Document 37ewvK0ZvOQkBXMm3dweaBLEO

Fromi Occonu3 Marine Pollution Fall 1974. Vol.18. No.l '' @. 1 DDTand in theAtlantic George R.Harvey The insecticide DDT was introduced to world biochemical processes, leading to a variety of agriculture and public health after World War II. unnatural symptoms. It was valued for both its toxicity to insects Public awareness of the possible effects and its persistence in the field. It is estimated of chlorinated hydrocarbons on the that over ten million tons have been used during environment was first roused by Rachel the last thirtv years. Polychlorinated biphenyls Carson in her now famous book Silent Spring. (PCB) were /irst introduced to the electrical published in 1962. Although the book industry in 1935 as dielectric and insulating contained many errors, it struck a sensitive Ouids. Because of their low conductivity, heat international nerve and catalyzed the formation stability, resistance to bacterial degradation, of federal pollution agencies and new areas 1 and solvent properties they soon found their of research funding, and heightened public i way into hundreds of commercial products, awareness of the classical science of ecology. s About one million tons have been manufactured Still, by 1970 tbere was no information ' to date. It was inevitable that the same proper* available on the presence, if any, of DDT or ties that make these chemicals so valuable in PCB in the open sea. commerce, agriculture, and health would lead Being uniquely situated at an oceanographic to their rcou mutation snd persistence in the laboratory with open-sea capabilities, we began environment. Also, since the oceans cover to study the distribution of chlorinated most of the surface of the globe, it would hydrocarbons in die sea by making a diverse have been reasonable to predict that large collection of fish and Crustacea on a cruise fractions of these chemicals would find their that transected the North Atlantic between way ro the sc:u These predictions would have the Cape Verde Islands and Woods Hole during r been of tittle concern if both DDT and PCB November and December of 1970. Since that ^ were not members of a class of organic time wc have made a dozen cruises into the compounds known as chlorinated open Atlantic to collect and analyze organisms, J hydrocarbons, substances that are physiologic all v active in a deleterious way. water, air, and sediments as a part of the Environmental Quality Program of the They arc not lethal, as arc the nerve gases, International Decade of Ocean Exploration ` but they insidiously interfere with important (1DOE), an office of the National Science Foundation. Tht irrmutilkm of rfifurmt hyjrorarboni in thr aurttit rnrironmrnt hot luJ to ri[>r<></t-/ir<- faiturrt in , ^Ifnbliiuu of lf.i bifJi. null Of thr Anoeajyo I flood kan ptlieon. (Fronklin Crt'st) When our woik began in 1970, we proceeded on the following assumptions: We would find mainly DDT and its derivatives 19 ' - ; ; ' ; \ ' | , ; | ` , > l ; DSW 031897 (i STLCOPCB4015859 * itr scrtxsftK* E irM(..ii**vMqr:nm ! A' r A ) ^ , ;: 1*V </;: / I j1 t ** . -7*. .. */*v /' > -< cT- *" -i 5.-fcnb\- 7--Vfo- x*j-t A-fX-<A-j^-tU- - -.|^j sediments 1 yin^ under 5500 meters (18.000 'TccFJ'oTivatcr./AIoTigthc coasToTthe Unitej States, DDT is more abundant and can be detected lifsediments, shellfish, and finfidi.^/ After exam Hi nig a large bo3y~oF ddtaVn the PCB and DDT content of seawater, plankton, and fish, we faced a second unexpected conclusion: there was no trend toward a decrease in the chlorinated hydrocarbon content of the water or the plankton as one went seaward. This is illustrated in Figure 1, Looking for an explanation, we measured the PCB and DDT content of the air over the Atlantic and the PCH released during the burning of municipal dumps may reach coastal waters via atmospheric transport and fallout. (Massachusetts Audubon Society) and little, if any, PCB; we would note decreasing concentrations of DDT in fish and water as we moved seaward; we would observe food chain magnification of chlorinated hydrocarbons in marine animals; and we would detect toxic effects of DDT and PCB. Fortunately, our approaches were flexible because all four assumptions were wrong. More than ten times as much DDT as PCB had bceiTused dunnV previous decades. All the J ;i DDT had been sprayed directly into the * f environment, while the PCB had to have leaked or been accidentally introduced. Yet, our first few analyses of Atlantic organisms collected m l 970 revealed ten to one nun'dred^tlincs1 -~mT>rc~PCB than pbT. These initial observations 'did not chlaange miring our subsequent worF ihd eventually led to the conclusion that f j)DT is not ns persistent as once believed and ^S^/i.i'|f`tjLj^!iit}'.'