Fluxes and retention of nutrients and organic carbon in Manko estuary, Okinawa, Japan: influence of river discharge variations

Estuaries are often considered important filters for inorganic and organic nutrients, as they are located between the land and sea. This study reports on the fluvial fluxes and estuarine transformations and retention of dissolved nutrients (total oxidized nitrogen [TON = NO2− and NO3−]), NH4+, PO43−, and dissolved organic carbon (DOC) in Manko estuary, Okinawa, Japan. The transport and transformation of dissolved nutrients and DOC varied widely among the eight conducted surveys due to variations in freshwater discharge and subsequent flushing times. Under high fluvial discharge, particularly during the May–June rainy season, the transport of nutrients and DOC accounted for up to 70%, 88%, 93%, and 53% of the annual transport of TON, NH4+, PO43−, and DOC, respectively. The flushing times of river water into the estuary, which varied from 0.5 to 46 days, were important in determining the degree to which fluvial nutrients were transformed and retained within the estuary. The effect of long flushing times was evident during the dry months (December–March), when biological and geochemical processes within the estuary removed most of the fluvial nutrients and DOC.

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Minimization of the Disinfection by-Product Precursors in Treated Waters Exposed to Ozone and Chlorine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.884-885.91 ◽

2014 ◽

Vol 884-885 ◽

pp. 91-95

Author(s):

Shang Chao Yue ◽

Le Jun Zhao ◽

Xiu Duo Wang ◽

Qi Shan Wang ◽

Feng Hua He

Keyword(s):

Drinking Water ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Water Supply ◽

River Water ◽

Water Samples ◽

Full Scale ◽

Ultraviolet Absorbance ◽

Treatment Processes ◽

Removal Efficiencies

The objectives of this study were to investigate impact of preoxidation on disinfection by-product (DBP) precursors in drinking water via two different preoxidation methods. The full-scale study was conducted on surface river water in a water supply plant in Tianjin, China. Two treatment trains were performed, with prechlorination and preozonation as preoxidation methods, respectively. The water samples were collected on different stages along the treatment processes and analyzed by following organic parameters: dissolved organic carbon (DOC), UV254 and specific ultraviolet absorbance (SUVA). The results indicated that Train 2 with preozonation was more effective to reduce DBP precursors. Preozonation possessed an excellent ability in the removal of UV254 and SUVA, the removal efficiencies were 25.14% and 18.77%, respectively, comparing to the removal rates of 6.66% and 5.64% during prechlorination, separately.

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Damming effect on carbon processing in a subtropical valley-type reservoir in the upper Mekong Basin

10.5194/egusphere-egu2020-26 ◽

2020 ◽

Author(s):

Lin Lin

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Rainy Season ◽

Water Discharge ◽

River Channels ◽

Particulate Carbon ◽

River Continuum ◽

Dissolved Carbon ◽

Carbon Retention ◽

Valley Type

Damming rivers has been identified as one of the most intense artificial perturbations on carbon transportation along the river continuum. To quantify the damming effect on the riverine carbon flux in the upper Mekong River, seasonal carbon fluxes were monitored in a subtropical valley-type reservoir (the Gongguoqiao Reservoir) in 2016. Annually, around 20% of the incoming carbon was sequestered within the reservoir with most of the carbon retention occurring in the rainy season. Since higher rainfalls and water discharge brought large amounts of terrestrial carbon into the reservoir in summer, the concentrations of dissolved organic carbon (DIC), particulate inorganic carbon (PIC) and particulate organic carbon (POC) in the topwater show significant decreasing trends from the river inlet to the outlet (p<0.01). During the cooler dry season (winter), however, the damming effect was much weaker. Precipitation of PIC owing to the alkaline environment and decelerated flow velocity contributed over half of the carbon retention in the reservoir. Correlation between suspended sediment concentration and carbon concentrations reveals that heavy sedimentation also resulted in the sequestration of particulate carbon. Yet the damming impact on the flux of dissolved organic carbon (DOC) was relatively weak due to the short water retention time and refractory nature of allochthonous carbon. The anti-season operation of the dam allowed little time for the decomposition of the incoming DOC in the rainy season. The differentiation processing of the carbon flow significantly increased the dissolved carbon proportion in the outflow. The dams could be acting as filters and the effect might be exacerbated in the cascading system. Accumulation of dissolved organic carbon possibly can accelerate eutrophication processes in the downstream reservoirs and thus altered the aquatic carbon dynamics in the downstream river channels.&#160;

