scholarly journals Dissolved inorganic nitrogen in a tropical estuary in Malaysia: transport and transformation

2019 ◽  
Vol 16 (14) ◽  
pp. 2821-2836 ◽  
Author(s):  
Shan Jiang ◽  
Moritz Müller ◽  
Jie Jin ◽  
Ying Wu ◽  
Kun Zhu ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
Dry Season ◽  
Similar Distribution ◽  
Tropical Estuary ◽  
Dissolved Inorganic Nitrogen ◽  
Wet Season ◽  
Terrestrial Organic Matter ◽  
Transport And Transformation

Abstract. Dissolved inorganic nitrogen (DIN), including nitrate, nitrite and ammonium, frequently acts as the limitation for primary productivity. Our study focused on the transport and transformation of DIN in a tropical estuary, i.e., the Rajang River estuary, in Borneo, Malaysia. Three cruises were conducted in August 2016 and February–March and September 2017, covering both dry and wet seasons. Before entering the coastal delta, decomposition of the terrestrial organic matter and the subsequent soil leaching was assumed to be the main source of DIN in the river water. In the estuary, decomposition of dissolved organic nitrogen was an additional DIN source, which markedly increased DIN concentrations in August 2016 (dry season). In the wet season (February 2017), ammonium concentrations showed a relatively conservative distribution during the mixing, and the nitrate addition was weak. La Niña events induced high precipitations and discharge rates, decreased reaction intensities of ammonification and nitrification. Hence similar distribution patterns of DIN species in the estuary were found in September 2017 (end of the dry season). The magnitude of riverine DIN flux varied between 77.2 and 101.5 t N d−1, which might be an important support for the coastal primary productivity.

scholarly journals Dissolved inorganic nitrogen in a tropical estuary at Malaysia: transport and transformation

2019 ◽  
Author(s):  
Shan Jiang ◽  
Moritz Müller ◽  
Jie Jin ◽  
Ying Wu ◽  
Kun Zhu ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
Dry Season ◽  
Ammonium Concentration ◽  
Tropical Estuary ◽  
Dissolved Inorganic Nitrogen ◽  
Wet Season ◽  
Terrestrial Organic Matter ◽  
Transport And Transformation

Abstract. Dissolved inorganic nitrogen (DIN), including nitrate, nitrite and ammonium, frequently acts as the limitation for primary productivity. Our study focused on the transport and transformation of dissolved inorganic nitrogen in a tropical estuary, i.e. Rajang river estuary, in Borneo, Malaysia. Three cruises were conducted in August 2016, February–March and September 2017, covering both dry and wet seasons. Before entering the coastal delta, decomposition of the terrestrial organic matter and the subsequent soil leaching was assumed to be the main source of DIN in the river water. In the estuary, decomposition of dissolved organic nitrogen was an additional DIN source, which markedly increased DIN concentrations in August 2016 (dry season). In the wet season (February 2017), ammonium concentration showed a relatively conservative distribution during the mixing and nitrate addition was weak. In September 2017 (dry season), La Niña induced high precipitation and discharge rates, decreased reaction intensities of ammonification and nitrification and hence the distribution of DIN species in the estuary water was similar with the trend found in the wet season. The magnitude of riverine DIN flux varied between 77.2 and 101.5 ton N d-1, which might be an important support for the coastal primary productivity.

scholarly journals Seasonal and spatial controls on N2O concentrations and emissions in low-nitrogen estuaries: Evidence from three tropical systems

2019 ◽  
Author(s):  
Rachel Murray ◽  
Dirk Erler ◽  
Judith Rosentreter ◽  
Naomi Wells ◽  
Bradley Eyre
Keyword(s):  
Inorganic Nitrogen ◽  
River Estuary ◽  
The Other ◽  
Dissolved Inorganic Nitrogen ◽  
Wet Season ◽  
Tropical Estuaries ◽  
Dry Seasons ◽  
Low Nitrogen ◽  
Fitzroy River ◽  
Wet And Dry Seasons

