Long Term Nutrient and Chlorophyll a Dynamics across Long Island Sound and Impacts on Dissolved Oxygen Conditions within the Western Sound (1991-2019)
type: CreativeWork
description: Nitrogen overload, eutrophication, and hypoxia have been challenging and persistent water quality problems in Long Island Sound (LIS) over the past decades with major impacts on commercial industries, ecology, and recreational activities in the region. Recognizing these problems, the EPA enforced three phases of the Clean Water Act (CWA) to reduce nitrogen loads in an effort to improve this important estuary. This study examines how nitrogen (NH3, NOx & TDN), chlorophyll a (CHLA), and dissolved oxygen (DO) concentrations changed in LIS over the past 30 years, in response to water quality regulations as well as changes in environmental conditions (i.e., temperature and precipitation). To address this overarching goal, we used water quality monitoring data collected by the Connecticut Department of Energy and Environmental Protection (CTDEEP), precipitation data from National Oceanic and Atmospheric Administration (NOAA) and discharge data from United States Geological Survey (USGS) from 1991 to 2019. Three main questions are addressed: 1) How do nitrogen loads and CHLA concentrations vary across the Sound and how have they changed over the past 30 years in response to regulations? 2) How representative is the CTDEEP "spring chlorophyll bloom" of CHLA conditions across the Sound and how does it relate to the development of hypoxic conditions in summer months? 3) What factors might explain observed high anomalies in CHLA concentrations in certain years, despite ongoing efforts to control excessive nutrient pollution? These questions focus on changes in nitrogen and CHLA considering regulation timestamps, spring chlorophyll bloom effects on summer DO, and environmental factors that might explain occurrences of anomalous spring chlorophyll blooms despite nutrient regulations. Spatially from western to eastern LIS there was a decreasing longitudinal gradient for both CHLA and nutrients, and an increasing gradient for bottom DO concentrations, inferring that where nutrient…
abstract: Nitrogen overload, eutrophication, and hypoxia have been challenging and persistent water quality problems in Long Island Sound (LIS) over the past decades with major impacts on commercial industries, ecology, and recreational activities in the region. Recognizing these problems, the EPA enforced three phases of the Clean Water Act (CWA) to reduce nitrogen loads in an effort to improve this important estuary. This study examines how nitrogen (NH3, NOx & TDN), chlorophyll a (CHLA), and dissolved oxygen (DO) concentrations changed in LIS over the past 30 years, in response to water quality regulations as well as changes in environmental conditions (i.e., temperature and precipitation). To address this overarching goal, we used water quality monitoring data collected by the Connecticut Department of Energy and Environmental Protection (CTDEEP), precipitation data from National Oceanic and Atmospheric Administration (NOAA) and discharge data from United States Geological Survey (USGS) from 1991 to 2019. Three main questions are addressed: 1) How do nitrogen loads and CHLA concentrations vary across the Sound and how have they changed over the past 30 years in response to regulations? 2) How representative is the CTDEEP "spring chlorophyll bloom" of CHLA conditions across the Sound and how does it relate to the development of hypoxic conditions in summer months? 3) What factors might explain observed high anomalies in CHLA concentrations in certain years, despite ongoing efforts to control excessive nutrient pollution? These questions focus on changes in nitrogen and CHLA considering regulation timestamps, spring chlorophyll bloom effects on summer DO, and environmental factors that might explain occurrences of anomalous spring chlorophyll blooms despite nutrient regulations. Spatially from western to eastern LIS there was a decreasing longitudinal gradient for both CHLA and nutrients, and an increasing gradient for bottom DO concentrations, inferring that where nutrient…
author: Perreira, Sherry
keywords: Long Island, nitrogen, chlorophyll a, oxygen, precipitation, temperature, Biogeochemistry, Environmental Health, Environmental Health and Protection, Environmental Monitoring, Other Earth Sciences, Water Resource Management
date published: 2021-01-01T08:00:00Z
date modified: 2026-07-24T01:57:53Z
provider: City University of New York - City College
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: City University of New York - City College