IJERD – International Journal of Environmental and Rural Development (2012) 3-1

Research article
erd

Short and Long Term Fate of Environmental Pollutants
and Their ManagementBARRY N. NOLLER*
The University of Queensland, Centre for Mined Land Rehabilitation, Australia
Email: b.noller@uq.edu.au
Received: 19 December 2011

Accepted: 2 April 2012(*: Corresponding Author)

Abstract There has been an increasing demand of chemical substances during this and thelast century. The use of chemicals for a long time has been identified as a negative impact
on the environment since it became apparent that residues could be transferred through thefood chain; remain in soil or sediment as intractable substances. Chlorinated pesticides
stand as a classic case of intractable substances and their residues remain dispersed
throughout the world. Even though banned, their use continued because of theireffectiveness as insecticides and availability. The effective use of DDT(dichlorodiphenyltrichloroethane) for control against malaria was recognized following its
removal but was reinstated for controlled situations. Arsenic is another classic casebecause its residues from the application of its compounds as insecticides for cattle dips
remain as buried residues that are intractable. The soil from such repositories requires
remediation. The recognition of problems associated with the lifetime of long persistence
substances led to the need to use low persistent pesticides for insect control. The impact ofincreasing use of pesticides and herbicides is now offset by available data which showsthat for many compounds, residues are undetectable in soil and groundwater. The USGS
found no significant build-up of low persistence pesticides in groundwater over a 15 years
period. Long-persistence or intractable compounds require specific techniques of soil
remediation to deal with their effects on plants and animals. Examples of substances that
may require soil remediation are arsenic, dioxins and DDT. A classic case of dioxin in soil
was spotted at Bien Hoa, Vietnam, where 1 ppm TCDD (2,3,7,8-Tetrachlorodibenzo-pdioxin) was found in soil. A remediation plan was put in place and the TCDD residues
were excavated and disposed in a repository. While exceptions occur, it is important torecognise that degradable chemicals should be used wherever possible in order to avoid
future remediation problems.
Keywords: pesticides, fate, long and short persistence, soil remediation

INTRODUCTION
The use of chemicals by mankind has become a necessary and inseparable activity for the
maintenance of livelihood, industrial, agricultural and recreational activities. Such use has led toinnumerable cases of contamination and transfers through the food chain damaging ecology andpoisoning people as occurred with methyl mercury at Minamata, Japan. The use of chemicals withlong persistence in the environment has been identified as a negative feature since it became
apparent that residues could be transferred through the food chain; remain in soil or sediment as
intractable substances. Chlorinated pesticides stand as a classic case of intractable substances as
their residues remain dispersed throughout the world. Even though banned, their use continued
because of their effectiveness as insecticides and availability. The use of DDT for control against
malaria was recognised following its removal but was reinstated for vector control and remained inuse under limited and controlled situations.
The recognition of problems associated with the lifetime of long persistence substances led to
the need to use low persistent pesticides for insect control. Although firmly in place, the general
theory is that all pesticides, including those having low persistence, are bad because of theⒸ ISERD126

