scholarly journals The distribution of sediment and water column nitrification potential in the hyper-turbid Ems estuary

2018 ◽  
Vol 80 (4) ◽  
Author(s):  
Tina Sanders ◽  
Hendrikus J. Laanbroek
Keyword(s):  
Water Column ◽  
Ems Estuary ◽  
Nitrification Potential

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>

Comparison of the performance of oscillating water column devices based on arrangements of water columns

2020 ◽  
Vol 14 (3) ◽  
pp. 7082-7093
Author(s):  
Jahirwan Ut Jasron ◽  
Sudjito Soeparmani ◽  
Lilis Yuliati ◽  
Djarot B. Darmadi
Keyword(s):  
Wave Propagation ◽  
Water Column ◽  
Water Depth ◽  
Graphical Form ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Water Columns ◽  
Single Column ◽  
Parallel Arrangement

The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.

Control of heat transfer in a geysering water column by ultrasound emission

2002 ◽  
Author(s):  
Hideo Kimoto ◽  
Takashi Fujii ◽  
Kenta Fujiwara
Keyword(s):  
Heat Transfer ◽  
Water Column

Extracellular enzymatic activities in the aquatic ecosystems of the Danube Delta. 2. Alkaline phosphatase activity

2021 ◽  
Vol 26 (1) ◽  
pp. 2269-2274
Author(s):  
IOAN PĂCEŞILĂ ◽  
EMILIA RADU
Keyword(s):  
Alkaline Phosphatase ◽  
Water Column ◽  
Aquatic Ecosystems ◽  
Temporal Dynamics ◽  
Extracellular Enzyme ◽  
Danube Delta ◽  
Phytoplankton Communities ◽  
Extracellular Enzymatic Activities ◽  
Adjacent Channels ◽  
Hydrolysis Of

Phosphorus is one of the most important inorganic nutrients in aquatic ecosystems, the development and functioning of the phytoplankton communities being often correlated with the degree of availability in assimilable forms of this element. Alkaline phosphatase (AP) is an extracellular enzyme with nonspecific activity that catalyses the hydrolysis of a large variety of organic phosphate esters and release orthophosphates. During 2011-2013, AP Activity (APA) was assessed in the water column and sediments of several aquatic ecosystems from Danube Delta: Roșu Lake, Mândra Lake and their adjacent channels – Roșu-Împuțita and Roșu-Puiu. The intensity of APA widely fluctuated, ranging between 230-2578 nmol p-nitrophenol L-1h-1 in the water column and 2104-15631 nmol p-nitrophenol g-1h-1 in sediment. Along the entire period of the study, APA was the most intense in Roșu-Împuțita channel, for both water and sediment samples. Temporal dynamics revealed its highest values in summer for the water column and in autumn for sediment. Statistical analysis showed significant seasonal diferences of the APA dynamics in spring vs. summer and autumn for the water column, and any relevant diferences for sediment.

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