AbstractEstuarine N2O emissions contribute to the atmospheric N2O budget, but little is known about estuary N2O fluxes under low dissolved inorganic nitrogen (DIN) conditions. We present high-resolution spatial surveys of N2O concentrations and water-air fluxes in three low-DIN (NO3−< 30µmol L−1) tropical estuaries in Queensland, Australia (Johnstone River, Fitzroy River, Constant Creek) during consecutive wet and dry seasons. Constant Creek had the lowest concentrations of dissolved inorganic nitrogen (DIN; 0.01 to 5.4µmol L−1of NO3−and 0.09 to 13.6µmol L−1of NH4+) and N2O (93–132% saturation), and associated lowest N2O emissions (– 1.4 to 8.4µmol m−2d−1) in both seasons. The other two estuaries exhibited higher DIN inputs and higher N2O emissions. The Johnstone River Estuary had the highest N2O concentrations (97–245% saturation) and emissions (– 0.03 to 25.7µmol m−2d−1), driven by groundwater inputs from upstream sources, with increased N2O input in the wet season. In the Fitzroy River Estuary, N2O concentrations (100–204% saturation) and emissions (0.03–19.5µmol m−2d−1) were associated with wastewater inputs, which had a larger effect during the dry season and were diluted during the wet season. Overall N2O emissions from the three tropical estuaries were low compared to previous studies, and at times water-air N2O fluxes were actually negative, indicating that N2O consumption occurred. Low water column NO3−concentration (i.e. < 5µmol L−1) appears to promote negative water-air N2O fluxes in estuary environments; considering the number of estuaries and mangrove creeks where DIN falls below this threshold, negative water-air N2O fluxes are likely common.

scholarly journals Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

2013 ◽  
Vol 10 (10) ◽  
pp. 6721-6736 ◽  
Author(s):  
C. Buzzelli ◽  
Y. Wan ◽  
P. H. Doering ◽  
J. N. Boyer
Keyword(s):  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
South Florida ◽  
External Loading ◽  
Dissolved Inorganic Nitrogen ◽  
Nutrient Inputs ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
Annual Variations

Abstract. Interactions among geomorphology, circulation, and biogeochemical cycling determine estuary responses to external nutrient loading. In order to better manage watershed nutrient inputs, the goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River estuary (CRE) and the St. Lucie Estuary (SLE), from 2002 to 2008. The Land–Ocean Interactions in the Coastal Zone (LOICZ) approach was used to generate water, salt, and DIN and DIP budgets. Results suggested that internal DIN production increases with increased DIN loading to the CRE in the wet season. There were hydrodynamic effects as water column concentrations and ecosystem nutrient processing stabilized in both estuaries as flushing time increased to >10 d. The CRE demonstrated heterotrophy (net ecosystem metabolism or NEM < 0.0) across all wet and dry season budgets. While the SLE was sensitive to DIN loading, system autotrophy (NEM > 0.0) increased significantly with external DIP loading. This included DIP consumption and a bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge to the SLE in 2005. Additionally, while denitrification provided a microbially-mediated N loss pathway for the CRE, this potential was not evident for the SLE where N2 fixation was favored. Disparities between total and inorganic loading ratios suggested that the role of dissolved organic nitrogen (DON) should be assessed for both estuaries. Nutrient budgets indicated that net internal production or consumption of DIN and DIP fluctuated with inter- and intra-annual variations in freshwater inflow, hydrodynamic flushing, and primary production. The results of this study should be included in watershed management plans in order to maintain favorable conditions of external loading relative to internal material cycling in both dry and wet seasons.

scholarly journals Inorganic Nitrogen Production and Removal along the Sediment Gradient of a Stormwater Infiltration Basin

