Nutrient pollution at the lower reaches of Mediterranean coastal rivers in Israel

2000 ◽  
Vol 42 (1-2) ◽  
pp. 147-152 ◽  
Author(s):  
B. Herut ◽  
N. Kress ◽  
H. Hornung
Keyword(s):  
Inorganic Nitrogen ◽  
Agricultural Runoff ◽  
Point Sources ◽  
Industrial Wastes ◽  
Nutrient Concentrations ◽  
Contamination Level ◽  
Nutrient Load ◽  
Nutrient Loads ◽  
Discharge Data ◽  
Coastal Rivers

This study represents the first attempt to evaluate the nutrient load introduced into the coastal waters by the rivers along the Mediterranean coast of Israel. Measurements of nutrient concentrations (phosphate, ammonium, nitrate, nitrite, silicic acid) at two or three stations along the lower river reaches (11 rivers) were carried out annually from 1990 up to 1998. Combining the nutrient concentrations with the monthly riverine discharges we assessed the nutrient load. In general, most of the coastal rivers contain high nutrient contamination level, compared to the criteria adopted by NOAA (USA) for coastal river estuaries. The high degree of contamination is attributed to extreme low natural flow combined with the discharge of domestic and industrial wastes, and with agriculture runoff. In terms of nutrient concentrations, the Kishon River is the most polluted, followed by the Soreq, Poleg and Alexander Rivers. The preliminary estimate is that the coastal rivers transport between ~2000 to 6000 tons of dissolved inorganic nitrogen (DIN) and between ~250–800 tons of dissolved inorganic phosphorus (DIP) to the sea. An additional 3500 and 3000 tons of DIN and DIP, respectively, are supplied through the Kishon River. The load of the Poleg River is unknown (no discharge data) but expected to be significant based on nutrient concentration measured. The total load of the coastal rivers constitutes a major component among the other land-base point sources such as the Gush Dan outfall. Our estimate probably represents minimal values, as it does not include diffused input of agricultural runoff nor the riverine particulate and dissolved organic nutrient loads (which are unknown).

scholarly journals Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1531
Author(s):  
Konstantinos Stefanidis ◽  
Aikaterini Christopoulou ◽  
Serafeim Poulos ◽  
Emmanouil Dassenakis ◽  
Elias Dimitriou
Keyword(s):  
Water Framework Directive ◽  
Inorganic Nitrogen ◽  
Inorganic Phosphorus ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Land Uses ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Loads ◽  
Phosphorus Loads

Reduction of nutrient loadings is often prioritized among other management measures for improving the water quality of freshwaters within the catchment. However, urban point sources and agriculture still thrive as the main drivers of nitrogen and phosphorus pollution in European rivers. With this article we present a nationwide assessment of nitrogen and phosphorus loads that 18 large rivers in Greece receive with the purpose to assess variability among seasons, catchments, and river types and distinguish relationships between loads and land uses of the catchment. We employed an extensive dataset of 636 field measurements of nutrient concentrations and river discharges to calculate nitrogen and phosphorus loads. Descriptive statistics and a cluster analysis were conducted to identify commonalties and differences among catchments and seasons. In addition a network analysis was conducted and its modularity feature was used to detect commonalities among rivers and sampling sites with regard to their nutrient loads. A correlation analysis was used to identify major possible connections between types of land uses and nutrient loads. The results indicated that the rivers Alfeios, Strymonas, and Aliakmonas receive the highest inorganic nitrogen loads while the highest inorganic phosphorus loads were calculated for the rivers Strymonas, Aliakmonas, and Axios. Concerning the temporal variation of loads, inorganic nitrogen presented a peak on March and gradually declined until October when the dry period typically ends for most regions of Greece. Inorganic phosphorus loads had the highest average value in August and the lowest in October. Thus, our findings confirmed the presence of a typical seasonal variation in nitrogen loads that follows the seasonality in hydrology where high surface runoff during the wet months contribute to higher river discharges and higher nitrogen loads from the catchment. On the contrary, high phosphorus loads persisted during dry months that could be attributed to a dilution effect. Furthermore, the results imply a clear connection between agriculture and both nitrogen and phosphorus. Overall, this work presents extensive information on the nitrogen and phosphorus loads that major rivers in Greece receive that can largely aid water managers to adapt and revise basin management plans in accordance with agricultural management (e.g., which months farmers should reduce the use of fertilizers) with the purpose of meeting the environmental targets defined by the Water Framework Directive (WFD).

