APL Home

Campus Map

Emilio Mayorga

Senior Oceanographer






B.S. Environmental Engineering Science, Massachusetts Institute of Technology, 1992

Ph.D. Chemical Oceanography, University of Washington, 2004


GeoHackWeek: Workshop on Geospatial Data Science

APL-UW researchers teamed with University and industry partners to explore open source geospatial software development during a workshop held 14–18 November.

14 Nov 2016

BiGCZ: Cyberinfrastructure for Bio and Geoscience processes in the Critical Zone

The goal of this project is to co-develop with the "Critical Zone" science community a high-performance web-based integration and visualization environment for joint analysis of cross-scale Bio and Geoscience processes in the Critical Zone (BiGCZ), spanning experimental and observational designs.

More Info

1 Dec 2013

The Critical Zone (CZ) is Earth's permeable near-surface layer -- from the atmosphere at the vegetation's canopy to the lower boundary of actively circulating groundwaters. The BiGCZ system will be an open-source software system leveraging the ODM2 information model and specifically designed to address the challenges of managing, sharing, analyzing and integrating diverse data from the multiple disciplines encompassing CZ science.

ODM2: Observations Data Model 2

ODM2 is a community information model aimed at extending interoperability of feature-based earth observations derived from sensors and samples and improve the capture, sharing, and archival of these data. ODM2 has been designed from a general perspective, with extensibility for achieving interoperability across multiple disciplines and systems that support publication of earth observations.

1 Aug 2012

More Projects


2000-present and while at APL-UW

Observations Data Model 2: A community information model for spatially discrete Earth observations

Horsburgh, J.S., and 11 others, including E. Mayorga, "Observations Data Model 2: A community information model for spatially discrete Earth observations," Environ. Model. Softw., 79, 55-74, doi:10.1016/j.envsoft.2016.01.010, 2016.

More Info

1 May 2016


We report an information model for spatially discrete Earth observations.

Scientists' ability to capture metadata describing observations is improved.

Results enhance information models and encodings of domain cyberinfrastructures.

Our design focused on more reliable data integration across scientific domains.

Results are open source, cross platform, and cross relational database compatible.

Land-based nutrient loading to LMEs: A global watershed perspective on magnitudes and sources

Lee, R.Y., S. Seitzinger, and E. Mayorga, "Land-based nutrient loading to LMEs: A global watershed perspective on magnitudes and sources," Environ. Dev., 17, Suppl. 1, 220-229, doi:10.1016/j.envdev.2015.09.006, 2015.

More Info

1 Jan 2016

Coastal resource management initiatives in recent years have moved towards ecosystem approaches such as embodied by Large Marine Ecosystems (LMEs). In this study, land-based dissolved inorganic nitrogen (DIN) loading to LMEs was evaluated using a spatially-explicit river export model (Global NEWS 2) for the year 2000 conditions and for a current trends analysis for the year 2050. Watershed export was aggregated by LME to estimate total DIN load and attribution to diffuse and point sources including natural biological fixation, agricultural biological fixation, fertilizer, manure, atmospheric deposition and sewage. Biological fixation in natural landscapes was the primary source of DIN to many LMEs, but in most (73%) LMEs, over half of the total DIN load was related to anthropogenic sources. Most of the anthropogenic DIN load across LMEs was related to agricultural sources especially fertilizer and manure. Fertilizer was the primary source of DIN to LMEs in most of Europe and Asia, while manure was the primary source in most of Central and South America. Agricultural biological fixation, sewage and atmospheric deposition in general supported a minor fraction of the DIN exported to LMEs although each was a dominant source to a few LMEs. If current trends continue, DIN export to coastal systems by 2050 relative to 2000 is predicted to increase by approximately 40–45% from Africa, South America, South Asia and Oceania. Almost half of the total global increase in DIN is from South Asia. Relatively smaller increases are predicted for North America, with slight decreases in Australia and Europe.

Large Marine Ecosystems: Status and Trends

IOC-UNESCO and UNEP, "Large Marine Ecosystems: Status and Trends" (Nairobi, Kenya: United Nations Environment Programme, 2016).

1 Jan 2016

More Publications

Transboundary River Basins: Status and Trends

UNEP-DHI and UNEP, "Transboundary River Basins: Status and Trends" (Nairobi, Kenya: United Nations Environment Programme, 2016).