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Impact of hurricanes on the flux of rainwater and Cape Fear River water dissolved organic carbon to Long Bay, southeastern United States

Global Biogeochemical Cycles ◽

10.1029/2004gb002229 ◽

2004 ◽

Vol 18 (3) ◽

pp. n/a-n/a ◽

Cited By ~ 35

Author(s):

G. Brooks Avery ◽

Robert J. Kieber ◽

Joan D. Willey ◽

G. Christopher Shank ◽

Robert F. Whitehead

Keyword(s):

United States ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Water ◽

Southeastern United States ◽

Long Bay ◽

Cape Fear River ◽

Cape Fear

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Hydrological controls on DOC : nitrate resource stoichiometry in a lowland, agricultural catchment, southern UK

10.5194/hess-2017-30 ◽

2017 ◽

Cited By ~ 2

Author(s):

Catherine M. Heppell ◽

Andrew Binley ◽

Mark Trimmer ◽

Tegan Darch ◽

Ashley Jones ◽

...

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Water ◽

Positive Relationship ◽

Agricultural Landscapes ◽

Lowland River ◽

Significant Positive Relationship ◽

Molar Ratios ◽

The Relationship

Abstract. The role that hydrology plays in governing the interactions between dissolved organic carbon (DOC) and nitrogen in rivers draining lowland, agricultural landscapes is currently poorly understood, yet important to assess given the potential changes to production and delivery of DOC and nitrate arising from climate change. We measured DOC and nitrate concentrations in river water of six reaches of the lowland River Hampshire Avon (Wiltshire, southern UK) in order to quantify the relationship between Baseflow Index (BFI) and DOC : nitrate molar ratios across contrasting geologies (Chalk, Greensand and clay). We found a significant positive relationship between nitrate and Baseflow Index (p

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Seasonal variations in concentration and lability of dissolved organic carbon in Tokyo Bay

Biogeosciences ◽

10.5194/bg-12-269-2015 ◽

2015 ◽

Vol 12 (1) ◽

pp. 269-279 ◽

Cited By ~ 17

Author(s):

A. Kubo ◽

M. Yamamoto-Kawai ◽

J. Kanda

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Water ◽

Seasonal Variations ◽

Relative Concentration ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Tokyo Bay ◽

Chl A

Abstract. Concentrations of recalcitrant and bioavailable dissolved organic carbon (DOC) and their seasonal variations were investigated at three stations in Tokyo Bay, Japan, and in two freshwater sources flowing into the bay. On average, recalcitrant DOC (RDOC), as a remnant of DOC after 150 days of bottle incubation, accounted for 78% of the total DOC in Shibaura sewage treatment plant (STP) effluent, 67% in the upper Arakawa River water, 66% in the lower Arakawa River water, and 78% in surface bay water. Bioavailable DOC (BDOC) concentrations, defined as DOC minus RDOC, were lower than RDOC at all stations. In freshwater environments, RDOC concentrations were almost constant throughout the year. In the bay, RDOC was higher during spring and summer than in autumn and winter because of freshwater input and biological production. The relative concentration of RDOC in the bay derived from phytoplankton, terrestrial, and open-oceanic waters was estimated to be 8–10, 21–32, and 59–69%, respectively, based on multiple regression analysis of RDOC, salinity, and chl a. In addition, comparison with previous data from 1972 revealed that concentrations of RDOC and BDOC have decreased by 33 and 74% at freshwater sites and 39 and 76% in Tokyo Bay, while the ratio of RDOC to DOC has increased. The change in DOC concentration and composition was probably due to increased amounts of STP effluent entering the system. Tokyo Bay exported mostly RDOC to the open ocean because of the remineralization of BDOC.

