Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to
THE NATIONAL ATMOSPHERIC DEPOSITION PROGRAM (NADP)
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1005767
Grant No.
(N/A)
Project No.
CA-D-LAW-5631-RR
Proposal No.
(N/A)
Multistate No.
NRSP-_OLD_3
Program Code
(N/A)
Project Start Date
Feb 20, 2015
Project End Date
Sep 30, 2019
Grant Year
(N/A)
Project Director
Dahlgren, R.
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Land, Air and Water Resources
Non Technical Summary
Water quality is an important issue affecting humans and wildlife. Humans have a tremendous affect on water quality having doubled inputs of nitrogen into global ecosystems through food production and energy consumption. The mobilization of anthropogenic N has been connected with increased N loading to aquatic ecosystems and associated ecosystem and human health effects. This study will examined the fate and transport of natural N sources and net anthropogenic nitrogen inputs (NANI) to several terrestrial and aquatic ecosystems. The primary objectives of this study are:1. To quantify natural and anthropogenic N inputs into a cross section of terrestrial and aquatic ecosystems in the Central Valley of California.2. To access the importance of various N loss mechanisms in attenuating leaching of N to rivers.3. To access the N leaching lag time associated with legacy N inputs to watersheds.4. To assess the ecological effects of natural and NANI on terrestrial and aquatic ecosystems. By better understanding controls on nitrogen inputs, fate and transport through various watersheds, we will be able to improve beneficial-management practices (BMPs) to enhance water quality. This knowledge will further enhance management, conservation and restoration activities for aquatic ecosystems supporting endangered species (e.g., Delta smelt). In terms of nutrient BMPs, it is critical to fully understand legacy nutrient impacts and the lag time between implementation of BMPs and the resulting effects of water quality. Often times BMPs are considered a failure because they do not result in the immediate impact anticipated.Results of this study will have immediate impact on the hydrologic and habitat design of restored tidal wetlands in the San Francisco Bay-Delta estuary. The hydrologic-nutrient interactions occurring in tidal wetlands is critical to optimizing food resource availability to aquatic ecosystems, as well as for removal of excess nutrients to limit hypoxia/anoxia. Furthermore, the results of these studies will impact soil nutrient management, forest harvest management practices, post wildland fire restoration activities, and design of constructed flow-through wetlands to capture nutrients from agricultural practices.I anticipate that the results of this study will contribute to enhanced aquatic ecosystem productivity and help sustain threatened/endangered aquatic species in California watersheds.
Animal Health Component
0%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1120320107030%
1120320205070%
Knowledge Area
112 - Watershed Protection and Management;

Subject Of Investigation
0320 - Watersheds;

Field Of Science
2050 - Hydrology; 1070 - Ecology;
Goals / Objectives
(c) critical loads in terrestrial and aquatic ecosystems
Project Methods
Watershed nutrient budgets will be developed to characterize nutrient inputs (atmospheric deposition, fertilizer, net food/feed inputs) and riverine nutrient export. Watersheds selected for investigation will include tidal wetlands, flow-through wetlands processing agricultural runoff waters, agricultural watersheds, and forested watersheds. Information on net anthropogenic inputs will be obtained from literature sources and supplemented with supplemental studies when necessary. Information for atmospheric deposition is available from the national Atmospheric Deposition Program and the California Air Resources Board. River flow and chemistry data for many watersheds of interest is available from Department of Water Resources' California Data Exchange Center (http://cdec.water.ca.gov). For specific terrestrial ecosystems, we will conduct rigorous investigations of denitrification and soil/vegetation/groundwater storage to complete the understanding of the processes affecting the discrepancy in the nutrient mass balance. Denitrification will be determined using enclosed chambers for surface emissions and well samples for groundwater; samples will be analyzed for nitrous oxide fluxes and di-nitrogen gas:argon gas ratios to estimate denitrification fluxes. For riverine and estuary systems, we will conduct continuous longitudinal monitoring for various water quality constituents (e.g., chlorophyll-a, temperature, turbidly, EC, pH, and dissolved oxygen using a YSI 6600 water quality sonde equipped with a flow-through cell). The YSI sonde will be monitored throughout the longitudinal profile and grab samples will be collected at water quality anomalies to assess factors contributing to changes in water quality conditions. Data from the GPS and YSI water quality sonde will be downloaded following completion of the longitudinal profile to produce maps of water quality parameters along various surface water transects. In addition, we will select some key surface waters for continuous temporal monitoring of water quality constituents to examine diel changes in water quality along the longitudinal