ecotoxicological assessment of contaminated land using ...

AUSTRALASIAN JOURNAL OF ECOTOXICOLOGY

Vol. 14, pp. 143-153, 2008

Contaminated land assessment in Thailand

Iwai and Noller Davis et al

ECOTOXICOLOGICAL ASSESSMENT OF CONTAMINATED LAND USING BIOMONITORING TOOLS FOR SUSTAINABLE LAND USE IN THAILAND Chuleemas Boonthai Iwai1,2,3* and Barry N Noller4 Department of Plant Sciences and Agricultural Resources, Land Resources and Environment Section, Faculty of Agriculture, Khon Kaen University, Khon Kaen, 40002, Thailand. 2 Research Centre for Environmental and Hazardous Substance Management, Khon Kaen University, Khon Kaen, 40002, Thailand. 3 Groundwater Research Center, Khon Kaen University, Khon Kaen, 40002, Thailand. 4 The University of Queensland, Centre for Mined Land Rehabilitation (CMLR), Brisbane, Qld 4072 Australia. 1

Manuscript received, 9/6/2008, accepted, 5/6/2009.

ABSTRACT As a developing country, Thailand has a significant issue with contaminated land and its remediation. Increasing levels of industrial and urban pollution, indiscriminate use of agrichemicals and poorly regulated disposal of a wide variety of hazardous wastes are putting a significant level of pressure on Thailand’s ecosystems. There is an urgent need for practical tools to assist with ecological risk assessment of contaminated land in Thailand. Reliance on soil criteria developed for overseas conditions and organisms may provide inadequate protection in Thailand where both soil and ecological receptors are, in many cases, unique to this country. Native soil organisms in Thailand may be more or less sensitive to contaminants compared to overseas test species. Therefore, standardised protocols for evaluating biodiversity and toxicity are being developed using native species with the aim of using locally generated data to better evaluate the ecological risks of contaminants in Thailand. This paper describes a biological indicator approach for ecological risk assessment of contaminated land in Thailand. This research found that ecotoxicological assessment provides a better basis for understanding the ecological impacts that contaminated sites cause under Thai environmental conditions. Thai soil invertebrate species were more sensitive to soil contaminants than similar species overseas. Different soil types from within Thailand also had an influence on the toxicity of contaminants to soil invertebrates. This study suggested that the collembolan, Cyphoderus sp. should be a useful alternative test species and more ecologically relevant to toxicity testing of Thai soils than the international test species, Folsomia candida. Soil biodiversity and functionality assessments also represent useful tools to assess contaminated land in Thailand. The data generated by this study will provide useful information for the pollution control authorities to assist with adequate protection and management of soil quality in Thailand. Key words: ecotoxicological assessment; contaminated land; biomonitoring; Thailand.

INTRODUCTION Thailand is located in the tropical Southeast Asia region between the latitudes of 6° - 20° N and longitudes of 97°- 106° E. The Kingdom has a total land area of 513 115 km2 and ranges in altitude from 0 m to 2564 m above mean sea level. Thailand is recognised as one of the most bioresourcerich countries of the world (Smitinand 1995). Rapid growth in the Thai economy and increasing human population has resulted in increased demand for land, energy, agricultural products, raw materials and investment opportunities. Expansion of these activities has caused significant losses of biodiversity in Thailand. Hazardous waste disposal is a significant environmental issue in Thailand, related to the increased use of hazardous materials and chemicals with the expansion of industrial and agricultural sectors (ONEP 2006). The Thai Pollution Control Department recently evaluated the trends in the production and management of hazardous waste in Thailand (Pollution Control Department 2005, 2006). From 1995 to 2004, the volume of solid waste per annum from households increased from 12.6 million tons p.a. to 14.6 million tons p.a. Of this amount, 20% was created within Bangkok, 30% in other municipal areas and the remaining *Author for correspondence, email: [email protected]

