From
the Editors of E / The Environmental Magazine
THIS
WEEK'S COLUMN
Dear
EarthTalk: I know that large fish contain
a lot of mercury, but where does it come from? And what
are we doing to prevent this contamination?
—Alison Bronner, Atlanta, GA
Once
mercury gets into the marine food chain, mostly
from human industrial sources such as coal-fired
electricity generation, smelting and the incineration
of waste, it “bioaccumulates” in the
larger ocean predators like the bluefin tuna pictured
here.
Mercury
in the fish we like to eat is a big problem in the United
States and increasingly around the world. Mercury itself
is a naturally occurring element that is present throughout
the environment and in plants and animals. But human industrial
activity (such as coal-fired electricity generation, smelting
and the incineration of waste) ratchets up the amount
of airborne mercury which eventually finds its way into
lakes, rivers and the ocean, where it is gobbled up by
unsuspecting fish and other marine life.
Once
this mercury gets into the marine food chain, it “bioaccumulates”
in the larger predators. That’s why larger fish
are generally riskier to eat than smaller ones. Those
of us who eat too much mercury-laden fish can suffer from
a range of health maladies including reproductive troubles
and nervous system disorders. The U.S. Environmental Protection
Agency (EPA) reports that human fetuses exposed to mercury
before birth “may be at an increased risk of poor
performance on neurobehavioral tasks, such as those measuring
attention, fine motor function, language skills, visual-spatial
abilities and verbal memory.” Up to 10 percent of
American women of childbearing age carry enough mercury
in their bloodstreams to put their developing children
at increased risk for developmental problems.
In
partnership with the U.S. Food and Drug Administration,
the EPA issues determinations periodically in regard to
how much mercury is safe for consumers to ingest from
eating fish. State and tribal environmental authorities
and/or health departments issue fish consumption advisories
for water bodies in their respective jurisdictions based
on federal guidelines. The EPA consolidates these local
and regional advisories on its website, where concerned
consumers and fisher folk can click on a map of the states
to find out which advisories may be in effect in their
area.
As
for which fish to avoid, the non-profit Environmental
Defense Fund (EDF), which runs the handy Seafood Selector
website, reports that people with mercury concerns should
steer clear of bluefin tuna, walleye, king mackerel and
marlin. Bluefish, shark, swordfish, wild sturgeon, opah
and bigeye tuna carry a proportionately large mercury
burden as well. Also of concern, but to a slightly lesser
extent, are orange roughy, Chilean sea bass, blue crab,
lingcod, Spanish mackerel, spotted seatrout, wahoo, grouper,
snapper, halibut, tile fish, rock fish and sable fish,
as well as blackfin, albacore and yellowfin tuna.
Beyond
what individuals can do to avoid mercury, the U.S. government
and states have begun working together to reduce mercury
emissions from power plants. Earlier this year the EPA
proposed new “Mercury and Air Toxics Standards”
regulating mercury emissions from utilities across the
country, with the goal of reducing the amount of mercury
emitted by coal burning by 91 percent by 2016. Elsewhere,
representatives from 140 countries signed on to reduce
global mercury pollution at a 2009 United Nations Environment
Program’s Governing Council meeting in Nairobi,
Kenya. The agreement commits signatory countries—including
the U.S.—to cutting back on the use and emission
of mercury. A legally binding treaty mandating just how
much each country will have to cut back mercury emissions
takes hold in 2013.
Dear
EarthTalk:Is it true that gas furnaces cost
less to run and burn cleaner than their oil counterparts?
If I make the switch, how long should I expect it to take
for me to pay back my initial investment? And are there
any greener options I should consider?
—Veronica Austin, Boston, MA
Natural
gas is both cheaper and has lower carbon emissions
than oil but its green-friendliness is overstated.
It is true
that natural gas has been a more affordable heat source
than oil for Americans in recent years. The federal Energy
Information Administration (EIA) reports that the average
American homeowner will pay only about $732 to heat their
home with gas this winter season (October 1 through March
31) versus a whopping $2,535 for oil heat. While the price
of natural gas has remained relatively stable in the last
few years, oil prices have been high and rising thanks
in large part to continued unrest in Middle Eastern oil
producing countries. Just two years ago the average winter
home oil heating bill was $1,752.
While oil prices
are likely to remain high and volatile in the foreseeable
future, most energy analysts agree that pricing for natural
gas, much of which is still derived domestically, is not
expected to rise or fluctuate substantially in the U.S.
any time soon. According to EIA economist and forecaster
Neil Gamson, the U.S. already has a glut of natural gas
and expects even more domestic production to come online
soon as drillers are set to open up the Marcellus Shale
in Pennsylvania and New York to more gas development.
Only about
eight percent of U.S. homes are on oil heat today. Most
are in the Northeastern U.S. and were built back in the
day when oil was the cheapest way to keep toasty through
the long winters. Many utilities have since put gas lines
into neighborhoods that didn’t have them in the
past, opening the door for homeowners to switch out old
inefficient oil furnaces for more efficient gas units.
The federal
government’s 30 percent tax credit (capped at $500)
for upgrading to a high efficiency furnace expires at
the end of 2011 but will likely be extended in one form
or another into 2012. In the meantime, some states, municipalities
and utilities offer their own incentives and low-interest
loans on upgraded, high-efficiency furnaces. Check what’s
available in your area via a zip code or map-based search
online at the website of the Database of State Incentives
for Renewables and Efficiency (DSIRE). Regardless of incentives,
gas furnaces tend to cost less than their oil counterparts
anyway, but installing one from scratch will incur an
extra thousand dollars or two to run a gas line to it
from the street. If natural gas continues to be substantially
cheaper than oil, the fuel cost savings alone would pay
back the up-front equipment and infrastructure investment
within five years in most cases.
Environmentally
speaking, gas has lower carbon emissions than oil, but
hydraulic fracturing (“fracking”)—the
highly controversial gas extraction method increasingly
employed today (drillers inject water, sand and chemicals
at high pressure underground to break through rock and
access the natural gas)—takes a heavy toll on surrounding
ecosystems and regional water quality. Most environmental
advocates would rather see people transition to truly
renewable heating sources like geothermal or solar. If
you’re going to the cost and trouble of switching
out an oil furnace for something new, a geothermal heat
pump may cost more ($7,500 and up) than a new gas heating
system but will save big bucks and emissions in the long
run. For those in reliably sunny areas, a solar heating
system will cost even more up front but can deliver similar
long term economic and environmental benefits.