flowpath. This will allow us to examine processes contributing to temporal variability including diel cycles driven by algal photosynthesis-respiration dynamics and processes affecting in-stream processing of nutrients. Water quality grab samples will be collected along longitudinal transects and across temporal events to fully characterize water quality conditions, including nutrients, turbidity, ion chemistry and other potential constituents contributing to aquatic ecosystem health. Laboratory quality assurance/quality control will follow the Surface Water Ambient Monitoring Program (SWAMP) protocols set by the California State Water Resources Control Board. This includes implementation of standard laboratory procedures including replicates, spikes, reference materials, setting of control limits, criteria for rejection, and data validation methods. For each sample collection, 10 -20% of the samples were replicated and analyzed with a laboratory blank, two matrix spikes, as well as a laboratory control standard.Extension/Outreach ActivitiesThe results of this project will be disseminated in written and oral communications with a wide range of stakeholders. I have an active extension and outreach program that involves on the ground meetings (individual to large groups) with farmers, ranchers, and municipalities within California. These efforts are focused on answering specific questions and promoting beneficial management practices to enhance environmental and water quality. I also interact regularly with local, state and federal water quality regulatory/management agencies to assist with specific questions and to perform directed research actions aimed at solving water quality/resource issues. These interactions involve personal meetings, group meeting and participation on technical advisory committees. My research team is very active in disseminating research results to the global scientific community involved in ecosystem sciences and processes regulating water quality and climate change. Sharing of ideas with the global audience promotes awareness in environmental quality and implementation of beneficial management practices to address degradation of environmental quality.

Progress 02/20/15 to 09/30/19

Outputs
Target Audience:Target Audience This project has a wide target audience which includes: 1. Farmers, ranchers, and municipalities throughout California and the western USA. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences, land management, and processes regulating water quality. Changes/Problems:PI Retired as of June 30, 2019 What opportunities for training and professional development has the project provided?The project has provided partial funding for graduate students, a profession laboratory technician, and several internships for undergraduate students in the environmental sciences. How have the results been disseminated to communities of interest?The results of this project have been disseminated in written and oral communications with: 1. Farmers, ranchers, and municipalities throughout California. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences and processes regulating water quality. 4. Results have been presented at the national meetings of the American Geophysical Union, Goldschmidt Conference, Ecological Society of America, and Soil Science Society of America. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The major accomplishment of this study was documenting the nitrogen input-output for the state of California and for the first time introducing the role of geologic nitrogen into global, regional and ecosystem level nitrogen cycling budgets. For the state of California, the major annual inputs were synthetic N fixation (590 Gg), fossil fuel NOx (359 Gg), feed imports (200 Gg), cropland fixation (196 Gg), natural land fixation (139 Gg), fiber imports (40 Gg), atmospheric imports (40 Gg), fossil fuel NH3 (36 Gg), water imports (18 Gg) and fossil fuel N2O (9 Gg). Major annual outputs and storage of N in California were groundwater storage of NO3 (348 Gg), NOx emissions (270 Gg), NH3 emissions (201 Gg), urban storage (198 Gg), N2 emissions (113 Gg), natural land storage (91 Gg), sewage discharge (82 Gg), food exports (79 Gg), landfills (71 Gg), cropland storage (65 Gg), river discharge (39 Gg), N2O emissions (38 Gg) and reservoirs (30 Gg). An existing paradigm regarding nitrogen inputs to wildland, terrestrial ecosystems is that the dominant source of nitrogen is from nitrogen fixation and atmospheric deposition. However, rock contains greater than 99% of Earth's reactive nitrogen and represents a large overlooked source of nitrogen to ecosystems. We investigated the factors that regulate rock N abundance and developed a new model for quantifying rock N mobilization fluxes across desert to temperate rainforest ecosystems in California. We analyzed the N content of 968 rock samples from 531 locations and compiled 178 cosmogenically derived denudation estimates from across the region to identify landscapes and ecosystems where rocks account for a significant fraction of terrestrial N inputs. Strong coherence between rock N content and geophysical factors, such as protolith, (i.e. parent rock), grain size, and thermal history, were observed. A spatial model that combines rock geochemistry with lithology and topography demonstrates that average rock N reservoirs range from 