Modelling of nitrate leaching from arable land into unsaturated soil and chalk 2. Model confirmation and application to agricultural and sewage sludge management

Andrews, Richard; Lloyd, John William; Lerner, David N.

doi:10.1016/s0022-1694(97)00008-5

Cited by 10 publications

(3 citation statements)

References 11 publications

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“…The model includes numerous nitrogen processes such as mineralization of soil organic-N and biosolids organic-N, nitrification, crop uptake, volatilization, denitrification, and N inputs from fertilizers and precipitation. Results of associated modeling scenarios were presented in an additional paper (Andrews et al, 1997b). Cartron and Weil (1998) showed differences in nitrogen uptake of corn depending on the application method (injection vs. surface incorporation) at an application rate of 157 kg plant available Nlha.…”

Section: Land Applicationmentioning

confidence: 99%

Simulating disinfection processes in chlorine contact tanks using various turbulence models and high-order accurate difference schemes

Wang

Falconer

1998

Water Research

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Section: Land Applicationmentioning

confidence: 99%

Simulating disinfection processes in chlorine contact tanks using various turbulence models and high-order accurate difference schemes

Wang

Falconer

1998

Water Research

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“…In the unsaturated zone of the Ryukyu limestone aquifer on Miyako‐jima Island in Okinawa Prefecture, the lag time for groundwater recharge from the ground surface (10 m) with fertilizer‐derived nitrogen was estimated to be 7 years (Ishida, Tsuchihara, & Imaizumi, ; Tashiro & Takahira, ). According to a review by Yoshimoto et al (), seepage through fractures and the matrix account for approximately 20% and 80% of the groundwater flux, respectively, with matrix seepage ranging approximately 5–16 years m −1 in the unsaturated zone of the chalk aquifers (Andrews, Lloyd, & Lerner, ; Black & Kipp, ; Dahan, Nativ, Adar, Berkowitz, & Ronen, ; Foster & Smith‐Carington, ; Petersona, Davisb, Brahanab, & Orndorff, ; Smith, Wearn, Richards, & Rowe, ; Wellings, ). Using chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF 6 ), Gooddy, Darling, Abesser, and Lapworth () analysed the lag times for water recharge through the unsaturated zone of a chalk aquifer with the groundwater table at different depths.…”

Section: Introductionmentioning

confidence: 99%

Hydrochemical behaviour of an underground dammed limestone aquifer in the subtropics

Nakaya

Yasumoto

et al. 2018

Hydrological Processes

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In an island area with limited surface water resources, the conservation of fresh groundwater resources is important for the maintenance of the water supply and irrigation system to be used in agricultural activity. In a limestone aquifer used for irrigation on a subtropical island, the progress of the dissolution behaviour of the aquifer and the effects of CO2 storage and chemical weathering of the aquifer must be understood to ensure sustainable groundwater use. In this study, hydrochemical behaviour of the Ryukyu limestone aquifer was investigated using the residence time of slowly flowing groundwater, which is contained by a 2.3‐km‐long underground man‐made dam constructed in 2005 located at the southern edge of Okinawa Island, Japan. Groundwater dating and horizontal flow velocity measurements indicate that the groundwater horizontal flow is slow in the underground dam area, whereas the saturation index (SI) for calcite indicates that the majority of the limestone exists in a supersaturated condition. The range of SI for gypsum was indicative of subsaturation, and the SI increased with the groundwater residence time, suggesting that the dissolution of CaSO4 tends to proceed slowly through the common ion effect. The dissolution of CaCO3, however, tends to be in suspension within about a residence time of 20 years. The apparent dissolution rate of Ca in the Ryukyu limestone aquifer in this area was estimated to be approximately 2.70–4.06 nmol cm−2 year−1, a value much lower than that of the early stages of the limestone dissolution. The estimated groundwater CO2 (gas) concentrations are two order high (about 0.3–7%) relative to atmospheric CO2 (about 0.04%), and the groundwater pH shows a tendency to decrease from 7.4 to 6.9 over the last approximately 20 years, indicating that the hydration reaction of CO2 occurs in the Ryukyu limestone aquifer. These findings imply that high CO2 produced in the subtropical zone is consumed slower than CO2 production during limestone dissolution, with the exclusion of the early stage of the chemical weathering process, and causes groundwater acidification in the underground dammed limestone aquifer.

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“…Numerous studies have reported the presence of nitrates in the groundwater of chalk aquifers in England (e.g., Young et al 1977;Wellings 1984;Carey and Lloyd 1985;Andrews et al 1997) and limestone aquifers in the United States (e.g., Scanlon 1990;Peterson et al 2002). The nitrogen loading processes in karst aquifers are strongly influenced by the characteristics of groundwater flow, which are closely related to hydrogeological features such as caves and caverns.…”

Section: Introductionmentioning

confidence: 99%

Groundwater flow and transport and potential sources of groundwater nitrates in the Ryukyu Limestone as a mixed flow aquifer in Okinawa Island, Japan

Yoshimoto

Tsuchihara

Ishida

et al. 2011

Paddy Water Environ

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We investigated the groundwater flow and the transport and potential source of groundwater nitrates in the typical karst setting of the Ryukyu Limestone aquifer in the southern part of Okinawa Island, Japan. Analysis of groundwater hydrographs indicated that this is a ''mixed flow'' aquifer with the coexistence of slow diffuse flow in the matrices and rapid conduit flow in the caves and caverns. This relationship is indicated by the travel time of groundwater flow: 70 days in the matrices of the aquifer and 6 days through the caves and caverns. The conduit flow system was also confirmed by the distribution of relatively low concentrations of 222 Rn near caverns. The sampling sites were categorized into upland field (UF) type and residential area (RA) type according to the land-use ratio on the upstream side with a 600-m influential radius, and cave and cavern (CC) type according to the hydrogeologic setting near two large caverns, even though the CC type should be categorized as the UF type from the viewpoint of land use. Cross plots of NO 3 -N versus SO 4 2-showed that the predominant source of UF groundwater nitrates was chemical fertilizer. A difference was observed in average d 15 N values between UF (8.9%) and RA (10.0%). On the other hand, the average d 15 N value for CC (10.5%) was similar to that for RA, indicating that CC nitrates were not related to the surrounding land use. This phenomenon is considered as evidence that CC groundwater nitrates were carried by rapid groundwater flow through caves and caverns from residential areas located higher upstream compared to the influential areas. According to previous studies, animal and human waste was considered the predominant sources of RA and CC groundwater nitrogen. The contribution ratio of chemical fertilizer (R CF ) was calculated using mass balance equations under assumed predictability. There was a relatively high correlation between the rate of upland areas and of residential areas and R CF . Average R CF for UF, RA and CC was 41, 27, and 25%, respectively.

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Modelling of nitrate leaching from arable land into unsaturated soil and chalk 2. Model confirmation and application to agricultural and sewage sludge management

Cited by 10 publications

References 11 publications

Simulating disinfection processes in chlorine contact tanks using various turbulence models and high-order accurate difference schemes

Simulating disinfection processes in chlorine contact tanks using various turbulence models and high-order accurate difference schemes

Hydrochemical behaviour of an underground dammed limestone aquifer in the subtropics

Groundwater flow and transport and potential sources of groundwater nitrates in the Ryukyu Limestone as a mixed flow aquifer in Okinawa Island, Japan

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