50% in non-municipal areas. The volume of solid waste from industry has increased from 9.8 million tons p.a. to 14.6 million tons p.a. over the same period (Pollution Control Department 2005). Thailand has also experienced an increase in the number of incidents involving toxic substances, from 21 cases in 2000 to 29 cases in 2004. Such incidents involved leakage, fire and explosion owing to the inefficient storage and transport of chemicals. The volume of hazardous waste in Thailand has increased from 1.12 million tons p.a. in 1995 to 1.81 million tons p.a. in 2004, while the volume of infectious waste has also increased from 18 200 tons p.a. in 1997 to 23 800 tons p.a. in 2004 (Pollution Control Department 2006). About 75-80% of hazardous waste is created by the industrial sector and the remaining 20-25% by communities. The capacity to treat industrial hazardous waste in Thailand has rarely reached more than half the total volume of the waste generated. Illegal disposal in public areas has occurred due to inefficient law enforcement. Appropriate facilities are still lacking for the treatment of hazardous waste created by the household sector; therefore, it is normally disposed together with general solid waste. However, solid waste management is not an appropriate disposal technique for hazardous wastes 143


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0.09 3.6 2 Oil spill incident * Soil samples from this site were taken to analyse soil pesticide residues.

Yasothon Soil Series contaminated Petro-station

sandy loam

0.07 1.5 3.2 Intentional disposal of unused motor oil Yasothon Soil Series contaminated

sandy loam Yasothon Soil Series contaminated

sandy loam

0.41 2.7 5

0.67 9.2 6.4

Using biological control agent and botanical insecticide Dumping of domestic and hazardous wastes Korat Soil Series uncontaminated

sandy loam

0.23 2.4 5.1 Using insecticide and herbicide Korat Soil Series contaminated

sandy loam

0.45 2.6 6 Using biological control agent Nampong Soil Series uncontaminated

sand

0.33 2 4.8 Using insecticide and herbicide Nampong Soil Series contaminated

Sugarcane Plot (Chemical)* Sugarcane Plot (Organic)* Horticulture Plot (Chemical) Horticulture Plot (Organic) Landfill and disposal site Garage

sand

3.71 6 Using insecticide and herbicide Yasothon Soil Series contaminated Cassava Plot

sandy loam

11 6.8 Yasothon Soil Series uncontaminated Forest

Soil Texture Soil type Degree of contamination

Field sites Nine field sites were selected in order to encompass a range of land uses, and associated levels of chemical contamination (Table 1), in north-east Thailand within 50 km from the city of Khon Kaen, 450 km north-east from the capital Bangkok (Bell and Seng 2004). This sub-region is characterised by

Type of Land Use

(i) Field based assessment of the effects of contamination from different land uses using a biological indicator approach based on soil biodiversity and soil functionality; (ii) Semi-field based assessment of the effects of contaminants on invertebrates in the soil ecosystem using a biological indicator approach based on soil biodiversity and soil functionality; and (iii) Laboratory based ecotoxicological tests for contaminants with Thai soil invertebrates and local soils.

Table 1. The key physical and physico-chemical characteristics of the field study sites.

MATERIALS AND METHODS In order to assess and develop tools to measure the ecotoxicological effects of contaminants on soil ecosystems under Thai conditions, different experimental sets of soils were subjected to a range of laboratory, semi-field and field experiments. The existing standardised test systems in term of test species, substrate and conditions were modified in order to reflect Thai soil ecosystems. The experiments of this study were divided into three parts:

Contaminant history

Although pesticide use and other contaminated land issues are significant in Thailand, the development of ecotoxicology to assist environmental management is in its infancy, and few studies regarding environmental distribution, toxic effects on soil organisms, or general impact on soil ecosystems have been undertaken (Iwai et al. 2007). Given the lack of relevant ecotoxicological data and the absence of practical risk management tools, ecotoxicological risk assessments in Thailand are also rarely undertaken. Therefore, the aim of this study was to develop ecotoxicological assessments as biomonitoring tools for contaminated land. Specifically, ecotoxicological assessments were conducted using a multifaceted approach that incorporated biodiversity assessments, bioindicators, toxicity tests, residue analysis and soil habitat parameters to: (i) assess the impact of contaminants in soils from sites with different land uses; and (ii) assess the suitability of such assessments as tools for sustainable land use management in Thailand.