80 to 534 mg N/kg across the nine geomorphic provinces of California and estimates for the rock N denudation flux ranged from 20 to 92 Gg/yr across the entire study area. Contrasting these data to global compilations suggests that our findings are broadly applicable beyond California and that the N abundance and variability in rock are well constrained across most of the Earth system. This study demonstrates that rock N may be an important contributor to ecosystem nitrogen inputs, especially in regions with rocks derived from sedimentary origins and those areas having high uplift rates. We further demonstrated that bedrock is a nitrogen source that rivals atmospheric nitrogen inputs across major sectors of the global terrestrial environment. Evidence drawn from the planet's nitrogen balance, geochemical proxies, and our spatial weathering model reveal that ~19 to 31 Tg of nitrogen are mobilized from near-surface rocks annually. About 11 to 18 Tg of this nitrogen are chemically weathered in situ, thereby increasing the unmanaged (preindustrial) terrestrial nitrogen balance from 8 to 26%. These findings provide a global perspective to reconcile Earth's nitrogen budget, with implications for nutrient-driven controls over the terrestrial carbon sink. Geologic contributions of nitrogen to aquatic ecosystems were also demonstrated to have a strong positive impact on salmon streams in northern California. Our results from volcanic spring-fed streams in northern California demonstrate that stable water flows and temperatures coupled with geologically-derived nutrients drive exceptional aquatic ecosystem productivity and resiliency. These spring-fed, nutrient-rich habitats are likely to be exceptionally important for conserving cold-water species impacted by global climate change. We attribute the primary source of nitrogen in the spring water to organic matter and/or ammonium incorporated in silicate minerals associated with marine sedimentary rocks. We analyzed unweathered bedrock samples from surficial outcrops that reflected normal burial diagenesis and those having undergone hydrothermal alteration. Unaltered samples showed nitrogen concentrations of 784-906 ppm N in mudstone and 453-498 ppm N in sandstone. In contrast, a hydrothermally altered mudstone located adjacent to younger intrusive igneous rocks displayed lower N concentrations of 100-118 ppm N, suggesting hydrothermal alteration as a potential mechanism for N release under elevated temperatures. Mineral nitrogen concentrations were elevated in spring sources with a mean nitrate-N concentration of 0.48 ppm compared to a mean nitrate concentration of 0.06 ppm for the runoff-dominated portions of the river system. We found no evidence that atmospheric deposition was a major source of nutrients in the spring water. In sum, we demonstrated that geologic N may have a major impact on terrestrial and aquatic ecosystems. Our findings for rock N weathering rates increase the preindustrial terrestrial nitrogen budget by 8 to 26%, with a modern-day rock N contribution to natural systems of 6 to 17% of total N inputs. Thus, geologic N contributions must be considered in nitrogen cycling budgets, especially in lithologies of sedimentary origin that cover about 75 percent of the Earth's surface.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Cai X, Yao L, Hu Y, Jiang H, Shen M, Hu Q, Wang Z, Dahlgren RA. Particle?Attached Microorganism Oxidation of Ammonia in a Hypereutrophic Urban River. Journal of Basic Microbiology
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Hu M, Liu Y, Zhang Y, Dahlgren RA, Chen D. Coupling Stable Isotopes and Water Chemistry to Assess the Role of Hydrological and Biogeochemical Processes on Riverine Nitrogen Sources. Water Research 150, 418-430
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Miller KE, Lai CT, Dahlgren RA, Lipson DA. Anaerobic Methane Oxidation in High-Arctic Alaskan Peatlands as a Significant Control on Net CH4 Fluxes. Soil Systems 3 (1), 7
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Liu H, Dahlgren RA, Larsen RE, Devine SM, Roche LM, O'Geen AT, Wong AJY, Covello S, Jin Y. Estimating Rangeland Forage Production Using Remote Sensing Data from a Small Unmanned Aerial System (sUAS) and PlanetScope Satellite. Remote Sensing 11 (5), 595


Progress 10/01/17 to 09/30/18

Outputs
Target Audience:This project has a wide target audience which includes: 1. Farmers, ranchers, and municipalities throughout California and the western USA. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences, land management, and water resource management. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided partial funding for one graduate student, one professional laboratory technician, and internships for 6 undergraduate students in the environmental sciences. How have the results been disseminated to communities of interest?The results of this project have been disseminated in written and oral communications with: 1. Farmers, ranchers, and municipalities throughout California. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences and processes regulating water quality. What do you plan to do during the next reporting period to accomplish the goals?Ongoing research is continuing to evaluate the effects of natural and anthropogenic sources of nutrients and potential organic contaminants on surface water chemistry.