^S!^y to ^'c noin"c of its introduction. KocciTtworlTat tlicTjulj1"*" Breeze (Florida) l.aEoratofv*orVncVO.S. ry**u~m^ onm-e--n--t-j-JT-rf ojji.c--tio--n---A- gency <(?E>P. A* ), h^s-sfyoiyxLdj,.uJl icji.al f-1 i fc~of DDTbf""* naturally illuminated seawater is .about ten days. Consequently, DDT is imw^ '~T~ unfret eernb !e iiLAtfantic deep-sea watcf^ir " sediments, while PCB has been measuretTin FIGURE J. FCB concentrations (in p*irts per trillion) in the fwr/dee water* of the North Atlantic in 1972. sediments beneath the water at several sites from inshore to the open sea. There we did find a very rapid decrease in concentrations away from the coast. This is illustrated for the atmospheric concentrations in Figure 2. The question we encountered was, if more PCB and DDT arc getting into the coastal ocean than into the open sea, why aren't concentrations higher in coastal waters, plankton, and fish? We now believe that the greater amounts of solid particles in the coastal waters can adsorb PCB and DDT from the water while falling to the sJt!iincnfsI~In fact, we have demonstrated in the laboratory that ocean particlcs--a mixture of clay, dcatl 20 DSW 031898 STLCOPCB4015860 plankton, algae skeletons, and so on--can adsorb one million times more PCB than an equal quantity of water can dissolve, in the open ocean, where there is very little particulate matter, the adsorption process is jlower. Thus, the near-shore ocean, which is the source of most of our fish, has been protected from having higher and probably toxic concentrations of chlorinated hydrocarbons in the water by virtue of having a higher load of solid particles. The blue water of the open ocean, because of its low particle population, would be ineffective in protecting the coastal zone. Fortunately, HCUR 2. KB concentrations in atmosphere directly over the western North Atlantic in spring 197J. kilogram). In contrast, barracuda contain about 10 micrograms per kilogram, and flying fish, which feed on plankton, contain one hundred times less PCD or DDT than plankton. Conversely, sharks, which, like barracuda, feed on anything that moves, contain PCB and DDT levels almost as high as those in plankton. In fact, there arc now sufficient . data from mapy sources in the scientific 1 literature to^conclude that food chain \ magnification of pollutants is not a useful I concept with water-breathing animals. 1 However, air-breathing animals such as seals, l sea lions, and sea birds do seem to I concentrate DDT*1uid PCB from their diets \ and to build up enormous quantities in their i fat stores. For example, open-ocean-feeding sea birds, such as the gjeat skua and the British storm petrol, can accumulate as much as 20 parts per million PCB from their diets. The reasons for the lack of food chain magnification among gilled organisms are unknown but probably relate to differences in body chemistry rather than trophic level. Differences in PCB concentrations in various water- and air-breathing animals are illustrated in Table 1. During our cruises we have not observed any^eflectljttributable to DDT'orTCBr'" Planktonic distrifmtron'ahdTHe^size'offnost much less PCB or DDT ever reaches the open ocean. Table 1 /^/ynothcr unexpected result of our data and that ofothers was a lack ol support Tor PCB Concentration* in Various Reservoirs of ilte Atlantic Ocean iliTAoiiiccnt of food cfiamAnagnTfication, as lirstpopulanzcd~l>y llachcl Carson^Altliough, Reservoir Concentrations (parts per billion) like others, we iourid some carnivorous fish Sea mammals 5000 with more chlorinated hydrocarbons than Sea birds 1200 herbivorous fish, or large fish with a higher Mixed plankton 200 body burden of DDT than small flsh, we also Finfull of upper ocean SO found the reverse in many eases. For example, Fish of miihwater depth* 10 plankton, although they arc at the base of the Bottom-living invertebrates 1 1 fond chain, contain the highest PCB Deep-sea sediments 1 concentrations of any organisms in the sea Seawater 0.001 analyzed to date (about 200 micrograms per NOTE: Data were taken from trvctil toured and averted. ! DSW 031899 21 V* V 1W uwi fish catches in the open ocean have not changed foras long as Institution scientists faff remember. There are fewer sharks now tHuTfiifteen years ago, but this can be blamed on the tuna long-lining industry. Also, few haddock are left on Georges Bank, but as a result of reckless overfishing. Marine mammals and sea birds do appear to have been adversely affected by DDT and PCB. California sea lion cows have shown an increased incidence of delivering premature {>ups while concentrating very high body evels of DDT and PCB from their environment. When a massive wreck of guillemots occurred in the Irish Sea in 