Control site (no contaminants)

Soil pH

Soil Moisture (%)

Like other developing countries, Thailand has an agriculturallybased economy which depends on intensive use of pesticides to increase agricultural productivity (Englande et al. 2008). The costs of agricultural pesticide use in Thailand were estimated to be about 5492 million baht in 1996 (~US200 million at the time) (Jungbluth 1996). Pesticides in the environment are of concern because of the risk of impacts to ecosystems (Crossan et al. 2005). In tropical countries this risk is often increased because safety measures to minimise the negative impact of these compounds are frequently not applied.

sandy loam

Soil Organic Matter (%)

in Thailand, because the potential release of hazardous chemicals into the soil ecosystem and transfer into the food chain threaten both human and ecological health.

0.51

Iwai and Noller

2.55



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the presence of high-clay floodplain soils with broad lateritic features giving overall low organic carbon content in sediment ( 0.05). Although not statistically significant, the pesticides did appear to result in slight to moderate 20–40% reductions in diversity compared to the control plots. The presence of plant cover, in the form of I. aquatica, in the field plots had no significant effect on the toxicity of the pesticides (P ≤ 0.05; based on 2-way ANOVA).

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Laboratory toxicity testing The LC50s for chlorpyrifos to Cyphoderus sp. and P. laevis in the three soil types after 7 and 14 d are shown in Table 7, and indicate marked increases in toxicity between days 7 and 14 for both species. Cyphoderus sp. appeared to be more sensitive than P. laevis at both times, although this difference was less pronounced at day 14. The different soil types had some influence on chlorpyrifos toxicity, particularly for Cyphoderus sp., but this influence was also less pronounced at day 14 compared to day 7. At day 14, there was a maximum four-fold difference in the toxicity of chlorpyrifos to Cyphoderus sp. between the soil types (i.e. LC50 range of 0.00007 – 0.00029 mg/kg dry soil), with toxicity being lowest and highest in the Korat and Nampong soils, respectively. The toxicity of chlorpyrifos between the soil types at day 14 to P. laevis was very similar (i.e. LC50 range of 0.00079 – 0.00091 mg/kg dry soil). The three soil types had a major influence on the effects of chlorpyrifos on reproduction of Cyphoderus sp. after 30-d exposure (Table 8). Chlorpyrifos significantly inhibited reproduction in the Korat, Yasothon and Nampong soils (relative to the control) at 0.00004, 0.000008 and < 0.000008 mg/kg dry soil, respectively. In the Nampong soil, no reproduction occurred in any of the chlorpyrifos treatments. As with the 14-d mortality data, chlorpyrifos toxicity was lowest and highest in the Korat and Nampong soils, respectively. In contrast to the effect on Cyphoderus sp., chlorpyrifos did not significantly affect the growth of P. laevis after 30-d exposure, up to the highest concentration tested of 0.01 mg/kg dry soil (Table 9).


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Table 4. Pesticide residues in soil of the two selected agricultural field study sites. Pesticide Organochlorines Alpha-HCH Beta-HCH Gamma-HCH Heptachlor Dicofol Heptachlor Epoxide Alpha-Endosulfan 4,4-DDE 2,4-DDD Beta-Endosulfan 2,4-DDT Endosulfan sulfate 4,4-DDT Carbamates Carbofuran Carbaryl

Sugarcane Organic Plot (µg/kg)

Sugarcane Chemical Agriculture Plot (µg/kg)

0.040 0.11 0.16 0.212 0.10 0.010 0.039 0.0615

0.034 0.13 0.075 0.212 2.823 0.037 0.13 0.126 0.050 0.274 0.123 1.430 1.100

0.61 2.53

0.921 5.123

Table 5. Soil invertebrate density, biodiversity (H’) and functionality (as litter decomposition rate) from field sites with different land-uses.

Type of land use

Soil invertebrates (Number/m2)

Biodiversity (H′)

Forest 0.95 ± 0.39a 68.06 ± 9.48a d 0.38 ± 0.12b Cassava Plot 15.31 ± 1.47 0.35 ± 0.20b Sugarcane Plot (Chemical) 7.14 ± 0.52f 0.45 ± 0.35ab Sugarcane Plot (Organic) 18.66 ± 2.16c e Horticulture Plot (Chemical) 0.39 ± 0.17b 11.02 ± 1.27 b Horticulture Plot (Organic) 0.69 ± 0.40ab 54.44 ± 4.08 0.31 ± 0.11b Landfill and disposal site 5.75 ± 0.41g Garage 0 0c Petro-station 0 as mean +se (n=3). 0c Data are expressed Values indicated by different letters in the same column are significantly different (P≤ 0.05).

