Shub Nitrogen v12

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    Nitrogen in Coastal Waters:

    Prepared by Janna Shub for The Nature Conservancy, January 2015

    Executive Summary

    Abstract: Nutrient pollution in water bodies is a topic of concern and debate to citizens and lawmakers. To retrieve reliable and up to date knowledge of this topic, this paper summarizes recent peer-reviewed scientific literature while focusing on nitrogen. This paper describes how human-derived nitrogen affects habitats and habitants of coastal ecosystems in Southern New England (NY, CT, RI and Cape Cod in MA). Major coastal habitats of concern include tidal marshes, seagrass meadows and shellfish riffs. Special attention is given to shellfish, as this is a major commercial commodity in the region. Special attention is also given to onsite wastewater treatment systems as those contribute significant nitrogen concentrations to adjacent coastal ecosystems. This paper also briefly summarizes the progress that has been made in the US to regulate nitrogen in order to diminish nitrogen adverse effects on aquatic coastal environments. Major adverse effects covered here include local acidification, low dissolved oxygen concentrations, elimination of seagrass meadows and conversion of tidal marshes into mudflats. This paper also touches on different nitrogen chemical forms and nitrogen coupling with carbon and phosphorus. The overall goal of this paper is to deepen our understanding of nitrogen driven changes, direct and indirect, in coastal environments. Hopefully this literature survey will stimulate discussion and effective action to reduce and ultimately eliminate detrimental nitrogen effects on coastal habitats.

    Key research findings: Loading coastal waters with excessive nitrogen causes the following major detrimental effects on coastal ecosystems:

    Increased plant and bacteria biomass that release CO2 into water during their decomposition, resulting in local increase in acidification. Local acidification reduces survival rates for many organisms, especially young ones. Shellfish is particularly vulnerable to ocean acidification because it needs to extract calcium from seawater.

    Blooming of algae, resulting in reduced light and elimination of seagrass meadows. Seagrass meadows are the habitat for scallops, and provide nutrients for various fish and wildlife.

    Excessive nitrogen stimulates growth of toxic algae and toxic cyanobacteria, resulting in release of toxins into the water column.

    Increased plant and bacteria biomass, which consume dissolved oxygen during respiration and decomposition, resulting in decreased dissolved oxygen levels. Low dissolved oxygen conditions may kill oxygen dependent organisms, especially immobile bottom organisms and young organisms.

    In tidal marshes, excessive nitrogen affects vegetation, eventually causing collapse of creek banks and thereby formation of mudflats.

    Healthy and robust tidal marshes, seagrass meadows, shellfish cliffs and benthic communities support wildlife, fisheries, protect the coast from storm surges and inspire humans. Degradation of coastal habitats undermines these basic environmental (food, shelter and spirituality) services that nature offers the human society.

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    Table of Content Executive Summary ....................................................................................................................................... 1

    Table of Content ........................................................................................................................................... 2

    List of Figures ................................................................................................................................................ 3

    List of Tables ................................................................................................................................................. 3

    Introduction .................................................................................................................................................. 4

    Overview of Nitrogen Effects ........................................................................................................................ 7

    Monitoring and Regulating Nitrogen ............................................................................................................ 8

    Sampling nitrogen ................................................................................................................................... 10

    Coupling with Phosphorus .......................................................................................................................... 11

    In the Water Column ................................................................................................................................... 11

    Organic nitrogen ..................................................................................................................................... 12

    Particulate nitrogen ................................................................................................................................ 13

    Hypoxia ....................................................................................................................................................... 14

    Acidification ................................................................................................................................................ 16

    Acidification effects on aquatic organisms ............................................................................................. 16

    Coastal acidification Northeastern US ................................................................................................. 18

    Tidal Marshes .............................................................................................................................................. 19

    Seagrass Meadows ...................................................................................................................................... 21

    Shellfish ....................................................................................................................................................... 23

    Oyster reefs ............................................................................................................................................. 23

    Scallops ................................................................................................................................................... 24

    Bacterial World ........................................................................................................................................... 25

    Trawling and muddy coastal seafloor ..................................................................................................... 26

    Toxic cyanobacteria ................................................................................................................................ 29

    Onsite Wastewater Treatment (OWT) Systems .......................................................................................... 31

    Spotlight on nutrient pollution in coastal groundwater ......................................................................... 32

    Innovative nitrogen removal systems ..................................................................................................... 33

    Permeability, redox and nutrient transport in groundwater .................................................................. 35

    Closing Comments ...................................................................................................................................... 36

    Bibliography ................................................................................................................................................ 37

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    List of Figures Figure 1: Historic trends in nitrogen concentrations in northeast estuaries (Roman et al., 2000). ............. 5

    Figure 2: Nitrogen delivery to the estuary (Hauxwell and Valiela, 2004). .................................................... 7

    Figure 3: Decomposition and respiration process ...................................................................................... 15

    Figure 4: Ocean acidification. ...................................................................................................................... 16

    Figure 5: Nutrient and light limitations for primary producers (Burkholder et al., 2007). ......................... 22

    Figure 6: Lifecycle of Ballots scallop and acidification effects (Richards et al., 2015) ............................... 24

    Figure 7: Nitrogen cycle in the ocean . .................................................................................................... 25

    Figure 8: Trawling effects22. ........................................................................................................................ 27

    Figure 9: Sediment oxygenation. ................................................................................................................ 28

    Figure 10: Effluent total nitrogen concentrations in field trials (Oakley et al., 2010) ................................ 34

    Figure 11: Nitrogen removal by OWT innovative technologies (Heufelder et al., 2007). .......................... 35

    List of Tables Table 1: EPA approved nitrogen numeric criteria in estuarine water bodies.............................................10

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    Introduction Nutrients tend to be limiting resources in big water bodies. In coastal ecosystems such as bays, lagoons

    and estuaries nitrogen is usually t