scholarly journals Nutrient Atmospheric Deposition on Utah Lake: A Comparison of Sampling and Analytical Methods

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 123
Author(s):  
Seth Michael Barrus ◽  
Gustavious Paul Williams ◽  
A. Woodruff Miller ◽  
M. Brett Borup ◽  
LaVere B. Merritt ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
Dissolve Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Total Load ◽  
Significant Difference ◽  
Utah Lake ◽  
Collection Methods

We describe modified sampling and analysis methods to quantify nutrient atmospheric deposition (AD) and estimate Utah Lake nutrient loading. We address criticisms of previous published collection methods, specifically collection table height, screened buckets, and assumptions of AD spatial patterns. We generally follow National Atmospheric Deposition Program (NADP) recommendations but deviate to measure lake AD, which includes deposition from both local and long-range sources. The NADP guidelines are designed to eliminate local contributions to the extent possible, while lake AD loads should include local contributions. We collected side-by-side data with tables at 1 m (previous results) and 2 m (NADP guidelines) above the ground at two separate locations. We found no statistically significant difference between data collected at the different heights. Previous published work assumed AD rates would decrease rapidly from the shore. We collected data from the lake interior and show that AD rates do not significantly decline away from the shore. This demonstrates that AD loads should be estimated by using the available data and geostatistical methods even if all data are from shoreline stations. We evaluated screening collection buckets. Standard unscreened AD samples had up to 3-fold higher nutrient concentrations than screened AD collections. It is not clear which samples best represent lake AD rates, but we recommend the use of screens and placed screens on all sample buckets for the majority of the 2020 data to exclude insects and other larger objects such as leaves. We updated AD load estimates for Utah Lake. Previous published estimates computed total AD loads of 350 and 153 tons of total phosphorous (TP) and 460 and 505 tons of dissolve inorganic nitrogen (DIN) for 2017 and 2018, respectively. Using updated collection methods, we estimated 262 and 133 tons of TP and 1052 and 482 tons of DIN for 2019 and 2020, respectively. The 2020 results used screened samplers with lower AD rates, which resulted in significantly lower totals than 2019. We present these modified methods and use data and analysis to support the updated methods and assumptions to help guide other studies of nutrient AD on lakes and reservoirs. We show that AD nutrient loads can be a significant amount of the total load and should be included in load studies.

scholarly journals Effects of Load Reductions on Phosphorus Concentrations in a Baltic Estuary—Long-Term Changes, Seasonal Variation, and Management Implications

2020 ◽  
Vol 44 (1) ◽  
pp. 30-43
Author(s):  
Jakob Walve ◽  
Maria Sandberg ◽  
Ragnar Elmgren ◽  
Christer Lännergren ◽  
Ulf Larsson
Keyword(s):  
Surface Water ◽  
Spring Bloom ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
P Concentration ◽  
Source Contributions ◽  
A Minor ◽  
Autumn And Winter

