scholarly journals Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary

2014 ◽  
Vol 11 (8) ◽  
pp. 12183-12221 ◽  
Author(s):  
N. K. Ganju ◽  
J. L. Miselis ◽  
A. L. Aretxabaleta
Keyword(s):  
Light Attenuation ◽  
Sediment Resuspension ◽  
Water Clarity ◽  
High Temporal Resolution ◽  
Barnegat Bay ◽  
Chl A ◽  
Seagrass Meadows ◽  
Boat Traffic ◽  
The Difference ◽  
Shallow Estuaries

Abstract. Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow eutrophic back-barrier estuary; two of the sites were located within designated Ecologically Sensitive Areas (ESAs). We sequentially deployed instrumentation measuring photosynthetically active radiation, chlorophyll a (chl a) fluorescence, dissolved organic matter fluorescence (fDOM; a proxy for colored DOM absorbance), turbidity, pressure, and water velocity at 10 min intervals over three week periods at each site. At the southernmost site, where sediment availability was highest, light attenuation was highest and dominated by turbidity and to a lesser extent chl a and CDOM. At the central site, chl a dominated followed by turbidity and CDOM, and at the northernmost site turbidity and CDOM contributed equally to light attenuation. At a given site, the temporal variability of light attenuation exceeded the difference in median light attenuation at the three sites, indicating the need for continuous high-temporal resolution measurements. Vessel wakes, anecdotally implicated in increasing sediment resuspension, did not contribute to local resuspension within the seagrass beds, though frequent vessel wakes were observed in the channels. With regards to light attenuation and water clarity, physical and biogeochemical variables appear to outweigh any regulation of boat traffic within the ESAs.

scholarly journals Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary

2014 ◽  
Vol 11 (24) ◽  
pp. 7193-7205 ◽  
Author(s):  
N. K. Ganju ◽  
J. L. Miselis ◽  
A. L. Aretxabaleta
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Light Attenuation ◽  
Sediment Resuspension ◽  
Water Clarity ◽  
Chl A ◽  
Seagrass Meadows ◽  
Boat Traffic ◽  
The Difference ◽  
Shallow Estuaries

Abstract. Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow eutrophic back-barrier estuary; two of the sites were located within designated Ecologically Sensitive Areas (ESAs). We sequentially deployed instrumentation measuring photosynthetically active radiation, chlorophyll a (chl a) fluorescence, dissolved organic matter fluorescence (fDOM; a proxy for colored dissolved organic matter (CDOM) absorbance), turbidity, pressure, and water velocity at 10 min intervals over 3-week periods at each site. At the southernmost site, where sediment availability was highest, light attenuation was highest and dominated by turbidity and to a lesser extent chl a and CDOM. At the central site, chl a dominated followed by turbidity and CDOM, and at the northernmost site turbidity and CDOM contributed equally to light attenuation. At a given site, the temporal variability of light attenuation exceeded the difference in median light attenuation between the three sites. Vessel wakes, anecdotally implicated in increasing sediment resuspension, did not contribute to local resuspension within the seagrass beds, though frequent vessel wakes were observed in the channels. With regards to light attenuation and water clarity, physical and biogeochemical variables appear to outweigh any regulation of boat traffic within the ESAs.

scholarly journals Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation

2016 ◽  
Vol 13 (2) ◽  
pp. 583-595 ◽  
Author(s):  
W. K. Oestreich ◽  
N. K. Ganju ◽  
J. W. Pohlman ◽  
S. E. Suttles
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Carbon Isotope ◽  
Light Attenuation ◽  
Stable Carbon Isotope ◽  
Colored Dissolved Organic Matter ◽  
Barnegat Bay ◽  
Absorption Ratio ◽  
Chincoteague Bay ◽  
Shallow Estuaries