Impacts
What was accomplished under these goals? Forest fires are increasing in both frequency and intensity in California and the western United States, potentially having great impacts on soil and water quality. While many studies have focused on the loss of mercury (Hg) from burned forests, little is known about the origins, concentration, reactivity, and bioavailability of Hg in residual ash materials. We examined Hg levels and reactivity in black ash (BA, low-to-moderate burn intensity) and white ash (WA, high burn intensity) generated from two recent wildfires in the Coastal Ranges of northern California. All ash samples contained measurable, but highly variable, Hg levels ranging from 4 to 125 ng/g. Ash samples had a highly variable fraction of Hg in recalcitrant forms (0 -75%), and this recalcitrant Hg pool appears to be associated with the black carbon fraction (i.e., charcoal) in ash samples. There was minimal release of Hg and low methylation potential during anoxic incubation of ash samples. Thus, the formation of wildfire ash can sequester Hg into relatively non-bioavailable forms, attenuating the potentially adverse effects of Hg erosion and transport to aquatic environments along with eroded wildfire ash. Wildfire-altered soil may also be an important source of polycyclic aromatic hydrocarbons (PAHs) in the environment. We quantified levels of 16 U.S. Environmental Protection Agency regulated PAHs, 3 chlorinated PAHs, and 6 brominated PAHs in nonburned forest soils and burned ash/soil samples covered with black ash (BA, low-to-moderate burn intensity) or white ash (WA, high burn intensity) from the 2013 Rim Fire in California. The PAH concentrations follow (mean ± standard deviation; μg/kg) BA (893 ± 285) > WA (515 ± 333) ≈ nonburned soils (247 ± 58). The PAH profiles were altered by both moderate and severe burn conditions with the size of aromatic structures following BA > WA > nonburned soils. Neither chlorinated nor brominated PAH concentrations were significantly elevated by moderate or severe wildfire. Overall, fire intensity and oxygen availability are critical in regulating soil PAH concentrations and profiles. Given the high erodibility of wildfire ash, these PAHs can be easily transported to rivers and reservoirs where they could impact the aquatic food web and drinking source water.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Origin, Reactivity, and Bioavailability of Mercury in Wildfire Ash P Ku, M Tsz-Ki Tsui, X Nie, H Chen, TC Hoang, JD Blum, RA Dahlgren, AT Chow Environmental Science & Technology
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Wildfire Burn Intensity Affects the Quantity and Speciation of Polycyclic Aromatic Hydrocarbons in Soils H Chen, AT Chow, XW Li, HG Ni, RA Dahlgren, H Zeng, JJ Wang ACS Earth and Space Chemistry
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Convergent evidence for widespread rock nitrogen sources in Earths surface environment BZ Houlton, SL Morford, RA Dahlgren Science 360 (6384), 58-62
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: A modification of the Regional Nutrient Management model (ReNuMa) to identify long-term changes in riverine nitrogen sources M Hu, Y Liu, J Wang, RA Dahlgren, D Chen Journal of Hydrology 561, 31-42.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Assessment of Long-Term Watershed Management on Reservoir Phosphorus Concentrations and Export Fluxes X Huang, H Chen, F Xia, Z Wang, K Mei, X Shang, Y Liu, R Dahlgren, M Zhang, H Huang International Journal of Environmental Research and Public Health 15 (10), 2169
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Influence of land use on the persistence effect of riverine phosphorus H Huang, Z Wang, D Chen, F Xia, X Shang, YY Liu, RA Dahlgren, K Mei Hydrological Processes 32 (1), 118-125
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Legacy nutrient dynamics at the watershed scale: principles, modeling, and implications D Chen, H Shen, M Hu, J Wang, Y Zhang, RA Dahlgren Advances in Agronomy 149, 237-313
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Stimulation of N2O emission by conservation tillage management in agricultural lands: A meta-analysis K Mei, Z Wang, H Huang, C Zhang, X Shang, RA Dahlgren, M Zhang, F Xia Soil and Tillage Research 182, 86-93
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Insight into pH Dependent Cr (VI) Removal with Magnetic Fe3S4 W Liu, L Jin, J Xu, J Liu, Y Li, P Zhou, C Wang, RA Dahlgren, X Wang Chemical Engineering Journal
