Download or read book Coupling the Effects of Dissolved Organic Matter and Nutrient Stoichiometry with Nutrient Uptake in Boreal Forest Headwater Streams written by Dana Fjare and published by . This book was released on 2015 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discontinuous permafrost affects the hydrology and distribution of vegetation in boreal forest watersheds, which in turn influence stream water chemistry. I investigated how loss of discontinuous permafrost with projected climate change might affect nutrient cycling in boreal forest headwater streams. I hypothesized that 1) the carbon, nitrogen, and phosphorus (C:N:P) ratio in dissolved organic matter (DOM) affects nutrient uptake due to stoichiometric constraints on autotrophic and heterotrophic nutrient assimilation, and 2) labile DOM affects nutrient uptake by increasing heterotrophic production. I tested my hypotheses using a series of instantaneous nutrient additions in nine headwater streams, with a factorial design manipulating both nutrient stoichiometry and DOM source. DOM was added as either acetate or leachate from birch leaves. Ambient nutrient uptake velocity (Vf-amb) was within the upper range of previously published literature values, ranging from 4.1-67.2 mm/min for N, 4.0-25.0 mm/min for P, and 4.2-34.5 mm/min for acetate. Uptake efficiency was similar for N and P added alone, in co-additions, and with DOM. Acetate and birch-DOM had similar effects on nutrient uptake, because both were sources of highly labile carbon. In 30-day laboratory bioavailability assays, birch and acetate-DOM exhibited ≥ 70% carbon loss. Vf-amb was in part explained by ambient stream chemistry, with Vf-amb for N weakly positively correlated with ambient P concentration, while Vf-amb for P and acetate was weakly negatively correlated with ambient N and ambient dissolved organic carbon, respectively. Consequently, inorganic nutrient availability may affect uptake of solutes as well as DOM lability. High demand for nutrients in boreal forest headwater streams suggests that uptake could increase concurrently with greater inorganic nutrient flux following a loss in permafrost extent.

Download or read book Nutrient Demand and Nitrogen Processing in Streams of the Hubbard Brook Experimental Forest written by Emily Snow Bernhardt and published by . This book was released on 2001 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Controls on Microbial Processing of Dissolved Organic Matter in Boreal Forest Streams written by Marie Schmidt and published by . This book was released on 2020 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the boreal forest, permafrost thaw is resulting in changes in vegetation and deepening of watershed flowpaths. Caribou-Poker Creeks Research Watershed contains sub-catchments underlain with varying permafrost extents (4-53% cover), providing the opportunity to study how permafrost extent affects water chemistry and nutrient cycling. I measured nitrogen (N), phosphorous (P), and carbon (C) processing ectoenzyme activity in the water column and sediment of headwater streams, and related ectoenzyme activity to nutrient and dissolved organic carbon (DOC) concentration. Additionally, I used nutrient diffusing substrata (NDS) to grow biofilms with enhanced inorganic N and P and labile C alone and in combination and measured ectoenzyme activity and respiration of biofilms in response to resource amendments. High P-processing enzyme activity across streams of the CPCRW indicated microbial P limitation. Respiration and organic matter processing enzymes of biofilms grown on NDS increased with labile C or labile C in combination with nutrient additions, implying that labile C limited or co-limited rates of DOM processing. Our results suggest that as climate warming and subsequent permafrost thaw alters terrestrial inputs of dissolved organic matter (DOM) and inorganic nutrients into streams, changes in inorganic P and labile C availability will control microbial processing of DOM.

