Transformations in DOC along a source to sea continuum; impacts of photo-degradation, biological processes and mixing

Jones, Timothy G. J.; Evans, C. D.; Jones, Davey L.; Hill, Paul W.; Freeman, Chris

doi:10.1007/s00027-015-0461-0

Cited by 44 publications

(44 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result corroborates that riverine DOC is regulated by a series of complex and interactively connected processes [17]. Climatic and hydrological factors mainly affect temporal variability rather than spatial distribution of riverine DOC [46,47].…”

Section: Spatial Patterns Of Doc Concentrationssupporting

confidence: 81%

“…Previous investigations showed large uncertainties or even contrasting results in explaining riverine DOC using climate variables, soil properties, land cover types, and hydrological conditions [17,46,53]. Our analyses, based on the extensive USGS observational dataset, provide a systematic examination of DOC variability and the associated environmental controls at regional and national scales.…”

Section: Environmental Controls On Doc Concentrationsmentioning

confidence: 96%

See 1 more Smart Citation

An Analysis of Terrestrial and Aquatic Environmental Controls of Riverine Dissolved Organic Carbon in the Conterminous United States

Yang

Zhang

et al. 2017

Water

View full text Add to dashboard Cite

Analyses of environmental controls on riverine carbon fluxes are critical for improved understanding of the mechanisms regulating carbon cycling along the terrestrial-aquatic continuum.Here, we compile and analyze riverine dissolved organic carbon (DOC) concentration data from 1402 United States Geological Survey (USGS) gauge stations to examine the spatial variability and environmental controls of DOC concentrations in the United States (U.S.) surface waters. DOC concentrations exhibit high spatial variability in the U.S., with an average of 6.42 ± 6.47 mg C/L (Mean ± Standard Deviation). High DOC concentrations occur in the Upper Mississippi River basin and the southeastern U.S., while low concentrations are mainly distributed in the western U.S. Soil properties such as soil organic matter, soil water content, and soil sand content mainly show positive correlations with DOC concentrations; forest and shrub land have positive correlations with DOC concentrations, but urban area and cropland demonstrate negative impacts; and total instream phosphorus and dam density correlate positively with DOC concentrations. Notably, the relative importance of these environmental controls varies substantially across major U.S. water resource regions. In addition, DOC concentrations and environmental controls also show significant variability from small streams to large rivers. In sum, our results reveal that general multi-linear regression of twenty environmental factors can partially explain (56%) the DOC concentration variability. This study also highlights the complexity of the interactions among these environmental factors in determining DOC concentrations, thus calls for processes-based, non-linear methodologies to constrain uncertainties in riverine DOC cycling.

show abstract

Section: Spatial Patterns Of Doc Concentrationssupporting

confidence: 81%

Section: Environmental Controls On Doc Concentrationsmentioning

confidence: 96%

An Analysis of Terrestrial and Aquatic Environmental Controls of Riverine Dissolved Organic Carbon in the Conterminous United States

Yang

Zhang

et al. 2017

Water

View full text Add to dashboard Cite

show abstract

“…If temperature solely caused increased reaction rates of photodegradation, there would be no change in carbon release from solutions in near‐blackout conditions at different temperatures; however, this is not the case in this study (Figure ). Other studies of photodegradation rates found little or no change to DOC concentration in near‐blackout conditions (Gennings et al, ; Jones et al, ; Moody et al, ; Obernosterer & Benner, ).…”

Section: Discussionmentioning

confidence: 93%

“…Jones et al () found DOC losses were negatively correlated to SUVA 254 (ratio of absorption at 254 nm to DOC concentration) after artificial irradiation, noting DOC containing a high proportion of high molecular weight coloured or aromatic compounds is more susceptible to UV degradation. The headland streamwater used here can be regarded as “UV‐labile” in comparison with older lake DOC, headwaters having rapid preferential photodegradation of more photosensitive DOC components (Molot & Dillon, ).…”

