It's not the oil, it's the nitrogen

On The Bay

Perceptions: What people believe they know about pollution does not always coincide with the scientific facts.

October 05, 2001|By Tom Horton | Tom Horton,SUN STAFF

WHAT WOULD rank as the worst pollutant of the Chesapeake Bay and the coastal environment in general over the last four decades? The "winner" in terms of media coverage is probably oil.

A search through the news library of The Sun shows more ink devoted to oil spills, large and small, than any other water pollutant.

That's not too surprising. Oil is highly visible. It slimes anything in its path, staining shorefront property and killing birds and marine life in wrenching, ugly ways.

Also, we know we are addicted to petroleum, and each spill forces us to agonize anew about the dirty consequences of our habit.

But in the overall scheme of things, oil as a cause of environmental decline would rank well down the list of culprits.

Colorless, odorless nitrogen, coming from treated sewage, polluted air and the runoff of fertilizer and manure, would be most scientists' pick for top pollutant of coastal waters.

The point is not to relax vigilance against oil spills, which doubtless would be a worse problem had it not been for all the media focus and public outrage.

The point is that perception plays a large role in how well we go about managing the environment -- including the perception that we can actually manage it at all.

Last May I talked to a poultry farmer along the lower Pocomoke River, where an excess of nutrients, including nitrogen, in farm runoff helped fuel a disastrous outbreak of the toxic microorganism Pfiesteria in 1997.

The farmer was more accepting than most of tougher limits the state has since imposed on spreading manure on crops; but he found it hard to believe the problem was as dire as regulators said.

Why? He could vividly recall the Pocomoke when he was growing up in the 1950s, and it often looked polluted -- with tomato peels from canneries, chicken guts, feathers and heads from poultry processing plants, and raw sewage and wastes from industries.

That's been cleaned up now, and to stand by the riverbank as we did that spring day, all you see is a beautiful vista of marshes and river, glowing in the evening sun.

A lot of people think the way that farmer does. The Eastern Shore river where I grew up, the Marshyhope near Federalsburg, looked much like the Pocomoke in the '50s. Just last week I walked across it with a friend who remarked how clear and clean the old creek looked these days.

Yet it is well documented that the loads of nitrogen and other fertilizers carried by all bay rivers now are to blame for the losses of oxygen and underwater grass habitat in the estuary, as well as increasing blooms of noxious algae.

It's a tricky business changing perceptions. You want people to take pride in their rivers, to enjoy them and protect them. Yet they need to know they are far from healthy -- though they look pretty good, better than they used to.

Perceptions can be changed. For most of this country's history, wetlands were perceived as "malarial," "dismal" and generally worthless unless drained or filled.

Science that proved their values as wildlife habitat and as filters for polluted runoff -- together with environmental and educational campaigns -- have come close to reversing that perception. But it has taken decades.

Few threats to the bay have roused more emotions and state action than disposal of spoil from dredging shipping channels. But with the exception of contaminated spoil from Baltimore Harbor, the actual impacts are -- like oil spills -- well down on the list of baywide insults.

Similarly, it is the firm perception of many watermen that the current abundance of rockfish is more the reason for low crab harvests than is overfishing of crabs.

They point to the bellies of rockfish, often found to be gorged with baby crabs -- never mind that scientific surveys consistently show rock eat only a small percentage of the baby crabs baywide.

But the watermen know what they see. Catch more rockfish, not fewer crabs, they say. It makes you wonder how crabs and rockfish managed to coexist before we were around to referee.

Farmers are struggling to change their perception that no one would apply more fertilizer than a crop needs. The fact is, crops aren't efficient at using fertilizer, so some is always left to run into rivers; and everyone fertilizes expecting a good growing year. When it doesn't happen, more fertilizer is left to run off.

A set of perceptions that worries me is what I call the changing baseline -- the tendency of newer generations to accept a lesser and degraded nature as normal. People move to the fast-suburbanizing Eastern Shore and see a deer and a fox and think they are in Eden. They catch four kinds of fish and never miss the three other kinds we drove nearly to extinction.

They walk through a wooded area with 60- to 80-year-old trees and think it's a full-fledged forest, when it's really a century or more from even beginning to exhibit the full range of habitat values.

Changing such perceptions -- without bashing people insensible -- is the challenge of environmental science and education.

The ultimate misperception, the one that's going to override all our bay restoration efforts unless it changes, is that we can continue to double population and double it again, while still managing our way to a cleaner environment.

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