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reputation of previously-used compounds, e.g. DDT (dichlorodiphenyltrichloroethane), dieldrin,
chlordane, etc. The impact following the increasing use of pesticides and herbicides is now offset
by available data which shows that residues are undetectable in soil and groundwater for many
compounds in use. Exceptions are compounds like endosulfan which is essentially a chlorinatedcompound and is often found as a residue in sediment (Boonthai-Iwai, 2007). The USGS (Gilliamet al. 2006) found no significant build-up of low persistence pesticides in groundwater over a 15years period. However, organochlorine pesticide compounds that were found in stream bed
sediments and fish tissue were no longer in use by 1990. Only dachtal, endosulfan, lindane,
methoxychlor and permethrin were used during the study period (Gilliam et al. 2006).
Long persistence or intractable compounds require specific techniques of soil remediation todeal with their effects on plants and animals. In-situ treatments are preferred for their removal fromsoil. Management practices that control erosion of soil may also help to reduce transport ofpesticides and their degradates to streams. However, in some cases, it may be necessary to remove
soil and treat it elsewhere to remove contaminants. Examples of substances that may require soil
remediation are arsenic, dioxins and DDT. While exceptions occur, it is important to recognise that
degradable chemicals should be used wherever possible in order to avoid future remediation
problems.
The key aspects to be considered with particular reference to pesticides and herbicides are: (i)persistence of chemicals in the environment; (ii) long persistence causes intractable residues andcontaminated waste; (iii) benefits of short term persistence chemicals and (iv) role ofenvironmental management to minimise risks.
GENERAL PERSISTENT CHEMICALS IN THE ENVIRONMENT
There are many examples where the use of persistent chemicals has led to serious pollution
episodes.
The use of arsenic compounds is a classic case. Residues from application as insecticide forcattle dips in Australia remain buried and intractable (Ng et al., 2003). The soil from suchrepositories requires remediation as it is contamination from an anthropogenic source. Arsenic
solutions for cattle tick control were widely used in Queensland and New South Wales from 1895
to 1955. Chemical investigations (Beard et al., 1992) of arsenic contaminated soils, obtained fromaround 1600 government-owned cattle dip sites near north eastern NSW, have revealed levels ofarsenic ranging up to 3000 mg/kg in the soil. Comparative bioavailability data were determined in
16 randomly selected soil samples with arsenic concentrations ranged from 700 to 2100 mg/kg andshowed that a large proportion of arsenic (III) was present (Table 1) (Ng et al., 2003). An extensive
cleanup program has been in place for several years to deal with the clean-up of contaminatedcattle dip soils.
Table 1 Arsenic speciation from 16 cattle dip soil samples (Ng et al., 2003)
Soil I.D.
12345678910111213141516Total Arsenic (mg/kg)
730
730
860
1300
700
2000
1400
980
750
2100
800
1000
1100
2000
830
900

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Arsenic (III) %
68
70
3875
70
71
57
7230
59
4374
88
67
8057

