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Chapter 1: Introduction
In the United States, where tourism is the largest industry, employer, and foreign revenue earner, coastal states earn 85% of all U.S. tourism revenues.[i] Besides being vital to the American economy, beaches are also varied and rich ecosystems. They are home to not only a number of different plant and animal species but also serve as fertile breeding grounds. Beneath the tranquil veneer of sand and surf is an ever-changing community of flora and fauna striving to maintain their habitats.
Fig. 1. 2003 Coastal County Population (Source: U.S. Census Bureau)[ii]
Coastal counties have become increasingly populated and are among the most crowded and developed in the nation today. In 2003, over 153 million Americans lived in the 673 coastal counties along the Atlantic and Pacific Oceans, Gulf of Mexico, and Great Lakes (see Figure 1), representing over 53 % of the total U.S. population.[iii]
An unfortunate consequence of this development has been the slow deterioration of these beaches, as population densities in coastal counties increase with each year. Coastal counties (excluding Alaska) average 300 persons per square mile, much higher than the national average of 98 persons per square mile.[iv] A study found that the number of closings and advisories at U.S. oceans and Great Lakes beaches in 2003 rose 51% from 2002.[v] While beachgoers are just beginning to understand traditional beach issues, such as erosion and water pollution, sand contamination is an important emerging issue. Scientists are voicing concern and raising questions regarding sand-borne indicator bacteria as a source of beach pollution.
About Beaches
How are beaches formed?
Over millions of years, sand and gravel from weathered rocks and other eroded surfaces are washed to sea by streams and rivers. Most sediment is suspended in seawater and is carried to the shoreline by two separate processes known in combination as littoral drift.[vi] In the first process, the long shore current flowing parallel to the shore carries this sedimentary material along the coast. This parallel flow is created by the action of waves breaking at an angle on the shore. Long shore transport can deliver up to a million cubic yards of sediment annually to a single beach.[vii] The second process involves the deposition of sand on shore by oscillating waves moving in a direction perpendicular to the shore. As the waves alternatively crash into and recede from the shore, sand is progressively pushed along the beach edge, resulting in the formation of a beach.
What are healthy and sick beaches?
In addition to the presence or absence of pollution, there are other factors that may affect the health of a beach. For instance, researchers in New Zealand concluded that the rate at which a beach is able to dry out may be indicative of its potential health impacts on humans and depends on the slope of the beach.[viii] Figure 2 compares a steep beach with a flat beach. With the water table being low in a steep beach, hydrostatic pressure is high and this enables the water to flow more quickly through the sand. These researchers suggest that this helps the beach to dry out faster and makes it less prone to bacteria contamination.
On a low-sloped beach however, the water takes more time to reach the sea, thus extending the drying out period. Under certain conditions such a beach will be more prone to erosion, especially during a major storm event.
Fig. 2. Healthy and sick beaches[ix]
One sign of a sick beach is the presence of crusting bacteria. On a sick beach polluted by fine particles or bacteria, there are not enough air channels and pockets available to let air replace the lost water. As the moisture and wetness evaporate from the drying sand, the subsequent vacuum that builds up pulls up the water table. The absence of air causes the water with solutes to rush in and fill up the vacuum. This action results in the formation of a crust that may contain high levels of bacteria and salt, causing the sand grains to cake together. According to these researchers, the presence of crusting bacteria may indicate a sickly beach and a potential health hazard.
Traditional Environmental Problems at Beaches
Beach Litter
While most Americans take care to enjoy our beaches respectfully, marine debris continues to be a problem for our coasts. In 2003, 450,000 volunteers picked up 7.6 million pounds of trash from 16,250 miles on shore and under water.[x] Despite repeated warnings on the destruction beach litter can cause to the surrounding flora and fauna, many continue to think of beaches as convenient trash cans and ashtrays.
Water Quality
Water quality problems have long plagued our nation’s coasts. With increasing crowds, most beaches now suffer from the presence of fecal coliforms, a bacterial indicator for human pathogens that may be present in the water. As overextended health departments strive to put adequate water monitoring programs in place, there is still a great deal of debate among the scientific community regarding the best possible way to keep beachgoers safe and healthy. The main sources of contamination for recreational waters are sewage overflows, agricultural and industrial discharges, storm water runoffs, the presence of birds and animals, and the beach users themselves.
How can a beachgoer benefit from this report?
This report is meant to enhance the science literacy of the beach going public about the state of our beaches today. The report examines the science of bacteria contamination in beach sands. As more studies reveal, our focus on water quality may have caused us to overlook the possibility of contaminated sand. Bacteria do exist in sand, and in some cases, survive better in sand than in water. Preliminary studies suggest that sand may actually serve as a reservoir for fecal bacteria and could possibly be a source of contamination to water. However, as this report goes on to discuss, only further research will reveal the true nature of the relationship between sand and bacteria.
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[i] National Oceanic and Atmospheric Administration, “Ocean Facts on Coastal Tourism” <http://www.yoto98.noaa.gov/facts/tourism.htm> (Accessed February, 2005).
[ii] Kristen Crosset et al., “Population Trends Along the Coastal United States 1998 – 2008,” a report for the National Oceanic and Atmospheric Administration. <http://www.oceanservice.noaa.gov/programs/mb/pdfs/coastal_pop_trends_complete.pdf>, September 2004.
[iii] Ibid.
[iv] Ibid.
[v] Mark Dorfman, “Testing the Waters 2003: A Guide to Water Quality at Vacation Beaches,” a report for the Natural Resource Defense Council, <http://www.nrdc.org/water/oceans/ttw/titinx.asp>, (Accessed February, 2005).
[vi] Ohio Office of Coastal Management, “Beaches” <http://www.dnr.state.oh.us/coastal/science/beaches.htm> (Accessed February 2005).
[vii] California Coastal Commission “California Coastal Resource Guide,” <http://ceres.ca.gov/ceres/calweb/coastal/beaches.html,> (Accessed February, 2005).
[viii] Floor Anthoni, “SeaFriends” <http://www.seafriends.org.nz>, New Zealand (Accessed March, 2005).
[ix] Ibid.
[x] Oregon State Parks and Recreational Dept. “International Beach Cleanup,” <http://www.solv.org/programs/fall_beach_cleanup.asp> (Accessed February, 2005).