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: A comprehensive risk assessment of metals in riverine surface sediments across the rural-urban interface of a rapidly developing watershed Z Wang, J Zhou, C Zhang, L Qu, K Mei, RA Dahlgren, M Zhang, F Xia Environmental Pollution
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Properties of bacterial communities attached to artificial substrates in a hypereutrophic urban river X Cai, L Yao, Q Sheng, L Jiang, RA Dahlgren, T Wang AMB Express 8 (1), 22
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Coupling stable isotopes and water chemistry to assess the role of hydrological and biogeochemical processes on riverine nitrogen sources M Hu, Y Liu, Y Zhang, RA Dahlgren, D Chen Water Research
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Distribution and source analysis of heavy metal pollutants in sediments of a rapid developing urban river system F Xia, L Qu, T Wang, L Luo, H Chen, RA Dahlgren, M Zhang, K Mei, H Huang Chemosphere 207, 218-228
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Inhibitory effects of natural organic matter on methyltriclosan photolysis kinetics W Liu, L Jin, K Chen, Y Li, RA Dahlgren, M Ma, X Wang RSC Advances 8 (38), 21265-21271
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Preferential accumulation of small (< 300 ?m) microplastics in the sediments of a coastal plain river network in eastern China Z Wang, B Su, X Xu, D Di, H Huang, K Mei, RA Dahlgren, M Zhang, X Shang Water research 144, 393-401


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Target Audience This project has a wide target audience which includes: 1. Farmers, ranchers, and municipalities throughout California and the western USA. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences, land management, and water quality. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided partial funding for one graduate student, one profession laboratory technician, and internships for 12 undergraduate students in the environmental sciences. How have the results been disseminated to communities of interest?The results of this project have been disseminated in written and oral communications with: 1. Farmers, ranchers, and municipalities throughout California. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences and processes regulating water quality. 4. Results have been presented at the national meetings of the California Society for Range Management and Soil Science Society of America. What do you plan to do during the next reporting period to accomplish the goals?Ongoing research is continuing the evaluate the effects of geologic sources of nitrogen on surface water chemistry, especially those associated with hydrothermal systems in the southern Cascades. We are evaluating the effects of geologic nitrogen inputs to surface water systems on primary and secondary productivity, aquatic habitats and fish populations.

Impacts
What was accomplished under these goals? Temperate streams reliant on surface runoff for flow are experiencing warmer and lower flows due to changing climate, reducing habitat quality for cold water-dependent fishes. An exception is spring-fed streams in volcanic terrains throughout the Pacific Ring of Fire. These streams are often fed by slowly draining deep groundwater aquifers that produce reliably cool summer baseflow. One subset of these streams ? those fed by long residence-time aquifers with abundant geologically-derived nitrogen and phosphorous ? may be critical to maintaining salmonids as environmental conditions shift under climate change. Our results from a volcanic spring-fed stream in northern California demonstrate that stable water flows and temperatures coupled with geologically-derived nutrients drive exceptional aquatic ecosystem productivity and resiliency. These spring-fed, nutrient-rich habitats are likely to be exceptionally important for conserving cold-water species impacted by global climate change. We attribute the primary source of nitrogen in the spring water to organic matter and/or ammonium incorporated in silicate minerals associated with marine sedimentary rocks. We analyzed unweathered bedrock samples from surficial outcrops that reflected normal burial diagenesis and those having undergone hydrothermal alteration. Unaltered samples showed nitrogen concentrations of 784-906 ppm N in mudstone and 453-498 ppm N in sandstone. In contrast, a hydrothermally altered mudstone located adjacent to younger intrusive igneous rocks displayed lower N concentrations of 100-118 ppm N, suggesting hydrothermal alteration as a potential mechanism for N release under elevated temperatures and/or fluid exchange. Mineral nitrogen concentrations were elevated in spring sources with a mean nitrate-N concentration of 0.48 ppm compared to a mean nitrate concentration of 0.06 ppm for the runoff-dominated portion of the river. In total, the spring water source provide 110 kg per day of nitrogen to the river system. We found no evidence that atmospheric deposition was a major source of nutrients in the spring water.