Nitrate source apportionment in the complex Nyando tropical river basin in Kenya

Nyilitya, Benjamin; Mureithi, Stephen Mwangi; Bauters, Marijn; Boeckx, Pascal

doi:10.1016/j.jhydrol.2020.125926

Cited by 20 publications

(6 citation statements)

References 61 publications

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“…Figure 8 shows a comparison between this study and tropical/subtropical groundwater nitrate contributions, estimated by Bayesian isotope mixing models. In general, our results agree with pan-tropical/subtropical trends, (Fadhullahet al, 2020;Gribilla et al, 2020;Jung et al, 2023;Liu et al, 2021;Mao et al, 2023;Nyilitya et al, 2021;Saka et al, 2023;Yu et al, 2020). AD: Atmospheric deposition; SN: soil nitrogen; CF: chemical fertilizers; and MS: manure and sewage.…”

Section: Tropical and Subtropical Nitrate Groundwater Legacysupporting

confidence: 90%

“…where the major nitrogen median contributions in mixed land use scenarios are driven by manure and sewage (∼45%) > SN (∼30%) > CF (∼17%) > atmospheric deposition (AD) (∼3%) (Fadhullahet al, 2020;Gribilla et al, 2020;Jung et al, 2023;Liu et al, 2021;Mao et al, 2023;Nyilitya et al, 2021;Saka et al, 2023;Yu et al, 2020). However, our results suggest greater nitrogen AD (Villalobos-Forbes et al, 2021) and manure and sewage contributions compared to the tropics.…”

Section: Tropical and Subtropical Nitrate Groundwater Legacymentioning

confidence: 54%

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Nitrate Legacy in a Tropical and Complex Fractured Volcanic Aquifer System

et al. 2023

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Nitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3− and Cl− concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl− and moderate NO3−/Cl− ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl− ratios and Cl− concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively.

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Section: Tropical and Subtropical Nitrate Groundwater Legacysupporting

confidence: 90%

Section: Tropical and Subtropical Nitrate Groundwater Legacymentioning

confidence: 54%

Nitrate Legacy in a Tropical and Complex Fractured Volcanic Aquifer System

et al. 2023

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“…3.4.2.12 Korhogo source 5 (factor 3). This source, which contributed 2.5% of the PM 2.5 mass, consisted of 78.2% and 42.7% Cl − and NO 3 − , respectively, which according to Nyilitya et al 80 are tracers of the agriculture source, through the use of pesticides, animal manure and fertilizers. Furthermore, chlorine (Cl − ), nitrogen (NO 3 − and NH 4 + ) and potassium (K + ) are the main constituents of pesticides, representing 98.9% of this source, conrming the link with agriculture, which is a very preponderant activity in the area.…”

Section: Environmental Science: Atmospheres Papermentioning

confidence: 98%

Chemical characterization of urban aerosols in Abidjan and Korhogo (Côte d'Ivoire) from 2018 to 2020 and the identification of their potential emission sources

Gnamien,

Liousse,

Keita

et al. 2023

Environ. Sci.: Atmos.

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“…With the purpose of analyzing the relative importance of different nitrate sources, most efforts were focused on applications of SIAR model based on δ 15 N/δ 18 O-NO 3 − (Yue et al, 2014;Nyilitya et al, 2021). In this study, we implemented a SIAR model based on δ 15 N/△ 17 O-NO 3 − for the first time in eastern China to provide a quantitative estimate for the probability distribution of the proportional contributions of nitrate from four potential sources (i.e., AD, SN, NF, and MS).…”

Section: Sources Of Nitratementioning

confidence: 99%