Abstract. Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter (fDOM), due to the ease of in situ fDOM sensor measurements. Fluorescence must be converted to CDOM absorbance for use in light attenuation calculations. However, this CDOM–fDOM relationship varies among and within estuaries. We quantified the variability in this relationship within three estuaries along the mid-Atlantic margin of the eastern United States: West Falmouth Harbor (MA), Barnegat Bay (NJ), and Chincoteague Bay (MD/VA). Land use surrounding these estuaries ranges from urban to developed, with varying sources of nutrients and organic matter. Measurements of fDOM (excitation and emission wavelengths of 365 nm (±5 nm) and 460 nm (±40 nm), respectively) and CDOM absorbance were taken along a terrestrial-to-marine gradient in all three estuaries. The ratio of the absorption coefficient at 340 nm (m−1) to fDOM (QSU) was higher in West Falmouth Harbor (1.22) than in Barnegat Bay (0.22) and Chincoteague Bay (0.17). The CDOM : fDOM absorption ratio was variable between sites within West Falmouth Harbor and Barnegat Bay, but consistent between sites within Chincoteague Bay. Stable carbon isotope analysis for constraining the source of dissolved organic matter (DOM) in West Falmouth Harbor and Barnegat Bay yielded δ13C values ranging from −19.7 to −26.1 ‰ and −20.8 to −26.7 ‰, respectively. Concentration and stable carbon isotope mixing models of DOC (dissolved organic carbon) indicate a contribution of 13C-enriched DOC in the estuaries. The most likely source of 13C-enriched DOC for the systems we investigated is Spartina cordgrass. Comparison of DOC source to CDOM : fDOM absorption ratios at each site demonstrates the relationship between source and optical properties. Samples with 13C-enriched carbon isotope values, indicating a greater contribution from marsh organic material, had higher CDOM : fDOM absorption ratios than samples with greater contribution from terrestrial organic material. Applying a uniform CDOM : fDOM absorption ratio and spectral slope within a given estuary yields errors in modeled light attenuation ranging from 11 to 33 % depending on estuary. The application of a uniform absorption ratio across all estuaries doubles this error. This study demonstrates that light attenuation coefficients for CDOM based on continuous fDOM records are highly dependent on the source of DOM present in the estuary. Thus, light attenuation models for estuaries would be improved by quantification of CDOM absorption and DOM source identification.

scholarly journals Colored dissolved organic matter in shallow estuaries: the effect of source on quantification

2015 ◽  
Vol 12 (10) ◽  
pp. 7301-7333
Author(s):  
W. K. Oestreich ◽  
N. K. Ganju ◽  
J. W. Pohlman ◽  
S. E. Suttles
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Light Attenuation ◽  
Stable Carbon Isotope ◽  
Colored Dissolved Organic Matter ◽  
Stable Carbon ◽  
Barnegat Bay ◽  
Absorption Ratio ◽  
Chincoteague Bay ◽  
Shallow Estuaries

Abstract. Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter (fDOM), due to the ease of in situ fDOM measurements. Fluorescence must be converted to CDOM absorbance for use in light attenuation calculations and models. However, this fDOM-CDOM relationship varies among and within estuaries. We quantified the variability in this relationship within three estuaries: West Falmouth Harbor (MA), Barnegat Bay (NJ), and Chincoteague Bay (MD, VA). Land use surrounding these estuaries ranges from urban to developed, with varying sources of nutrients and organic matter. Measurements of fDOM and CDOM absorbance were taken along a terrestrial-to-marine gradient in all three estuaries. The ratio of the absorption coefficient at 340 nm (m−1) to fDOM (QSU) was higher in West Falmouth Harbor (1.22) than in Barnegat Bay (0.22) and Chincoteague Bay (0.17). The fDOM-CDOM absorption ratio was variable between sites within West Falmouth Harbor and Barnegat Bay, but consistent between sites within Chincoteague Bay. Stable carbon isotope analysis for constraining the source of dissolved organic matter in West Falmouth Harbor and Barnegat Bay yielded δ13C values ranging from −19.7 to −26.1‰ and −20.8 to −26.7‰, respectively. Stable carbon isotope mixing models of DOC in the estuaries indicate contributions from marine plankton, terrestrial plants, and Spartina cordgrass. Comparison of DOC source to fDOM-CDOM absorption ratio at each site demonstrates the influence of source on optical properties. Samples with a greater contribution from marsh (Spartina) organic material had higher fDOM-CDOM absorption ratios than samples with greater contribution from terrestrial organic material. Applying a uniform fDOM-CDOM absorption ratio and spectral slope within a given estuary yields errors in modeled light attenuation ranging from 11–33% depending on estuary. The application of a uniform absorption ratio across all estuaries doubles this error. These results demonstrate that continuous monitoring of light attenuation in estuaries requires some quantification of CDOM absorption and source to refine light models.