Download or read book Pulse of the Stream written by Catherine Grace Winters and published by . This book was released on 2016 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biotic and abiotic factors both play critical roles in the cycling of organic matter and nutrients in aquatic ecosystems. Understanding the relative control of these factors on solute fate and transport in fluvial systems is important for understanding how climatic changes can affect water quality. Many processes that control solute cycling in streams occur at sub-daily scales, making high-frequency, in situ, sub-hourly measurements important for capturing the response of dissolved organic matter and nutrients to changes in the strength of controlling processes. The tightly coupled aquatic and terrestrial environments present in headwater streams make them particularly useful systems for studying high-frequency changes in water chemistry. In this study, we examined the patterns of dissolved organic carbon, nitrate, dissolved oxygen, temperature, dissolved organic matter fluorescence, and stream discharge using in-stream measurements at sub-hourly to monthly time scales to understand the daily and seasonal controls of aquatic organic matter and nutrient processing. We also conducted a laboratory incubation to measure the effects of dissolved organic carbon and nutrient treatments on consumption of carbon and nitrogen in our system. Our main objectives were to identify: 1) the relative controls of diel biotic and abiotic processes on stream dissolved organic carbon and nitrate-N; and 2) the mechanisms controlling rapid autumnal changes in dissolved organic carbon and nitrate-N in stream runoff. We found that hydrology plays a key role in transporting solutes to a forested headwater stream in the Piedmont Region, Maryland; however, once solutes reach the stream biotic controls dominate the stream solute patterns. Biology is an important regulator of diel patterns of streamwater dissolved organic carbon and nitrate concentrations during springtime and autumn leaf fall. Diel cycling is most apparent during the spring prior to leaf out when the water temperature is increasing. Where patterns were evident, nitrate (annual average in second order stream: 17:00) and discharge (17:28) reached their minimums during the afternoon within a few hours of the peaks in dissolved oxygen (13:16), temperature (15:17), dissolved organic carbon (16:06), and dissolved organic matter fluorescence (17:23). Larger amplitudes of dissolved oxygen, nitrate, dissolved organic carbon, and dissolved organic matter fluorescence correspond with larger daily temperature changes. Laboratory incubations showed increased consumption of nitrogen in the presence of labile carbon, but not in the presence of labile carbon plus nutrients, which indicates our system is carbon limited. Autumn dissolved organic carbon and nitrate dynamics also indicate our system is carbon limited. Increased rates of leaf litter fall corresponded with increased consumption of stream nitrate leading to a late October depression, or annual minimum, in nitrate concentration. Storm events accelerated the recovery of stream nitrate to early autumn concentrations as nitrate was mobilized and transported from soils to the stream. Hydrology is important for solute transport to and export from the stream. Autotrophic activity dominates on the daily scale, while heterotrophic activity controls seasonal responses in organic matter and nutrient cycling in this forested watershed. Carbon and nitrogen dynamics have been studied in other forested systems, as well, but the controlling processes vary among these watershed. Our results highlight the importance of understanding controlling processes within specific watersheds when making large scale predictions of the potential export of carbon and nitrogen from forested systems.

