性(ESC和ENT>；1 MPN/100毫升)，但浓度有所不同。在一些浅井中，最高记录到24000 mpn/100mL。来自深井的水对污染的敏感性较低，只有4%的样本ESC和23%的样本ENT呈阳性。ESC和ENT的浓度也较低，最大浓度分别为5MPN/100mL和28MPN/100mL。水井之间的污染波动通过四种典型的水文气候强迫反应来描述：(I)雨季开始时的冲刷，(Ii)雨季过程中的稀释，(Iii)旱季期间的浓度，以及(Iv)对风暴的天气反应。以前试图将粪便/水传播疾病的流行与时间因素(例如旱季与雨季)联系起来的研究产生了不同的结果。我们的研究可能有助于解释导致这些不同观测结果的相关水文机制。目前，泰国的大多数社区都有“改进”的卫生系统。然而，由于这些系统的不可持续实施，原本可行的饮用水资源以丰富的当地地下水的形式已经成为真正的健康危害。
We investigated the impacts of on-site sanitation systems to local groundwater. In this year-long study, we monitored the response of faecal contamination levels to hydroclimatological factors including rainfall and groundwater table. Concentration of faecal indicators-E. coli (ESC), Enterococcus (ENT), nitrate-in thirteen pairs of shallow and deep wells were determined every 7-14 days. All samples from shallow wells were tested positive for faecal contamination (ESC and ENT > 1 MPN/100 mL) but concentration varies. A maximum of 24,000 MPN/100 mL were recorded in some shallow wells. Water from deep wells showed lower susceptibility to contamination with only 4 and 23% of samples tested positive for ESC and ENT, respectively. Concentrations of ESC and ENT were lower too, with a maximum of 5 MPN/100 mL and 28 MPN/100 mL, respectively. Fluctuation in contamination among the wells was described by four archetypal responses to hydroclimatological forcing: (i) flushing during the onset of wet season, (ii) dilution over the course of the wet season, (iii) concentration during the dry season, and (iv) synoptic response to storms. Previous studies attempting to link the prevalence of faecal/waterborne diseases and temporal factors (e.g., dry vs wet season) have produced differing outcomes. Our study may help explain the relevant hydrological mechanisms leading to these varying observations. Presently, most communities in Thailand have access to 'improved' sanitation systems. However, due to the unsustainable implementation of these systems, the otherwise viable drinking-water resources in the form of the abundant local groundwater has become a genuine health hazard.