Influence of Salmonine Predation and Weather on Long-Term Water Quality Trends in Lake Michigan

1986 ◽  
Vol 43 (2) ◽  
pp. 435-443 ◽  
Author(s):  
Donald Scavia ◽  
Gary L. Fahnenstiel ◽  
Marlene S. Evans ◽  
David J. Jude ◽  
John T. Lehman
Keyword(s):  
Water Quality ◽  
Management Practices ◽  
Lake Michigan ◽  
Sediment Resuspension ◽  
Weather Conditions ◽  
Water Clarity ◽  
Alosa Pseudoharengus ◽  
Calanoid Copepods ◽  
Chl A ◽  
Secchi Disk Transparency

Trends in Lake Michigan water quality over 1975–84 appear to reflect reduced nutrient loadings as indicated by gradual declines in spring total phosphorus (TP) and summer epilimnetic chlorophyll a (Chl a). Deviations from these trends during 1977 and 1983–84 were apparently caused by abiotic and biotic factors, respectively. Prolonged ice cover during 1977 decreased sediment resuspension resulting in lower TP, reduced Chl a levels, and increased water clarity. A similar dramatic result occurred in 1983 and to a lesser extent in 1984, but via a different mechanism. Burgeoning populations of stocked salmonines reduced populations of the planktivorous alewife (Alosa pseudoharengus), which allowed large Daphnia to flourish. Because the Daphnia are more voracious and nonselective grazers than the formerly dominant calanoid copepods, they reduced seston concentrations, causing dramatic increases in Secchi disk transparency. These exceptions demonstrate the far-reaching consequences that unusual weather conditions and fish management practices may have on water quality indicators.

scholarly journals Trophic Responses of the Asian Reservoir to Long-Term Seasonal and Interannual Dynamic Monsoon

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2066 ◽  
Author(s):  
Md Mamun ◽  
Ji Yoon Kim ◽  
Kwang-Guk An
Keyword(s):  
Trophic State ◽  
Suspended Solids ◽  
Light Attenuation ◽  
Algal Growth ◽  
Water Clarity ◽  
Algal Community ◽  
Trophic State Index ◽  
Chl A ◽  
Blue Green Algae

The main objectives of the study were to determine the trophic response of the temperate reservoir to seasonal and interannual variabilities of monsoon inorganic solids and nutrients along the gradients of the morphologically complex Asian reservoir using long-term datasets between 2000–2018. Nutrient regime (total nitrogen—TN, total phosphorus—TP), total suspended solids (TSS), and chlorophyll-a (CHL-a) were primarily affected by an intensity of summer monsoon and the longitudinal structure of riverine (Rz), transitional (Tz), and lacustrine (Lz) zone. The reservoir is a nitrogen-rich system and the phosphorus content of the water was relatively low, and it had low mean N:P ratios (<40), implying a P-limiting system. The Lz was a highly P-limited zone in comparison to Rz and Tz zone during both drought (2015) and flood year (2011). The TP content was higher in the mainstem (S3) than the embankment (S4 and S6) of the reservoir due to the monsoon river inputs of the nutrients. Nonparametric Mann–Kendall tests indicated that TP decreased over the long-term years in the Rz, while it did not show any trend in Tz, Lz, IT1, and IT2. TN showed an increasing trend in Rz, Tz, Lz, and IT2 except for IT1. The empirical regression model for chlorophyll nutrients showed that CHL-a had a strong positive relationship with TP (R2 = 0.67, p < 0.01) than TN (R2 = 0.06, p < 0.01), supporting the view that algal growth in lentic systems responds to TP enrichment and TP may provide a reliable basis for predicting algal biomass. The seasonality of CHL-a and TP showed a monomodal pattern and indicates that summer TP influences summer algal growth in Tz, Lz, and IT2. The water clarity (SD) of the reservoir was significantly (p < 0.01) influenced by TP (R2 = 0.62), TSS (R2 = 0.67), and CHL-a (R2 = 0.68) rather than TN (R2 = 0.10). The non-algal light attenuation coefficient (Kna) was determined mainly by suspended solids and the monsoon hydrology. The trophic state was much higher when assessments were based on TSI (CHL-a) than on TSI (TP) and TSI (SD). TSI (CHL-a) indicated the eutrophic state of the reservoirs except for the zone of Lz during the premonsoon season. Analysis of trophic state index deviation (TSID) suggested that the blue-green algae dominated the algal community, and the effects of non-algal turbidity and zooplankton grazing were minor in the reservoir.