Download or read book Decomposition of Dissolved Organic Matter in Arctic and Boreal Streams written by Audrey Mutschlecner and published by . This book was released on 2017 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arctic and boreal rivers connect terrestrial, oceanic, and atmospheric carbon (C) pools by transporting and processing dissolved organic matter (DOM). DOM composition influences its susceptibility to decomposition (biolability), which in turn determines whether the associated C is respired, stored, or exported. High-latitude ecosystems are changing rapidly due to processes such as permafrost thaw, shifts in vegetative communities, and increasing discharge, and each of these processes can influence the composition of DOM reaching rivers. The eventual fate of riverine DOM, whether it is mineralized or exported, shifts the balance of global C pools. Therefore, to understand how changes to high-latitude ecosystems influence the global C cycle, we must be able to connect patterns in DOM composition to its biolability and subsequent fate within the C cycle. The objectives of this study were to describe spatial and temporal patterns in DOM composition and biolability, and to determine links between the composition and biolability of DOM. I sampled DOM from streams along an Arctic-boreal gradient in interior Alaska throughout the year. I measured DOM biolability and nutrient limitation of decomposition in laboratory incubations and characterized DOM composition using optical properties and chemical analysis. I found that temporal patterns in DOM composition corresponded to seasonal trends in the hydrology of high-latitude catchments, linking DOM source to shallow, organic-rich flowpaths in spring and deeper groundwater flows in winter. Biolability was low, indicating that the majority of riverine DOM is recalcitrant to biological decomposition. I observed increased biolability in response to phosphorus (P) addition, particularly during spring, indicating that phosphorus limits DOM decomposition. To further examine the mechanisms driving C processing in streams, I also conducted a series of whole-stream experiments to compare the relative influence of molecular composition and nutrient content of DOM. I added leaf leachate to boreal streams and measured C retention, which represents both biological uptake and sorption. The leachates varied by molecular composition, due to differences in tissue chemistry of plant species, and in nutrient content, because the leaves were collected from plots with different fertilization regimes. Retention was greatest for leachates derived from trees that had been fertilized with P, indicating P-limitation of biological uptake of C or preferential sorption of P-containing organic molecules. Although leachates varied in molecular composition as determined by optical properties, these differences did not correspond to a difference in uptake rates by species. These patterns in DOM retention indicate that nutrient content is a greater constraint on C uptake than molecular composition. Together, the two studies suggest that export is the primary fate of ambient DOM in high-latitude streams, but that C processing is highly sensitive to inputs of bioavailable DOM. The coupling between the P and C cycles observed in both studies highlights the potential for nutrient availability to constrain or promote CO2 emissions from C-rich, high-latitude catchments.

Download or read book Evaluating Long term Nutrient Impacts Within Agricultural Headwater Streams written by Ashlee Marie Balcerzak and published by . This book was released on 2020 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the first chapter of my thesis, I investigate the water quality improvement that can be expected from grass filter strips in agricultural headwater streams. Grass filter strips consist of herbaceous vegetation planted at the edge of agricultural fields next to a stream or river, intended to control non-point source pollution by trapping sediments, nutrients, and pesticides flowing into streams. Because they take agricultural land out of production, grass filter strips have been incentivized in the United States, and so it is important to know their effectiveness. My study objective was to understand the impacts of riparian habitat types on nutrient concentrations over time in agricultural headwater streams. Eight streams within the Upper Big Walnut Creek Watershed in central Ohio were selected, possessing unplanted riparian habitats with remnant vegetation, grass filter strips, or forested riparian habitats. Weekly water samples for the measurement of nutrient concentrations were collected from each stream reach from March 2007 to February 2017. Annual mean nitrogen and phosphorus concentrations did not differ (P > 0.05) among riparian habitat types. Dissolved organic carbon was influenced through the interaction effects of riparian habitat type and year and riparian habitat type and season. Forested riparian habitat types may be used to manage DOC levels in agricultural headwater streams. Grass filter strips were not more effective in reducing nitrogen and phosphorus concentrations than filter strips having other vegetation. In the second chapter of my thesis, I study the ability of a less rigorous estimation of stream discharge to replicate state-of-the-art discharge estimates and, when combined with water quality sampling, nutrient loads. Estimation of stream and river discharge is important for understanding its impact on water quality, habitat, living organisms present in the water, and the surrounding ecosystem. Since state-of-the-art monitoring techniques are expensive for estimating stream discharge, it is important to evaluate less rigorous methods for possible use in estimating discharge and nutrient loading. In this paper I explore the use of the Manning’s equation for use in discharge estimation in agricultural headwater streams. My goal was to predict discharge and nutrient loads in agricultural headwater streams. My objectives were to 1) evaluate the Manning’s Approach against state-of-the-art measurements for predicting discharge, and 2) explore the influence of discharge predictions from the Manning’s Approach on nutrient loading. Six sites from three streams within the Upper Big Walnut Creek Watershed in central Ohio were selected based on available discharge measurements and nutrient data. Weekly water samples for the measurement of nitrogen and phosphorus were collected from each stream from January 2007 to December 2013, along with geomorphic measurements for estimating velocity and discharge using stage and cross-sectional area of flow. The Manning’s Approach did not meet performance metrics at five of the six sites. Nutrient loads were adequately estimated at two of six sites, but at many sites loading showed considerable bias due to inaccuracies in discharge estimation. Thus, I find mixed support the Manning’s Approach will lead to an effective prediction in nutrient loads within agricultural headwater streams.

