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The Clark Fork Voluntary Nutrient Reduction Program (VNRP) was a multi-party agreement between state government, municipal governments, private industry and environmental groups with the explicit goal to: "restore beneficial uses and eliminate nuisance algae growth in the Clark Fork from Warm Springs to the Flathead confluence…" The VNRP was carried out from 1998-2008 by Butte-Silver Bow County, City of Deer Lodge, Missoula City-County government, City of Missoula, Smurfit-Stone Container Corporation, DEQ and the Clark Fork Coalition, all facilitated by the Tri-State Water Quality Council, based in Sandpoint, Idaho. The work done by the VNRP signatories was recognized nationwide, and prominently highlighted in numerous EPA case studies and documents about how to do nutrient management at a river basin scale. * VNRP signatories decreased nutrient discharge in all areas of the river, including decreases of wastewater nutrients of 30% in total nitrogen and 72% in total phosphorus from 1988 to 2008. *This effort translated into major reductions of nutrients in the Clark Fork, both in the upper river and in the middle river near Missoula, with mean total phosphorus concentrations dropping by half during the period 1988-2007. *The algae targets were met about 30% of the time in the upper and middle river, and 70% of the time in the river below Missoula, with an improving trend in compliance downstream of Missoula. The upper Clark Fork near Deer Lodge has tougher algae targets, and a notoriously difficult species of algae to control, and that trend is not yet showing improvement.

Intro -- Series Editor's Preface -- Contents -- 1 An Introduction to Biogeochemistry of the Critical Zone -- References -- 2 Hot Spots and Hot Moments in the Critical Zone: Identification of and Incorporation into Reactive Transport Models -- 2.1 Introduction -- 2.1.1 Definition of Terms -- 2.1.2 Scope and Overall Impact -- 2.2 Capturing Scales and Complexity Using Models -- 2.2.1 Hot Spots Within the Hyporheic Zone-The Redox Microzone Concept -- 2.2.2 HSHMs at the Floodplain Scale -- 2.2.3 HSHMs Along River Corridors -- 2.3 Current Understanding and the Path Forward -- 2.3.1 A Conceptual Take on HSHMs Using a Trait-Based Framework -- 2.3.2 Improvements in Field-Scale Characterization of Hyporheic Zones -- 2.3.3 Recent Developments in Observation and Modeling of Hot Spots Featuring the Sediment Water Interface -- 2.4 How Can Models Contribute? -- 2.4.1 Scale Aware Modeling/Parameterization -- 2.4.2 A Preemptive Prioritization of HSHMs -- 2.5 Concluding Remarks -- References -- 3 Constraints of Climate and Age on Soil Development in Hawai'i -- 3.1 Understanding Critical Zone Functioning Through State Factor Analysis -- 3.2 Physiographic Setting -- 3.3 Analytical Approach -- 3.4 Development of Critical Zone Properties Across the Hawaiian Islands -- 3.4.1 Weathering Depth and Chemical Denudation -- 3.4.2 Conditioning Lava Flows for Critical Zone Development -- 3.5 Biogeochemical Properties of Hawaiian Critical Zone -- 3.5.1 Weathering and Soil Properties -- 3.6 Soil Process Domains and Pedogenic Thresholds in Hawai'i -- 3.6.1 Process Domains -- 3.6.2 Transitions Among Process Domains -- 3.7 Conclusions -- References -- 4 Biofilms in the Critical Zone: Distribution and Mediation of Processes -- 4.1 Introduction -- 4.2 Documenting Environmental Biofilms Using the Scanning Electron Microscope -- 4.3 Biofilms in the Critical Zone.