scholarly journals A potential new fabric evaluation approach by capturing brain perception under fabric contact pressure

2018 ◽  
Vol 89 (16) ◽  
pp. 3312-3325 ◽  
Author(s):  
Jie Yuan ◽  
Weidong Yu ◽  
Kemin Chen ◽  
Zhongwei Zhang ◽  
Yi Li ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Inhibitory Effect ◽  
High Temporal Resolution ◽  
Non Invasive ◽  
Evaluation Approach ◽  
Postcentral Gyrus ◽  
Comfort Perception ◽  
Peak Points ◽  
The Difference ◽  
Fabric Comfort

The problem of the transmission mechanism of textile perception and the barrier to express textile cognition directly are the two major issues in the field of textile evaluation. In this study, an advanced biomedical imaging technology, functional magnetic resonance imaging, which is non-invasive and has a high temporal resolution and spatial resolution, was utilized to describe the features of brain perception in the brain mask areas under increased fabric contact pressures, and thus it was attempted to provide a new approach to express fabric comfort perception. As a result, we found that when fabric contact pressure increased from 0.5 to 1.5 kPa, both maximum activation intensity T Z and activation proportion K of the peak points were transferred from the postcentral gyrus in the SI to the amygdala, and were negative activations. Therefore, we drew the conclusion that both a lower and a higher fabric contact pressure (about 1 kPa of proper comfort fabric pressure) would produce a brain signal inhibitory effect on the SI and amygdala. The difference was the fact that the inhibition role on the SI was more obvious under a lower pressure, while the inhibition role on the amygdala was more remarkable under a higher pressure, which meant that the SI, particularly the postcentral gyrus in the SI, was likely to play a significant role in surface tactile perception of fabrics, while the amygdala might be related to the fabric oppressing sensation.

Prediction Changes for Nonstationary Multi-Temporal Satellite Images using HMM

2017 ◽  
pp. 387-406
Author(s):  
Ali Ben Abbes ◽  
Imed Riadh Farah
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Satellite Image ◽  
Remotely Sensed ◽  
High Temporal Resolution ◽  
Remotely Sensed Data ◽  
Vegetation Monitoring ◽  
Area Of Interest ◽  
Multi Temporal ◽  
The Difference

Due to the growing advances in their temporal, spatial, and spectral resolutions, remotely sensed data continues to provide tools for a wide variety of environmental applications. This chapter presents the benefits and difficulties of Multi-Temporal Satellite Image (MTSI) for land use. Predicting land use changes using remote sensing is an area of interest that has been attracting increasing attention. Land use analysis from high temporal resolution remotely sensed images is important to promote better decisions for sustainable management land cover. The purpose of this book chapter is to review the background of using Hidden Markov Model (HMM) in land use change prediction, to discuss the difference on modeling using stationary as well as non-stationary data and to provide examples of both case studies (e.g. vegetation monitoring, urban growth).

Quantum yield of the marine benthic microflora of near-shore coastal Penang, Malaysia

2005 ◽  
Vol 56 (7) ◽  
pp. 1047 ◽  
Author(s):  
A. McMinn ◽  
S. Sellah ◽  
W. A. Wan Ab. Llah ◽  
M. Mohammad ◽  
F. Md. Sidik Merican ◽  
...  
Keyword(s):  
Primary Production ◽  
Suspended Solids ◽  
Euphotic Zone ◽  
Water Clarity ◽  
Quantum Yields ◽  
Chl A ◽  
Near Shore ◽  
High Concentrations ◽  
A Minor ◽  
Reduced Water

Benthic microalgal communities often contribute more than 30% of the primary production of shallow coastal and estuarine areas. At Muka Head Penang (Pulau Pinang) and the Songsong Islands (Pulau Songsong), Kedah, Malaysia, high concentrations of suspended solids and phytoplankton biomass (10.6 mg Chl a m−3) has reduced water clarity such that the euphotic zone of these areas is less than 2 m and 3 m deep respectively. The benthic microalgal communities, which were composed of the diatom genera Cocconeis, Fragilaria, Paralia and Pleurosigma, had a low biomass, had low maximum quantum yields (0.325 ± 0.129), were poorly adapted to their light environment and were constantly light limited. These characteristics suggest that the benthic microalgal communities were likely to have made only a minor contribution to the total primary production of the area.

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