Section: Discussionmentioning

confidence: 99%

Controls on fluvial carbon efflux from eroding peatland catchments

Brown

Goulsbra

Evans

2018

Hydrological Processes

View full text Add to dashboard Cite

Global peatlands store an unparalleled proportion of total global organic carbon but it is vulnerable to erosion into fluvial systems. Fluvial networks are being recognized as areas of carbon transformation, with eroded particulate organic carbon processed to dissolved organic carbon and CO2. Existing studies indicate biodegradation and photodegradation as key processes controlling the transformation of organic carbon in fluvial systems, with initial concentrations of dissolved organic carbon (DOC) identified as a control on the rate of carbon mineralization. This study manipulates temperature and incident light intensity to investigate carbon mineralization rates in laboratory simulations of peatland sediment transport into fluvial systems. By directly measuring gaseous CO2 emissions from sampled stream water, the relationship of temperature and light intensity with carbon efflux is identified. In simulations where sediment (as particulate organic matter, POM) is absent, temperature is consistently the dominant factor influencing carbon efflux rates. This influence is independent of the initial DOC concentration of the water sample. In simulations where POM was added, representing a peatland river receiving eroded terrestrial sediment, initial DOC concentration predicts 79% of the variation in total gaseous carbon efflux whereas temperature and light intensity predict 12% and 3%, respectively. When sampled stream water's mineralization rates in the presence of added POM are analysed independently, removing DOC as a model variable, the dominant variable affecting CO2 efflux is opposite for each sample. This study presents novel data suggesting peatland erosion introduces further complexity to dynamic stream systems where rates of carbon transformation processes and the influence of specific environmental variables are interdependent. Anthropogenic climate change is identified as a leading risk factor perpetuating peatland erosion; therefore, understanding the fate of terrestrial sediment in rivers and further quantifying the benefits of protecting peatland soils will be of increasing importance to carbon budgeting and ecosystem function studies.

show abstract

“…Increased exports of DOC are problematic for multiple reasons. DOC in fluvial systems can be mineralized to CO 2 , thereby contributing to atmospheric CO 2 concentrations (Cole et al, ; Jones, Evans, Jones, Hill, & Freeman, ). Additionally, DOC affects light attenuation and can therefore affect the functioning of aquatic ecosystems (Karlsson, Byström, Ask, Persson, & Jansson, ), and DOC can bind with trace metals, some toxic (Lawlor & Tipping, ; Rothwell, Evans, Daniels, & Allott, ).…”

Section: Introductionmentioning

confidence: 99%

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Peacock

Jones

Futter

et al. 2018

Hydrological Processes

Self Cite

View full text Add to dashboard Cite

The globally widespread drainage of peatlands has often been shown to lead to increased concentrations and fluxes of dissolved organic carbon (DOC) in streams and rivers. Elevated DOC concentrations have implications for carbon cycling, ecosystem functioning, and potable water treatment. Peatland rewetting, principally through ditch blocking, is often carried out with the expectation that this will reduce DOC concentrations. Uncertainty still remains as to whether drainage, or its reversal via ditch blocking, will also lead to changes in the molecular composition of DOC/dissolved organic matter (DOM), which have the potential to affect downstream processing and treatability of U.K. drinking water supplies. To investigate this question, we used a replicated experiment consisting of 12 parallel ditches on an upland bog and took samples of ditch water, pore water, and overland flow water for 4 years. After a brief preblocking baseline period, eight ditches were blocked using two methods. A complementary suite of optical metrics, chemical measurements, and analytical techniques revealed that ditch blocking had no consistent effect on DOM quality, up to 4 years after blocking. Where significant differences were found, effect size calculations demonstrated that these differences were small and would therefore have minimal impact upon water treatability. Furthermore, some differences between ditches were evident before blocking took place, highlighting the need for robust baseline monitoring before intervention. Based on our results from a hillslope‐scale experiment, we were unable to identify clear evidence that peatland ditch blocking will deliver benefits in terms of DOM treatability in potable water supplies, although we also did not find any evidence of short‐term deterioration in water quality during the restoration period. We conclude that, although peatland restoration can be expected to deliver other benefits such as reduced carbon loss and enhanced biodiversity, it is doubtful whether it will lead to improvements in drinking water treatability.

show abstract

Transformations in DOC along a source to sea continuum; impacts of photo-degradation, biological processes and mixing

Cited by 44 publications

References 55 publications

An Analysis of Terrestrial and Aquatic Environmental Controls of Riverine Dissolved Organic Carbon in the Conterminous United States

An Analysis of Terrestrial and Aquatic Environmental Controls of Riverine Dissolved Organic Carbon in the Conterminous United States

Controls on fluvial carbon efflux from eroding peatland catchments

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

Contact Info

Product

Resources

About