AbstractNutrient concentrations in coastal waters are influenced not only by land runoff, point sources, and water exchange with the sea but are also modified by settlement to and release from sediments. This complicates evaluation of measures to reduce nutrient loads. We used a mass-balance box model to calculate long-term (1968–2015) and seasonal source contributions to phosphorus (P) concentrations and cycling in the stratified Stockholm inner archipelago (IA), Baltic Sea. A drastic reduction of sewage P loads in the early 1970s reduced sewage from the major to a minor P source. Further P load reductions in the 1990s cut the direct contribution from the sewage point sources to the annual mean surface water P concentration from 10 μg l−1 (25%) to < 4 μg l−1 (12%). The largest contributions to the surface water P concentration are now (from 1996) inflowing seawater (37%), freshwater (25%), and P recycling from sediments below 20 m depth (26%). Variations in freshwater flushing give higher P concentrations in dry years, when dilution of P inputs from sediments and sewage is small, while in wet years, these inputs are greatly diluted. Source-partitioned phosphate uptake shows that the spring bloom is fueled mainly by P of seawater and freshwater origin, while the contribution from sewage point sources is minor. Since sediment P release is mostly recycled P from the settled spring bloom, the P inputs from seawater and freshwater are now the major drivers of the IA P cycle. Recycling of P from sediments boosts surface water P concentrations in autumn and winter, affecting management target concentrations.

scholarly journals Flood water quality and marine sediment and nutrient loads from the Tully and Murray catchments in north Queensland, Australia

2009 ◽  
Vol 60 (11) ◽  
pp. 1123 ◽  
Author(s):  
Jim Wallace ◽  
Lachlan Stewart ◽  
Aaron Hawdon ◽  
Rex Keen ◽  
Fazlul Karim ◽  
...  
Keyword(s):  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Large Contribution ◽  
Nutrient Loads ◽  
Nitrogen And Phosphorus ◽  
Annual Average ◽  
Nitrogen Loads ◽  
Flood Flows

Current estimates of sediment and nutrient loads from the Tully–Murray floodplain to the Great Barrier Reef lagoon are updated by taking explicit account of flood events. New estimates of flood discharge that include over-bank flows are combined with direct measurements of sediment and nutrient concentrations in flood waters to calculate the loads of sediment and nutrient delivered to the ocean during 13 floods that occurred between 2006 and 2008. Although absolute concentrations of sediment and nutrient were quite low, the large volume of water discharged during floods means that they make a large contribution (30–50%) to the marine load. By not accounting for flood flows correctly, previous estimates of the annual average discharge are 15% too low and annual loads of nitrogen and phosphorus are 47% and 32% too low respectively. However, because sediments may be source-limited, accounting for flood flows simply dilutes their concentration and the resulting annual average load is similar to that previously estimated. Flood waters also carry more dissolved organic nitrogen than dissolved inorganic nitrogen and this is the opposite of their concentrations in river water. Consequently, dissolved organic nitrogen loads to the ocean may be around twice those previously estimated from riverine data.

Influence of climate,geology and humans on spatial and temporal nutrient geochemistry in the subtropical Richmond River catchment, Australia

2001 ◽  
Vol 52 (2) ◽  
pp. 235 ◽  
Author(s):  
Lester J. McKee ◽  
Bradley D. Eyre ◽  
Shahadat Hossain ◽  
Peter R. Pepperell
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Agricultural Land ◽  
Anthropogenic Impacts ◽  
Inorganic Nitrogen ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
River Catchment

Water quality was monitored on a spatial and temporal basis in the subtropical Richmond River catchment over two years. Nutrient concentrations varied seasonally in a complex manner with highest concentrations (maximum =3110 µg N L – 1 and 572 µg P L –1 ) associated with floods. However, median (444 µg N L – 1 and 55 µg P L – 1 ) concentrations were relatively low compared with other parts of the world. The forms of nitrogen and phosphorus in streams varied seasonally, with greater proportions of inorganic nitrogen and phosphorus during the wet season. Minimum nutrient concentrations were found 2—3 months after flood discharge. With the onset of the dry season, concentration increases were attributed to point sources and low river discharge. There were statistically significant relationships between geology and water quality and nutrient concentrations increased downstream and were significantly related to population density and dairy farming. In spite of varying geology and naturally higher phosphorus in soils and rocks in parts of the catchment, anthropogenic impacts had the greatest effects on water quality in the Richmond River catchment. Rainfall quality also appeared to be related both spatially and seasonally to human activity. Although the responses of the subtropical Richmond River catchment to changes in land use are similar to those of temperate systems of North America and Europe, the seasonal patterns appear to be more complex and perhaps typical of subtropical catchments dominated by agricultural land use.