1 Jan 2016

Data management strategy to improve global use of ocean acidification data and information

Garcia, H.E., et al., including E. Mayorga and J.A. Newton, "Data management strategy to improve global use of ocean acidification data and information," Oceanography, 28, 226-228, doi:10.5670/oceanog.2015.45, 2015.

More Info

1 Jun 2015

Ocean acidification (OA) refers to the general decrease in pH of the global ocean as a result of absorbing anthropogenic CO2 emitted in the atmosphere since preindustrial times (Sabine et al., 2004). There is, however, considerable variability in ocean acidification, and many careful measurements need to be made and compared in order to obtain scientifically valid information for the assessment of patterns, trends, and impacts over a range of spatial and temporal scales, and to understand the processes involved. A single country or institution cannot undertake measurements of worldwide coastal and open ocean OA changes; therefore, international cooperation is needed to achieve that goal. The OA data that have been, and are being, collected represent a significant public investment. To this end, it is critically important that researchers (and others) around the world are easily able to find and use reliable OA information that range from observing data (from time-series moorings, process studies, and research cruises), to biological response experiments (e.g., mesocosm), data products, and model output.

A full greenhouse gases budget of Africa: Synthesis, uncertainties, and vulnerabilities

Valentini, R., et al., including E. Mayorga, "A full greenhouse gases budget of Africa: Synthesis, uncertainties, and vulnerabilities," Biogeosciences, 11, 381-407, doi:10.5194/bg-11-381-2014, 2014.

More Info

28 Jan 2014

This paper, developed under the framework of the RECCAP initiative, aims at providing improved estimates of the carbon and GHG (CO2, CH4 and N2O) balance of continental Africa. The various components and processes of the African carbon and GHG budget are considered, existing data reviewed, and new data from different methodologies (inventories, ecosystem flux measurements, models, and atmospheric inversions) presented. Uncertainties are quantified and current gaps and weaknesses in knowledge and monitoring systems described in order to guide future requirements. The majority of results agree that Africa is a small sink of carbon on an annual scale, with an average value of –0.61 ± 0.58 Pg C yr-1. Nevertheless, the emissions of CH4 and N2O may turn Africa into a net source of radiative forcing in CO2 equivalent terms. At sub-regional level, there is significant spatial variability in both sources and sinks, due to the diversity of biomes represented and differences in the degree of anthropic impacts. Southern Africa is the main source region; while central Africa, with its evergreen tropical forests, is the main sink. Emissions from land-use change in Africa are significant (around 0.32 ± 0.05 Pg C yr-1), even higher than the fossil fuel emissions: this is a unique feature among all the continents. There could be significant carbon losses from forest land even without deforestation, resulting from the impact of selective logging. Fires play a significant role in the African carbon cycle, with 1.03 ± 0.22 Pg C yr1 of carbon emissions, and 90% originating in savannas and dry woodlands. A large portion of the wild fire emissions are compensated by CO2 uptake during the growing season, but an uncertain fraction of the emission from wood harvested for domestic use is not. Most of these fluxes have large interannual variability, on the order of ± 0.5 Pg C yr-1 in standard deviation, accounting for around 25% of the year-to-year variation in the global carbon budget.

Despite the high uncertainty, the estimates provided in this paper show the important role that Africa plays in the global carbon cycle, both in terms of absolute contribution, and as a key source of interannual variability.

Global carbon dioxide emissions from inland waters

Raymond, P.A., et al., including E. Mayorga, "Global carbon dioxide emissions from inland waters," Nature, 503, 355-359, doi:10.1038/nature12760, 2013.

More Info

20 Nov 2013

Carbon dioxide (CO2) transfer from inland waters to the atmosphere, known as CO2 evasion, is a component of the global carbon cycle. Global estimates of CO2 evasion have been hampered, however, by the lack of a framework for estimating the inland water surface area and gas transfer velocity and by the absence of a global CO2 database. Here we report regional variations in global inland water surface area, dissolved CO2 and gas transfer velocity. We obtain global CO2 evasion rates of 1.8 +0.25/-0.25 petagrams of carbon (Pg C) per year from streams and rivers and 0.32 +0.25/-0.25 Pg C yr-1 from lakes and reservoirs, where the upper and lower limits are respectively the 5th and 95th confidence interval percentiles. The resulting global evasion rate of 2.1 Pg C yr-1 is higher than previous estimates owing to a larger stream and river evasion rate. Our analysis predicts global hotspots in stream and river evasion, with about 70 per cent of the flux occurring over just 20 per cent of the land surface. The source of inland water CO2 is still not known with certainty and new studies are needed to research the mechanisms controlling CO2 evasion globally.

