scholarly journals Suspended Particular Matter drives the spatial segregation of nitrogen turnover along the hyper-turbid Ems estuary

2021 ◽  
Author(s):  
Gesa Schulz ◽  
Tina Sanders ◽  
Justus E. E. van Beusekom ◽  
Yoana G. Voynova ◽  
Andreas Schöl ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Nitrous Oxide ◽  
Water Column ◽  
Anthropogenic Activities ◽  
Inorganic Nitrogen ◽  
Nitrate Removal ◽  
Tidal River ◽  
Nutrient Loads ◽  
Ems Estuary ◽  
Nitrogen Turnover

Abstract. Estuaries are nutrient filters and change riverine nutrient loads before they reach coastal oceans. They have been extensively changed by anthropogenic activities like draining, deepening, and dredging to meet economic and social demand, causing significant regime changes like tidal amplifications and in some cases to hyper-turbid conditions. Furthermore, increased nutrient loads, especially nitrogen, mainly by agriculture cause coastal eutrophication. Estuaries can either act as a sink or as a source of nitrate, depending on environmental and geomorphological conditions. These factors vary along an estuary, and change nitrogen turnover in the system. Here, we investigate the factors controlling nitrogen turnover in the hyper-turbid Ems estuary (Northern Germany) that has been strongly impacted by human activities. During two research cruises in August 2014 and June 2020, we measured water column properties, dissolved inorganic nitrogen, dual stable isotopes of nitrate and dissolved nitrous oxide concentration along the estuary. Overall, the Ems estuary acts as a nitrate sink in both years. However, three distinct biogeochemical zones exist along the estuary. A strong fractionation (~ 26 ‰) of nitrate stable isotopes points towards nitrate removal via water column denitrification in the hyper-turbid Tidal River, driven by anoxic conditions in deeper water layers. In the Middle Reaches of the estuary nitrification gains in importance turning this section into a net nitrate source. The Outer Reaches are dominated by mixing with nitrate uptake in 2020. We find that the overarching control on biogeochemical nitrogen cycling, zonation and nitrous oxide production in the Ems estuary is exerted by suspended particulate matter concentrations and the linked oxygen deficits.

Biogeochemical zonation reveals three zones of nitrogen turnover in the Ems estuary

2021 ◽  
Author(s):  
Gesa Schulz ◽  
Tina Sanders ◽  
Kirstin Dähnke
Keyword(s):  
Stable Isotopes ◽  
Water Column ◽  
Coastal Waters ◽  
Inorganic Nitrogen ◽  
Dissolved Inorganic Nitrogen ◽  
Middle Reach ◽  
Ems Estuary ◽  
Nitrogen Turnover ◽  
Spatial Shift ◽  
Nitrate Distribution

<p>Estuaries are nutrient filters for coastal waters and can act as nitrate sink or source depending on predominant microbial processes, environmental conditions and geomorphological characteristics. Such environmental factors can change along the estuary itself. This study aims to identify different zones of nitrogen turnover in the Ems estuary and to determine the main processes.</p><p>Water column properties, dissolved inorganic nitrogen and dual stable isotopes of nitrate were measured along the Ems estuary during two research cruises in August 2014 and June 2020. Based on mixing calculations and stable isotope changes, we found that the estuary in both years is clearly divided into three zones that vary in the predominant nitrate turnover pathways. This was confirmed by principle component analysis.</p><p>The zonation mainly corresponded to changes in the geomorphology of the estuary, but a spatial shift of the zones occurred between 2014 and 2020. In both years, the most upstream zone acted as a clear nitrate sink. A strong fractionation (~30 ‰) of nitrate stable isotopes points towards removal by water column denitrification in this hyperturbid estuarine section.  In the middle reach of the estuary, nitrification gained in importance, turning this section into a net nitrate source during both sampling campaigns. In contrast to the biogeochemical active inner zones, mixing dominates nitrate distribution in the outermost section of the estuary.</p><p>Overall, the Ems estuary acted as a nitrate sink in both years. However, the zonation showed that relative stable zones of nitrification and denitrification existed along the estuary, which can change – and possibly move – when biogeochemical properties vary. </p>

scholarly journals Depth–Sequential Investigation of Major Ions, δ18o, δ2h and δ13C in Fractured Aquifers of the St. Lawrence Lowlands (Quebec, Canada) Using Passive Samplers

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1806
Author(s):  
Guillaume Meyzonnat ◽  
Florent Barbecot ◽  
José Corcho Alvarado ◽  
Daniele Luigi Pinti ◽  
Jean-Marc Lauzon ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Major Ions ◽  
Anthropogenic Activities ◽  
Carbon Sources ◽  
Passive Samplers ◽  
Flow Paths ◽  
Aquifer Heterogeneity ◽  
Fractured Aquifers ◽  
Fractured Carbonate ◽  
Observation Wells

