Measurements of groundwater seepage flux onto a coral reef: Spatial and temporal variations

Lewis, John B.

doi:10.4319/lo.1987.32.5.1165

Cited by 87 publications

(67 citation statements)

References 12 publications

(9 reference statements)

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“…Our 2370-mL chamber would be most applicable where the flow rates cover 10-200 mL min -1 (5-100 cm d -1 ). Our 544 mL chamber works best at slower flows (1-50 mL min -1 or 0.5-25 cm d -1 ), more typical of seepage rates observed in marine, estuarine and freshwater systems (Lee 1977;Bokuniewicz 1980;Lewis 1987;Taniguchi and Fukuo 1993;Boyle 1994;Robinson et al 1998;Paulsen et al 2001;.…”

Section: Comments and Recommendationsmentioning

confidence: 99%

An automated dye‐dilution based seepage meter for the time‐series measurement of submarine groundwater discharge

Sholkovitz

Herbold

Charette

2003

Limnology & Ocean Methods

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We designed an automated seepage meter that can detect and quantify both groundwater outflow and seawater infiltration. Based on a dye‐dilution technique, this instrument provides high‐resolution time‐series data for submarine groundwater discharge to the coastal zone. The dye‐dilution method involves two repeatable steps: (1) the timed injection of a water‐soluble dye into a “dye‐mixing chamber” mounted in series with a seepage chamber and (2) the subsequent timed measurements of the absorbance of the dyed solution. The rate at which the dyed solution is diluted by the inflow or outflow of water is directly proportional to the flow rate moving through the surface area of the seepage housing. In addition to describing the instrument's components and the operating principle, we provide examples of laboratory flow calibrations and field deployments. As indicated by two sets of time‐series studies, this instrument has performed reliably in field tests at Waquoit Bay (Cape Cod, Massachusetts) and Shelter Island (Long Island, New York). The instrument has yielded hydrologically consistent flow rates and has revealed major and subtle connections between tidal stage and the rate and direction of submarine groundwater discharge.

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Section: Comments and Recommendationsmentioning

confidence: 99%

An automated dye‐dilution based seepage meter for the time‐series measurement of submarine groundwater discharge

Sholkovitz

Herbold

Charette

2003

Limnology & Ocean Methods

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“…More recently, they have been used to measure seepage rates into lakes, estuaries, and coral reefs (Lee 1977;Fellows and Brezonik 1980;Lewis 1987). Seepage meters are bottomless drums made by cutting off the top or bottom 15 cm of a "55-gallon" (204 liter) drum (Lee 1977).…”

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confidence: 99%

Anomalous, short‐term influx of water into seepage meters

Shaw¹,

Prepas²

1989

Limnology & Oceanography

125

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Laboratory and field tests revealed that there was an anomalous, short‐term influx of water into plastic bags after they were attached to seepage meters. Plastic bags (3.5‐liter capacity) were submerged in an 830‐liter tank of stagnant water; within 45 min, the volume of water in bags that initially were empty increased to 297 ml, bags prefilled with 1,000 and 2,000 ml of water increased by 160 ml, and bags prefilled with 3,000 ml decreased in volume. At Narrow Lake, Alberta, the anomalous, short‐term (30 min) influx of water averaged 237 ml to bags that were initially empty, but the anomaly was effectively eliminated when bags were prefilled with 1,000 ml of water before they were attached to seepage meters. The impact of the anomaly on calculated seepage rates was greatest when seepage rates were low, e.g. 0.3 ml m−2 min−1. The anomaly may be due to mechanical properties of the bag, and it may be alleviated by partially filling bags before they are attached to seepage meters.

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“…Seasonal variation is present in the river discharge as inferred from precipitation (Wang et al, 2005) and there might be an increase in the groundwater discharge and associated nutrient fluxes in summer as in other coastal systems (e.g., Lewis, 1987;Costa et al, 2006;Kelly and Moran, 2002;Wang et al, 2015). However, the relative changes in the groundwater discharge and associated nutrient fluxes would be much smaller than those of the river.…”

Section: Seasonal and Regional Extrapolationsmentioning

confidence: 96%

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Wang

et al. 2018

Biogeosciences

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Abstract. To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a timeseries observation of these nutrients and 228 Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228 Ra, 45.3 dpm 100 L −1 , appeared at low tide and the minimum, 14.0 dpm 100 L −1 , appeared during a flood tide in the spring tide. The activity of 228 Ra was significantly correlated with water depth and salinity in the spring-neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R 2 ≥ 0.9 and P < 0.05) at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitritedepleted, nitrate-and phosphate-rich less saline groundwater and nitrite-rich, nitrate-and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NO x ) and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NO x and phosphate were significantly correlated with regression slopes of 4.60 (R 2 = 0.16) in the spring tide and 13.4 (R 2 = 0.75) in the neap tide, similar to the composition of these nutrients in the water column, 5.43 (R 2 = 0.27) and 14.2 (R 2 = 0.76), respectively. This similarity indicates that the composition of nutrients in the water column of the reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R 2 = 0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring-neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

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Measurements of groundwater seepage flux onto a coral reef: Spatial and temporal variations

Cited by 87 publications

References 12 publications

An automated dye‐dilution based seepage meter for the time‐series measurement of submarine groundwater discharge

An automated dye‐dilution based seepage meter for the time‐series measurement of submarine groundwater discharge

Anomalous, short‐term influx of water into seepage meters

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

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