DISCUSSION Little research in ecotoxicology has been carried out in Thailand and, usually, the techniques and procedures that are most often applied are more relevant to developed and mostly temperate countries. The soil organisms and physico-chemical environmental parameters in Thailand are tropical and different from temperate locations. Generally, the potential risks of contaminants on the structure and function of soil ecosystems in Thailand have been ignored in environmental assessments. Soil biodiversity reflects the mix and populations of diverse living organisms in the soil. These organisms interact with one another and with plants and animals forming a web of biological activity. Environmental factors, including temperature, moisture, acidity and several chemical components of the soil affect soil biological activity (Anderson 1994). Clearly, for productive sustainable

Decomposition rate (%) 98.67 ± 0.55a 60.00 ± 4.58b 21.23 ± 5.88e 45.53 ± 5.75d 48.60 ± 6.74d 83.63 ± 5.08c 12.47 ± 4.23e 0.7 ± 0.26f 1.09 ± 0.31f

agriculture, the complex interaction among these factors must be understood so that they can be managed as an integrated system. Changes that occur to soil characteristics may alter the physiological condition of the biota and the interactions between soil organisms and toxicants. The ecotoxicological impacts of contaminants to soil organisms can be affected by soil environmental factors (soil characteristics) such as pH, organic matter and moisture, while they also depend on the chemical nature of the toxicant. This study demonstrated that field assessment and monitoring approaches measuring biological activity (via endpoints such as soil organism density and diversity and litter decomposition rate, the latter being an indicator of soil functionality), can be sensitive to contamination (and probably other stressors) caused by different land uses in Thailand. The soil types showed differences in diversity of soil invertebrates and litter decomposition rate and were associated negatively with the 149


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Table 6. Soil invertebrate density, biodiversity (H’) and functionality (as litter decomposition rate) in soils from field plots at Khon Kaen University experimental station with or without plant (Ipomoea aquatica) cover, exposed to atrazine, carbofuran or chlorpyrifos for 30 days.

Treatment* Control Plot Control Plot + plant Atrazine Atrazine + plant Carbofuran Carbofuran + plant Chlorpyrifos Chlorpyrifos + plant

Soil invertebrates (Number/m2)

Biodiversity (H′)

Decomposition rate (%)

48.75 ± 24.88ab 57.50 ± 26.46a 23.25 ± 3.78b 21.00 ± 10.36b 13.50 ± 10.54b 13.25 ± 9.18b 15.25 ± 8.42b 16.50 ± 15.42b

0.55 ± 0.19a 0.55 ± 0.12 a 0.41 ± 0.04ab 0.41 ± 0.08ab 0.31 ± 0.12b 0.31 ± 0.27b 0.33 ± 0.09b 0.37 ± 0.21b

83.53 ± 6.32a 84.70 ± 7.02a 74.00 ± 7.00a 75.60 ± 10.02a 72.60 ± 5.69a 73.80 ± 7.01a 65.00 ± 5.51b 54.80 ± 5.51b

Data are expressed as mean +se (n=3). Values indicated by different letters in the same column are significantly different (P ≤ 0.05; based on 1-way ANOVA; 2-way ANOVA confirmed that the presence/absence of plants in the plots had no significant effect on any of the biological responses (P ≤ 0.05). * See Materials and Methods for application rates of the pesticides.

Table 7. Acute toxicity of chlorpyrifos to the springtail, Cyphoderus sp., and woodlouse, Porcellio laevis, after exposure for 7 and 14 days. Soil Series

LC50 (mg/kg dry soil) (95% Confidence Limits) 7 days

Korat Yasothon Nampong

14 days

Cyphoderus sp.

P. laevis

Cyphoderus sp.