scholarly journals Understanding the hydrological and physicochemical drivers of Phormidium proliferation in the Hutt and Waipoua Rivers

2021 ◽  
Author(s):  
◽  
Emily Martin
Keyword(s):  
Water Column ◽  
Inorganic Nitrogen ◽  
Fine Sediment ◽  
Sediment Deposition ◽  
Point Sources ◽  
Warning Signs ◽  
Nutrient Concentrations ◽  
Available Phosphorus ◽  
Growth Monitoring ◽  
Management Options

<p>The Hutt and Waipoua rivers are affected annually by proliferations of the potentially toxic benthic cyanobacteria - Phormidium. Ingestion of these mats has resulted in numerous dog deaths and is therefore a risk to human health. This has resulted in the establishment of warning signs at many recreational sites on these rivers during summer months. Recent research has concluded that river flow and water column nutrients are two of the primary factors regulating Phormidium growth. Proliferations tend to form in rivers where there is slightly elevated water column dissolved inorganic nitrogen, low dissolved reactive phosphorus, and during periods of stable flow. It has been hypothesised that fine sediment may provide a source of phosphorus for Phormidium. These mats ‘capture’ fine sediment suspended in the water column, which becomes incorporated into the mat matrices when motile Phormidium filaments move over the sediment. Diffusive boundary layers at the surface of the mats limit the flow of nutrients and gases between mat and bulk river water, creating conditions (for example, lower dissolved oxygen, elevated pH) conducive to the release of phosphorus from sediment.  The aim of this project was to identify why Phormidium proliferates in certain parts of the Hutt and Waipoua rivers, as well as investigate the relationship between fine sediment and mat growth. Monitoring of river data was carried out in the Hutt and Waipoua Rivers between November 2014 and May 2015. Over this period, physicochemical and hydrological data was monitored to identify the influencing factors of Phormidium abundance. During February 2015, sediment traps were deployed to determine the sedimentation rates in parallel to Phormidium cover at each site. The collected fine sediment was fractionated and analysed for biologically available phosphorus. Finally, a manipulative study using stream channel mesocosms was undertaken to provide causative evidence that fine sediment deposition influences Phormidium growth. In this three-week study, four mesocosms were deployed containing different fine sediment treatments. Biomass samples were collected at regular intervals to determine total photosynthetic biomass and Phormidium specifically.  Phormidium cover during 2014-15 was influenced by water column nitrate-nitrite nitrogen concentrations and sediment deposition. Phormidium cover was considerably lower compared to previous years, with a maximum cover of 20.7% occurring in the Hutt River during February 2015. Analysis of historical flow and nutrient data suggests that the annual variation in Phormidium proliferation over the summer months was site specific and not generally driven by flow or nutrient concentrations.  It is likely that fine sediment plays a role in providing Phormidium mats with phosphorus in the Hutt and Waipoua River. This is shown through phosphorus concentrations within Phormidium mat water, which were 200-fold higher than the bulk water column. Maximum values of sedimentation, 272.0 g/m²/day, and biologically available phosphorus (bound to sediment) 1.4 mg P g⁻¹, occurred at sites with the highest Phormidium cover, which further confirms this correlation. Furthermore, mesocosm experiments showed that Phormidium biomass increased significantly (p=0.015) with an increased amount of sediment. However, the maximum biomass of 64.75 mg/m² did not occur in the mesocosm channel with the most sediment added to it. This suggests that a deposition threshold exists due to the attenuation of light.  Findings from this research provide some insights in to management options which may help to mitigate Phormidium proliferations in the future. The data indicates that reducing sediment inputs, or resuspension of fine sediment during flood remediation works, would reduce Phormidium proliferations. Riparian planting as well as the collaboration with local councils is needed to help reduce diffuse and remaining point sources of sediment and river bed disturbance during flood protection activities. Using a combination of observational and experimental studies, this research has shown that multiple factors influence Phormidium proliferation, and has highlighted the key role that fine sediment plays. Suggestions for future studies include in-river experiments to further explore the role of fine sediment and the optimisation of mesocosms, which may also help to investigate finer scale data on causative factors such as sediment thresholds.</p>

