Hudson River notes and figs.pdf

Hudson River notes: Source (start): Lake Tear of the Clouds on Mount Marcy (5344 feet elev) in the Adirondack Mountains Mouth (end): The Battery (NY Harbor) The Upper Hudson River: The river flows down from Lake Tear of the Clouds, 160 miles to the Federal Dam at Troy. The river drops more than 4...

Hudson River notes: Source (start): Lake Tear of the Clouds on Mount Marcy (5344 feet elev) in the Adirondack Mountains Mouth (end): The Battery (NY Harbor) The Upper Hudson River: The river flows down from Lake Tear of the Clouds, 160 miles to the Federal Dam at Troy. The river drops more than 4,300 feet in elevation between these two points The Lower Hudson River: Troy Dam is the demarcation between the upper and lower Hudson River. Below the dam, the river's elevation drops only a few feet over the rest of its 153 mile course to New York City. The Hudson Estuary: Estuaries are bodies of water and their surrounding coastal habitats - where rivers meet the sea. Estuaries are tidal because of the connection to the sea. Estuaries have unique plant and animal communities because their waters are brackish—a mixture of fresh water draining from the land and salty seawater. The lower Hudson River estuary is the portion of the Hudson River extending from the Battery at the southern tip of Manhattan north to Stony Point at the northern end of Haverstraw Bay. Watershed: All the land that drains to a body of water. Numerous small tributary streams contribute water to the Hudson, and these streams collect their water from an area of land that includes most of eastern NY state and some of VT, CT, NJ and Mass (13,326 square miles) Climate in the Hudson River watershed: cold winters, warm summers, precip evenly distributed throughout the year Factors affecting climate: -Elevation (lower pressure at higher altitudes causes lower temperature) -Latitude (warmer at equator because solar energy is more intense at the equator and diminishes toward the poles) -Proximity to ocean (less diurnal and seasonal temp variation due to moist air; and increased precip due to more moisture avail from nearby ocean = maritime) Moist air gains and loses heat more slowly that dry air and therefore land near water has a more moderate climate: Specific heat capacity of a substance is the amount of heat per unit mass required to raise the temperature by one degree Celsius. Water has a very high specific heat capacity: 4.18 J/g ° C That means it takes 4.18 joules of heat energy to raise one gram of water one degree Celsius. Dry air (at temps between 0 and 30 ° C ) has a specific heat capacity of 1.00 J/g ° C Water vapor (moist air) has a specific hear capacity of 2.00 J/g ° C. Dry air heats up and cools down more quickly than moist air. This is what we mean when we say that water moderates Earth's climate by buffering large fluctuations in temperature. Use specific heat equation to show that water does not heat up as much as air when you add 250 J of heat to each substance. q = mc∆T Tides and currents: The Hudson Estuary is tidal because it is connected to the Atlantic ocean. Since it is tidal, the river flows both ways. The tides reach all the way to the Federal Dam at Troy. Flood: ocean water flows up the river (N) Ebb: ocean water flows back out to sea (S) Slack: the point when the current is switching between flood and ebb Knot is unit used to measure the speed of the current. 1 knot = 1.15 miles per hour The gravitational pull by the moon and the sun on the oceans causes the tides. Two high tides and two low tides occur each day. Why does a given location on Earth experience two high tides and two low tides per 24 hour period?: Earth makes one complete rotation on its axis in 24 hours. As Earth rotates on its axis, a given location is lined up with the moon twice and is perpendicular to the moon twice in that 24 hour period. High tides occur at a given location when that location is lined up with the moon. This alignment causes a strong gravitational pull. Low tides occur when the location is perpendicular to the moon. This alignment causes a weaker gravitational pull. So, at a given location, 2 high tides and 2 low tides occur in 24 hours. While the Earth rotates on its axis, making one full rotation in 24 hours, the moon is revolving around the Earth, taking approximately one month to do so. See animation at: http://www.sumanasinc.com/webcontent/animations/content/moonphase.html MONTHLY CHANGES IN THE TIDE: Spring tides: Sun pulls parallel w/moon; higher than normal tides during full and new moons http://oceanservice.noaa.gov/education/kits/tides/media/supp_tide06a.html Neap tides: Sun pulls @ 90° to moon; lower than normal tides during quarter moons Salinity (concentration of salt is measured as follows: one gram of salt per 1000 g of water = PPT or PSU). 1 L of water weighs 1 kg or 1000 g so PSU, PPT and g/L are all equivalent. Since the Hudson is tidal, parts of it are salty. The mixing of the fresh and salt water causes “brackish” conditions. The Hudson’s salinity varies from about 2 to 20 g/L. Compare this to the average salinity of the ocean which is about 35 g/L (range is 32-37 g/L). Why does salinity in the Hudson vary from 2 – 20 g/L? Current conditions in the river: http://hudson.dl.stevens-tech.edu/maritimeforecast/PRESENT/ Stratification: Density of water varies with salinity and temperature. Density = mass/volume (units are in g/ml) Density of water at 39°F (4°C) is 1 g/ml. Density of salt water is > 1g/ml. So, saltwater is more dense than freshwater. If saltwater meets freshwater, the saltwater would become the bottom layer and the freshwater would be the top layer. This layering is called salt stratification or “salt wedge”. Cold water more dense than warm water. If cold water meets warm water, the cold water would be the bottom layer. This layering is called thermal stratification. The HR does not routinely stratify thermally. Salt front: When the tide comes in and floods up the river, the leading edge of the salt water is called the “salt front”. The salt front is defined as 100 mg/L chloride concentration. 