P. laevis

0.00475 (0.00119-0.01446) 0.00055 (0.00014-0.00139) 0.00036 (0.00005-0.00110)

0.01150 (0.00425-0.02584) 0.00976 (0.00418-0.01967) 0.00720 (0.00233-0.01686)

0.00029 (0.00006-0.00076) 0.00013 (0.00002-0.00030) 0.00007 (0-0.00028)

0.00080 (0.00009-0.00242) 0.00091 (0.00017-0.00243) 0.00079 (0.00008-0.00253)

degree of site contamination, with the greatest biological activity associated with control treatments. This is the first study of this kind in Thailand, and demonstrates that biological assessment approaches can provide a critical line of evidence for risk assessments of contaminated land. The laboratory toxicity tests also demonstrated that soil quality characteristics can influence the effect of pesticides on soil organisms. The toxicity of chlorpyrifos to Cyphoderus sp. and P. laevis was lower in Korat soil than the Yasothon and Nampong soils. This result may be because of the higher clay content in Korat soil. Soils with a higher organic content have a greater sequestering capacity, which reduces the availability of insecticide to induce toxic effects (Wiles and Frampton 1996). Moreover, Racke (1993) reported that the slightly acidic nature of soils would retard the rate of degradation of chlorpyrifos and therefore chlorpyrifos would be more persistent than in alkaline conditions. This is consistent with the pH ranges of the soils, with the Korat soil, in which chlorpyrifos was least toxic, having the highest pH (4.61) and the Nampong soil, in which chlorpyrifos was least toxic, the lowest pH (4.29). Comparisons of effect concentrations determined in this study with literature values indicated that Cyphoderus sp. was more sensitive to chlorpyrifos than the ISO international 150

test species, Folsomia candida. For chlorpyrifos, the 7-day LC50 of 0.005 mg/kg in Korat soil for Cyphoderus sp. was almost two orders of magnitude lower than the value of 0.18 mg/kg for F. candida (Herbert et al. 2004). Similarly, the EC50 values for Cyphoderus sp. reproduction were much lower than the value of 0.065 mg/kg for F. candida (Herbert et al. 2004). P. laevis was less sensitive to chlorpyrifos than Cyphoderus sp. No comparable LC50 data for chlorpyrifos were available for P. laevis. Overall, relatively few data are available concerning the effects of chlorpyrifos on Thai soil invertebrates. The use of existing ecotoxicological data for tropical conditions in Thailand may lead to inaccurate interpretation of effects because most of the ecotoxicological data are based on standardised studies developed for developed, mostly temperate countries. The validity of the assumption that species from different climatic (or other) regions differ in their sensitivity to contaminants has been questioned and examined in a number of studies using aquatic species (e.g. Dyer and Belanger 1997; Markich and Camilleri 1997; Brix and DeForest 2001; Hobbs et al. 2004; Hose and Van den Brink 2004; Maltby et al. 2005; Chapman and McDonald 2006; Kwok et al. 2007). However, the evidence is conflicting with some studies (Maltby et al. 2005; Hose and Van den Brink, 2004) finding no differences while others have found


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Table 8. Production of offspring by the springtail, Cyphoderus sp., following exposure to chlorpyrifos at various concentrations for 30 days.

Chlorpyrifos concentration (mg/kg dry soil) 0 0.000008 0.00004 0.0002 0.001

Number of offspring (Mean ± se) Korat Soil Series

Yasothon Soil Series

Nampong Soil Series

8.2 ± 1.62a* 7.0 ± 1.76a 4.0 ± 1.83b 1.7 ± 1.57c 0.7 ± 0.82c

10.1 ± 2.38a 3.7 ± 1.42b 1.1 ± 0.88c 0 0

9.3 ± 1.49a 0 0 0 0

Data are expressed as mean + se (n=10). Values indicated by different letters in the same column are significantly different (P ≤ 0.05). Table 9. Body weights of the woodlouse, Porcellio laevis, following exposure to chlorpyrifos at various concentrations for 30 days. Chlorpyrifos concentration (mg/kg dry soil) 0 0.00008 0.0004 0.002 0.01

Weight (g n = 40 Korat Soil Series

Yasothon Soil Series

Nampong Soil Series

± ± ± ± ±

± ± ± ±

± ± ± ± ±

±

Data are expressed as mean ± se.