The Hubbard Brook Experimental Forest (HBEF) was established in 1955 by the U.S. Department of Agriculture, Forest Service out of concerns about the effects of logging increasing flooding and erosion. To address this issue, within the HBEF hydrological and micrometeorological monitoring was initiated in small watersheds designated for harvesting experiments. The Hubbard Brook Ecosystem Study (HBES) originated in 1963, with the idea of using the small watershed approach to study element fluxes and cycling and the response of forest ecosystems to disturbances, such as forest management practices and air pollution. Early evidence of acid rain was documented at the HBEF and research by scientists at the site helped shape acid rain mitigation policies. New lines of investigation at the HBEF have built on the long legacy of watershed research resulting in a shift from comparing inputs and outputs and quantifying pools and fluxes to a more mechanistic understanding of ecosystem processes within watersheds. For example, hydropedological studies have shed light on linkages between hydrologic flow paths and soil development that provide valuable perspective for managing forests and understanding stream water quality. New high frequency in situ stream chemistry sensors are providing insights about extreme events and diurnal patterns that were indiscernible with traditional weekly sampling. Additionally, tools are being developed for visual and auditory data exploration and discovery by a broad audience. Given the unprecedented environmental change that is occurring, data from the small watersheds at the HBEF are more relevant now than ever and will continue to serve as a basis for sound environmental decision-making. ; Public domain authored by a U.S. government employee

A comprehensive cross-biome assessment of major nitrogen (N) species that includes dissolved organic N (DON) is central to understanding interactions between inorganic nutrients and organic matter in running waters. Here, we synthesize stream water N chemistry across biomes and find that the composition of the dissolved N pool shifts from highly heterogeneous to primarily comprised of inorganic N, in tandem with dissolved organic matter (DOM) becoming more N-rich, in response to nutrient enrichment from human disturbances. We identify two critical thresholds of total dissolved N (TDN) concentrations where the proportions of organic and inorganic N shift. With low TDN concentrations (0-1.3 mg/L N), the dominant form of N is highly variable, and DON ranges from 0% to 100% of TDN. At TDN concentrations above 2.8 mg/L, inorganic N dominates the N pool and DON rarely exceeds 25% of TDN. This transition to inorganic N dominance coincides with a shift in the stoichiometry of the DOM pool, where DOM becomes progressively enriched in N and DON concentrations are less tightly associated with concentrations of dissolved organic carbon (DOC). This shift in DOM stoichiometry (defined as DOC:DON ratios) suggests that fundamental changes in the biogeochemical cycles of C and N in freshwater ecosystems are occurring across the globe as human activity alters inorganic N and DOM sources and availability. Alterations to DOM stoichiometry are likely to have important implications for both the fate of DOM and its role as a source of N as it is transported downstream to the coastal ocean. ; National Science Foundation (NSF) through the Long-Term Ecological Research Network Office (LNO), National Center for Ecological Analysis and Synthesis (NCEAS), University of California-Santa Barbara [1545288]; NSFNational Science Foundation (NSF) [1556603]; New Hampshire Agricultural Experiment Station; USDA National Institute of Food and Agriculture McIntire-Stennis Project [1006760, 1016163]; Natural Environment Research Council, UK Large Grant [NE/K010689/1] ; Published version ; This work was conducted as a part of the Stream Elemental Cycling Synthesis Group funded by the National Science Foundation (NSF) under grant DEB#1545288, through the Long-Term Ecological Research Network Office (LNO), National Center for Ecological Analysis and Synthesis (NCEAS), University of California-Santa Barbara. The authors acknowledge the efforts of Julien Brun for assistance with data synthesis and the efforts of multiple individuals who collected and analyzed samples. Partial support for ASW during data synthesis and manuscript preparation was provided by NSF grant DEB#1556603 (Deciphering Dissolved Organic Nitrogen). Partial funding was provided by the New Hampshire Agricultural Experiment Station. This is Scientific Contribution 2880. This work was supported by the USDA National Institute of Food and Agriculture McIntire-Stennis Project 1006760. Support for AA was provided by the USDA National Institute of Food and Agriculture McIntire-Stennis Project 1016163. Partial support for PJJ and CAY was provided by Natural Environment Research Council, UK Large Grant NE/K010689/1 (DOMAINE: Characterizing the Nature, Origins and Ecological Significance of DOM in Freshwater Ecosystems). The authors are also grateful for feedback from two anonymous reviewers whose comments significantly improved this manuscript. This paper is dedicated to the memory of Dr. John Schade, a friend, colleague, and mentor to many of us. John studied ecological stoichiometry in freshwater ecosystems and led the Long-Term Ecological Research (LTER) group at the US National Science Foundation. ; Public domain authored by a U.S. government employee