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Influence of land use on the persistence effect of riverine phosphorus H Huang, Z Wang, D Chen, F Xia, X Shang, YY Liu, RA Dahlgren, K Mei Hydrological Processes 32 (1), 118-125
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Adsorption and reduction of roxarsone on magnetic greigite (Fe3S4): Indispensable role of structural sulfide W Liu, Z Ai, RA Dahlgren, L Zhang, X Wang Chemical Engineering Journal 330, 1232-1239
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Mechanisms for high potassium selectivity of soils dominated by halloysite from northern California, USA Y Takahashi, RA Dahlgren, H Kanno, M Nanzyo, T Takahashi Soil Science and Plant Nutrition, 1-10
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Antibiotic resistance genes in an urban river as impacted by bacterial community and physicochemical parameters ZC Zhou, J Zheng, YY Wei, T Chen, RA Dahlgren, X Shang, H Chen Environmental Science and Pollution Research 24 (30), 23753-23762
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Performance of two bioswales on urban runoff management Q Xiao, EG McPherson, Q Zhang, X Ge, R Dahlgren Infrastructures 2 (4), 12
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Prediction of dissolved oxygen concentration in hypoxic river systems using support vector machine: a case study of Wen-Rui Tang River, China X Ji, X Shang, RA Dahlgren, M Zhang Environmental Science and Pollution Research, 1-15
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Water quality trend and change-point analyses using integration of locally weighted polynomial regression and segmented regression H Huang, Z Wang, F Xia, X Shang, YY Liu, M Zhang, RA Dahlgren, K Mei Environmental Science and Pollution Research, 1-11
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: The genesis and exodus of vascular plant DOM from an oak woodland landscape PJ Hernes, RGM Spencer, RY Dyda, AT O'Geen, RA Dahlgren Frontiers in Earth Science 5, 9
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Long-term (19802010) changes in cropland phosphorus budgets, use efficiency and legacy pools across townships in the Yongan watershed, eastern China D Chen, M Hu, Y Guo, J Wang, H Huang, RA Dahlgren Agriculture, Ecosystems & Environment 236, 166-176
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Soil genesis and mineralogy across a volcanic lithosequence SG Wilson, JJ Lambert, M Nanzyo, RA Dahlgren Geoderma 285, 301-312


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:This project has a wide target audience which includes: 1. Farmers, ranchers, and municipalities throughout California and the western USA. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences, land management, and processes regulating water quality. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided partial funding for one graduate student, one profession laboratory technician, and internships for 12 undergraduate students in the environmental sciences. How have the results been disseminated to communities of interest?The results of this project have been disseminated in written and oral communications with: 1. Farmers, ranchers, and municipalities throughout California. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences and processes regulating water quality. 4. Results have been presented at the national meetings of the American Geophysical Union, Ecological Society of America, and Soil Science Society of America. What do you plan to do during the next reporting period to accomplish the goals?Ongoing research is continuing the evaluate the effects of geologic sources of nitrogen on surface water chemistry, especially those associated with hydrothermal systems in the southern Cascades. We are evaluating the effects of geologic nitrogen inputs to surface water systems on primary and secondary productivity, aquatic habitats and fish populations.