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Concentration, UV-spectroscopic characteristics and fractionation of DOC in stormflow from an urban stream, Southern California, USA

Environmental Chemistry ◽

10.1071/en06046 ◽

2007 ◽

Vol 4 (1) ◽

pp. 35 ◽

Cited By ~ 5

Author(s):

John A. Izbicki ◽

Isabel M. Pimentel ◽

Russell Johnson ◽

George R. Aiken ◽

Jerry Leenheer

Keyword(s):

Public Health ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Rainy Season ◽

Health Issues ◽

Santa Ana ◽

Public Supply ◽

Tributary Stream ◽

Unknown Composition ◽

Santa Ana River

Environmental context. There is concern that there may be public health issues associated with dissolved organic carbon (DOC) because of its unknown composition and reactivity to disinfection in water used for public supply. Here, changes in the concentration and composition of DOC in stormflow (1995–2004) in the Santa Ana River and its tributaries is evaluated based on its optical properties, molecular weight and solubility differences of the contributing DOC components. Such a study may allow improved water management in the future. Ongoing work in the study area has shown that DOC in surface water diverted for groundwater recharge degrades to near natural levels in underlying aquifers pumped for public supply. Abstract. The composition of dissolved organic carbon (DOC) in stormflow from urban areas has been greatly altered, both directly and indirectly, by human activities and there is concern that there may be public health issues associated with DOC, which has unknown composition from different sources within urban watersheds. This study evaluated changes in the concentration and composition of DOC in stormflow in the Santa Ana River and its tributaries between 1995 and 2004 using a simplified approach based on the differences in the optical properties of DOC and using operationally defined differences in molecular weight and solubility. The data show changes in the composition of DOC in stormflow during the rainy season and differences associated with runoff from different parts of the basin, including extensive upland areas burned prior to the 2004 rainy season. Samples were collected from the Santa Ana River, which drains ~6950 km2 of the densely populated coastal area of southern California, during 23 stormflows between 1995 and 2004. Dissolved organic carbon (DOC) concentrations during the first stormflows of the ‘winter’ (November to March) rainy season increased rapidly with streamflow and were positively correlated with increased faecal indicator bacteria concentrations. DOC concentrations were not correlated with streamflow or with other constituents during stormflows later in the rainy season and DOC had increasing UV absorbance per unit carbon as the rainy season progressed. DOC concentrations in stormflow from an urban drain tributary to the river also increased during stormflow and were greater than concentrations in the river. DOC concentrations in stormflow from a tributary stream, draining urban and agricultural land that contained more than 320000 animals, mostly dairy cows, were higher than concentrations in stormflow from the river and from the urban drain. Fires that burned large areas of the basin before the 2004 rainy season did not increase DOC concentrations in the river during stormflow after the fires – possibly because the large watershed of the river damped the effect of the fires. However, the fires increased the hydrophobic neutral organic carbon fraction of DOC in stormflow from the urban drain and the tributary stream.

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Export of Dissolved Organic Carbon from a Ponded Freshwater Marsh Receiving Diverted Mississippi River Water

The Scientific World JOURNAL ◽

10.1100/tsw.2008.156 ◽

2008 ◽

Vol 8 ◽

pp. 1210-1218 ◽

Cited By ~ 3

Author(s):