Download or read book Microbial and Photochemical Cycling of Dissolved Organic Matter in Boreal Headwater Streams written by Doreen Franke and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a key global energy source and carbon reservoir that links terrestrial and aquatic biogeochemical cycling. Allochthonous organic matter is abundant in boreal headwater streams, and environmental changes such as variation in nutrient availability and changes to watershed landscape composition have great potential for altering the DOM source, its composition and cycling. This dissertation focuses on two of the main drivers of aquatic carbon and nutrient cycling: the photochemical and the microbial processing of DOM in boreal headwater streams; specifically (i) how the photochemical lability of DOM varies between reaches within headwater streams, among headwater streams and an associated large river reach, (ii) how stream biofilm mineralization may be regulated by watershed organic matter source and composition, increased labile carbon, nitrogen, and phosphorus availability, and (iii) whether algal carbon sources are important to supporting stream biofilms and if such sources influence the use of allochthonous DOM in nutrient-enriched streams. The results suggest changes in landscape and nutrient availability have the potential to alter the photochemical and biogeochemical cycling of DOM. DOM photolability was increased upstream relative to downstream and the river DOM. This may be due to differences in DOM source and composition, and suggests losses in photolabile DOM downstream and in the lower reaches of the watershed. The phototransformation of DOM into low molecular weight compounds and nutrients such as ammonium is likely relevant to the carbon and nutrient cycling in boreal watersheds. Results here further suggest that boreal stream biofilm mineralization of DOM is regulated by watershed DOM source and composition. Labile carbon sources, such as algal inputs, may also play an important role in regulating DOM mineralization and the processing of nutrients by these biofilms. In nutrient-impacted streams, where primary production is high relative to nutrientpoor streams, biofilms may be stimulated to incorporate algal carbon sources. Yet in the boreal streams studied here, added labile carbon rarely enhanced the mineralization of extant stream DOM suggesting autotrophic-heterotrophic interactions represent a more important priming effect relative to changing DOM source in boreal streams.

Download or read book Resource Limitation of Autotrophs and Heterotrophs in Boreal Forest Headwater Streams written by Sophie Alden Weaver and published by . This book was released on 2019 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: In stream biofilms, autotrophs and heterotrophs are responsible for the majority of in stream nutrient transformations. In boreal forest catchments, discontinuous permafrost can lead to variation in nutrient and energy resources, which can control competition for nutrients between autotrophs and heterotrophs within these biofilms. I was interested in determining what resources control nutrient utilization by autotrophs and heterotrophs in headwater streams in the boreal forest of interior Alaska. I hypothesized that the outcome of competition between autotrophs and heterotrophs for inorganic nutrients would be dependent on the availability of (i) organic carbon, (ii) light, or (iii) inorganic nutrients. To measure resource limitation and competition at both patch and reach scales, I deployed nutrient diffusing substrata and conducted nutrient uptake experiments in streams along a permafrost gradient at the Caribou-Poker Creeks Research Watershed in interior Alaska. At the patch scale, autotrophs were light and nutrient limited, whereas heterotrophs were carbon and nutrient limited, and at the reach scale, light had the largest influence on nutrient uptake. Heterotrophs exhibited a larger response to nutrient enrichment when stream ambient carbon stocks were more bioavailable. Autotrophic biomass and productivity was suppressed when labile carbon was available to heterotrophs, suggesting that heterotrophs outcompete autotrophs for nutrients when a labile carbon source is introduced. The positive responses to nutrient and carbon additions suggest that the hypothesized increased nutrient and carbon exports into fluvial networks with permafrost degradation will impact biofilm structure and function, with the potential to influence nutrient export and stream ecosystem function downstream.

