EarthTalk / From the Editors of E - The Environmental Magazine
Published 12:30 pm, Wednesday, August 17, 2011
Dear EarthTalk: What is a "dead zone" in an ocean or other body of water? -- Victor Paine, Tallahassee, Fla.
So-called dead zones are areas of large bodies of water -- typically in the ocean but also occasionally in lakes and even rivers -- that do not have enough oxygen to support marine life. The cause of such "hypoxic" (lacking oxygen) conditions is usually eutrophication, an increase in chemical nutrients in the water, leading to excessive blooms of algae that deplete underwater oxygen levels. Nitrogen and phosphorous from agricultural runoff are the primary culprits, but sewage, vehicular and industrial emissions and even natural factors also play a role in the development of dead zones.
Dead zones occur around the world, but primarily near areas where heavy agricultural and industrial activity spill nutrients into the water and compromise its quality accordingly. Some dead zones do occur naturally, but the prevalence of them since the 1970s -- when dead zones were detected in Chesapeake Bay off Maryland as well as in Scandinavia's Kattegat Strait, the mouth of the Baltic Sea, the Black Sea and the northern Adriatic -- hints at mankind's impact. A 2008 study found more than 400 dead zones worldwide, including in South America, China, Japan, southeast Australia and elsewhere.
Perhaps the most infamous U.S. dead zone is an 8,500 square mile swath (about the size of New Jersey) of the Gulf of Mexico, not far from where the nutrient-laden Mississippi River, which drains farms up and down the Midwest, lets out. Besides decimating the region's once teeming shrimp industry, low oxygen levels in the water there have led to reproductive problems for fish, leading to lack of spawning and low egg counts. Other notable U.S. dead zones today occur off the coasts of Oregon and Virginia.
Fortunately, dead zones are reversible if their causes are reduced or eliminated. For example, a huge dead zone in the Black Sea largely disappeared in the 1990s following the fall of the Soviet Union, after which there was a huge spike in the cost of chemical fertilizers throughout the region. And while this situation was largely unintentional, the lessons learned have not been lost on scientists, policy makers and the United Nations, which has been pushing to reduce industrial emissions in other areas around the globe where dead zones are a problem. To wit, efforts by countries along the Rhine River to reduce sewage and industrial emissions have reduced nitrogen levels in the North Sea's dead zone by upwards of 35 percent.
In the U.S., dead zones have also been reduced in the Hudson River and San Francisco Bay following clean-up efforts. Hypoxic conditions continue to plague the Gulf of Mexico, however, with matters made worse by pollution unleashed by Hurricane Katrina and the BP oil spill, as well as by a federal push to increase Midwest corn production, which effectively loads even more algae-inducing nutrients into the already overloaded system.
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The Mississippi Basin/Gulf of Mexico Water Nutrient Task Force, a coalition of federal, state and tribal agencies, has been busy monitoring the dead zone and recommending ways to reduce it since its formation in 1997. But with industrial and agricultural activity throughout Gulf and Midwestern states only increasing -- and Mother Nature not making the job any easier -- the task force has an uphill battle on its hands.
Contact: Mississippi Basin/Gulf of Mexico Water Nutrient Task Force, www.epa.gov/owow_keep/msbasin.
Dear EarthTalk: I am a retailer and have had customers ask whether the plastic bags in wine boxes are BPA free or not. What can I tell them? -- Chris Tod, via e-mail
The short answer is: "It depends." A fairly recent innovation in wine packaging, the so-called Bag-in-Box (BIB) dispenser makes use of a plastic bag with a nozzle surrounded by a corrugated cardboard box. The whole package sits easily on a shelf and usually features a built-in spout for easy pouring and resealing.
The main benefit is that each box can hold about four bottles-worth of wine, and the BIB technology prevents oxidation, keeping the wine fresh for up to six weeks after the seal has been broken initially.
Besides costing less to manufacture than glass bottles, the Bag-in-Box apparatus, invented by Scholle packaging a half century ago, weighs significantly less, stacks more efficiently (meaning more wine can go with each container load) and will not shatter if dropped. As such, they are easier to transport, which keeps costs down and reduces the carbon footprint of the entire distribution process.
While U.S. wine buyers traditionally have viewed wine in a box as cheap and unsavory, several American and European wineries are working to turn that view around by putting out award-winning vintages by the box. Eco-conscious yet no less discriminating wine consumers are helping to drive the growing demand for boxed wines in the U.S., which currently command about 10 percent of U.S. supermarket wine sales.
But boxed wine may have an environmental dark side: Some of the plastic bags inside the boxes contain Bisphenol-A (BPA), a synthetic chemical that has been in use for four decades to strengthen plastic food containers and other items but recently has been linked to a range of human health problems. "A growing amount of scientific research has linked BPA exposure to altered development of the brain and behavioral changes, a predisposition to prostate and breast cancer, reproductive harm, diabetes, obesity and cardiovascular disease," reported the non-profit Natural Resources Defense Council.
The bags are made out of No. 7 plastic, a catchall category typically containing mixed types of plastic ("polycarbonate"), combined for various practical reasons. As more and more research comes to light, many environmentalists and public health advocates are warning consumers to avoid storing any food or drinks in containers made out of No. 7 plastic, as there is likelihood that BPA could be part of the mix.
Most wineries offering boxed wines make it clear if their plastic bags do not contain BPA. For one, Scholle Packaging, inventors of the BIB system and one of the largest wine box manufacturers, uses only BPA-free No. 7 plastic in their bags. Perini, Campo Largo, Bota Box and many other box wines come in BPA-free packaging.
The simple way to know is to read the labels when you're wine shopping.
Also, don't think that by avoiding boxed wine you are necessarily avoiding BPA. Researchers have found that the plastic stoppers so many of us use to cap an unfinished bottle, not to mention the lining of concrete vats used to store wine at many wineries, contain and can leach BPA into your glass. That's not to say that all wine contains BPA; quite the contrary, in fact, as most bottled wine still never comes into contact with plastic and as such does not carry any BPA-stigma. Regardless, the more you know, the safer you can be -- so that the worst thing you get from your wine is a hangover.
EarthTalk is by Roddy Scheer and Doug Moss of E - The Environmental Magazine (www.emagazine.com). Send questions to: email@example.com.