1969, investigators initially concluded that PCB toxicity probably could not be blamed. More recently, however, after having collected additional data, they determined that the dead guillemots had about twice the PCB concentration of healthy birds collected in the same area, and that PCB was the cause of the wreck. Data collected during observations of a colony of terns near Long Island have shown a correlation between deformed chicks and PCB levels. DDT and mercury concentrations in the terns did not correlate with the incidence of deformed young as well as did PCB levels. Recent work at the Marine Biological Laboratory in Woods Hole demonstrated that sewage applied to a marsh in various amounts caused aberrant behavior and death among the fiddler crab population. The DDT fraction of an extract ol the sewage produced the same effects. Also, the various species in a population of marine algae treated with environmental levels of PCB in a laboratory culture system gradually shifted to a few dominant species, although the total biomass remained constant. In each case cited above, there is an apparent causal relationship between the observed effect and the presence of DDT and/or PCB. However, there is no absolute proof because many other chemicals were also present. Unfortunately, by the rime such proof could be demonstrated, irreversible ; V ' flWhi\\fc'ftfowftIC+1 *UKml*****]f,).. DDT residues are transported to the ocean via rivers (surface rurto/D and atmosphere* Routes ofatmospheric transport include aerial drift during application, and vaporization from soil cold plants. (EPA-Doeumerieat Cltarles O *R ear) damage could be done to a whole population. We therefore cannot delay installation of control programs until the .harmful effects of chemicals in the sea are demonstrated beyond douEtT "" * The situation may be improving, thanks mostly to pressure from scientific and citizen groups that arose during the late 1960s. DDT has been essentially banned in the United States, except for a few special applications. The use of PCB has been restricted in the United States, Europe, and Japan to products that minimize the possibility of leakage to the environment. Since those restrictions were made, the DDT content of coastal marine shellfish has decreased to a level where monitoring by the EPA has been discontinued. PCB concentrations in North Atlantic seawater have decreased forty fold since 1972, and there now appears to be a constant, but lower, leakage fro'm the cities to the sea. The response of the marine environment to these restrictions has been more rapid than we anticipated, and most welcome. However, we cannot assume that persistence of any concentration of a foreign substance is harmless to the environment. Although DDT and PCB levels have decreased to the point where wc should be concerned rather than alarmed, research . should continue for the following reasons. 22 DSW 031900 I.VWiidMU .Lx* ***<***> * In the years ahead, as the world food shortage intensifies, there will probably be massive use of persistent agricultural chemicals because of the favorable economics of spraying only once a year, if we know bow these chemicals move in the environment, where they go, and how long they last, we can use them more wisely, with minimal damage to the environment, especially the seas. Furthermore, although PCB and DDT may be phased out of use, other chemicals will have to replace them. New chemicals will find new uses. Rather than being armed with perfect hindsight, we should be prepared with intelligent predictions of possible use patterns and thereby avoid unnecessary pollution of the seas. Finally, it has been very difficult to trace and understand the movement and cycling of organic carbon compounds in the oceans. They can come from land or be synthesized by algae in surface waters. Bacteria can make organic matter or degrade it in surface waters or bottom sediments. Studies of the movements and whereabouts of the chlorinated hydrocarbons DPT and PCB, which originate on land and arc not made within the sea, can contribute greatly to our knowledge of the cycling of natural organic matter. The seas arc like a giant, complicated organism composed mostly of water, with some solid materials (dust, fish, whales), all interacting in ways that determine the movements of foreign chemicals through the ocean. We believe the effects of foreign chemicals on ocean life arc controlled by regular chemical, physical, and biological processes that we are trying to understand. Only when we understand these processes can we effectively protect the ocean from a premature senility. Ctorgc R. Harvey is an associate scientist fa the Department of Chemistry, Woods Holt Oceanographic Institution. DSW 031901 23