Seasonal Oxygen Depletion in Chesapeake Bay

Taft, Jay L.; Taylor, W. Rowland; Hartwig, Eric O.; Loftus, Randy W.

doi:10.2307/1352079

Cited by 170 publications

(88 citation statements)

References 16 publications

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“…Averaged over the entire year, oxygen consumption in 208 pm filtered water declined from 38 pg O2 1-' h-' in the upper Duplin River, to 33 yg O2 1-I h-' 1.6 km offshore, to 29 pg O2 1-' h-' 10 km offshore. Although the rate of heterotrophic metabolism in the estuary is comparable to that observed in other very productive estuarine regions (Patten 1961, Taft et al 1980, the rates measured in the nearshore zone are an order of magnitude higher than in most continental shelf regions (Riley 1941, Christensen & Packard 1976, Garside & Malone 1978.…”

Section: Total Plankton Respiration In the Georgia Coastal Zonesupporting

confidence: 50%

Size fractionated metabolism of coastal microbial plankton

Hopkinson¹,

Sherr²,

Wiebe³

1989

Mar. Ecol. Prog. Ser.

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The quantitative significance of microbial heterotrophs in overall plankton metabolism was investigated in estuarine and coastal waters off the Georgia coast (USA). Three size classes were examined: < 208 pm, < 10 pm and < 1 p m Respiration was measured by monitoring the rate of oxygen consumption in water samples incubated at in situ temperatures in the dark. Rates by all size classes of plankton were highest in the upper reaches of the Duplin h v e r estuary during summer (52.4 pg O2 1-l h-') and lowest 10 km offshore during winter (10.1 pg O2 1-l h-'). Respiration by organisms passing a 1 pm screen exceeded rates in 208 pm and 10 pm filtered samples, but this enhancement decreased w~t h increasing distance offshore. This increased bacterial (< 1 pm) respiration could not be attributed to artifacts of the filtration procedure or to bacterial growth. Respiration results were consistent with concurrently conducted studies of bacterioplankton growth and bactivorous microprotozoan grazing. Static models of carbon and nitrogen flow between bacterioplankton and heterotrophic protozoa suggest that the C/N ratio of the bacterial food source could largely dictate organic carbon conversion efficiency of planktonic bacteria, the relative role of bacteria and microprotozoans as recyclers of nitrogen and the rate of organic carbon utilization. The relative importance of bacterial nitrogen remineralization decreases as the C/N ratio of the organic substrate increases. Results of this study are discussed in context of the microbial loop and the trophic flow leading to higher organisms.

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Section: Total Plankton Respiration In the Georgia Coastal Zonesupporting

confidence: 50%

Size fractionated metabolism of coastal microbial plankton

Hopkinson¹,

Sherr²,

Wiebe³

1989

Mar. Ecol. Prog. Ser.

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“…As these estrogenic compounds generally also need oxygen for their degradation, oxygen depletion by processes such as eutrophication and degradation of organic matter (Paerl et al 1998;Smith et al 1999; Relative NP concentration in the sediment at the start (C 0 ) and the end (C e ) of the reactor experiments. = C 0 , = C e reactor 1, = C e reactor 2, = C e reactor 3, = C e reactor 4 Taft et al 1980) lead to an increased estrogenic compound concentration in bulk river water because biodegradation cannot counter balance the desorption and mass transfer. More estrogenic compounds will enter the bulk water during resuspension than when the sediment is present in a sediment bed.…”

Section: Perspectives Of Other Estrogenic Compoundsmentioning

confidence: 99%

Nonylphenol mass transfer from field-aged sediments and subsequent biodegradation in reactors mimicking different river conditions