General and isotopic geochemistry of groundwater is an essential tool to decipher hydrogeological contexts and flow paths. Different hydrogeochemical patterns may result from the inherent physical aquifer heterogeneity, which may go unnoticed without detailed investigations gathered from multilevel or multiple observation wells. An alternative to overcome the frequent unavailability of multiple wellbores at sites is to perform a detailed investigation on the single wellbore available. In this perspective, the aim of this study is to use passive samplers to sequentially collect groundwater at depths in long–screened wellbores. Such investigation is carried out for major ions and stable isotopes compositions (δ2H, δ18O, δ13C) at ten sites in the context of fractured carbonate aquifers of the St. Lawrence Lowlands (Quebec, Canada). The information gathered from the calco–carbonic system, major ions and stable isotopes report poorly stratified and evolved groundwater bodies. Contribution of water impacted by anthropogenic activities, such as road salts pollution and carbon sources from C4 vegetation, when they occur, are even observed at the greatest depths. Such observations suggest quick flow paths and efficient mixing conditions, which leads to significant contributions of contemporary groundwater bodies in the fractured aquifers investigated down to depths of about 100 m. Although physical aquifer investigation reported few and heterogeneously distributed fractures per wellbore, hydrogeochemical findings point to at overall well interconnected fracture networks in the aquifer and high vulnerability of groundwater, even at significant depths.

scholarly journals Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

2018 ◽  
Vol 15 (20) ◽  
pp. 6127-6138 ◽  
Author(s):  
Qixing Ji ◽  
Claudia Frey ◽  
Xin Sun ◽  
Melanie Jackson ◽  
Yea-Shine Lee ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Chesapeake Bay ◽  
Water Column ◽  
N2o Emissions ◽  
N2o Production ◽  
Isotope Tracer ◽  
Relative Contribution ◽  
Environmental Controls ◽  
Long Run ◽  
Nitrate And Nitrite

Abstract. Nitrous oxide (N2O) is a greenhouse gas and an ozone depletion agent. Estuaries that are subject to seasonal anoxia are generally regarded as N2O sources. However, insufficient understanding of the environmental controls on N2O production results in large uncertainty about the estuarine contribution to the global N2O budget. Incubation experiments with nitrogen stable isotope tracer were used to investigate the geochemical factors controlling N2O production from denitrification in the Chesapeake Bay, the largest estuary in North America. The highest potential rates of water column N2O production via denitrification (7.5±1.2 nmol-N L−1 h−1) were detected during summer anoxia, during which oxidized nitrogen species (nitrate and nitrite) were absent from the water column. At the top of the anoxic layer, N2O production from denitrification was stimulated by addition of nitrate and nitrite. The relative contribution of nitrate and nitrite to N2O production was positively correlated with the ratio of nitrate to nitrite concentrations. Increased oxygen availability, up to 7 µmol L−1 oxygen, inhibited both N2O production and the reduction of nitrate to nitrite. In spring, high oxygen and low abundance of denitrifying microbes resulted in undetectable N2O production from denitrification. Thus, decreasing the nitrogen input into the Chesapeake Bay has two potential impacts on the N2O production: a lower availability of nitrogen substrates may mitigate short-term N2O emissions during summer anoxia; and, in the long-run (timescale of years), eutrophication will be alleviated and subsequent reoxygenation of the bay will further inhibit N2O production.

scholarly journals Greenhouse gases, global warming and glacier ice melt in Nepal

2007 ◽  
Vol 8 ◽  
pp. 1-7
Author(s):  
Krishna B. Karki
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Greenhouse Gases ◽  
Greenhouse Effect ◽  
Anthropogenic Activities ◽  
Mineral Fertilizer ◽  
Water Shortage ◽  
Water Volume ◽  
Greenhouse Gasses ◽  
Glacier Ice

Concentration of greenhouse gases has been found increasing over the past centuries. Carbon dioxide (9-26% greenhouse effect), methane (4-9%), and nitrous oxide (3-6%) are the three principal greenhouse gasses though chloroflourocarbon and halon are also included as greenhouse gasses but are in very small greenhouse effect. These gasses are produced both from natural process and anthropogenic activities .Increase of these greenhouse gasses from nature in the atmosphere is mainly from the decomposition of organic matter, nitrification and denitrification of nitrogen including respiration by the plants. Anthropogenic production of carbon dioxide is from burning of fossil fuel whereas for methane livestock and paddy cultivation. Agricultural activities mainly use of mineral fertilizer is responsible for nitrous oxide emission. Increase of these gasses in atmosphere increases temperature that further accelerates evaporation of moisture from the earth’s surface. Increase in water vapor in the atmosphere will further aggravate temperature rise. This increase in atmospheric temperature has direct effect in the melting of glacier ice in Nepalese Himalaya. Melting of ice and increases water volume in the glacier fed rivers and glacier lakes. Rise in water volume beyond its capacity the glacial lakes bursts releasing millions of cubit meters of water and takes million of lives and properties downstream. If this continues there will be no more ice left in the Himalaya and in the long run all the rivers of Nepal will go dry and country will face serious water shortage for drinking, irrigation and other purposes. The Journal of AGRICULTURE AND ENVIRONMENT Vol. 8, 2007, pp. 1-7

scholarly journals Change of mineral and organic nitrogen forms in a long term fertilization experiment (literature)

