you're reading...

Coastal Management

New York City’s poop is a source of greenhouse gas emissions. Now what?

Article: Brigham, B.A., J.A. Bird, A.R. Juhl, C.J. Zappa, A.D. Montero, and G.D. O’Mullan (2019). Anthropogenic inputs from a coastal megacity are linked to greenhouse gas concentrations in the surrounding estuary. Limn. Oceanogr. 00, 2019, 1-15. doi: 10.1002/lno.11200.

A recent study at the City University of New York (CUNY) has linked urban pollution in the Hudson River to enhanced greenhouse gas (GHG) emissions from the water to the air. Researchers urge for more studies to focus on the source locations of pollution to determine exactly how it is impacting local ecosystems and the ability of the estuary to absorb CO2 – also known as carbon cycling.

A brief history of pollution in the Hudson

Figure 1: The Hudson River Estuary: from New York City to Albany (image credit: NYS WRI)

The Native Americans of the Hudson Valley – primarily the Mohican and Lenape tribes – once called what is now the Hudson River the Mahicantuck, which loosely translates to “the river that flows two ways.” Long before Europeans arrived in the 1600s and settled along the banks of the Mahicantuck, the Natives had observed that the river ebbed and flowed with the tides, drawing the salty water of the Atlantic into and out of the estuary. This tidal pattern can mix fresh and brackish water together, cultivating a diverse coastal habitat for much of their fish bounty. During that era, oysters, sturgeon, striped bass, and herring were prevalent.

Fast forward to the early 1900s, and the Hudson had changed considerably. Near the flourishing coastal metropolis known as New York City, seas of garbage floated in the water. Fish populations had been suffocated by low oxygen. By 1927, the once booming oyster industry had all but reached its end after pollution had contaminated these filter-feeders. The situation escalated through the mid-20th century as the human population continued to grow, indiscriminately dumping industrial toxic waste and sewage into the once diverse and productive estuary.

Since the Clean Water Act was enacted in 1972, the condition of the Hudson River has vastly improved. While the oyster population remains inedible, oyster restoration efforts are starting to look promising. Still, pollution remains a big problem for the Hudson River Estuary (HRE). Billions of gallons of sewage are deposited at depth every year, and the accumulation of chemicals by factory dumping in the last century is still detectable in the river’s food web and sediments.

Monitoring the river that flows two ways

In this study, researchers measured concentrations of greenhouse gases in the surface waters of the HRE at midchannel sites as well as in surrounding tributaries (streams flowing into the larger river) and embayments (coastal indentations) that supply freshwater to the main channel (see Fig. 1).

A total of 31 sites were measured from NYC to Albany in 2013 and 2014, mainly by the riverkeeper patrol boat, R. Ian Fletcher, during its monthly water quality surveys. Surface waters were pumped onboard and a number of sensors were used to record concentrations of carbon (CO2), methane (CH4), nitrogen, oxygen, chlorophyll-a (a pigment emitted by photosynthetic algae), and enterococci (bacteria that serve as a poop indicator in water).

With the help of salinity measurements, the researchers identified the salt concentrations that characterized different regions of the estuary. Water temperatures determined the amount of CO2 that could be stored in the water, and wind speeds informed the calculated rate at which gases were transferred between the air and water.

How polluted is the Hudson today?

Perhaps unsurprisingly, the researchers found elevated levels of CO2 and CH4 in the surface waters near urban tributaries, where inputs of carbon and nitrogen were high compared to the middle of the channel. CH4 concentrations in general were highest in urban areas, especially around NYC. At about 99% of the sites, GHG concentrations in water exceeded those of the overlying air, meaning that water was a source of GHGs to the atmosphere. GHG emissions (i.e., gas transfer from the water to the air) were also influenced by the winds in each region, which typically cause stronger air-sea gas exchange at higher wind speeds.

The variations in CO2 and CH4 levels were largely explained by oxygen, enterococci, and chlorophyll-a levels, especially in salty waters, which indicated that these elevated GHGs were the result of urban wastewater input from about 50 sewage delivery sites in nearby tributaries and embayments. In contrast, GHGs in Albany were explained by different parameters – namely, oxygen saturation, river discharge, and temperature – and exhibited the lowest CO2 concentrations of all of the regions. This result demonstrated that conditions can vary drastically along a single estuary, emphasizing the need to carry out continued studies  to understand the role different urban estuaries might play in carbon cycling.

Estuaries: carbon sources, carbon sinks

Figure 2: The Statue of Liberty surrounded by the mouth of the Hudson Bay on the Lower East Side of Manhattan. Since 1984, the Hudson River has been a Superfund site in an effort to curb pollution.  (image credit: SBA73, Flickr)

While many coastal habitats like salt marshes and mangroves are known to capture carbon from the atmosphere, urban estuaries like the HRE usually do the opposite. Such estuaries are abundant in nutrients from sewage and river runoff, allowing bacteria to multiply, emit carbon dioxide, deplete oxygen, and spread toxins. This can make conditions nearly unlivable for other organisms and potentially cause harmful algal blooms. As such, it is vital to monitor the impact of anthropogenic inputs on ecosystems and carbon cycling in similar urban estuaries.

Carbon cycling – which influences climate by regulating the amount of carbon dioxide present in the air – is driven primarily by differences in carbon concentrations between the ocean and atmosphere. The role of coastal regions and estuaries in the global carbon cycle is still unclear, but studies like these are essential to providing the data needed to inform local communities as well as climate scientists.


No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 9 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 9 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 12 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com