Download or read book Does Dissolved Organic Matter Impact Primary Production A Study on the Effects of Terrestrially Derived Dissolved Organic Matter on Primary Production in Nutrient poor Boreal Lakes written by Bryanna Sherbo and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few decades, spatial and temporal variation in concentrations of allochthonous dissolved organic carbon (DOC) has been increasing in surface waters of boreal lakes around the world with climate change. Terrestrial landscapes export large amounts of organic matter into lakes, primarily as DOC. It is understood that DOC impacts primary production through its combined effects on light and nutrient availability. However, there remains uncertainty as to the mechanisms that cause DOC to have positive or negative effects on algal productivity. In a survey of 6-7 lakes spanning a DOC gradient (3.5-9.4 mg L-1) at International Institute of Sustainable Development-Experimental Lakes Area (IISD-ELA) in northwestern Ontario, we determined the effects of DOC on whole-lake metabolism (gross primary production (GPP), respiration, and net ecosystem production (NEP)) and depth integrated net primary production (NPP). Using in situ diel free-water oxygen method and in vitro partial pressure of CO2 incubations, we found that primary production was significantly impacted by DOC. In general, the effects of DOC on algal productivity was negative, although there was some evidence for the stimulation of whole ecosystem production by nutrients at low DOC concentrations. Epilimnetic chlorophyll, GPP, and community respiration increased significantly with DOC, and total depth integrated and sub-epilimnetic NPP decreased significantly with DOC. Lakes with the highest proportion of sub-epilimnetic production had well developed deep chlorophyll maxima (DCM). DCM were negatively correlated with DOC and are viewed as ecological hotspots for higher trophic levels. DCM and sub-epilimnetic productivity were eliminated in lakes with DOC values > 7.1 mg L-1. These results substantiate the influence of allochthonous DOC on aquatic food webs and highlight the combined effects of DOC on light and nutrient availability. The association of DOC with epilimnetic nutrients caused an increase in epilimnetic GPP (chapter 2) and decreasing light availability caused a decrease in total and sub-epilimnetic NPP (chapter 3). These contrasting effects of DOC on primary production provide further insight into the balance between nutrients and light with increasing concentrations of DOC.

Download or read book Biogeochemical Cycling in Lake Superior Tributaries written by Ashley Anne Coble and published by . This book was released on 2015 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seasonal and spatial variability in environmental factors may affect dissolved organic matter composition and nutrient transformation and retention in streams. The objective of this research was to quantify and describe seasonality, quantity, and quality of nutrient processing and export of ammonium (NH4), soluble reactive phosphate (SRP), and dissolved organic carbon (DOC) into Lake Superior through intensive study in a small 1st order watershed coupled with snapshot measurements across 12 tributaries that varied in size, location, and wetland coverage. Our results suggest biodegradable C is exported from a small headwater stream year-round and that DOC mineralization rates can be stimulated by additions of NH4 and labile C (Chapter 2). We found that biodegradable DOC varied synchronously among 3 rivers that varied in size by three orders of magnitude. Furthermore, these rivers exported 9 to 17% of annual DOC in biodegradable form, which may then fuel biological activity in nearshore zones of Lake Superior. Modeling of historical loads of DOC suggests that spring loads of DOC have increased and fall loads have decreased over a 26 year period, but annual loads have not (Chapter 3). Across eleven tributaries variability in NH4 uptake velocity was explained by watershed area, discharge, and fluorescence index of DOC (indicator of microbial and terrestrial sources; Chapter 4). Temporally detailed measurements (every 2 to 4 weeks for 3 years) of nutrient uptake in a small headwater stream indicated light availability, algal and periphyton biomass, solute concentrations, and pH were important predictors of NH4 uptake velocity (Chapter 5). We found a similar magnitude of NH4 uptake velocity during winter and summer measurements while SRP uptake velocity was greater in summer than winter (Chapter 5). Overall the greatest uptake velocities were observed in spring and fall for NH4, in spring for SRP and in fall for DOC (Chapter 5). Collectively, this research demonstrates the temporally dynamic nature of biodegradable carbon and nutrient uptake, the tight coupling of C and N cycling, and the role of DOM composition in stream nutrient uptake in northern temperate forested streams.