2014 ◽  
pp. 43-47
Author(s):  
Judit Horváth ◽  
János Kátai
Keyword(s):  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Essential Element ◽  
Nitrogen Forms ◽  
Organic Form ◽  
The Sustainable Development ◽  
Nitrogen Turnover ◽  
Mineralization Processes ◽  
Living Organisms

The research topic has timeliness, since the rational utilization and protection of the soil, besides the conservation of its diverse functions is part of the sustainable development. Research of the long-term experiments is esentially important, because it can model the term effects in the same place, under the same conditions. If we want to get accurate informations about the occured changes, way and danger of changes, we should track the resupply and effect of the mineral nutrients and the removed quantity of nutrients with the harvest. Nitrogen is an essential element for living organisms, it is present in the soil mainly in organic form. In general only only a low percentage of the total nitrogent content can be used directly by plants in the soil. This inorganic nitrogen is produced by the transformation of organic contents through mineralization processes and it get into the soil by the fertilization. The plants incorporote the mineral nitrogen into our bodies. This is how nitrogen turnover is realized when mineral forms become organic and organic forms become mineral. The purpose of our paper is to make a literature before our research.

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.

Metabolic alkalinity release from the Elbe estuary to the North Sea

2021 ◽  
Author(s):  
Mona Norbisrath ◽  
Jeannette Hansen ◽  
Kirstin Dähnke ◽  
Tina Sanders ◽  
Justus E. E. van Beusekom ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Water Column ◽  
Fresh Water ◽  
North Sea ◽  
Total Alkalinity ◽  
Elbe Estuary ◽  
Metabolic Processes ◽  
The North ◽  
Carbon Species ◽  
The North Sea

<p>The Elbe is the largest river entering the German Bight. Its estuary is a heavily used waterway connecting the sea to Germany’s biggest port in Hamburg. The Elbe navigation channel is continuously dredged, and agricultural fertilizer input from the catchment ensuing large phytoplankton blooms in the river Elbe exerts additional anthropogenic pressure. Biogeochemistry in the estuary is additionally governed by the North Sea and its strong tidal cycles, which ensure an exchange of fresh and marine waters.</p><p>The aims were to quantify the release of the carbon species total alkalinity (TA) and dissolved inorganic carbon (DIC) along the Elbe estuary, and to estimate the contribution of aerobe and anaerobe metabolic processes. Therefore, we used water samples collected continuously during a cruise in June 2019, to measure TA and DIC, and the stable isotopes of nitrate. We applied mass balances, to characterize the metabolic activity and detect their effect on the carbon species</p><p>The Elbe estuary could be subdivided into two parts: 1) an outer marine driven part, which is dominated by conservative mixing, also visible in higher TA than DIC values, and 2) an inner fresh water part in which metabolic processes play an important role.</p><p>We found a strong increase in TA and DIC (several hundred µmol kg<sup>-1</sup>) in the Hamburg port area, with higher DIC than TA values. We unraveled the water column impacts of nitrification and denitrification on TA and DIC by analyzing the stable isotopes δ<sup>15</sup>N-NO<sub>3</sub><sup>-</sup> and δ<sup>18</sup>O-NO<sub>3</sub><sup>-</sup>, and identified water column nitrification as a dominant pelagic process in the port of Hamburg and in the fresh water part further downstream. Because nitrification cannot explain the significant increase of TA and DIC in the port region, anaerobic processes such as denitrification in the sediment also appear to play an important role.</p><p> </p>

scholarly journals Managing Municipal Wastewater Treatment to Control Nitrous Oxide Emissions from Tidal Rivers

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1255
Author(s):  
Chandra Sekhar Akella ◽  
S. Murty Bhallamudi
Keyword(s):  
Nitrous Oxide ◽  
Municipal Wastewater ◽  
High Tide ◽  
Tidal River ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Municipal Wastewater Treatment ◽  
Water Release ◽  
Decision Variables ◽  
Waste Load

Waste load allocation management models were developed for controlling nitrous oxide emissions from a tidal river. The decision variables were treatment levels at wastewater discharging stations and the rate of upstream water release. The simulation model for N2O emissions from the river was embedded in the optimization model and the problem was solved using the simulated annealing technique. In two of the models, the total cost was minimized, while in the third model, emissions from the river were minimized for a specified constraint on the available money. Proof-of-concept studies, with hypothetical scenarios for contaminant loading but realistic flow conditions corresponding to the Tyne River, UK, were carried out. It was found that the treatment cost could be reduced by 36% by treating wastewater discharges in the upper reaches more during the high tide as compared to during low tide. For the same level of N2O emissions, approximately 16.7% lesser costs could be achieved by not only treating the wastewater but also inducing dilution by releasing more water from the upstream side. It was also found that beyond a limit, N2O emissions cannot be reduced significantly by spending more money on treatment and water release.

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