Point and diffuse load of nutrients to the Baltic Sea by river basins of North East Germany (Mecklenburg-Vorpommern)

1998 ◽  
Vol 38 (10) ◽  
pp. 147-155 ◽  
Author(s):  
H. Behrendt ◽  
A. Bachor
Keyword(s):  
Baltic Sea ◽  
River Basins ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Nutrient Load ◽  
The Baltic Sea ◽  
Drainage Systems ◽  
Diffuse Sources ◽  
Nutrient Emissions ◽  
The Baltic

The results of a study on the riverine nutrient emissions and loads of nine river basins of the country Mecklenburg-Vorpommern to the Baltic Sea are presented for the period 1992 to 1994. The basins represent about 76% of the Baltic Sea catchment area of Mecklenburg-Vorpommern. The population living in the basins causes point emissions of 1752 tN/a and 293 tP/a. The analysis of diffuse emissions of nutrients is based on digitized maps of the land use and the soil types, the livestock numbers in the basins and measurements on the nutrient concentrations in the groundwater and drainage areas. The used method considers different pathways of diffuse sources as load from urban areas, erosion, load by groundwater, and drainage systems, atmospheric deposition, and direct load by agricultural activities. The dominant pathway of nitrogen emissions is the emissions of drainage. For phosphorus the emissions by erosion, groundwater and drainage are the main sources. The emissions of point sources contribute to the total emissions to 10% (N) and 25% (P), respectively. The measured nutrient load at the monitoring stations of the rivers is in all cases lower than the sum of the nutrient emissions. This behaviour can be explained by intensive retention processes in the rivers, which depends on the specific runoff, and for nitrogen additionally on the area of surface water in the basin. Measures against the high nutrient load have to be focussed on the reduction of diffuse sources, especially the emissions of nitrogen and phosphorus by drainage systems have to be reduced, and additionally in the case of phosphorus the emissions by erosion and by direct agricultural load.

scholarly journals Understanding the hydrological and physicochemical drivers of Phormidium proliferation in the Hutt and Waipoua Rivers

2021 ◽  
Author(s):  
◽  
Emily Martin
Keyword(s):  
Water Column ◽  
Inorganic Nitrogen ◽  
Fine Sediment ◽  
Sediment Deposition ◽  
Point Sources ◽  
Warning Signs ◽  
Nutrient Concentrations ◽  
Available Phosphorus ◽  
Growth Monitoring ◽  
Management Options

