Purpose

This study was conducted to assess the capability of the lumped parameter model (LPM), an efficient model due to its analytical nature and the limited data requirements, to estimate health risks from nitrate in groundwater in arid and semi-arid climates.

Methods

To assess the capability of LPM, two scenarios were established: one for estimation of hazard quotient (HQ) via monitoring nitrate concentration in groundwater and the other using the LPM. After nitrate was monitored in 148 randomly-selected wells, a modified LPM was used to estimate water volume and nitrate concentration, which ultimately led to the development of a model for estimating HQ. The performances of LPM were assessed using the coefficient of determination, percentage standard deviation, and root mean square error. To compare health risk maps Kriging, Spline, Inverse distance weighted, and natural neighbor models were run using geographical information system (GIS).

Results

Linear analysis revealed a strong correlation between HQ values estimated in LPM and monitoring scenarios in arid climate compared to semi-arid (r = 0.962, n = 22, p = 0.00), suggesting that the LPM was more accurate in predicting nitrate concentration in the arid climate. Uncertainty analysis showed that LPM outputs were sensitive to several parameters, especially leakage from cesspits, which are involved in the sources and sinks of nitrate in the groundwater. In addition, it was found that the natural neighbor was the most appropriate model with the lowest errors for preparing health risk maps from nitrate.

Conclusions

The obtained results revealed that LPM can be effectively used to estimate nitrate concentration in groundwater in arid climates and thereby LPM is an appropriate model to estimate health risk from nitrate in this climate.

中文翻译：

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用于研究干旱和半干旱气候条件下饮用水中硝酸盐浓度和健康风险评估的集总参数模型。

目的

本研究旨在评估集总参数模型 (LPM) 的能力，这是一种有效的模型，由于其分析性质和有限的数据要求，可估计干旱和半干旱气候中地下水中硝酸盐的健康风险。

方法

为了评估 LPM 的能力，建立了两种情景：一种是通过监测地下水中的硝酸盐浓度来估计危害商 (HQ)，另一种是使用 LPM。在随机选择的 148 口井中监测硝酸盐后，使用改进的 LPM 来估计水量和硝酸盐浓度，最终导致开发了用于估计 HQ 的模型。使用决定系数、百分比标准偏差和均方根误差来评估 LPM 的性能。为了比较健康风险图，使用地理信息系统 (GIS) 运行克里金法、样条曲线、反距离加权和自然邻域模型。

结果

线性分析显示，与半干旱相比，LPM 中估计的 HQ 值与干旱气候监测情景之间存在很强的相关性（r  = 0.962，n  = 22，p  = 0.00），表明 LPM 在预测硝酸盐浓度方面更准确气候干旱。不确定性分析表明，LPM 输出对几个参数很敏感，尤其是污水坑的泄漏，它涉及地下水中硝酸盐的源和汇。此外，发现自然邻域是最合适的模型，用于从硝酸盐制备健康风险图时误差最小。

结论

所得结果表明，LPM 可有效地用于估计干旱气候下地下水中的硝酸盐浓度，因此 LPM 是估计该气候下硝酸盐对健康风险的合适模型。