Download or read book Mobilization of Soil Dissolved Organic Matter in Mesic Boreal Forests of Newfoundland and Labrador Canada written by Keri L. Bowering and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mobilization of soil dissolved organic matter (DOM) distributes carbon and nutrients within ecosystems and links terrestrial to aquatic environments. As a hydrologically and biogeochemically mediated flux, DOM mobilization encapsulates a number of interacting ecological processes. This presents a major challenge for identifying the main drivers of DOM mobilization at different spatial and temporal scales. In this thesis, I use two mesic boreal forest research platforms to investigate the drivers of DOM mobilization from the organic horizon at different spatiotemporal scales. Using an experimentally harvested site, I show that total annual DOC flux from O horizons is due to both vertical and lateral flow, and was 30% percent greater in the harvested plots with significantly reduced organic horizons. Additionally, the C:N of DOM and absorbance characteristics of samples in both treatments demonstrated a stronger control of season over harvesting on the composition of DOM mobilized. One of the most significant of these seasonal controls was the snowpack insulation throughout winter. The lower C:N, higher SUVA254nm and lower molecular weight of chromophoric DOM mobilized during winter and snowmelt indicates relatively more decomposed DOM, compared to that mobilized in summer and autumn. This shows that the decomposition of soil organic matter underneath a consistently deep snowpack is a key determinant of the composition of DOM mobilized from O horizons during winter and the hydrologically significant snowmelt period. Additionally, I show that air temperature and snowpack duration best explain DOM mobilization dynamics both interannually within boreal sites and among boreal forest sites along a climate transect. This suggests that air temperature indirectly affects DOC mobilization through a direct control on snowpack season length in these forests. Furthermore, climate influenced differences in ecosystem properties such as organic horizon thickness, moss coverage and stand density, may additionally influence DOM mobilization through a direct control on soil hydrology. These results enhance our understanding of the relationship between boreal forest soil organic matter and soil DOM and the potential impacts of climate change on soil organic matter losses as DOM, contributing to a predictive understanding of forest C and nutrient distribution and the potential effect on aquatic environments.

Download or read book Dissolved Organic Carbon Dynamics in Tallgrass Prairie Streams written by Sophie Alexandra Higgs and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Contrary to the previous notion that a stream acts primarily as the transporter of materials from land to oceans, research has shown that in-stream processing of organic matter and nutrients is significant and relevant at a global scale. Dissolved organic carbon (DOC) is the most abundant form of organic carbon in streams and has been demonstrated as an important source of energy supporting stream food webs. Understanding the dynamics of DOC in streams is, therefore, important in determining the contribution of flowing waters to global carbon storage and release. However, DOC exists as many different compounds, varying in source, composition, and quality. The composition of DOC that ends up in streams is partly controlled by the surrounding watershed, and landscape effects on DOC quality and quantity in streams have been observed. In the North American Tallgrass prairie, woody encroachment has led to changes in riparian vegetation, potentially altering the DOC received by the stream, and making it important to understand rates of DOC transformation as landscape alterations continue. The heterogeneity of the DOC pool makes it difficult to fully describe its components and to measure transformation rates. DOC uptake, or biological use, has been estimated through several methods including in-stream additions of various DOC sources and bottle incubations of stream water and sediments. One problem with addition methods for calculating uptake is that the DOC pool is difficult to replicate and additions of simple compounds or organic leachates do not represent total dissolved organic carbon (TDOC) dynamics. Another potential issue is that additions of a labile compound could potentially alter microbial activity through a priming effect and therefore distort ambient DOC uptake estimates. Finally, uptake parameters are mostly calculated assuming benthic uptake while recent studies have shown that planktonic uptake of DOC can also be significant. We conducted this study with these three considerations in mind. In the first chapter, we describe our use of in situ additions of glucose and bur oak leaf leachate in prairie stream reaches and concentrations of specific components to determine uptake dynamics of various specific DOC components, from a simple sugar to more complex plant compounds. We calculated uptake parameters of glucose and two different oak leaf components. We found that using glucose concentrations rather than TDOC concentrations, as has been done in previous studies, to measure uptake parameters resulted in higher uptake rates, indicating the importance of measuring the specific component added. Through leaf leachate additions, we found that an amino acid like component was consistently taken up faster than a humic-like component. The second chapter addresses the questions of uptake location and priming through a series of recirculating chamber incubations. We found that benthic uptake of leaf leachate was more important than that in the water column. Finally, elevated uptake of one leaf leachate component in the presence of glucose indicated a priming effect on microbial DOC uptake.

