Understanding the fate of sanitation-related nutrients in a shallow sandy aquifer below an urban slum area

Nyenje, Philip M.; Havik, J.C.N.; Foppen, Jan Willem; Muwanga, Andrew; Kulabako, Robinah

doi:10.1016/j.jconhyd.2014.06.011

Cited by 17 publications

(18 citation statements)

References 58 publications

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“…The average Cl − concentration in groundwater is found to be nearly 40 times higher than in rainwater with concentration (1.5 mg/L) [46], 120 times than spring water (0.55 mg/L) and 37 times higher than deep groundwater (4.7 mg/L) [34]. Similar results were also reported in the aquifers overlain by areas with on-site sanitation and unmanaged wastewater system [7]. Despite the dilution mechanism during the rainy season explained by Todd and Mays [42], the fact that the average Cl − concentration during the wet season is similar to that during the dry season, indicates the infiltration of Cl − from unsaturated soil.…”

Section: Chemical Contamination In Groundwatersupporting

confidence: 75%

“…An increased water table height in a wet season most likely increases the amount of dissolved oxygen in the groundwater carried by precipitation. On the other hand, a higher concentration of dissolved Fe 2+ reflects the reducing condition of the groundwater [7] which is likely to be affected by the dominance of heterotrophic (in presence of carbon) and chemolithoautotrophic reactions (Equations (2) and (3)) [44]. The presence of Fe 2+ in both the clay-and gravel-bearing areas in this study shows the prevalence of a reducing environment followed by the residence time during the dry season.…”

Section: Redox Environmentmentioning

confidence: 67%

“…Both developed and developing countries are experiencing serious issues due to anthropogenic groundwater contamination and recharge through leakage into the water supply network, municipal sewage, and onsite waste disposal [1][2][3][4]. These concerns are more severe in areas in which groundwater is the primary source of fresh water [5,6], as well as in the densely populated areas of developing countries due to improper infrastructure [7][8][9]. The groundwater beneath such areas may contain various organic and inorganic compounds that readily affect the groundwater environment [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Although the status of nitrogen contamination was reported previously, continuous monitoring of nitrogen contamination in groundwater is important to reveal the current conditions with respect to the growing population. Regardless of the contamination distribution, the availability of nitrogen compounds depends upon the redox processes in groundwater [7]. Rainfall also controls the redox processes in unsaturated zones by introducing dissolved oxygen during its infiltration.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal

Shakya

Nakamura

Kamei

et al. 2019

Water

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: The increasing concentration of nitrogen compounds in the groundwater is of a growing concern in terms of human health and groundwater quality. Although an excess of nitrogen compounds in the groundwater of the Kathmandu Valley has been reported, the seasonal variations of the fate of the nitrogen compounds and their relationships to the subsurface sediments are unknown. In this study, spatially distributed shallow dug well samples were collected during both the dry and wet seasons of 2016, and the nitrogen compound, chloride (Cl−), and iron (Fe2+) concentrations were analyzed. Two shallow dug wells and one deep tube well were monitored monthly for 2 years. Although NH4-N concentrations were similar in the clay-dominated areas during both seasons (1 and 0.9 mg-N/L), they were lower in the gravel-dominated areas during wet season (1.8 > 0.6 mg-N/L). The NO3-N concentration differed depending upon the soil type which increased during the wet season (clay 4.9 < 13.6 mg-N/L and gravel 2.5 < 6.8 mg-N/L). The Fe2+ concentration, however, was low during the wet season (clay 2.7 > 0.4 mg/L and gravel 2.8 > 0.3 mg/L). Long-term analysis showed higher fluctuation of nitrogen compounds in the gravel-bearing areas than in the clay-bearing areas.

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Section: Chemical Contamination In Groundwatersupporting

confidence: 75%

Section: Redox Environmentmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal

Shakya

Nakamura

Kamei

et al. 2019

Water

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“…Further, entry of groundwater into the pits cannot be ruled out. While raised pit latrines were reportedly fully lined, research has shown that the contamination of shallow aquifers in slum areas of Kampala is attributed to wastewater infiltration from pit latrines (Nyenje, Foppen, Kulabako, Muwanga, & Uhlenbrook, 2013;Nyenje, Havik, Foppen, Muwanga, & Kulabako, 2014). Therefore, pit latrines are either not fully lined or they leak.…”

Section: Relating Status Of Pit Latrines To Their Performancementioning

confidence: 99%

Performance of pit latrines in urban poor areas: A case of Kampala, Uganda

Nakagiri

Kulabako

Nyenje

et al. 2015

Habitat International

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a b s t r a c tIn many urban poor areas of Sub-Saharan Africa (SSA), demand for human excreta disposal is met, predominantly by pit latrines. This study aimed at determining the status of pit latrines (design, construction, operation and maintenance) and its influence on latrine performance (filling, smell and insect nuisance). The study was conducted on 130 pit latrines in typical urban poor areas of Kampala, Uganda. Data on design, construction, usage, operation and performance of the pit latrines was collected by interviews, observations and measurements; and analysed by descriptive statistics, bi-variate analysis and logistic regression. Results showed that the level of pit content was predicted by rain or storm water entry, terrain, cleaning before or after use and number of households using the latrine. Smell was predicted by cleanliness, stance length, superstructure material and whether the latrine was private or public. The predictor of presence of flies was the superstructure material. To improve the performance of pit latrines in urban poor areas, researchers and practitioners should develop local latrine design standards (dimensions, construction materials and number of users) and cleaning guidelines for local policy makers to implement.

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Hydrogeology of an urban weathered basement aquifer in Kampala, Uganda

et al. 2022

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Weathered basement aquifers are vital sources of drinking water in Africa. In order to better understand their role in the urban water balance, in a weathered basement aquifer in Kampala, Uganda, this study installed a transect of monitoring piezometers, carried out spring flow and high-frequency groundwater level monitoring, slug tests and hydrochemical analyses, including stable isotopes and groundwater residence time indicators. Findings showed a typical weathered basement aquifer with a 20–50-m thickness. Groundwater recharge was 3–50 mm/year, occurring during sustained rainfall. Recharge to a deep groundwater system within the saprock was slow and prolonged, while recharge to the springs on the valley slopes was quick and episodic, responding rapidly to precipitation. Springs discharged shallow groundwater, mixed with wastewater infiltrating from onsite sanitation practices and contributions from the deeper aquifer and were characterised by low flow rates (< 0.001 m3/s), low pH (<5), high nitrate values (61–190 mg/L as NO3), and residence times of <30 years. The deeper groundwater system occurred in the saprolite/saprock, had low transmissivity (< 1 × 10−5 m2/s), lower nitrate values (<20 mg/L as NO3), pH 6–6.5 and longer residence times (40–60 years). Confined groundwater conditions in the valleys were created by the presence of clay-rich alluvium and gave rise to artesian conditions where groundwater had lower nitrate concentrations. The findings provide new insights into weathered basement aquifers in the urban tropics and show that small-scale abstractions are more sustainable in the deeper groundwater system in the valleys, where confined conditions are present.

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Understanding the fate of sanitation-related nutrients in a shallow sandy aquifer below an urban slum area

Cited by 17 publications

References 58 publications

Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal

Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal

Performance of pit latrines in urban poor areas: A case of Kampala, Uganda

Hydrogeology of an urban weathered basement aquifer in Kampala, Uganda

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