School of Geography and the Environment, University of Oxford, South Parks Road, OX1 3QY Oxford, United Kingdom.
School of Earth Sciences, Addis Ababa University, Arat Killo Campus, NBH1 King George VI St, Addis Ababa, Ethiopia.
Sci Total Environ. 2023 Dec 15;904:166929. doi: 10.1016/j.scitotenv.2023.166929. Epub 2023 Sep 7.
Reliance on groundwater is increasing in Sub-Saharan Africa as development programmes work towards improving water access and strengthening resilience to climate change. In lower-income areas, groundwater supplies are typically installed without water quality treatment infrastructure or services. This practice is underpinned by an assumption that untreated groundwater is typically suitable for drinking due to the relative microbiological safety of groundwater compared to surface water; however, chemistry risks are largely disregarded. This article systematically reviews groundwater chemistry results from 160 studies to evaluate potential health risk in two case countries: Ethiopia and Kenya. Most studies evaluated drinking water suitability, focusing on priority parameters (fluoride, arsenic, nitrate, or salinity; 18 %), pollution impacts (10 %), or overall suitability (45 %). The remainder characterised general hydrogeochemistry (13 %), flow dynamics (10 %), or water quality suitability for irrigation (3 %). Only six studies (4 %) reported no exceedance of drinking water quality thresholds. Thus, chemical contaminants occur widely in groundwaters that are used for drinking but are not regularly monitored: 78 % of studies reported exceedance of contaminants that have direct health consequences ranging from hypertension to disrupted cognitive development and degenerative disease, and 81 % reported exceedance of aesthetic parameters that have indirect health impacts by influencing perception and use of groundwater versus surface water. Nevertheless, the spatiotemporal coverage of sampling has substantial gaps and data availability bias is driven by a) the tendency for research to concentrate in areas with known water quality problems, and b) analytical capacity limitations. Improved in-country analytical capacity could bolster more efficient assessment and prioritisation of water chemistry risks. Overall, this review demonstrates that universal and equitable access to safe drinking water (Sustainable Development Goal target 6.1) will not be achieved without wider implementation of groundwater treatment, thus a shift is required in how water systems are designed and managed.
由于发展计划致力于改善供水并增强对气候变化的适应能力，撒哈拉以南非洲地区对地下水的依赖度正在增加。在低收入地区，地下水供应通常在没有水质处理基础设施或服务的情况下安装。这种做法的依据是，由于地下水相对于地表水具有相对较高的微生物安全性，未经处理的地下水通常适合饮用；然而，化学风险在很大程度上被忽视了。本文系统地回顾了 160 项研究的地下水化学结果，以评估两个案例国家（埃塞俄比亚和肯尼亚）的潜在健康风险。大多数研究评估了饮用水的适宜性，重点关注优先参数（氟化物、砷、硝酸盐或盐度；18%）、污染影响（10%）或整体适宜性（45%）。其余的则描述了一般水文地球化学（13%）、水流动力学（10%）或灌溉用水质量适宜性（3%）。只有 6 项研究（4%）报告没有超过饮用水质量阈值。因此，用于饮用的地下水广泛存在化学污染物，但这些污染物并未得到定期监测：78%的研究报告称，直接影响健康的污染物超标，范围从高血压到认知发育障碍和退行性疾病；81%的研究报告称，感官参数超标，通过影响地下水与地表水的感知和使用，间接影响健康。尽管如此，采样的时空覆盖范围仍存在很大差距，数据可用性偏差主要由以下因素驱动：a）研究倾向于集中在已知水质问题的地区，b）分析能力的限制。提高国内的分析能力可以加强对水化学风险的更有效评估和优先排序。总体而言，本综述表明，如果不更广泛地实施地下水处理，普遍和公平地获得安全饮用水（可持续发展目标 6.1 目标）将无法实现，因此需要转变水系统的设计和管理方式。