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A classic example of dioxin in soil is located in Bien Hoa, Vietnam, where 1 ppm; 2,3,7,8tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD or TCDD) was found. The build up from the residuesof TCDD in Agent Orange storage at the former US air base resulted in a highly concentrated zone
(Quynh, 2005). Run-off accumulated in a nearby lake led to accumulation of TCDD in fish andother food items consumed by local people who received a significant dose of TCDD and thus wereaffected. A remediation plan was put in place and the TCDD residues have been excavated anddisposed in a repository.
Although many toxic organochlorine pesticides are now banned in Vietnam, they are still in
use and cause concern to people. Herbicides used during the Vietnam War severely polluted areasof Southern Vietnam. The study of the distribution of chemical impurities from herbicide
application during the war has been useful for finding appropriate control measures (Quynh, 2005).
Methods for sampling and analysis of organochlorines in soils, animal, human fat tissue and blood
sample collection were applied and samples sent to international laboratories for dioxin analysis byhigh resolution gas chromatography – high resolution mass spectrometry (HRGC-HRMS). A studyof organochlorine pesticides and polychlorinated biphenyls (PCBs) in food samples from Ho Chi
Minh City 1989 showed that the most notable compound detected in biological tissue was DDT.
Concentrations of DDT, hexachlorocyclohexane (HCH) and polychlorinated biphenyls (PCBs) in
the soil in Tay Ninh and Binh Duong provinces in 1992 were also high where DDT was sprayed.
PCBs contamination of cultivated land occurred during the war. Organochlorine pesticides and
PCB levels in food samples from various sites were measured in Vietnam in 1992 and showed thepresence of pollution of foodstuffs with PCBs, DDTs, HCHs, aldrin and dieldrin that werewidespread in Vietnam. Dioxin accumulation has been observed in soil, animals and humans. In
some limited sites it has been observed under geographical conditions, where Agent Orange
herbicide drums were stored. The development of measures to solve contamination problems andprevent effects to the health of people has continued.
BENEFITS OF SHORT PERSISTENCE CHEMICALS
Chemicals which act quickly to induce an action or to control a pest are clearly preferred to thosewhich remain active for decades. Pesticides are widely used in agriculture to control pests (weeds,insects or pathogens) and thereby increase yield and farm income. They remain an essential tool for
agricultural industries in the production of high quality products and are a key component ofintegrated crop management (ICM) in cropping systems worldwide with around 2.56 million
tonnes used per year (Pretty, 2005). Pesticides are generally applied as sprays to produce coverageof droplets containing the active ingredient on the target (e.g. an insect, leaf surfaces or part of aplant). Spray may be lost to non-target areas within a crop such as deposition on the soil or nontarget plant surfaces and the action of wind may result in spray moving from the sprayed area.
There are increasing concerns over the effect of pesticides in the environment, particularly when
they move beyond a field boundary. By utilising techniques that maximise deposition on the spraytarget, it is possible to both improve the efficacy of pesticide applications and limit the movementof liquid droplets away from their point of release, both within and outside a target area.
For optimum control of pests and weeds in agricultural cropping situations, the grower isrequired to take careful consideration of many factors (Dorr et al., 2006). These include chemical
selection, crop type, pesticide resistance, crop yield, costs of production, farmers revenue, spraying
equipment (e.g. type of sprayer, nozzle selection, operating parameters), spraying techniques (e.g.
buffer zones, no spray areas), meteorology (temperature, relative humidity, wind speed anddirection) and sensitive areas downwind (e.g. non-target crops, livestock, aquatic organisms andareas that people occupy). Managing these factors in an integrated, holistic manner is often very
complex. It requires combining tools, resources and information from several sources to optimise
the application. Many parameters can also change during application (e.g. wind speed anddirection) and application techniques must then be modified to prevent possible contamination of
non-target areas. Failure to rapidly and appropriately manage these complex inter-relatedparameters has been the reason behind many pesticide drift incidents.
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An important observation in the USGS study (Gilliom et al., 2006) was that the pesticides
most frequently detected in streams and groundwater were those with greatest use either during thestudy period or in the past and with the greatest mobility and/or persistence in the hydrologicalsystem. Subsurface drains may help protect deep underground water, but increase pesticidetransport to streams.
ROLE OF ENVIRONMENTAL MANAGEMENT TO MINIMISE RISKS
Risks to public health and the environment associated with pesticide use can be minimised if
correct management decision is made. For a spray operation to be effective it needs to control pests(and hence increase crop yield and gross income) with a minimum of off-target environment andpublic health damage (Dorr et al. 2007). By combining spray models which give pesticide exposureand dose-response models with decision theoretical tools, various management options can beevaluated to maximise the effectiveness of plant protection products and minimise risks to publichealth and the environment from agricultural spraying activities. Risk assessment is a process fororganising what we know about health and environmental risk and making judgements about risk
(Ricci, 2006). It commonly adopts the following model: (i) Hazard Identification; (ii) Dose –Response (Toxicity) Assessment; (iii) Exposure Assessment; and (iv) Risk Characterisation.
In the risk assessment process, exposure studies of biota need to take account of formulationof the pesticide and its bioavailability. It is necessary to combine good quality application data withpesticide chronic toxicity data, generally the data required for registration of a pesticide. The risks
to the environment need to take account of effects on: (i) terrestrial species; and (ii) aquatic species(Suter II, 1995). Other key areas include drinking water area exposure assessments and protection of
non-target sensitive crops.
The control of contaminated waste is best dealt with by minimising its creation. Prevention ofpollution requires attention to source reduction, the use of recycling, treatment and disposal options.
Pollution prevention more broadly requires managing chemicals to reduce risk by identifying theirpresence and estimating all releases. Waste minimisation can be enhanced by applying source
reduction and introducing product changes.
The recognition of the limits of science and technology has been proposed as reasons why
science and technology alone cannot solve pollution problems or meet the challenges of sustainable
development (Huesmann, 2003). The key aspects cited were: (i) Failure of reductionism; (ii) Limits
imposed by conservation of mass principle; (iii) Order at expense of more disorder; (iv) Myths
about recycling and renewable energy – trapping in environmental cycles; (v) Technology factor
cannot be eliminated in order to improve eco-efficiency; and (vi) Long term protection of theenvironment and sustainable life style are not primarily technological but social and moral issues.
It is recognised that both biology and chemistry determine the availability of toxic chemical
species in soils and sediments. The transport of solutes in soil is dominated by diffusion and isdemonstrated by the significant presence of more polar herbicides such as atrazine foundextensively in US streams (Gilliom, 2006). The precise nature of chemical and biologicalinteractions depends on bioavailability and the role of bioturbation-driven chemical releaseprocesses.
Existing standards and guidelines for exposure to individual pesticides may not address all
potential effects because actual exposure is most often a mixture of multiple pesticides anddegradates (Gilliom, 2006). Additional research is required regarding the toxicities of mixtures tohumans, aquatic life, livestock and wildlife because of the wide range of chemicals now found inorganisms (Hileman, 2007).
CONCLUSIONS
An increasing demand for chemical substances during the last century led to the use of chemicals
with long persistence in the environment. This activity has been identified as a negative featuresince it became apparent that residues could be transferred through the food chain, remains in soil
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IJERD – International Journal of Environmental and Rural Development (2012) 3-1