et al. 2009

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Purpose Sediments can function as secondary source for water pollution of aerobically biodegradable nonhalogenated organic compounds, which are persistent in anaerobic sediments. The mass transfer of compounds from sediment to bulk water depends on hydraulic conditions. In this study, desorption, mass transfer and biodegradation are investigated under settled and resuspended sediment conditions for branched nonylphenol (NP), which was used as model compound for aerobically biodegradable and anaerobic persistent compounds. Materials and methods Continuous flow through reactor experiments were performed in duplicate with aged NP polluted sediment under sterile and non-sterile conditions to investigate the mass transfer and combined mass transfer and biodegradation. Results and discussion The mass transfer of NP from the sediment bed to the bulk water decreased from 5.1± 0.6 μg d -1 to a stable value of 0.3±0.02 μg d -1 . The desorbed NP in the non-sterile reactors was biodegraded in the first 20 days of the experiment. At the end of the settled sediment conditions, the biodegradation became very limited, and the mass transfer was comparable to the mass transfer under sterile conditions. Upon resuspension, the NP concentration in the bulk water increased instantaneously in all reactors with a factor of 100. This immediate, increased mass transfer of NP from the sediment was larger than the amount that can be biodegraded under optimal conditions. Under non-sterile conditions, a second increase in the mass transfer was observed. However, the amount of desorbing NP during this second increase in mass transfer can be biodegraded under optimal environmental conditions. Conclusions NP desorbs continuously at low concentrations from the sediment bed into the bulk water, which can almost be completely biodegraded. Resuspension of NP-polluted sediment initially led to an increase in the desorbing NP concentrations and can be followed by a subsequent reduction of the concentrations due to biodegradation under environmental conditions where biodegradation of NP can occur.

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“…Elevated inputs of both nitrogen and phosphorus to the Chesapeake watershed have resulted in excessive phytoplankton production within the Bay (Malone et al 1986(Malone et al , 1988Boynton et al 1982;Correll 1987;Jordan et al 1991a, b;Gallegos et al 1992;Harding 1994;Harding and Perry 1997). Consequently, submerged aquatic vegetation has declined (Kemp et al 1983;Orth and Moore 1983) and hypoxic conditions have increased in both magnitude and extent (Taft et al 1980;Officer et al 1984). The detrimental ecological effects of increased nutrient loading to the Chesapeake Bay have led to the multi-state Chesapeake Bay Agreement, which seeks to reduce nutrient discharges to Chesapeake Bay watershed streams and rivers (Boesch et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Net anthropogenic phosphorus inputs: spatial and temporal variability in the Chesapeake Bay region

et al. 2008

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We estimated net anthropogenic phosphorus inputs (NAPI) in the Chesapeake Bay region. NAPI is an index of phosphorus pollution potential. NAPI was estimated by quantifying all phosphorus inputs and outputs for each county. Inputs include fertilizer applications and non-food phosphorus uses, while trade of food and feed can be an input or an output. The average of 1987The average of , 1992The average of , 1997The average of , and 2002 NAPI for individual counties ranged from 0.02 to 78.46 kg P ha -1 year -1 . The overall area-weighted average NAPI for 266 counties in the region was 4.52 kg P ha -1 year -1 , indicating a positive net phosphorus input that can accumulate in the landscape or can pollute the water. Large positive NAPI values were associated with agricultural and developed land cover. County area-weighted NAPI increased from 4.43 to 4.94 kg P ha -1 year -1 between 1987 and 1997 but decreased slightly to 4.86 kg P ha -1 year -1 by 2002. Human population density, livestock unit density, and percent row crop land combined to explain 83% of the variability in NAPI among counties. Around 10% of total NAPI entering the Chesapeake Bay watershed is discharged into Chesapeake Bay. The developed land component of NAPI had a strong direct correlation with measured phosphorus discharges from major rivers draining to the Bay (R 2 = 0.81), however, the correlation with the simple percentage of developed land was equally strong. Our results help identify the sources of P in the landscape and evaluate the utility of NAPI as a predictor of water quality.

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Seasonal Oxygen Depletion in Chesapeake Bay

Cited by 170 publications

References 16 publications

Size fractionated metabolism of coastal microbial plankton

Size fractionated metabolism of coastal microbial plankton

Nonylphenol mass transfer from field-aged sediments and subsequent biodegradation in reactors mimicking different river conditions

Net anthropogenic phosphorus inputs: spatial and temporal variability in the Chesapeake Bay region

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