R. D. DeLaune ◽

C. B. Johnson ◽

R. P. Gambrell ◽

A. Jugsujinda

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Water ◽

Mississippi River ◽

Wetland Loss ◽

Freshwater Marsh ◽

River Diversion ◽

Marsh Soil ◽

Northern Portion ◽

Mississippi River Water

A series of diversion projects has been implemented to reintroduce Mississippi River water into Louisiana's coastal wetlands in order to reduce wetland loss. The export of dissolved organic carbon (DOC) was measured in a 3,700-ha ponded freshwater marsh that receives diverted Mississippi River water. Results show that highly organic marsh soil and plant material are a source of DOC. DOC, on average, was 3 mg/l greater in outlet water as compared to the concentration in river water entering the wetland. DOC in water leaving the marsh was higher in summer months, with a concentration up to 18 mg/l. Based on a discharge of 1,000 ft3/sec (28.3 m3/sec), it was estimated that the equivalent of 7,335 kg/day of DOC would be exported from the marsh into Lake Cataouatche, located in the northern portion of the Louisiana Barataria Basin estuary. Results suggest that river diversion would likely increase the export of DOC from the marsh as compared to normal transport associated with rainfall and tidal exchange.

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Seasonal changes of dissolved organic carbon photo-oxidation rates in a tropical humic lagoon: the role of rainfall as a major regulator

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f07-103 ◽

2007 ◽

Vol 64 (9) ◽

pp. 1266-1272 ◽

Cited By ~ 35

Author(s):

Albert Luiz Suhett ◽

André Megali Amado ◽

Alex Enrich-Prast ◽

Francisco de Assis Esteves ◽

Vinicius Fortes Farjalla

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Rainy Season ◽

Annual Rainfall ◽

Rainfall Regime ◽

Photo Oxidation ◽

Oxidation Rates ◽

Doc Concentration ◽

In The Beginning

In this paper, we report the seasonal variation of photo-oxidation rates in a tropical humic lagoon and its relation to annual rainfall regime. Photo-oxidation rates ranged from 8.96 to 415.06 µmol C·L–1·day–1, being higher in the beginning to middle of the rainy season and declining throughout the year. Although dissolved organic carbon (DOC) concentration, water color, and sunlight incidence were generally higher in the rainy season, photo-oxidation rates were not significantly related to any of these parameters. Photo-oxidation seems to be influenced mainly by changes in DOC photoreactivity, which was up to threefold higher early in the rainy season, when inputs of fresh allochthonous DOC take place. In the following months, in addition to being continuously degraded by sunlight, DOC is also removed from the water column by processes such as microbial degradation and sedimentation, leading to a decline in DOC concentration and photoreactivity throughout the year until the next rainy season. Thus, the dynamics of DOC inputs caused by the rainfall regime in Comprida Lagoon lead to a yearly pulse of DOC photoreactivity and photo-oxidation rates. We believe this pulse model also fits other aquatic ecosystems subject to similar seasonal inputs of allochthonous DOC, although rainfall would not necessarily be the driving factor.

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Estimation of Biochemical Oxygen Demand Based on Dissolved Organic Carbon, UV Absorption, and Fluorescence Measurements

Journal of Chemistry ◽

10.1155/2013/243769 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 12

Author(s):

Jihyun Kwak ◽

Bumju Khang ◽

Eunhee Kim ◽

Hyunook Kim

Keyword(s):

Wastewater Treatment ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

River Water ◽

Biochemical Oxygen Demand ◽

Treatment Plant ◽

Oxygen Demand ◽

Fluorescence Measurements ◽

Wwtp Effluent ◽

Software Sensors

Determination of 5-d biochemical oxygen demand (BOD5) is the most commonly practiced test to assess the water quality of surface waters and the waste loading. However, BOD5is not a good parameter for the control of water or wastewater treatment processes because of its long test period. It is very difficult to produce consistent and reliable BOD5results without using careful laboratory quality control practices. This study was performed to develop software sensors to predict the BOD5of river water and wastewater. The software sensors were based on the multiple regression analysis using the dissolved organic carbon (DOC) concentration, UV light absorbance at 254 nm, and synchronous fluorescence spectra. River water samples and wastewater treatment plant (WWTP) effluents were collected at 1-hour interval to evaluate the feasibility of the software sensors. In short, the software sensors developed in this study could well predict the BOD5of river water (r=0.78) and for the WWTP effluent (r=0.90).

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