The carbon budget of South Asia

Patra, P.K., et al., including E. Mayorga, "The carbon budget of South Asia," Biogeosciences, 10, 513-527, doi:10.5194/bg-10-513-2013, 2013.

25 Jan 2013

NANOOS partnerships for assessing ocean acidification in the Pacific Northwest

Newton, J., D. Martin, E. Mayorga, A. Devol, R. Feely, S. Alin, B. Dewey, B. Eudeline, A. Barton, and A. Suhbier, "NANOOS partnerships for assessing ocean acidification in the Pacific Northwest," Proc. MTS/IEEE Oceans 2012, 14-19 October, Hampton Road, VA, doi:10.1109/OCEANS.2012.6405086, 2012.

More Info

14 Oct 2012

Ocean acidification has serious implications for the economy and ecology of the Pacific Northwest United States. A combination of factors renders the Pacific coast and coastal estuaries particularly vulnerable to acidified water. The Northwest Association of Networked Ocean Observing Systems, NANOOS, the Regional Association of the United States Integrated Ocean Observing System, IOOS, is set up to deliver coastal data to serve the needs and decisions of its region. NANOOS has worked through IOOS with the NOAA Ocean Acidification Program, NOAA PMEL, academic, local, and commercial and tribal shellfish growing partners to provide existing observing assets to accommodate pCO2 and pH sensors, to deliver data streams from these and other providers, including that from sensors in shellfish hatcheries, and to network this capacity regionally and nationally. This increase in data access regarding OA is of value to scientists, managers, educators, and shellfish growers who are especially appreciative of the near real-time readouts of the data, upon which to make hatchery and remote setting decisions. This is a regional example of NANOOS and IOOS contributions to societal impacts from ocean acidification.

The carbon budget of terrestrial ecosystems in East Asia over the last two decades

Piao, S.L., and 38 others including E. Mayorga, "The carbon budget of terrestrial ecosystems in East Asia over the last two decades," Biogeosciences, 9, 3571-3586, doi:10.5194/bg-9-3571-2012, 2012.

More Info

7 Sep 2012

This Regional Carbon Cycle Assessment and Processes regional study provides a synthesis of the carbon balance of terrestrial ecosystems in East Asia, a region comprised of China, Japan, North and South Korea, and Mongolia. We estimate the current terrestrial carbon balance of East Asia and its driving mechanisms during 1990–2009 using three different approaches: inventories combined with satellite greenness measurements, terrestrial ecosystem carbon cycle models and atmospheric inversion models. The magnitudes of East Asia's terrestrial carbon sink from these three approaches are comparable: –0.293±0.033 PgC yr-1 from inventory–remote sensing model–data fusion approach, –0.413±0.141 PgC y-1 (not considering biofuel emissions) or –0.224±0.141 PgC yr-1 (considering biofuel emissions) for carbon cycle models, and –0.270±0.507 PgC yr-1 for atmospheric inverse models. Here and in the following, the numbers behind ± signs are standard deviations. The ensemble of ecosystem modeling based analyses further suggests that at the regional scale, climate change and rising atmospheric CO2 together resulted in a carbon sink of –0.289±0.135 PgC yr-1, while land-use change and nitrogen deposition had a contribution of –0.013±0.029 PgC yr-1 and –0.107±0.025 PgC yr-1, respectively. Although the magnitude of climate change effects on the carbon balance varies among different models, all models agree that in response to climate change alone, southern China experienced an increase in carbon storage from 1990 to 2009, while northern East Asia including Mongolia and north China showed a decrease in carbon storage. Overall, our results suggest that about 13–27% of East Asia's CO2 emissions from fossil fuel burning have been offset by carbon accumulation in its terrestrial territory over the period from 1990 to 2009. The underlying mechanisms of carbon sink over East Asia still remain largely uncertain, given the diversity and intensity of land management processes, and the regional conjunction of many drivers such as nutrient deposition, climate, atmospheric pollution and CO2 changes, which cannot be considered as independent for their effects on carbon storage.