Impacts
What was accomplished under these goals? An existing paradigm regarding nitrogen inputs to wildland, terrestrial ecosystems is that the dominant source of nitrogen is from nitrogen fixation and atmospheric deposition. However, rock contains greater than 99% of Earth&#39;s reactive nitrogen and may represent a large overlooked source of nitrogen to ecosystems. Thus, a major question remains over the direct importance of rock N weathering inputs to terrestrial biogeochemical cycling. We investigated the factors that regulate rock N abundance and developed a new model for quantifying rock N mobilization fluxes across desert to temperate rainforest ecosystems in California, USA. We analyzed the N content of 968 rock samples from 531 locations and compiled 178 cosmogenically derived denudation estimates from across the region to identify landscapes and ecosystems where rocks account for a significant fraction of terrestrial N inputs. Strong coherence between rock N content and geophysical factors, such as protolith, (i.e. parent rock), grain size, and thermal history, were observed. A spatial model that combines rock geochemistry with lithology and topography demonstrates that average rock N reservoirs range from 80 to 534 mg N/kg across the nine geomorphic provinces of California and estimates for the rock N denudation flux ranged from 20 to 92 Gg/yr across the entire study area. These values compare to natural atmospheric inputs of about 140Gg/yr. The model highlights regional differences in rock N mobilization and points to the Coast Ranges, Transverse Ranges, and the Klamath Mountains as regions where rock N could contribute significant N to terrestrial ecosystems. Contrasting these data to global compilations suggests that our findings are broadly applicable beyond California and that the N abundance and variability in rock are well constrained across most of the Earth system. This study demonstrates that rock N may be an important contributor to ecosystem nitrogen inputs, especially in regions with rocks derived from sedimentary origins and those areas having high uplift rates.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Morford SL, Houlton BZ, Dahlgren RA (2016) Geochemical and tectonic uplift controls on rock nitrogen inputs across terrestrial ecosystems. Global Biogeochemical Cycles DOI: 10.1002/2015GB005283.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Hu M, Chen D, Dahlgren RA (2016) Modeling nitrous oxide (N2O) emission from rivers: A global assessment. Global Change Biology. DOI: 10.1111/gcb.13351.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Hinshaw SE, Dahlgren RA (2016) Nitrous oxide fluxes and dissolved N gases (N2 and N2O) within riparian zones along the agriculturally impacted San Joaquin River. Nutrient Cycling in Agroecosystems 105:85-102.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Oliver AA, Spencer RGM, Deas ML, Dahlgren RA (2016) Impact of seasonality and anthropogenic impoundments on dissolved organic matter dynamics in the Klamath River (Oregon/California, USA). Journal of Geophysical Research: Biogeosciences 121:1946-1958.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Chen D, Hu M, Guo Y, Wang J, Huang H, Dahlgren RA (2017) Long-term (1980 -2010) changes in cropland phosphorus budgets, use efficiency and legacy pools across townships in the Yongan watershed, eastern China. Agriculture, Ecosystems & Environment 236:166-176.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Wilson SG, Lambert JJ, Nanzyo M, Dahlgren RA (2017) Soil genesis and mineralogy across a volcanic lithosequence. Geoderma 285:301-312.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Wang JJ, Dahlgren RA, Er?an MS, Karanfil T, Chow AT (2016) Temporal variations of disinfection byproduct precursors in wildfire detritus. Water Research 99, 66-73.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Chen D, Hu M, Guo Y, Dahlgren RA (2016) Modeling forest/agricultural and residential nitrogen budgets and riverine export dynamics in catchments with contrasting anthropogenic impacts in eastern China between 1980 -2010. Agriculture, Ecosystems and Environment 221:145 -155.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Chen D, Hu M, Wang J, Guo Y, Dahlgren RA (2016) Factors controlling phosphorus export from agricultural/forest and residential systems to rivers in eastern China, 1980 -2011. Journal of Hydrology 533:53-61.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Takahashi T, Dahlgren RA (2016) Nature, properties and function of aluminum-hums complexes in volcanic soils. Geoderma 263:110-121.
  • Type: Books Status: Published Year Published: 2016 Citation: Tomich TP, Brodt S, Dahlgren RA, Scow KM: The California Nitrogen Assessment - Challenges and Solutions for People, Agriculture, and the Environment. University of California Press, Oakland, CA.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Lusardi RA, Bogan MT, Moyle PB, Dahlgren RA (2016) Environment shapes invertebrate assemblage structure differences between volcanic spring-fed and runoff rivers in northern California. Freshwater Science 35:1010 -1022.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Chen Q, Mei K, Dahlgren RA, Wang T, Gong J, Zhang M (2016) Impacts of land use and population density on seasonal surface water quality using a modified geographically weighted regression. Science of The Total Environment 572:450-466.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Wilson SG, Lambert JJ, Dahlgren RA (2016) Seasonal phosphorus dynamics in a volcanic soil of northern California. Soil Science Society of America Journal 80:1222-1230.