or sediment as intractable substances. Chlorinated pesticides stand as a classic case of intractable
substance and their residues remain dispersed throughout the world. Even though banned, their use
continued because of their effectiveness as insecticides and availability. Arsenic is another classic
case and its residues from application of its compounds as insecticides for cattle dips remain asburied residues that are intractable and requiring remediation. The recognition of problems
associated with the lifetime of long persistence substances led to the need to use low persistentpesticides for insect control. The impact of increasing use of pesticides and herbicides is now offset
by available data which shows that many compounds residues are undetectable in soil andgroundwater. The USGS found no significant build-up of low persistence pesticides in groundwaterover a 15 years period. Long-persistence or intractable compounds require specific techniques ofsoil remediation to deal with their effects on plants and animals. Examples of substances that may
require soil remediation are arsenic, dioxins and DDT. A classic case of dioxin in soil could beseen in Bien Hoa, Vietnam, where 1 ppm TCDD was found in soil, requiring a remediation plan toexcavate and dispose the TCDD residues in a repository. While exceptions occur, it is important torecognise that degradable chemicals should be used wherever possible in order to avoid future
remediation problems.
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Gilliom, R.J., Barbash, J.E., Crawford, C.G., Hamilton, P.A., Martin, J.D., Nakagaki, N., Nowell, L.H., Scott,J.C., Stackelberg, P.E., Thelin, G.P. and Wolock, D.M. 2006. The   quality   of   our   nation’s   water:  Pesticides   in   the   Nation’s   Streams   and   groundwater   1992-2001. National Water-Quality Assessment
Program. Circular 1291. US Department of the Interior US Geological Survey, Virginia, USA.
Hileman, B. 2007. Tracking the chemicals in us. C&EN April 23, 32-34.
Huesemann, M.J. 2003. Recognising the limits of Environmental Science and Technology. Environ. Sci.
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Ng, J.C., Noller, B., Bruce, S. and Moore, M.R. 2003. Bioavailability of metals and arsenic at contaminatedsites from cattle dips, mined land and naturally occurring mineralisation origins. Proceedings of theFifth National Workshop on the Assessment of Site Contamination. National Environment Protection
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Pretty,J. 2005. Sustainability in agriculture, Hester, R. E. & Harrison, R. M., Eds. RSC Publishing, U.K.
Quynh, H.T. 2005. Organochlorine pesticides and dioxin in Vietnam. report on workshop on contaminatedagricultural land management and remediation. OPCW Hanoi, Vietnam, 11-13.
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Springer: Dordrecht, NL.
Suter II, G.W. 1995. In Fundamentals of Aquatic Toxicology, 2 Ed, 803-816.

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