The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 2005

Luyssaert, S., et al., including E. Mayorga, "The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 2005," Biogeosciences, 9, 3357-3380, doi:10.5194/bg-9-3357-2012, 2012.

More Info

24 Aug 2012

Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000–2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO2, CO, CH4 and N2O balances of Europe following a dual constraint approach in which (1) a land-based balance derived mainly from ecosystem carbon inventories and (2) a land-based balance derived from flux measurements are compared to (3) the atmospheric data-based balance derived from inversions constrained by measurements of atmospheric GHG (greenhouse gas) concentrations. Good agreement between the GHG balances based on fluxes (1294 ± 545 Tg C in CO2-eq yr-1), inventories (1299 ± 200 Tg C in CO2-eq yr-1) and inversions (1210 ± 405 Tg C in CO2-eq yr-1) increases our confidence that the processes underlying the European GHG budget are well understood and reasonably sampled. However, the uncertainty remains large and largely lacks formal estimates. Given that European net land to atmosphere exchanges are determined by a few dominant fluxes, the uncertainty of these key components needs to be formally estimated before efforts could be made to reduce the overall uncertainty. The net land-to-atmosphere flux is a net source for CO2, CO, CH4 and N2O, because the anthropogenic emissions by far exceed the biogenic sink strength. The dual-constraint approach confirmed that the European biogenic sink removes as much as 205 ± 72 Tg C yr-1 from fossil fuel burning from the atmosphere. However, This C is being sequestered in both terrestrial and inland aquatic ecosystems. If the C-cost for ecosystem management is taken into account, the net uptake of ecosystems is estimated to decrease by 45% but still indicates substantial C-sequestration. However, when the balance is extended from CO2 towards the main GHGs, C-uptake by terrestrial and aquatic ecosystems is offset by emissions of non-CO2 GHGs. As such, the European ecosystems are unlikely to contribute to mitigating the effects of climate change.

Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere

Aufdenkampe A. K., E. Mayorga, P.A. Raymond, J.M. Melack, S.C. Doney, S.R. Alin, R.E. Aalto, and K. Yoo, "Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere," Frontiers Ecol. Environ., 9, 53-60, doi: 10.1890/100014, 2011.

More Info

1 Feb 2011

Streams, rivers, lakes, and other inland waters are important agents in the coupling of biogeochemical cycles between continents, atmosphere, and oceans. The depiction of these roles in global-scale assessments of carbon (C) and other bioactive elements remains limited, yet recent findings suggest that C discharged to the oceans is only a fraction of that entering rivers from terrestrial ecosystems via soil respiration, leaching, chemical weathering, and physical erosion. Most of this C influx is returned to the atmosphere from inland waters as carbon dioxide (CO2) or buried in sedimentary deposits within impoundments, lakes, floodplains, and other wetlands. Carbon and mineral cycles are coupled by both erosion-deposition processes and chemical weathering, with the latter producing dissolved inorganic C and carbonate buffering capacity that strongly modulate downstream pH, biological production of calcium-carbonate shells, and CO2 outgassing in rivers, estuaries, and coastal zones. Human activities substantially affect all of these processes.

The NANOOS Visualization System (NVS): Lessons learned in data aggregation, management and reuse, for a user application

Mayorga, E., T. Tanner, R. Blair, A.V. Jaramillo, N. Lederer, C.M. Risien, and C. Seaton, "The NANOOS Visualization System (NVS): Lessons learned in data aggregation, management and reuse, for a user application," In Proceedings, MTS/IEEE OCEANS 2010, Seattle, 20-23 September, doi:10.1109/OCEANS.2010.5663792 (MTS/IEEE, 2010).

More Info

20 Sep 2010

The mission of NANOOS is to coordinate and support the development, implementation, and operations of a regional coastal ocean observing system (RCOOS) for the Pacific Northwest region, as part of the U.S. IOOS. A key objective for NANOOS is to provide data and user-defined products to a diverse group of stakeholders in a timely fashion, and at spatial and temporal scales appropriate for their needs. To this end, NANOOS developed the NANOOS Visualization System (NVS), which aggregates, displays and serves meteorological and oceanographic data, derived from buoys, gliders, tide gauges, HF Radar, meteorological stations and satellites, as well as model forecast information in such a way that it presents end users with a rich, informative and user friendly experience.

