Bisphenol A (BPA) and the Environment

Info: "Bisphenol A: Information Sheet." E Safety

Bisphenol A (referred to as BPA) is a chemical used in the manufacturing of polycarbonate plastics and epoxy resins.  Needless to say, huge amounts of BPA are used every year around the world and releases into the environment are inevitable.  Some environmental exposure comes from actual releases from industrial effluents and biological wastewater treatment plants.  Dust particulates and vaporized BPA are also produced, but their impacts are minimal (the vapor is rapidly degraded by sunlight).  Based on the properties of BPA, about 50% of BPA in the environment has the potential to bind to soils and sediments and the rest remains in the water column.  Other sources of BPA in the environment include the adsorption from plastic in the marine environment or leachate from landfills.  As more plastic is thrown away or discarded of in nature, more and more BPA is filtered into the environment.  This is a potential hazard because BPA has been proven to affect different organisms' reproduction and estrogen cycles. 

Floating Island of Plastic



Affects of Aerosolized Brevetoxins from Florida Red Tide on Healthy Workers

Article: Backer, Lorraine C. et al. "Occupational Exposure to Aerosolized Brevetoxins during Florida Red Tide Events: Effects on a Healthy Worker Population." Environmental Health Perspectives 113.5 (2005).

This article covers a study conducted to see how the aerosolized brevetoxins released by the Karenia brevis dinoflagellates in a Red Tide affect a healthy person's respiratory and pulmonary health.  The effects of the brevetoxins on humans after being consumed in shellfish tissue has been well documented in the past, but the effects from environmental exposures, such as being in aerosol form were uncertain.  The studied focused on 28 full-time lifegaurds along Florida's gulf coast because they were healthy and their beaches did not close during red tide events -- causing them to work onshore and even stay in the lifegaurd towers at least 6 hours every shift.  An occupational, epidemiological study was constructed to determine the respiratory effects of a red tide and if mild outdoor exercise during a red tide decreased pulmonary performance or increased self-reported symptoms. 

Red Tide

The results of the study showed an increase in self-reported upper respiratory problems and headaches during exposure to the brevetoxins from the red tide (but not an increase in lower repsiratory problems).  Pulmonary effects were present, but not significant. 

El Nino and La Nina

Article: Philander, S.G.H. "El Nino and La Nina." Journal of the Atmospheric Sciences 42.23 (1985).

This article provided me with alot of technical information on how El Nino and La Nina work together and make up the Southern Oscillation.  The term El Nino refers to a period in which the sea surface water temperature is HIGHER than normal in the eastern Pacific Ocean.  This period accompanied by a high air surface pressure in the west Pacific.  As El Nino's complement, La Nina refers to a period in which the sea surface water temperature is LOWER than normal in the east Pacific.  La Nina also includes a low air surface pressure in the western Pacific.  The atmospheric components of these cycles is known as the Southern Oscillation.  Meterologic and oceanographic characteristics, including pressure, temperature, precipitation, wind stress and sea level are all affected by El Nino and La Nina.  Their individual effects are highly complementary of one another.  The picture below depicts the drastic differences between water temperature during an El Nino event and a La Nina event.  El Nino is shown in the top left globe, while La Nina is pictured in the bottom right globe. 



Bathymetric Maps and Hypsographic Curves

Bathymetric maps are maps that represent underwater depths (in oceans, seas, or lakes) at specific coordinates as topographic maps show elevation at specific locations on the Earth's surface.  Most bathymetric maps show isobaths (lines of equal depths) as contours for the body of water.  This gives a person an idea of how the basin of the body of water is shaped. 

Similar to bathymetric maps, hypsographic curves show a relationship between the Earth's surface and water depth (or elevation).  However, unlike bathymetric maps, a hypsographic curve shows a relationship between elevation or underwater depth and the amount of Earth's surface covered.  For example, if a hypsographic curve existed for a lake of interest, and one wanted to know what the surface area of the lake would be if the water level dropped to a specific depth, say 10 feet, the curve could be used. 

In class, we created a hypsographic curve from a given bathymetric map of a lake ranging from 0-11 feet in depth.  Using a square cutout of the scale (representing 10,000 square meters) and precise cutouts of the lake following each depth contour, the area at each depth was determined through a weight-area relationship (0.103 grams = 10,000 square meters).  Next, the hypsographic curve was created in Excel by plotting the areas on the x-axis versus the depths (in reverse order with 0 meters at the top of the graph) on the y-axis.  The resulting curve is shown below in Figure 1.

Another useful curve shows lake volume as a function of water depth.  This sort of graph can easily be created from a hypsographic curve.  First, the change in depth between two data points (surface to 1 meter down, for example) must be determined.  Then the recorded surface areas at the two points can be averaged and multipled by the change in depth, resulting in a volume in cubic meters.  The midpoints for each change in depth are the plotted on the y-axis in reverse order versus the volumes on the x-axis.  The volume vs. depth graph for the bathymetric map given in class is shown below in Figure 2.

Using the volume graph, one can also determine the total volume of a body of water.  To do so, the total volumes at each depth range from surface to the deepest point are added together.  This is a very easy calculation is the data is set up in Excel.  The total volume of the lake used in class was found to be 820,728 cubic meters.