differences (Dyer and Belanger 1997; Markich and Camilleri 1997; Brix and DeForest 2001; Hobbs et al. 2004; Chapman and McDonald 2006; Kwok et al. 2007). The point of this study was to focus on the use of local Thai soil species to conduct ecotoxicological tests and make further comparison with other literature data. The soil ecotoxicological testing methods used in this study, based on native soil invertebrates and assessing chronic reproduction and growth effects under Thai conditions have, to some extent, addressed the problems associated with the use of international standardised test species and methods. However, the test designs require further optimisation and validation, while tests for additional regionally relevant species should also be developed. The various biological assessment approaches employed in this study are suitable as tools for the assessment and biomonitoring of contaminated land for sustainable land use in Thailand. The selection of each particular technique will be dependent on each site, resources and facilities available. Whilst the bioassay developed in Europe using F. candida is sensitive and useful for ecological risk assessments of contaminated soils (ISO 1999), it has little ecological relevance to Thai soil ecosystems because F. candida is rarely found in Thai soils. In addition, Thai soils tend to have lower organic matter content than the European soils from which much the toxicity data are generated. For example, the OECD artificial soil used in Collembola tests, which is formulated to reflect European soil conditions, has higher pH and organic matter content than most Thai soils. This is an inexpensive test method compared with the cost of undertaking chemical analysis of contaminated soil.

As highlighted above, ecotoxicology and ecological risk assessment are relatively new environmental assessment tools for Thailand, and the development of these fields in Thailand is in its infancy. Although contaminated land issues are of great concern in Thailand, regulatory laws are not equitably enforced. There are some difficulties in carrying out terrestrial field and/or laboratory ecotoxicological tests in Thailand that parallel aquatic ecotoxicity testing as follows: (i) Lack of integration of policy and regulation to support and enforce the need of the tests; (ii) Lack of recognition by relevant organisations in Thailand of the significance of ecotoxicological impacts on the soil ecosystem; (iii) Lack of advocacy from both private sectors and government organisations; (iv) Lack of human resources for ecotoxicology and ecotoxicological testing; and (v) Lack of adequate financial support from administrators for developing ecotoxicological capabilities (Tapaneeyakul 2008). There are no comparable soil ecotoxicology data for Thai soil invertebrates. Therefore, there is an urgent need to fill this gap of knowledge by conducting ecotoxicological monitoring of contaminated land in Thailand. The legislation for integration of soil ecotoxicological testing into both government policy and law enforcement should be pushing forward and increasing awareness and concern.

CONCLUSIONS Although contaminated land is assessed worldwide, each country, or at least region, has unique characteristics that that will determine the impact of soil contaminants. For this reason universal standards for soil contamination are often inappropriate to apply to local situations. Thus, to determine the impacts of contaminants, site-specific factors 151



must be examined and comprehensive investigations of biotic and abiotic interactions are required. This study found that the broadening of the assessment approach for soil contamination from focusing just on chemical concentrations to also including ecotoxicological methods provided a better understanding of the ecological risks of contaminated sites under Thailand’s environmental conditions. Field and semi-field assessments measuring community level structural and functional responses to contaminated soils were effective in detecting effects of different land uses and individual pesticides. In addition, two Thai soil species, the springtail, Cyphoderus sp., and woodlouse, P laevis, were successfully used in laboratory-based toxicity assessments of the pesticide chlorpyrifos. These species are more ecologically relevant to Thai soils than international test species and also benefit from the fact that they are readily collectable, and easy to maintain and breed in culture. Moreover, they were found to be more sensitive to chlorpyrifos than the international test species, F. candida. However, additional endpoints, such as enzyme activity or avoidance, should be also further investigated. From this study, the growth of the woodlouse may not be a suitable endpoint for giving an early warning of exposure to pesticides. Overall, the results of this study suggested that the springtail, Cyphoderus sp., should be a useful alternative test species to F. candida for terrestrial ecotoxicological testing in Thailand. Chemical analysis alone is inadequate for comprehensively assessing the impact of pollution on soil invertebrates. Integration of biological, physiological and chemical data can often yield significant advances in hazard assessment and act as a suitable baseline for making site-specific risk assessments.