First released in November 2009, NVS has already undergone several significant updates. While its original focus and continued strength is on near-real-time (NRT) observations from stationary platforms (buoys, coastal stations, etc.), it has evolved to include other types of observations as well as forecast information. NVS integrates data from a wide diversity of providers across the region, ranging from county agencies, private industry and regional partnerships, to core IOOS federal programs, and state agencies and academic groups that are principal partners in NANOOS' Data Management and Communication (DMAC) efforts. Regional and national feedback confirms that NVS has been well received by ocean observing and stakeholder communities alike.

This paper discusses, in detail, NVS 2.0, which was released in August 2010. In particular, we provide an in depth look at the database schema, metadata, data harvesting, and component communication. In addition, we discuss the NVS data management and communication approach in the context of the IOOS DMAC interoperability and standards-based efforts, highlighting the strengths and weaknesses of application-focused vs. strong-interoperability-focused approaches. Lessons learned both from technical and project management perspectives are also presented.

Lastly, we discuss future plans for NVS. Anticipated improvements include automating asset metadata discovery and processing using IOOS standard protocols, and a NANOOS implementation of ERDDAP that will support NVS by replacing multiple, data-source-specific data harvesters with more generic and easier-to-maintain NERDDAP harvesters; and by enabling customized data subsetting and download capabilities that will be accessible through the NVS user interface.

Global Nutrient Export from WaterSheds 2 (NEWS 2): Model development and implementation

Mayorga, E., S.P. Seitzinger, J.A. Harrison, E. Dumont, A.H.W. Beusen, A.F. Bouwman, B. Fekete, C. Kroeze, and G. Van Drecht, "Global Nutrient Export from WaterSheds 2 (NEWS 2): Model development and implementation," Environ. Model. Softw., 25, 837-853, doi:10.1016/j.envsoft.2010.01.007, 2010.

More Info

1 Jul 2010

Global NEWS is a global, spatially explicit, multi-element and multi-form model of nutrient exports by rivers. Here we present NEWS 2, the new version of Global NEWS developed as part of a Millennium Ecosystem Assessment scenario implementation from hindcast (1970) to contemporary (2000) and future scenario trajectories (2030 & 2050). We provide a detailed model description and present an overview of enhancements to input datasets, emphasizing an integrated view of nutrient form sub-models and contrasts with previous NEWS models (NEWS 1). An important difference with NEWS 1 is our unified model framework (multi-element, multi-form) that facilitates detailed watershed comparisons regionally and by element or form. NEWS 2 performs approximately as well as NEWS 1 while incorporating previously uncharacterized factors. Although contemporary global river export estimates for dissolved inorganic nitrogen (DIN) and particulates show notable reductions, they are within the range of previous studies; global exports for other nutrient forms are comparable to NEWS 1. NEWS 2 can be used as an effective tool to examine the impact of polices to reduce coastal eutrophication at regional to global scales. Continued enhancements will focus on the incorporation of other forms and sub-basin spatial variability in drivers and retention processes.

Sub-regional and downscaled-global scenarios of nutrient transfer in river basins: The Seine-Scheldt-Somme case study

Thieu, V., E. Mayorga, G. Billen, and J. Garnier, "Sub-regional and downscaled-global scenarios of nutrient transfer in river basins: The Seine-Scheldt-Somme case study," Glob. Biogeochem. Cycles, 24, doi:10.1029/2009GB003561, 2010.

More Info

29 May 2010

In an attempt to downscale the global prospective scenarios established by the Millennium Ecosystem Assessment to the level of three individual watersheds (the Seine, Somme, and Scheldt rivers), we examined the application of the regional RIVERSTRAHLER model, based on a mechanistic representation of in-stream processes, in tandem with the semiempirical Global Nutrient Export from Watersheds (NEWS) model, by downscaling the input data of the latter into information required by the former. Overall, the model simulates the major trends of the changes that occurred in 1970–2000, although with some discrepancies revealing the weakness of certain hypothesis in the global approach. For the future, the prediction is a significant decrease in total nitrogen and phosphorus fluxes into the sea compared to those of 2000. We showed the benefits of combining a process-based approach of nutrient transfer at the local scale with the use of global-scale models for integrating the development of socioeconomic driving forces acting at the global level.