100 mg/L same as 0.1 g/L = PSU = PPT http://ny.water.usgs.gov/projects/dialer_plots/saltfront.html Location of salt front in river miles upstream from mouth: 10/14-09/15: numbers in the table are river miles above The Battery, NYC at slack tide: OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP MEAN --- --- 50.7 48.7 62.1 57.6 36.1 57.9 49.8 --- 67.6 --- MAX --- --- 61.3 64.8 68.8 67.5 74.1 61.5 62.7 --- 73.1 --- MIN --- --- 36.3 33.0 54.9 42.2 19.4 54.9 37.2 --- 61.3 --- MED --- --- 50.7 54.3 61.6 60.6 34.7 57.9 47.8 --- 67.5 --- Dissolved Oxygen (DO) in mg/L: In the Hudson River water, oxygen ranges from 8 – 14 mg/L. Air always has 21% oxygen. Oxygen content of water is critical for an aquatic organism’s survival. Oxygen content of water in the Hudson is largely controlled by 1: photosynthesis and respiration 2: exchange with the atmosphere Decades ago, the Hudson frequently had inadequate amounts (4 mg/L or less) of DO. Now it is much better because of the Clean Water Act of 1972. The NYS Water Quality Standard for dissolved oxygen is 4 mg/L for most of the Hudson River Estuary. Cold water holds more oxygen than warm water. (why: warm water molecules are more active and push out gases including oxygen.) Suspended sediment in the Hudson River DIM DOM PIM POM: DOM (Dissolved Organic Matter): Comes from: watershed soils, decomposition in the river, pollution Roles: food for bacteria, can support food chain, can carry/transport non-water soluble pollutants. http://www.hrecos.org/index.php?option=com_content&view=article&id=119&Itemid=85 Pollution threats to an estuary: PROBLEM: In addition to nutrients, the water coming off the watershed also often brings with it all of the pollutants that were applied to the lands in the watershed like pesticides, petroleum products, etc. Over 13,000 square miles of land drains into the Hudson. Water Quality in The Lower Hudson Watershed: Water quality in the Lower Hudson Watershed varies widely and in influenced by a wide range of pollutants and sources. -municipal wastewater -combined sewer overflows (CSOs) -urban/stormwater runoff -industrial & agricultural activities -lawn pesticide and herbicide runoff Clean Water Act of 1972: http://www2.epa.gov/laws-regulations/summary-clean- water-act The Clean Water Act (CWA) establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters. Under the CWA, EPA has implemented pollution control programs such as setting wastewater standards for industry. Also set are water quality standards for all contaminants in surface waters. The CWA made it unlawful to discharge any pollutant from a point source* into navigable waters, unless a permit was obtained. One example is sewage. Funded the construction of sewage treatment plants under the construction grants program. Industrial, municipal, and other facilities must obtain permits if their discharges go directly to surface waters. *Point sources are discrete conveyances such as pipes or man-made ditches. Of what ecological value is an estuary? Habitats associated with estuaries, such as salt marshes and mangrove forests, act like enormous filters. As water flows through a salt marsh, marsh grasses and peat (a spongy matrix of live roots, decomposing organic material, and soil) filter pollutants such as herbicides, pesticides, and heavy metals out of the water, as well as excess sediments and nutrients. One reason that estuaries are such productive ecosystems is that the water filtering through them brings in nutrients from the surrounding watershed. These nutrients stimulate the food chain. Phytoplankton, zooplankton, fish, crabs, birds, terrapins… Estuaries and their surrounding wetlands are also buffer zones. They stabilize shorelines and protect coastal areas, inland habitats and human communities from floods and storm surges from hurricanes. When flooding does occur, estuaries often act like huge sponges, soaking up the excess water. Estuarine habitats also protect streams, river channels and coastal shores from excessive erosion caused by wind, water and ice. Ecological significance: regionally significant as a productive estuary regionally significant fish populations wintering and migratory birds primary nursery and overwintering area for striped bass home to several federally and state-listed species Food web in the Hudson: starts with the producers (plants) just like on land: phytoplankton! Shellfish species are abundant, including northern quahog, soft clam and eastern oyster; however, the waters are not certified for human consumption of shellfish. The predominant crustaceans include grass shrimp, sand shrimp, and blue crab. Early life stage blue crab larvae require high salinities and, therefore, this is a prime adult blue crab spawning region. Oysters are KEYSTONE SPECIES in the HR Estuary. Two major functions in the ecosystem: 1 Oysters are filter-feeders: They remove nutrients, algae, plankton, and/or pollutants from the water column, which contributes to cleaner, clearer water = positive impact on water quality. This supports the growth of other marine ecosystems that rely on light from the sun, like seagrass beds and other plant life. 2 Oysters are the only bivalves that build a reef: Natural oyster reefs are built by larval oysters attaching to adult live or dead oysters and creating a vertical structure into the water column. This structure provides habitat for many other marine organism. This increases the species richness and biodiversity of the region. (Oyster reefs can also provide shoreline protection.) Fish in the Hudson: Anadromous fish reproduces in fresh water but spends most of life in the sea. Ex: shad, striped bass, sturgeon, winter flounder, bay anchovy, hogchoker. Catadromous fish reproduces in salt water but lives in fresh water. Ex: American eel, weak fish, blue fish, pipe fish and others.