ACKNOWLEDGEMENTS This research was financially supported by Khon Kaen University Research Funding year 2006-2007 and Groundwater Research Centre KKU. The authors wish to express their sincere thanks to Khon Kaen University for its financial support and to the Faculty of Agriculture and Department of Plant Sciences and Agricultural Resources, Land Resources and Environment Section, KKU for their generous support on facilities to carrying out this experiment. Many thanks to Dr Kathryn O’ Halloran, Landcare Research, Lincoln, New Zealand for her useful and meaningful suggestions and advice. We would like to express our acknowledgements to Dr Rick van Dam from the Environmental Research Institute of the Supervising Scientist, Australia, for his kindness on suggestions on, and edits to, the manuscript. Many thanks also to Ms Yupin Pratad, Ms Yuppadee Rattanapun and Ms Benjawan Sawedwong for research assistance.

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REFERENCES Abbott TS. 1985. Soil Testing Service: Methods and Interpretation. NSW Department of Agriculture, accessed at http://www.environment.nsw.gov.au/resources/soils/ testmethods/awc.pdf Anderson JM. 1994. Functional attributes of biodiversity in land use systems. In Soil Resilience and Sustainable Land Use, Greenland DJ and Szabolcs I (Eds), CAB International, Wallingford, UK, pp. 267-290. AOAC. 1995. AOAC Method 29.013 p 537. In Organochlorine and Organophosphorus Pesticide Residues. AOAC Official Methods of Analysis, 16th Edition, Corneliussen PE, McCully KA, McMahon B, and Newsome WH (Eds), AOAC International, Arlingtom, Va, USA. Bell RW and Seng V. 2004. Rain fed lowland rice-growing soils of Cambodia, Laos and North-east Thailand. In Water in Agriculture ACIAR Proceedings No. 116e Canberra, Australia, pp. 161-173. Black CA. 1965. Method of Soil Analysis. Part a. Agronomy 9. American Society Agronomy, Madison, Wis. USA. Blair JM and Crossley DA Jr. 1988. Litter decomposition, nitrogen dynamics and litter microarthropods in a southern Appalachian hardwood forest 8 years following clear cutting. Journal of Applied Ecology 25, 683-698. Brix KV and DeForest DK. 2001. Assessing acute and chronic copper risks to freshwater aquatic life using species sensitivity distributions for different taxonomic groups. Environmental Toxicology and Chemistry 20, 1846-1856. Chapman PM and McDonald BG. 2006. Global geographic differences in marine metals toxicity. Marine Pollution Bulletin 52, 1081-1084. Cornu S, Luizao F, Rouiller J and Lucas Y. 1997. Comparative study of litter decomposition and mineral element release in two Amazonian forest ecosystems: litterbag experiments. Pedobiologia 41, 456-471. Cottenie A.1980. Soil and Plant Testing as a Basis of Fertilizer Recommendation. FAO. Rome. Crossan AN, Nguyen Thi, Trang T, Pham NH and Kennedy IR. 2005. Safer Selection and Use of Pesticides: Integrating Risk Assessment, Monitoring and Management of Pesticides. ACIAR Monograph 117. Australian Centre for International Agricultural Research, Canberra, Australia. Dyer SD and Belanger SE. 1997. An initial evaluation of the use of Euro/North American fish species for tropical effects assessments. Chemosphere 35, 2767-2781. Englande AJ Jr, Novotny JR, Promakasikorn L, Bedoya D, Wang X and Tirado R. 2008. The impact of agricultural chemicals on the environment and public health in SouthSouth East Asia – Status and control strategies for diffuse pollution. In 12th International Conference on Integrated Diffuse Pollution Management. IWA. Khon Kaen Thailand. Finney DJ. 1971. Probit Analysis. New York: Cambridge University Press.