Global nutrient river export: A scenario analysis of past and future trends

Seitzinger, S., E. Mayorga, A.F. Bouwman, C. Kroeze, A.H.W. Beusen, G. Billen, G. Van Drecht, E. Dumont, B.M. Fekete, J. Garnier, and J.A. Harrison, "Global nutrient river export: A scenario analysis of past and future trends," Glob. Biogeochem. Cycles, 24, doi:10.1029/2009GB003587, 2010.

More Info

13 May 2010

An integrated modeling approach was used to connect socioeconomic factors and nutrient management to river export of nitrogen, phosphorus, silica and carbon based on an updated Global NEWS model. Past trends (1970–2000) and four future scenarios were analyzed. Differences among the scenarios for nutrient management in agriculture were a key factor affecting the magnitude and direction of change of future DIN river export.

In contrast, connectivity and level of sewage treatment and P detergent use were more important for differences in DIP river export. Global particulate nutrient export was calculated to decrease for all scenarios, in part due to increases in dams for hydropower. Small changes in dissolved silica and dissolved organics were calculated for all scenarios at the global scale. Population changes were an important underlying factor for river export of all nutrients in all scenarios. Substantial regional differences were calculated for all nutrient elements and forms. South Asia alone accounted for over half of the global increase in DIN and DIP river export between 1970 and 2000 and in the subsequent 30 years under the Global Orchestration scenario (globally connected with reactive approach to environmental problems); DIN river export decreased in the Adapting Mosaic (globally connected with proactive approach) scenario by 2030, although DIP continued to increase. Risks for coastal eutrophication will likely continue to increase in many world regions for the foreseeable future due to both increases in magnitude and changes in nutrient ratios in river export.

Nutrients export by rivers to the coastal waters of Africa: Past and future trends

Yasin, J.A., C. Kroeze, and E. Mayorga, "Nutrients export by rivers to the coastal waters of Africa: Past and future trends," Glob. Biogeochem. Cycles, 24, doi:10.1029/2009GB003568, 2010.

More Info

11 May 2010

We analyze past and future trends in nitrogen (N), phosphorus (P), and carbon (C) export by rivers to the coastal waters of Africa as calculated by the Global Nutrient Export to WaterShed (NEWS) models for the period 1970–2050. Between 1970 and 2000 the total nutrient export by African rivers increased by 10–80%. For future years (2000–2050) we calculate an increase in the total loads of dissolved forms of N and P, but decreasing trends for dissolved organic C and particulate forms of N and P. There are large regions that deviate from these pan-African trends. We explore the regional patterns and the underlying processes, in particular for the Nile, Zaire, Niger, and Zambezi. In the future, anthropogenic sources may, in large parts of Africa, become larger contributors to riverine nutrient loads than natural sources.

Increasing anthropogenic nitrogen inputs and riverine DIN exports from the Changjiang River basin under changing human pressures

Yan, W., E. Mayorga, X. Li, S.P. Seitzinger, and A.F. Bouwman, "Increasing anthropogenic nitrogen inputs and riverine DIN exports from the Changjiang River basin under changing human pressures," Glob. Biogeochem. Cycles, 24, doi:10.1029/2009GB002575, 2010.

More Info

24 Apr 2010

In this paper, we estimate the inputs of nitrogen (N) and exports of dissolved inorganic nitrogen (DIN) from the Changjiang River to the estuary for the period 1970–2003, by using the global NEWS-DIN model. Modeled DIN yields range from 260 kg N km-2 yr-1 in 1970 to 895 kg N km-2 yr-1 in 2003, with an increasing trend. The study demonstrated a varied contribution of different N inputs to river DIN yields during the period 1970–2003. Chemical fertilizer and manure together contributed about half of the river DIN yields, while atmospheric N deposition contributed an average of 21% of DIN yields in the period 1970–2003. Biological N fixation contributed 40% of DIN yields in 1970, but substantially decreased to 13% in 2003. Point sewage N input also showed a decreasing trend in contribution to DIN yields, with an average of 8% over the whole period. We also discuss possible future trajectories of DIN export based on the Global NEWS implementation of the Millennium Ecosystem Assessment scenarios. Our result indicates that anthropogenically enhanced N inputs dominate and will continue to dominate river DIN yields under changing human pressures in the basin. Therefore, nitrogen pollution is and will continue to be a great challenge to China.

