Interactions of warming and altered nutrient load timing on the phenology of oxygen dynamics in Chesapeake Bay

JAWRA Journal of the American Water Resources Association, Journal Year: 2023, Volume and Issue: 59(2), P. 429 - 445

Published: Jan. 10, 2023

Abstract The effects of nutrient loading on estuaries are well studied, given the multitude negative water quality and ecosystem that have been attributed to excess nitrogen phosphorus. A current gap in this knowledge involves sensitivity seasonal cycles estuarine biogeochemical processes direct (warming) indirect influences (nutrient load timing) climate change. We used a coupled hydrologic–biogeochemical model investigate changes phenology hypoxia related Chesapeake Bay under three different hydrologic regimes. Shifts earlier timing during idealized simulations reduced overall annual hypoxic volume, resulting from discernable, but relatively small reductions phytoplankton biomass both sediment water‐column respiration. Simulated increases temperature caused an increase spring/early summer volume associated with elevated respiration rates, exhaustion organic matter early decrease late summer/fall due lowered Warming were larger than scenarios where warming was restricted spring when it applied all months year. These begin process understanding potential impacts future climatic key eutrophication.

Language: Английский

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Droughts and deluges: changes in river discharge and the carbonate chemistry of an urbanized temperate estuary

Frontiers in Marine Science, Journal Year: 2024, Volume and Issue: 11

Published: July 5, 2024

Long Island Sound (LIS) is a highly urbanized estuary that receives high inputs of nitrogen pollution leading to summertime hypoxia in the bottom waters its western region. Though LIS has been well-studied for decades, there paucity information regarding eutrophication-induced acidification due challenges obtaining high-precision observations marine carbonate system. In this work, we established time-series carbon dioxide (CO 2 ) system through measurements dissolved inorganic (DIC) and total alkalinity (TA) during thirteen sampling events between March 2020 August 2022. This time span captured both seasonal interannual variation, including contrast two historic drought years (2020 2022) one high-freshwater flow year with significant tropical storm activity (2021). Observations revealed reduced (WLIS) (minimum aragonite saturation state, Ω ar > 1.5) high-river discharge summer 2021, corresponding decrease DIC/TA ratio Housatonic River. By contrast, water DIC were higher summers 2022 (bottom = 0.9-1.0 0.85-0.9 respectively), more acidified conditions persistent undersaturation <1.0 1.1 2022, respectively). Increased river mitigated respiration-induced WLIS, likely combination decreased estuarine residence riverine DIC/TA. These results motivate future studies chemistry freshwater endmembers relation dynamics, consideration climate related shifts physical biological dynamics time.

Language: Английский

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Managed Nitrogen Load Decrease Reduces Chlorophyll and Hypoxia in Warming Temperate Urban Estuary

Frontiers in Marine Science, Journal Year: 2022, Volume and Issue: 9

Published: July 22, 2022

Many urban estuaries worldwide suffer from excess phytoplankton and hypoxia (low oxygen) due to high nutrient loads. A common water quality management strategy is require wastewater treatment facility upgrades. This case study examines Narragansett Bay, a warming temperate mid-latitude estuary with seasonal periodic hypoxia, during June through September 2005 2019. Within this period, numerous facilities were upgraded nitrogen removal over several years. The response of the bay more consistent “textbook” expectations for reduced chlorophyll than what was seen in many other systems—despite its complex coastline geometry, river inputs, widely-distributed facilities. River flow drives inter-annual variability increased load, density stratification, chlorophyll, wet Mean 2013-2019 bay-wide total load 34% less 2005-2012 mean, reduction about 10 6 kg yr-1, comparable range flow-driven variations. Chlorophyll Index Hypoxia event-based metrics applied high-frequency time series observations at eight sites quantify exceedances severe moderate thresholds. Relatively steady 33% 16% declines, thresholds, occurred 2007 declined markedly by 2009 2014 respectively, remained or near zero explains declines better physical processes including flow, tidal variations, winds, sea level differences, temperatures. 55% higher 2005-2019 mean would increase non-treatment loads an amount managed decrease, so future summers could partially reverse improvements. Long-term trends include 0.5°C decade -1 , which reduces oxygen saturation 0.1 mg l . rate likely lower bound temperature-driven decreases, because can also accelerate growth bacterial consumption. Without warming, decrease have curtailed effectively. Climate should be least as important eutrophication decline because, addition influences, long-term increases stratification.

Language: Английский

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The influences of phenology, spatial distribution, and nitrogen form on Long Island Sound phytoplankton biomass and taxonomic composition

Estuarine Coastal and Shelf Science, Journal Year: 2023, Volume and Issue: 292, P. 108451 - 108451

Published: July 26, 2023

Language: Английский

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High-frequency Dissolved Oxygen Dynamics in an Urban Estuary, the Long Island Sound

Estuaries and Coasts, Journal Year: 2023, Volume and Issue: 47(2), P. 415 - 430

Published: Oct. 8, 2023

Language: Английский

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