zMessages from Departments and Centers of NILIM

Seeking beautiful, trash-free oceans

PhotoSUDO Tsutomu, Director
Coastal and Marine Department(Keywords) Drift trash, cooperation with the private sector, numerical model, remote sensing
1. Introduction
The amount of trash that drifts along and onto theshores of the East China Sea and Sea of Japan has
been increasing in recent years. This trash, which
drifts into sea areas around Japan and then onto its
coastlines, is causing problems that include
degradation of marine and coastal environments.
Much of the trash is made of artificial materials that
do not exist in the natural world, such as plastic.
Because it is not biodegradable, once the trash entersthe environment, it will exist as semipermanent drift
trash unless it is recovered. This phenomenon occurs
not only in the East China Sea and the Sea of Japan.
In the North Pacific Ocean near Hawaii, there is a highconcentration of trash called the Great Pacific Garbage
Patch that is roughly twice the size of Texas.
There are many cases where regions faced withserious drift trash problems are also grappling with theproblem of declining population. In such regions, thecost of disposing of onshore drift trash is an excessive
burden on local government finances. And even if
no financial problems exist, trash that drifts ashore
tends to remain where it is because it cannot bereached by people, to say nothing of heavy equipment.
Moreover, it is clear that some of the trash that drifts
ashore comes from other countries.
Given these circumstances, Japan enacted a “Law for
the Promotion of Marine Litter Disposal” in July 2009
to preserve favorable coastal sceneries andenvironments and to promote smooth disposal andcontrol generation of driftage.
In addition torequiring coast managers and others to take necessary
measures to dispose of driftage, the law enables thegovernment to quickly enact laws and implement
necessaryfinancialmeasurestopromotecountermeasures against driftage.
The law’senactment represents a significant step toward
resolving the drift trash problem, and it is expectedthat even further measures will be taken in the future.
To solve the drift trash problem, it will be importantto reduce the amount of trash that washes out to sea aswell as to collect trash that is already in the sea.
Accomplishing this will require clarification of trashsources and drift processes together with continuousmonitoring. The Coastal and Marine Department isengaged in research in these areas in cooperation withconcerned organizations.
The content of thisresearch is presented below.
2. Drift trash prediction experiment in the East
China Sea
Implemented under the Ministry of theEnvironment’s Global Environment Research Fund,
this research is a collaborative undertaking involving
researchers from Ehime University, the University ofTokyo, NILIM, and AIST as well as an NGO (JapanEnvironmental Action Network [JEAN]) and local
citizens (Goto City). The main research objectives
are: 1) identification of places of origin, seasons, andamounts of drift trash; 2) prediction of drift seasonsand locations based on the results; and 3) preparationof recommendations on methods for continuous trashsurvey. Figure 1 provides a research outline.

Figure 1: Research outline1)

zMessages from Departments and Centers of NILIM
To begin, drift trash is collected on Fukue Island ofthe Goto Island chain. The trash is then sorted,counted, and weighed. The origins of PET plastic
bottles, lighters, and other items are deduced fromlabels and other clues with the help of the NGO andlocal residents. Then the locations of origin, seasonsof origin, and amounts are back-calculated from asimulation that is based on data obtained in this way.
From this, predictions of trash drift to the Goto Islands
are made using these calculations as boundaryconditions.
To identify areas where trashaccumulates, which is information necessary for trashcollection on the sea, sea areas of accumulation arededuced in real time from surface flow distribution
data that are obtained from high-frequency (HF) ocean
surface radar for the areas off the west coasts of theGoto Islands. Web camera-based technology formonitoring drift trash is used to verify the accuracy of
season and location predictions.
From this research, it has become apparent that large
amounts of trash drift ashore during the winter, andthat there are clear seasonal fluctuations in locations oforigin and deduced by-country drift amounts.
Moreover, the researchers successfully performed
inverse-estimation based on simulations of drift trash.
At the present time, research is focusing on one-monthprediction of drift trash with forecasted wind patterns
issued by the Japan Meteorological Agency, using theinverse
estimates
asboundaryconditions.
Furthermore, the researchers developed methods for
identifying trash accumulation regions using theresults of HF radar observations, and a method forquantifying movement speed and coverage area by
analyzing digital images of trash that is scattered overmarine surfaces.
3. Issues for the future
The researchers believe that the “drift trash
prediction experiment in the East China Sea”
produced value data and developed useful methods forresolving problems associated with drift trash. They
also intend to make proposals on regional andlong-term trash monitoring in the future based on thedeveloped
image-analysis
technologies
andcorrelations among the amounts of various trash types
that were actually collected.
It should be noted that many organisms—including
drifting seaweed, juvenile fish, and floating
larvae—gather in marine areas of accumulated trash,and thus the possibility exists that collecting all
floating matter could have a serious impact onorganisms that, for example, use the junction between
two currents in their life cycles. Consequently, it
may be necessary to engage in technical developmentthat goes one step beyond “effective collection” to“appropriate collection.”
Furthermore, hazardous substances such as PCB andDDT are absorbed in the surfaces of plastic drift trashin high densities. This suggests that drift trash is not
only a problem in terms of scenic beauty but also aserious problem for the ecology. As a result, it isthought that efforts to tackle the drift trash problem
will be required from the standpoint of transport ofhazardous materials as well.
4. ConclusionEveryone wants to see beautiful, trash-free oceans.
There can be no doubt that the best way to achieve thiswill be to not release trash into the ocean.
Although we may prefer not to think about it, it ispossible that hazardous substances attached to drift
trash are becoming concentrated through the foodchain and winding up in the fish on our dinner tables.
Moreover, it is reported that much of the Great PacificGarbage Patch is made up of trash originating fromJapan. Thus, we must recognize that we are not only
the victims of the drift trash problem but also its
perpetrators. Each of us must understand the drift
trash problem and do take whatever action we can tosolve it.
At the same time, however, no matter how much westrive to reduce the amount of trash that is discharged
into the ocean, some trash will always end up there
nonetheless. Thus, in collaboration with variousorganizations, the researchers intend to continue theirresearch toward development of technologies forappropriate collection and ascertainment of the effects
of drift trash.

1) Isobe, Atsuhiko, “East China Sea marine-litter
prediction experiment conducted by citizens andresearchers”, Ship & Ocean Newsletter, No.205, pp.
2-3 (2009)