Streams play a key role in the global carbon cycle. The balance between carbon intake through photosynthesis and carbon release via respiration influences carbon emissions from streams and depends on temperature. However, the lack of a comprehensive analysis of the temperature sensitivity of the metabolic balance in inland waters across latitudes and local climate conditions hinders an accurate projection of carbon emissions in a warmer future. Here, we use a model of diel dissolved oxygen dynamics, combined with high-frequency measurements of dissolved oxygen, light and temperature, to estimate the temperature sensitivities of gross primary production and ecosystem respiration in streams across six biomes, from the tropics to the arctic tundra. We find that the change in metabolic balance, that is, the ratio of gross primary production to ecosystem respiration, is a function of stream temperature and current metabolic balance. Applying this relationship to the global compilation of stream metabolism data, we find that a 1 degrees C increase in stream temperature leads to a convergence of metabolic balance and to a 23.6% overall decline in net ecosystem productivity across the streams studied. We suggest that if the relationship holds for similarly sized streams around the globe, the warming-induced shifts in metabolic balance will result in an increase of 0.0194 Pg carbon emitted from such streams every year. ; National Science Foundation (NSF)National Science Foundation (NSF) [EF-1258994]; NSFNational Science Foundation (NSF) [EF-1065255, EF-1065286, EF-1065055, EF-1065682, EF-1065267, EF-1064998, EF-1065377]; Northern Australian Environmental Resources Hub of the National Environmental Science Program; Scale, Consumers and Lotic Ecosystem Rates project ; The authors thank K. Gido for his contribution in obtaining funding and designing the field experiments. K. Gido, J. Drake, C. Osenberg and J. Minucci provided comments on earlier versions of this paper. Georgia Advanced Computing Resource Center provided the computing facility. This study was supported by the National Science Foundation (NSF, grant EF-1258994) and is part of the Scale, Consumers and Lotic Ecosystem Rates project supported by NSF grant EF-1065255. Data collection at each site was supported by NSF grants EF-1065286, EF-1065055, EF-1065682, EF-1065267, EF-1064998 and EF-1065377, and the Northern Australian Environmental Resources Hub of the National Environmental Science Program. ; Public domain authored by a U.S. government employee

Studies of trophic-level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen N-15-ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying physical, chemical, and biological features. N transfer efficiencies from primary uptake compartments (PUCs; heterotrophic microorganisms and primary producers) to primary consumers was lower (mean 11.5%, range 100%). Total N transferred (as a rate) was greater in streams with open compared to closed canopies and overall N transfer efficiency generally followed a similar pattern, although was not statistically significant. We used principal component analysis to condense a suite of site characteristics into two environmental components. Total N uptake rates among trophic levels were best predicted by the component that was correlated with latitude, DIN:SRP, GPP:ER, and percent canopy cover. N transfer efficiency did not respond consistently to environmental variables. Our results suggest that canopy cover influences N movement through stream food webs because light availability and primary production facilitate N transfer to higher trophic levels. ; National Science FoundationNational Science Foundation (NSF) [NSF-DEB 1052399, DBI-1401954]; Department of Energy's Office of Science, Biological and Environmental Research; U.S. DOEUnited States Department of Energy (DOE) [DE-AC05-00OR22725]; U.S. Department of EnergyUnited States Department of Energy (DOE) [DE-AC05-00OR22725] ; We thank everyone who participated in the individual tracer experiments used in this analysis. We are grateful for the leadership and friendship of the late Pat Mulholland, whose legacy continues to inspire. This manuscript is the product of a workshop funded by a National Science Foundation grant (NSF-DEB 1052399) to M. R. Whiles and W. K. Dodds. Partial support during manuscript preparation to N. A. Griffiths was from the Department of Energy's Office of Science, Biological and Environmental Research. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. S. M. Collins was supported by a National Science Foundation Postdoctoral Research Fellowship in Biology (DBI-1401954). ; Public domain authored by a U.S. government employee