Anthropogenic nutrient loads and season variability drive high atmospheric N2O fluxes in a fragmented mangrove system

AbstractFragmented mangroves are generally ignored in N2O flux studies. Here we report observations over the course of a year from the Mangalavanam coastal wetland in Southern India. The wetland is a fragmented mangrove stand close to a large urban centre with high anthropogenic nitrogen inputs. The study found the wetland was a net source of N2O to the atmosphere with fluxes ranging between 17.5 to 117.9 µmol m−2 day−1 which equated to high N2O saturations of between 697 and 1794%. The average dissolved inorganic nitrogen inputs (80.1 ± 18.1 µmol L−1) and N2O emissions (59.2 ± 30.0 µmol m−2 day−1) were highest during the monsoon season when the rainfall and associated river water inputs and terrestrial runoff were highest. The variation in N2O dynamics was shown to be driven by the changes in rainfall, water column depth, salinity, dissolved oxygen, carbon, and substrate nitrogen. The study suggests that fragmented/minor mangrove ecosystems subject to high human nutrient inputs may be a significant component of the global N2O budget.

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Modeling and forecasting riverine dissolved inorganic nitrogen export using anthropogenic nitrogen inputs, hydroclimate, and land-use change

Journal of Hydrology ◽

10.1016/j.jhydrol.2014.05.024 ◽

2014 ◽

Vol 517 ◽

pp. 95-104 ◽

Cited By ~ 22

Author(s):

Hong Huang ◽

Dingjiang Chen ◽

Baifa Zhang ◽

Lingzao Zeng ◽

Randy A. Dahlgren

Keyword(s):

Land Use ◽

Land Use Change ◽

Inorganic Nitrogen ◽

Dissolved Inorganic Nitrogen ◽

Nitrogen Export ◽

Nitrogen Inputs ◽

Modeling And Forecasting ◽

Anthropogenic Nitrogen

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Anthropogenic nitrogen pollution in mangrove ecosystems along Dar es Salaam and Bagamoyo coasts in Tanzania

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2021.112415 ◽

2021 ◽

Vol 168 ◽

pp. 112415

Author(s):

Blandina R. Lugendo ◽

Ismael A. Kimirei

Keyword(s):

Dar Es Salaam ◽

Nitrogen Pollution ◽

Mangrove Ecosystems ◽

Anthropogenic Nitrogen

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Nutrient status and winter hardiness of red spruce foliage

Canadian Journal of Forest Research ◽

10.1139/x89-115 ◽

1989 ◽

Vol 19 (6) ◽

pp. 754-758 ◽

Cited By ~ 24

Author(s):

Richard M. Klein ◽

Timothy D. Perkins ◽

Helen L. Myers

Keyword(s):

Inorganic Nitrogen ◽

Sufficient Conditions ◽

Nutrient Status ◽

Cloud Water ◽

Winter Hardiness ◽

Red Spruce ◽

Anthropogenic Sources ◽

Freezing Injury ◽

Ion Leakage ◽

Anthropogenic Nitrogen

Increased ecosystem loading with inorganic nitrogen compounds derived from anthropogenic sources has been proposed to prolong vegetative growth of spruce, rendering them more susceptible to winter injury. Severely nutrient-deficient 4-year-old red spruce (Picearubens Sarg.) seedlings and adequately fertilized seedlings were provided with synthetic cloud water lacking or containing nitrate, ammonium, or both, for a full growing season, and then exposed to normal winter chilling. Needles from these seedlings were stressed at −25 or −30 °C, and freezing injury was measured as ion leakage. Cloud water condensates had no effect on hardiness of needles of either nutrient status. Initially nutrient-sufficient seedlings transferred to nutrient-deficient conditions also exhibited no change in hardiness. Severely nutrient-deficient seedlings had needles that were significantly more sensitive to winter injury than seedlings under nutrient-sufficient conditions. Improving the nutrient status of initially nitrogen-deficient seedlings reduced their sensitivity to freezing injury. Based upon experimental results and consideration of the amounts of inorganic nitrogen reaching upper-elevation conifer forests, there is no evidence to support the hypothesis that anthropogenic nitrogen supplies significantly reduce winter hardiness of spruce foliage. It is improbable that winter injury due to elevated anthropogenic nitrogen is a causal factor in contemporary forest decline.

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

Hydrology ◽

10.3390/hydrology8030123 ◽

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.

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

10.5194/bg-2021-321 ◽

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.

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Increasing nutrient inputs risk a surge of nitrous oxide emissions from global mangrove ecosystems

One Earth ◽

10.1016/j.oneear.2021.04.007 ◽

2021 ◽

Author(s):

Feng Mao ◽

Sami Ullah ◽

Steven M. Gorelick ◽

David M. Hannah ◽

Stefan Krause

Keyword(s):

Nitrous Oxide ◽

Nitrous Oxide Emissions ◽

Nutrient Inputs ◽

Mangrove Ecosystems

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

Water Science & Technology ◽

10.2166/wst.2000.0306 ◽

2000 ◽

Vol 42 (1-2) ◽

pp. 147-152 ◽

Cited By ~ 8

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).

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

Marine and Freshwater Research ◽

10.1071/mf08356 ◽

2009 ◽

Vol 60 (11) ◽

pp. 1123 ◽

Cited By ~ 40

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.

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