Magnitudes and sources of dissolved inorganic phosphorus inputs to surface fresh waters and the coastal zone: A new global model

Harrison, J.A., A.F. Bouwman, E. Mayorga, and S. Seitzinger, "Magnitudes and sources of dissolved inorganic phosphorus inputs to surface fresh waters and the coastal zone: A new global model," Global Biogeochem. Cycles, 24, doi: 10.1029/2009GB003590, 2010.

More Info

20 Jan 2010

As a limiting nutrient in aquatic systems, phosphorus (P) plays an important role in controlling freshwater and coastal primary productivity and ecosystem dynamics, increasing frequency and severity of harmful and nuisance algae blooms and hypoxia, as well as contributing to loss of biodiversity. Although dissolved inorganic P (DIP) often constitutes a relatively small fraction of the total P pool in aquatic systems, its bioavailability makes it an important determinant of ecosystem function.

Here we describe, apply, evaluate, and interpret an enhanced version of the Global Nutrient Export from Watersheds (NEWS)–DIP model: NEWS–DIP–Half Degree (NEWS–DIP–HD). Improvements to NEWS–DIP–HD over the original NEWS DIP model include (1) the preservation of spatial resolution of input data sets at the 0.5 degree level and (2) explicit downstream routing of water and DIP from half-degree cell to half-degree cell using a global flow-direction representation. NEWS–DIP explains 78% and 62% of the variability in per-basin DIP export (DIP load) for U.S. Geological Survey (USGS) and global stations, respectively, similar to the original NEWS–DIP model and somewhat more than other global models of DIP loading and export. NEWS–DIP–HD output suggests that hot spots for DIP loading tend to occur in urban centers, with the highest per-area rate of DIP loading predicted for the half-degree grid cell containing Tokyo (6366 kg P km-2 yr-1). Furthermore, cities with populations >100,000 accounted for 35% of global surface water DIP loading while covering less than 2% of global land surface area. NEWS–DIP–HD also indicates that humans supply more DIP to surface waters than natural weathering over the majority (53%) of the Earth's land surface, with a much larger area dominated by DIP point sources than nonpoint sources (52% versus 1% of the global land surface, respectively). NEWS–DIP–HD also suggests that while humans had increased DIP input to surface waters more than fourfold globally by the year 2000, human activities such as dam construction and consumptive water use have somewhat moderated the effect of humans on P transport by preventing (conservatively) 0.35 Tg P yr-1 (~20% of P inputs to surface waters) from reaching coastal zones globally.

The NANOOS Visualization System: Aggregating, displaying, and serving data

Risien, C.M., J.C. Allan, R. Blair, A.V. Jaramillo, D. Jones, P.M. Kosro, D. Martin, E. Mayorga, J.A. Newton, T. Tanner, and S.A. Uczekaj, "The NANOOS Visualization System: Aggregating, displaying, and serving data," In Proceedings, MTS/IEEE Oceans, Biloxi, MS, 26-29 October (MTS/IEEE, 2009).

More Info

26 Oct 2009

The Northwest Association of Networked Ocean Observing Systems (NANOOS) is one of eleven Regional Associations of the US Integrated Ocean Observing System (IOOS). NANOOS serves the Pacific Northwest from the US/Canada border to Cape Mendocino on the northern California coast. Its mission is to coordinate and support the development, implementation, and operations of a regional coastal ocean observing system (RCOOS) for the Pacific Northwest region, as part of IOOS. A key objective for NANOOS is to provide data and user-defined products regarding the coast, estuaries and ocean to a diverse group of end users in a timely fashion, and at spatial and temporal scales appropriate for their needs.