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 320
Author(s):  
Qianyao Si ◽  
Mary G. Lusk ◽  
Patrick W. Inglett
Keyword(s):  
Removal Efficiency ◽  
N Mineralization ◽  
Inorganic Nitrogen ◽  
Dry Season ◽  
Pollutant Removal ◽  
Net N Mineralization ◽  
Wet Season ◽  
Inorganic N ◽  
N Removal ◽  
Stormwater Infiltration

Stormwater infiltration basins (SIBs) are vegetated depressions that collect stormwater and allow it to infiltrate to underlying groundwater. Their pollutant removal efficiency is affected by the properties of the soils in which they are constructed. We assessed the soil nitrogen (N) cycle processes that produce and remove inorganic N in two urban SIBs, with the goal of further understanding the mechanisms that control N removal efficiency. We measured net N mineralization, nitrification, and potential denitrification in wet and dry seasons along a sedimentation gradient in two SIBs in the subtropical Tampa, Florida urban area. Net N mineralization was higher in the wet season than in the dry season; however, nitrification was higher in the dry season, providing a pool of highly mobile nitrate that would be susceptible to leaching during periodic dry season storms or with the onset of the following wet season. Denitrification decreased along the sediment gradient from the runoff inlet zone (up to 5.2 μg N/g h) to the outermost zone (up to 3.5 μg N/g h), providing significant spatial variation in inorganic N removal for the SIBs. Sediment accumulating around the inflow areas likely provided a carbon source, as well as maintained stable anaerobic conditions, which would enhance N removal.

scholarly journals Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

2013 ◽  
Vol 10 (2) ◽  
pp. 2377-2413
Author(s):  
C. Buzzelli ◽  
Y. Wan ◽  
P. H. Doering ◽  
J. N. Boyer
Keyword(s):  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
South Florida ◽  
Biogeochemical Model ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Tropical Estuaries ◽  
Flushing Time ◽  
Management Actions

Abstract. Interactions among watershed nutrient loading, circulation, and biogeochemical cycling determine the capacity of estuaries to accommodate introduced nutrients. Baseline quantification of loading, flushing time, export, and internal processes is essential to understand responses of sub-tropical estuaries to variable climate and nutrient loading. The goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River Estuary (CRE) and the St. Lucie Estuary (SLE), from 2002–2008 spanning various climatic conditions. The Land Ocean Interactions in the Coastal Zone (LOICZ) Biogeochemical Model was used to generate water, salt, and (DIN and DIP) budgets. The predicted increase in internal DIN production for the CRE vs. the SLE was associated with increased external DIN loading. Water column DIN concentrations decreased and stabilized in both estuaries as flushing time increased to > 10 d. The CRE demonstrated heterotrophy or balanced metabolism across all seasonal budgets. Although the SLE was also sensitive to DIN loading, system autotrophy and net ecosystem metabolism increased with DIP loading to this estuary. This included a huge DIP consumption and bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge in 2005. Additionally, while denitrification offered a loss pathway for inorganic nitrogen in the CRE, this potential was not evident for the smaller and more anthropogenically altered St. Lucie Estuary. Disparities between total and inorganic loading ratios suggested that management actions should examine the role of dissolved organic nitrogen (DON) in attempts to reduce both nitrogen and phosphorus inputs to the SLE. Establishment of quantitative loading limits for anthropogenically impacted estuaries requires an understanding of the inter-seasonal and inter-annual relationships for both N and P, circulation and flushing, variability in plankton community composition, and the dynamics of DON.

scholarly journals Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

2016 ◽  
Vol 13 (8) ◽  
pp. 2415-2428 ◽  
Author(s):  
Denise Müller ◽  
Hermann W. Bange ◽  
Thorsten Warneke ◽  
Tim Rixen ◽  
Moritz Müller ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Inorganic Nitrogen ◽  
Monsoon Season ◽  
Peat Soil ◽  
Dry Season ◽  
N2o Emissions ◽  
Wet Season ◽  
Tropical Estuaries ◽  
Ch4 Emissions ◽  
Nitrogen Concentrations