Progress 02/20/15 to 09/30/15

Outputs
Target Audience:This project has a wide target audience which includes: 1. Farmers, ranchers, and municipalities throughout California and the western USA. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences, land management, and processes regulating water quality. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided partial funding for one graduate students, one profession laboratory technician, and internships for 2 undergraduate students in the environmental sciences. How have the results been disseminated to communities of interest?The results of this project have been disseminated in written and oral communications with: 1. Farmers, ranchers, and municipalities throughout California. 2. Local, state and federal water quality regulatory/management agencies. 3. The global scientific community involved in ecosystem sciences and processes regulating water quality. 4. Results have been presented at the national meetings of the American Geophysical Union, American Chemical Society, and Soil Science Society of America. What do you plan to do during the next reporting period to accomplish the goals?Ongoing research is continuing the evaluate the effects of severe wildfires (Wragg Fire and Rocky Fire) in the summer of 2015 in northern California on nitrogen transformations, dissolved organic matter and mercury dynamics. Ash samples were collected from these fires prior to rainfall events and we are currently collecting stream water runoff from the watersheds to assess the effects of wildfire on water quality.

Impacts
What was accomplished under these goals? The results of our wildfire studies evaluated the effects of wildfires on the molecular transformation of nitrogen by high and low intensity wildfires in the presence (oxidation) and absence (pyrolysis) of oxygen. Forest fires occur with increasing frequency and severity in the western United States, potentially altering the chemistry and quantity of dissolved nitrogen, dissolved organic matter (DOM), and disinfection byproduct (DBP) precursors exported from forested watersheds. However, little is known concerning effects of the fire triangle (heat, oxygen, and fuel) on nitrogen and DOM alteration. Using detritus from Pinus ponderosa and Abies concolor (dominant species in forests in the western United States), we prepared DOM from unburned and burned detritus under hypoxic (pyrolysis) and oxic conditions (thermal oxidation) at 250 and 400 C. DOM characteristics and chlorine reactivity were evaluated by absorption and fluorescence spectroscopy and chlorination-based DBP formation potential tests. Spectroscopic results suggest that burned-detritus extracts had lower molecular weight (reflected by increased E2:E3 and fluorescence index) and divergent aromaticity (reflected by SUVA254) depending on oxygen availability. Temperature and oxygen availability interacted to alter the chlorine reactivity of fire-affected DOM. Increasing temperature from 50 to 400 C resulted in decreased reactivities for trihalomethane and chloral hydrate formation and divergent reactivities for haloacetonitrile formation (unchanged for pyrolysis and increased for oxidation) and haloketone formation (increased for pyrolysis and decreased for oxidation). We demonstrate that DBP precursors in fire-affected forest detritus are highly dependent on temperature and oxygen availability.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Wang JJ, Dahlgren RA, Ers?an MS, Karanfil T, Chow AT (2015) Wildfire altering terrestrial precursors of disinfection byproducts in forest detritus. Environmental Science and Technology. 49, 59215929.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Wang JJ, Dahlgren RA, Chow AT (2015) Controlled burning of forest detritus altering spectroscopic characteristics and chlorine reactivity of dissolved organic matter. Environmental Science and Technology. 49, 1401914027.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Morford SL, Houlton BZ, Dahlgren RA (2015) Direct quantification of long-term rock nitrogen inputs to temperate forest ecosystems. Ecology doi.org/10.1890/15-0501.1.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Brauer N, Maynard JJ, Dahlgren RA, O'Geen AT (2015) Fate of nitrate in seepage from a restored wetland receiving agricultural tailwater. Ecological Engineering 81:207 -217.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Chen D, Guo Y, Hu M, Dahlgren RA (2015) A lagged variable model for characterizing temporally dynamic export of legacy anthropogenic nitrogen from watersheds to rivers. Environmental Science and Pollution Research. 22, 11314-11326.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Chen D, Hu M, Guo Y, Dahlgren RA (2015) Influence of legacy phosphorus, land use, and climate change on anthropogenic phosphorus inputs and riverine export dynamics. Biogeochemistry 123, 99 -116.