Download or read book Effects of Inorganic Nutrients and Dissolved Organic Carbon on Oxygen Demand in Select Rivers in Northern Utah written by Joseph L Crawford and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sewage, agricultural runoff, and atmospheric deposition have greatly increased the amount of nutrients (largely nitrogen (N) and phosphorus (P)) in surface water nationwide. Excess nutrients are associated with algal blooms and dissolved oxygen depletion in many water bodies, but linkages between nutrients and dissolved oxygen have been largely correlative. Biochemical oxygen demand (BOD) is a regulated water quality parameter that is aimed at describing the amount of oxygen consumed during the decomposition of organic matter. Despite the awareness that excess nutrients are linked to dissolved oxygen in rivers, few studies in the nutrient criteria literature discuss BOD measurements or how nutrients may impact BOD. Accordingly, I used factorial experiments to test the effect of inorganic nutrients (as N, P and N+P) and dissolved organic carbon on BOD measurements in Utah streams. The study was carried out from January through summer base flow in 2011, allowing me to evaluate the effects of spatial and temporal variation of ambient nutrient concentration on oxygen demand. The study design included measurements in streams above and below nutrient point-sources (publicly owned treatment works) and several reference sites. I used classification and regression trees to identify thresholds of TN and TP that separate BOD response to nutrients into statistically distinct groups. My results show that seasonal variation affected BOD levels. As temperatures rose and water levels increased during peak runoff, I observed the highest BOD response to nutrient additions. I also found a significant correlation between BOD and ambient nutrient concentrations during that time period. I identified potential nutrient-related thresholds that could be used to assign numeric criteria that would protect designated uses. The threshold values I found for TN and TP were 0.56 mg/L and 0.09 mg/L, respectively. My results suggest that BOD may be sensitive to nutrient inputs and my experimental approach could be used as one line of evidence to support nutrient criteria related to aquatic life uses.

Download or read book Limnology written by Robert G. Wetzel and published by Academic Press. This book was released on 2001-05-10 with total page 1023 pages. Available in PDF, EPUB and Kindle. Book excerpt: Limnology is the study of the structural and functional interrelationships of organisms of inland waters as they are affected by their dynamic physical, chemical, and biotic environments. Limnology: Lake and River Ecosystems, Third Edition, is a new edition of this established classic text. The coverage remains rigorous and uncompromising and has been thoroughly reviewed and updated with evolving recent research results and theoretical understanding. In addition, the author has expanded coverage of lakes to reservoir and river ecosystems in comparative functional analyses.