<p>The Hutt and Waipoua rivers are affected annually by proliferations of the potentially toxic benthic cyanobacteria - Phormidium. Ingestion of these mats has resulted in numerous dog deaths and is therefore a risk to human health. This has resulted in the establishment of warning signs at many recreational sites on these rivers during summer months. Recent research has concluded that river flow and water column nutrients are two of the primary factors regulating Phormidium growth. Proliferations tend to form in rivers where there is slightly elevated water column dissolved inorganic nitrogen, low dissolved reactive phosphorus, and during periods of stable flow. It has been hypothesised that fine sediment may provide a source of phosphorus for Phormidium. These mats ‘capture’ fine sediment suspended in the water column, which becomes incorporated into the mat matrices when motile Phormidium filaments move over the sediment. Diffusive boundary layers at the surface of the mats limit the flow of nutrients and gases between mat and bulk river water, creating conditions (for example, lower dissolved oxygen, elevated pH) conducive to the release of phosphorus from sediment.  The aim of this project was to identify why Phormidium proliferates in certain parts of the Hutt and Waipoua rivers, as well as investigate the relationship between fine sediment and mat growth. Monitoring of river data was carried out in the Hutt and Waipoua Rivers between November 2014 and May 2015. Over this period, physicochemical and hydrological data was monitored to identify the influencing factors of Phormidium abundance. During February 2015, sediment traps were deployed to determine the sedimentation rates in parallel to Phormidium cover at each site. The collected fine sediment was fractionated and analysed for biologically available phosphorus. Finally, a manipulative study using stream channel mesocosms was undertaken to provide causative evidence that fine sediment deposition influences Phormidium growth. In this three-week study, four mesocosms were deployed containing different fine sediment treatments. Biomass samples were collected at regular intervals to determine total photosynthetic biomass and Phormidium specifically.  Phormidium cover during 2014-15 was influenced by water column nitrate-nitrite nitrogen concentrations and sediment deposition. Phormidium cover was considerably lower compared to previous years, with a maximum cover of 20.7% occurring in the Hutt River during February 2015. Analysis of historical flow and nutrient data suggests that the annual variation in Phormidium proliferation over the summer months was site specific and not generally driven by flow or nutrient concentrations.  It is likely that fine sediment plays a role in providing Phormidium mats with phosphorus in the Hutt and Waipoua River. This is shown through phosphorus concentrations within Phormidium mat water, which were 200-fold higher than the bulk water column. Maximum values of sedimentation, 272.0 g/m²/day, and biologically available phosphorus (bound to sediment) 1.4 mg P g⁻¹, occurred at sites with the highest Phormidium cover, which further confirms this correlation. Furthermore, mesocosm experiments showed that Phormidium biomass increased significantly (p=0.015) with an increased amount of sediment. However, the maximum biomass of 64.75 mg/m² did not occur in the mesocosm channel with the most sediment added to it. This suggests that a deposition threshold exists due to the attenuation of light.  Findings from this research provide some insights in to management options which may help to mitigate Phormidium proliferations in the future. The data indicates that reducing sediment inputs, or resuspension of fine sediment during flood remediation works, would reduce Phormidium proliferations. Riparian planting as well as the collaboration with local councils is needed to help reduce diffuse and remaining point sources of sediment and river bed disturbance during flood protection activities. Using a combination of observational and experimental studies, this research has shown that multiple factors influence Phormidium proliferation, and has highlighted the key role that fine sediment plays. Suggestions for future studies include in-river experiments to further explore the role of fine sediment and the optimisation of mesocosms, which may also help to investigate finer scale data on causative factors such as sediment thresholds.</p>

Reducing Nutrient Loads in Northern Irish Catchments: A Modelling Approach Based on Load Apportionment and Flow Pathway Identification

2021 ◽  
Author(s):  
Russell Adams ◽  
Donnacha Doody
Keyword(s):  
Water Quality ◽  
Large Scale ◽  
Agricultural Land ◽  
Assessment Tool ◽  
Ecological Status ◽  
Point Sources ◽  
Load Reduction ◽  
Nutrient Loads ◽  
Flow Pathways ◽  
Flow Pathway