152



Garcia M. 2004. Effects of pesticides on soil fauna: Development of ecotoxicological test methods for tropical regions. In Ecology and Development Series No. 19, 2004. Paul LG, Vlek Denich M, Martius C and van de Giesen N (Eds). Cuvillier Verlag, Göttingen, Germany. Herbert IN, Svendsen C, Hankard PK and Spurgeon DJ. 2004. Comparison of instantaneous rate of population increase and critical-effect estimates in Folsomia candida exposed to four toxicants. Ecotoxicology and Environmental Safety 57, 175–183. Hobbs DA, Warne MStJ and Markich SJ. 2004. Utility of northern hemisphere metal toxicity data in Australasia. Setac Globe 5, 38-39. Hose GC and Van den Brink PJ. 2004. Confirming the species-sensitivity distribution concept for endosulfan using laboratory, mesocosm, and field data. Archives of Environmental Contamination and Toxicology 47, 511-520. ISO (International Standardization Organization). 1999. Soil Quality - Inhibition of Reproduction of Collembola (Folsomia candida) by Soil Pollutants. ISO 11267. Geneva, Switzerland. Iwai CB, Sujira H, Somporn A, Komarova T, Mueller J and Noller B. 2007. Monitoring pesticides in the paddy field ecosystem of north-eastern Thailand for environmental and health risks. Chapter 16, In Rational Environmental Management of Agricultural Chemicals. ACS Symposium Series 966. Kennedy IR, Solomon KR, Gee SJ, Crossan AN, Wang S and Sanchez-Bayo F. (Eds) American Chemical Society. Washington, DC. pp. 259-273. Jackson ML. 1960. Soil Chemical Analysis. Prentice Hall, Inc, Englewood Cliffs. New Jersey, USA. Jungbluth F. 1996. Crop Protection Policy in Thailand: Economic and Political Factors Influencing Pesticide Use. Pesticide Policy Project Publication Series No.5, December 1996 Institut für Gartenbauökonomie, Universität Hannover, Hannover, Germany. Krebs CJ. 1999. Ecological Methodology. 2nd Ed. Benjamin/ Cummings. Menlo Park, CA, USA. 620 pp. Kwok KWH, Leung KMY, Chu VKH, Lam PKS, Morritt D, Maltby L, Brock TCM, Van den Brink PJ, Warne MStJ and Crane M. 2007. Comparison of tropical and temperate freshwater species sensitivities to chemicals: Implications for deriving safe extrapolation factors. Integrated Environmental Assessment and Management 3, 49-67.

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Archives of Environmental Contamination and Toxicology 46, 377-384. ONEP. 2006. State of Thailand Environment 2004-2005. Office of National Resources and Environmental Policy and Policy. Bangkok, Thailand. Patcharaprecha P. 1994. Soil and Plant Analysis. Department of Soil Sciences, Faculty of Agriculture, Khon Kaen University, Thailand. Pollution Control Department. 2005. State of Environmental Quality of Thailand. Pollution Control Department, Thailand. Pollution Control Department. 2006. State of Environmental Quality of Thailand. Pollution Control Department, Thailand. Racke KD. 1993. Environmental fate of chlorpyrifos. Reviews of Environmental Contamination and Toxicology 131, 1-150. Robertson JL and Preisler HK. 1992. Pesticide Bioassays with Arthropods. CRC Press Inc., London. Smit CE and van Gestel CAM. 1998. Effects of soil type, prepercolation, and ageing on bioaccumulation and toxicity of zinc for the springtail Folsomia candida. Environmental Toxicology and Chemistry 17, 1132–1141. Smitinand T. 1995. Overview of the status of biodiversity in tropical and temperate forests. In Proceedings of a IUFRO Symposium on Measuring and Monitoring Biodiversity in Tropical and Temperate Forests held at Chiang Mai, Thailand August 27th- September 2nd, 1994. Boyle TJB and Boontawee B. (Eds). Center for International Forestry Research, (CIFOR), Bogor, Indonesia. pp. 1-4. Tapaneeyakul N. 2008. Perspective of ecotoxicological conduction for water quality monitoring in Thailand. In Interdisciplinary Studies on Environmental Chemistry — Biological Responses to Chemical Pollutants, Murakami Y, Nakayama K, Kitamura S-I, Iwata H and Tanabe S, (Eds), Terra Scientific Publishing Company, Tokyo, Japan, pp. 31–35. Wiles JA and Frampton GK. 1996. A field bioassay approach to assess the toxicity of insecticide residues on soil to collembola. Pesticide Sciences 47, 273-285.

Maltby L, Blake N, Brock TCM and Van den Brink PJ. 2005. Insecticide species sensitivity distributions: Importance of test species selection and relevance to aquatic ecosystems. Environmental Toxicology and Chemistry 24, 379-388. Markich SJ and Camilleri C. 1997. Investigation of Metal Toxicity to Tropical Biota: Recommendations for Revision of the Australian Water Quality Guidelines. Report Number 127, Supervising Scientist, Canberra. OECD. 2001. Collembola reproduction test. In: OECD Guideline for the testing of chemicals in terrestrial isopod. 153