Download or read book Hydrologic Dynamics Control Dissolved Organic Matter Export from Watersheds written by Rebecca Anne Bellmore and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is an important component of nutrient cycling and energy transfer within and between ecosystems. Understanding controls over the magnitude and quality of DOM that is transferred from soils to surface water is needed to better characterize the terrestrial-aquatic carbon flux and effects of terrestrial DOM on downstream ecosystems. A meta-analysis of the response of in-stream dissolved organic nitrogen concentration (DON) to high flow events indicates that DON typically increases with flow across a wide range of ecosystem types, likely as novel DOM sources in the landscape are mobilized and transported to streams and rivers. Mechanisms controlling DOM export, including dissolved organic carbon (DOC) and DON concentrations and the quality of DOM, were examined in a small agricultural catchment in eastern Washington State. In the soil column, DOC concentration declined and source of DOM shifted from humic-like and plant-derived to microbially-derived with depth through the profile. Across seasons and years, DOM exported via drain discharge during low flows resembled that found deep in the soil profile, and DOM exported during high flows suggests topsoil and litter sources contribute to export. A simple mixing model suggests that litter leachate can contribute over 50% of DOM during peak flow. Based on modeled contributions of litter, topsoil and subsoil DOM during storm events, DOC concentration is over-predicted, except for peak flows, suggesting removal via sorption and/or microbial decomposition in the soil column control DOC export on the timescale of events. Although the character of exported DOM shifts with flow conditions, laboratory incubations suggest bioavailability to the stream sediment microbial community is consistently low, with a maximum of 7% loss over 6 days, indicating exported DOM is likely transported beyond the immediate stream reach. An analysis of anticipated effects of climate change on the flow regime in the catchment projects the wettest years to become more variable, with non-linear effects on the magnitude of DOC export. Finally I explore how climate change assessments can be incorporated into nonpoint source nutrient management plans, despite current uncertainty about the magnitude and timeframe of climate effects on nutrient loading.

Download or read book The Use of Headwater Catchments to Understand the Age Availability and Fate of Organic Matter Exported from Terrestrial to Fluvial Systems written by Christopher Dempsey and published by . This book was released on 2013 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Headwater streams provide a critical interface between terrestrial and aquatic ecosystems. Significant quantities of dissolved organic carbon are stored in soils and a portion of this is transported through river systems on an annual basis. This organic carbon is an important energy source for microbial communities and its quality has important implications for its availability and transport to downstream reaches. Prior studies have focused on dissolved organic carbon in large river systems. While important, these studies can be affected by anthropogenic influences and by large-scale heterogeneity in geology and vegetation across large watersheds. Here we provide insight into the export, quality, and fate of dissolved organic carbon in headwater streams. We utilized small catchments with varying land use types in Pennsylvania to assess changes to the quality of dissolved organic carbon during storm events and nutrient addition experiments. The agricultural site exports significantly higher concentrations of DOC per watershed area. During storm events we observed little change in the fluorescence organic carbon signal and an increase in SUVA254. Biolability decreased with increasing discharge in the forested watersheds. Nutrient addition experiments indicated an increase in microbial respiration with both nitrogen and phosphorous. Batch culture experiments show that much of the organic carbon transported in headwater streams is respired to the atmosphere as CO2. Land use is important to DOC export, DOC biolability, and bacterial growth efficiency, but has minimal influence on the export of aged DOC. Hydrology played a more important role than land use in controlling the export, availability, and fate of dissolved organic carbon in headwater streams.

Download or read book Developing a Method for Continuously Monitoring Dissolved Organic Carbon Concentration in Boreal Forest Headwater Streams written by Christian Javier Gaviria Salazar and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Headwater streams are an important medium through which carbon from the landscape is transported into aquatic ecosystems in the form of dissolved organic carbon (DOC), an ecologically significant and, until the last decade, underestimated pool of mobile carbon. Boreal forests contain a great fraction of the worlds terrestrial carbon and are considered a large carbon sink. However, they are vulnerable to climate change and can easily become sources of atmospheric carbon. To better understand how our landscapes are responding to climate change we can monitor DOC within headwater streams which integrate and quickly respond to changes of the surrounding landscape. However, continuous monitoring for DOC is difficult and must be monitored via proxy-measurements. This thesis demonstrates an approach to develop and monitor the performance of a model developed to estimate DOC from UV-VIS absorbance and other data from in-situ probes.