Abstract. Estuaries are sources of nitrous oxide (N2O) and methane (CH4) to the atmosphere. However, our present knowledge of N2O and CH4 emissions from estuaries in the tropics is very limited because data are scarce. In this study, we present first measurements of dissolved N2O and CH4 from two estuaries in a peat-dominated region of northwestern Borneo. Two campaigns (during the dry season in June 2013 and during the wet season in March 2014) were conducted in the estuaries of the Lupar and Saribas rivers. Median N2O concentrations ranged between 7.2 and 12.3 nmol L−1 and were higher in the marine end-member (13.0 ± 7.0 nmol L−1). CH4 concentrations were low in the coastal ocean (3.6 ± 0.2 nmol L−1) and higher in the estuaries (medians between 10.6 and 64.0 nmol L−1). The respiration of abundant organic matter and presumably anthropogenic input caused slight eutrophication, which did not lead to hypoxia or enhanced N2O concentrations, however. Generally, N2O concentrations were not related to dissolved inorganic nitrogen concentrations. Thus, the use of an emission factor for the calculation of N2O emissions from the inorganic nitrogen load leads to an overestimation of the flux from the Lupar and Saribas estuaries. N2O was negatively correlated with salinity during the dry season, which suggests a riverine source. In contrast, N2O concentrations during the wet season were not correlated with salinity but locally enhanced within the estuaries, implying that there were additional estuarine sources during the wet (i.e., monsoon) season. Estuarine CH4 distributions were not driven by freshwater input but rather by tidal variations. Both N2O and CH4 concentrations were more variable during the wet season. We infer that the wet season dominates the variability of the N2O and CH4 concentrations and subsequent emissions from tropical estuaries. Thus, we speculate that any changes in the Southeast Asian monsoon system will lead to changes in the N2O and CH4 emissions from these systems. We also suggest that the ongoing cultivation of peat soil in Borneo is likely to increase N2O emissions from these estuaries, while the effect on CH4 remains uncertain.

scholarly journals Seasonal Distribution of Nutrients and Primary Productivity on the Eastern Continental Shelf of Venezuela as Influenced by the Orinoco River

2016 ◽  
Author(s):  
JAIME BONILLA ◽  
William James Senior
Keyword(s):  
Continental Shelf ◽  
Primary Productivity ◽  
Coastal Upwelling ◽  
Nutrient Status ◽  
Dry Season ◽  
Wet Season ◽  
Orinoco River ◽  
Carbon 14 ◽  
Low Salinity ◽  
The Caribbean

Nitrogenous nutrients, dissolved silicate, and salinity were measured in surface waters and shallowhydrocasts along similar cruise tracks during the spring (dry season) and fall (wet season) of 1988. Bothcruises transected the eastern Caribbean, transited the Gulf of Paria, ran parallel to the Orinoco Deltaand into the main channel of the Orinoco River. Trends in primary productivity were also measuredby daily carbon 14 incubations. In both seasons, samples covered the range from highly oligotrophicand transparent to highly productive and rich in biogenic and abiogenic particulate matter. Most of theOrinoco outflow appears to turn N to NW and remains in shallow waters off Venezuela andsurrounding Trinidad, permitting benthic regeneration of river-borne nutrients. However, the role ofthe Orinoco and associated low-salinity coastal waters in fertilizing large areas of the easternCaribbean basin, as suggested by satellite imagery, can be approximated crudely from the nutrientcomposition at Boca de Dragon, which is representative of the nutrient status of these waters as theyflow into deeper Caribbean waters. Additional nutrients may be supplied to the area primarily fromAmazon-derived water entering the Caribbean Basin further north, with some coastal upwelling alongthe continental shelf in the dry season.

Sign in / Sign up

Export Citation Format

Share Document