&lt;p&gt;Northern Ireland has been somewhat overlooked in terms of water quality modelling in the past. Many of its catchments have consistently failed to meet Water Framework Directive targets especially due to high levels of dissolved nutrients and poor ecological status. A catchment based modelling study to address this issue has not been undertaken here previously and the approach described here uses two water quality models to achieve this aim. The objectives of the modelling were firstly to identify the total load reductions (in terms of Phosphorus (P)) required to reduce in-stream loadings sufficiently for concentrations of soluble reactive P (SRP) to be reduced to achieve the WFD &amp;#8220;Good&amp;#8221; status levels, and secondly to split these loadings into diffuse and point components. The third objective was to identify the most likely flow pathways for the transport of the diffuse component of P to the watercourses particularly for the agricultural (mostly intensive grassland farming) land use which dominates in almost all NI catchments.&lt;/p&gt;&lt;p&gt;The first model applied is the Source Load Apportionment Model (SLAM) developed by the Irish EPA. This model provides a large-scale assessment of the point and diffuse load components across catchments where multiple pressures are occurring. The second model us the Catchment Runoff Flux Assessment Tool (CRAFT) which is able to back-calculate nutrient loads associated with three major flow pathways. SLAM is a static model which uses averaged loadings from diffuse agriculture and non-agricultural land uses, and point sources (where information can be obtained from various sources) to calculate N and P exports. For P, the agricultural diffuse load component uses an enhanced version of the export coefficient approach based on combining the sources of P from applied nutrients (slurry and fertiliser) and soil P. A modelling tool allows the user to evaluate load reduction scenarios where one or several components of P (both point and diffuse) are adjusted downwards to achieve the catchment&amp;#8217;s required load reduction. The CRAFT model works on a dynamic (daily) modelling scale and has simulated sub-catchments where the SLAM model has identified the need for significant load reductions. It identifies the different reductions (P export) that are required for each flow pathway, which will then inform on the type of additional measures (e.g. sediment traps, riparian buffer strips and wetlands) that may also be required.&lt;/p&gt;&lt;p&gt;The initial aim of this study is to complete a pilot application to the trans-border (UK and ROI) Blackwater catchment (1360 km&lt;sup&gt;2&lt;/sup&gt;). Through a review of alternative modelling options for the whole area of NI, an assessment of whether this approach is suitable for application to the entire territory can be made.&lt;/p&gt;

Modelling nitrogen transport across compartments over northern Europe

2021 ◽  
Author(s):  
Stefan Hagemann ◽  
Ute Daewel ◽  
Volker Matthias ◽  
Tobias Stacke
Keyword(s):  
Baltic Sea ◽  
Land Surface ◽  
Climate Model ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Regional Climate ◽  
Marine Ecosystem ◽  
Coupled System ◽  
Nutrient Concentrations ◽  
Nutrient Loads

&lt;p&gt;River discharge and the associated nutrient loads are important factors that influence the functioning of the marine ecosystem. Lateral inflows from land carrying fresh, nutrient-rich water determine coastal physical conditions and nutrient concentration and, hence, dominantly influence primary production in the system. Since this forms the basis of the trophic food web, riverine nutrient concentrations impact the variability of the whole coastal ecosystem. This process becomes even more relevant in systems like the Baltic Sea, which is almost decoupled from the open ocean and land-borne nutrients play a major role for ecosystem productivity on seasonal up to decadal time scales.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;In order to represent the effects of climate or land use change on nutrient availability, a coupled system approach is required to simulate the transport of nutrients across Earth system compartments. This comprises their transport within the atmosphere, the deposition and human application at the surface, the lateral transport over the land surface into the ocean and their dynamics and transformation in the marine ecosystem. In our study, we combine these processes in a modelling chain within the GCOAST (Geesthacht Coupled cOAstal model SysTem) framework for the northern European region. This modelling chain comprises:&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;ul&gt;&lt;li&gt;Simulation of emissions, atmospheric transport and deposition with the chemistry transport model CMAQ at 36 km grid resolution using atmospheric forcing from the coastDat3 data that have been generated with the regional climate model COSMO-CLM over Europe at 0.11&amp;#176; resolution using ERA-Interim re-analyses as boundary conditions&lt;/li&gt; &lt;li&gt;Simulation of inert processes at the land surface with the global hydrology model HydroPy (former MPI-HM), i.e. considering total nitrogen without any chemical reactions&lt;/li&gt; &lt;li&gt;Riverine transport with the Hydrological Discharge (HD) model at 0.0833&amp;#176; spatial resolution&lt;/li&gt; &lt;li&gt;Simulation of the North Sea and Baltic Sea ecosystems with 3D coupled physical-biogeochemical NPZD-model ECOSMO II at about 10 km resolution&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We will present first results and their validation from this exercise.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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