To this end, NANOOS is developing a web mapping portal, the NANOOS Visualization System (NVS), that aggregates, displays and serves near real-time coastal, estuarine, oceanographic and meteorological data, derived from buoys, gliders, tide gauges, HF Radar, meteorological stations, satellites and shore based coastal stations, as well as model forecast information in such a way that it presents end users with a rich, informative and meaningful experience. NVS makes use of a variety of services, including the Google Maps service and a data translation and visualization service known as ERDDAP (Environmental Research Division's Data Access Program), compliant Open Geospatial Consortium (OGC) web standards such as the Sensor Observation Service (SOS), Web Map Service (WMS), and Keyhole Markup Language (KML), as well as the Open-source Project for a Network Data Access Protocol (OPeNDAP) as served and cataloged by the NANOOS THREDDS (Thematic Realtime Environmental Distributed Data Services) Data Server (TDS). These heterogeneous data streams are transformed on-the-fly to other formats or representations, which NVS makes available to the end user via a Google Maps interface.

We will describe in detail the NVS development process and will demonstrate the ability of NVS to serve as a portal for one-stop access to near real-time regional data and forecast products, including NOAA's first seven core variables (ocean currents, temperature, salinity, water level, waves, chlorophyll and surface winds), by describing the data flows from NANOOS funded coastal and ocean observing and forecasting assets as well as Federal assets. In addition, we will describe future development plans that include greater functionality, iteratively improving NVS based on feedback received at planned training workshops and from identified stakeholders, and updating NVS to be compliant with future IOOS and OGC standards.

The Earth's natural water cycles

Vorosmarty, C., D. Conley, P. Doll, J. Harrison, P. Letitre, E. Mayorga, J. Milliman, S. Seitzinger, J. van der Gun, and W. Wollheim, "The Earth's natural water cycles," in The United Nations World Water Development Report 3: Water in a Changing World, 166-180 (Paris: UNESCO World Water Assessment Programme, 2009).

16 Mar 2009

Fluxes of nutrients and selected organic pollutants carried by rivers

Liu, K.-K., S. Seitzinger, E. Mayorga, J. Harrison, and V. Ittekkot, "Fluxes of nutrients and selected organic pollutants carried by rivers," in Watersheds, Bays, and Bounded Seas: The Science and Management of Semi-Enclosed Marine Systems, E.R. Urban, Jr., et al., eds., 141-167 (Washington, D.C., Island Press, 2009).

1 Jan 2009

The regional and global significance of nitrogen removal in lakes and reservoirs

Harrison, J., R. Maranger, R. Alexander, A. Giblin, P.A. Jacinthe, E. Mayorga, S. Seitzinger, D. Sobota, and W. Wollheim, "The regional and global significance of nitrogen removal in lakes and reservoirs," Biogeochemistry, 93, 143-157, 2009.

More Info

1 Jan 2009

Human activities have greatly increased the transport of biologically available nitrogen (N) through watersheds to potentially sensitive coastal ecosystems. Lentic water bodies (lakes and reservoirs) have the potential to act as important sinks for this reactive N as it is transported across the landscape because they offer ideal conditions for N burial in sediments or permanent loss via denitrification. However, the patterns and controls on lentic N removal have not been explored in great detail at large regional to global scales.

In this paper we describe, evaluate, and apply a new, spatially explicit, annual-scale, global model of lentic N removal called NiRReLa (Nitrogen Retention in Reservoirs and Lakes). The NiRReLa model incorporates small lakes and reservoirs than have been included in previous global analyses, and also allows for separate treatment and analysis of reservoirs and natural lakes. Model runs for the mid-1990s indicate that lentic systems are indeed important sinks for N and are conservatively estimated to remove 19.7 Tg N year-1 from watersheds globally. Small lakes (<50 km2) were critical in the analysis, retaining almost half (9.3 Tg N year-1) of the global total. In model runs, capacity of lakes and reservoirs to remove watershed N varied substantially at the half-degree scale (0–100%) both as a function of climate and the density of lentic systems. Although reservoirs occupy just 6% of the global lentic surface area, we estimate they retain ~33% of the total N removed by lentic systems, due to a combination of higher drainage ratios (catchment surface area:lake or reservoir surface area), higher apparent settling velocities for N, and greater average N loading rates in reservoirs than in lakes. Finally, a sensitivity analysis of NiRReLa suggests that, on-average, N removal within lentic systems will respond more strongly to changes in land use and N loading than to changes in climate at the global scale.

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center