Distribution and fate of HCH isomers and DDT metabolites in a tropical environment–case study Cameron Highlands–Malaysia
© Saadati et al.; licensee Chemistry Central Ltd. 2012
Received: 28 September 2012
Accepted: 1 November 2012
Published: 7 November 2012
The serious impact effects of persistent organic pollutants such as organochlorine pesticides, especially dichlorodiphenyltrichloroethane family (DDTs) and hexachlorocyclohexane isomers (HCHs) have been causing widespread concern, despite effective control on their manufacturing, agricultural and vector practices. In that, in addition to the previous global limitations on DDTs usage, α-HCH, β-HCH and lindane have also became an on-going topic of global relevance based on the latest Stockholm Convention list on 10th of May 2009. Concentrations of dichlorodiphenyltrichloroethane family (DDTs) and hexachlorocyclohexane isomers (HCHs) were determined by GC-ECD in Cameron Highlands, the main vegetables and flowers farming area in Malaysia as an agricultural tropical environment. A total of 112 surface water and sediment samples at eight points were collected along the main rivers in the area namely Telom and Bertam in the dry and wet seasons of 2011.
Total concentration of HCH isomers ranged from not detected to 25.03 ng/L in the water (mean of 5.55 ±6.0 ng/L), while, it ranged from 0.002 to 59.17 ng/g (mean of 8.06±9.39 ng/g) in the sediment. Total concentration of DDT and its metabolites in the water samples varied from not detected to 8.0 ng/L (mean of 0.90±1.66 ng/g), whereas, it was in the range of 0.025 to 23.24 ng/g (mean of 2.55±4.0 ng/g) in the surface sediment samples. The ratio of HCHs and DDTs composition indicated an obvious historical usage and new inputs of these pesticides. Among alpha, beta, gamma and delta isomers of HCH, gamma was the most dominant component in the sediment and water as well. Some seasonal variations in the level of selected pesticides were noted.
The results illustrate distribution, behaviour and fate of HCHs, and DDTs have closely connected with topological and meteorological properties of the area beyond their chemical characterizations. The features of environmental circumstances exceed one or more of these characters in importance than the other. Although the results show that the situation is better than 1998, the impact of persistent agrochemicals such as lindane and 4,4′DDE are revealed in a key tropical area of Malaysia.
KeywordsHCHs DDTs POPs Tropical environment Cameron highlands
Organochlorine pesticide levels in countries nearby the study area and the world
Mae Llong river
the pacific countries
coastal marine environment
rivers in Okinawa island
4.22 – 461
Minjiang river estuary
the river estuary
Lagos lagoon complex
In 2002, Malaysia was a signatory to the Stockholm Convention on POPs and it was committed to carrying out a GEF/UNEP-funded project for the gradual growth of a National Implementation Plan (NIP) for POPs management . In fact, the use of pesticides in Malaysia was not subjected to regulatory control until the Agricultural Chemicals Board was established under the Agricultural Chemicals Act 1974. The use of persistent OCPs was then gradually controlled by a series of governmental rules. This policy led to their controlled use in the mid 1970s.
Historically, pesticides have been used to enhance the crop yields in Malaysia since the Second World War . The country became a model for the World Health Organization (WHO), following the successful control of malaria mosquito vectors by DDT during the 1950s. . Most of the regulated pesticides under the Pesticide Act 1974 were used in the sector until they were banned in the late 1990s . Despite that residues of these pesticides have been frequently found in various media of the environment such as water, sediment and biota [18, 36, 39].
Md. Sani  pointed out that there is no integrated programme to monitor pesticides compared with other hazardous chemicals. Tropical rainforest areas, such as Malaysia are traditionally agriculture-based countries. In peninsular Malaysia, Cameron Highlands is a tourist resort which is the second most important state for growing vegetables (mostly cabbage, tomato, and leafy vegetables), and are also important for tea, flowers and fruit. In addition, Cameron Highlands Catchment area is a source of water supply to many areas of Peninsular Malaysia . Sg.Telom, Sg.Bertam and Sg.Lemoi are the three main rivers of the Cameron Highlands Catchment, which drains the northern, middle and southern sections of the highlands. Over the years, the condition of the rivers, lake and ponds has been degraded in terms of water pollution, river environment and ecosystem . Based on previous studies, the middle of the Cameron Highlands catchment area with its agriculture and urban pollution sources are the most exposed part of the area. Because of the agricultural activities, the land clearing for development and the road construction, the water quality of rivers has declined . The previous study of Lee et al.  showed HCH and DDT levels between 38.3 and 78.3 ng/g and between 19.0 and 113.8 ng/g respectively in the sediment of the Cameron highlands Rivers in 1998. From this study, the risk of contamination by intensive agriculture activities was assumed. Likewise, even though lindane was banned in 2003 in Malaysia , there is still evidence of lindane existence in the environment [25, 45, 46].
This study was performed to investigate the existence and associated risks of organochlorine pesticides namely hexachlorocyclohexane isomers (HCH) and dichlorodiphenyltrichloroethane family (DDT) in the aqueous phase, including water and sediment in the Cameron Highlands Catchment Area.
Result and discussion
Topological and meteorological effects
HCHs and DDTs distribution in eight stations in water (ng/L) and surface sediment (ng/g) of Bertam and Telom rivers-2011-Cameron Highlands-Malaysia
HCHs in the water and sediment
HCHs in the sediment ranged from not detected to 59.17 (Figure 1), with a mean of 8.06 ng/g, which is quite similar Zhou et al.  study (2.43-86.25 ng/g) in Daya Bay China. Higher values of HCHs (19.0-113.8 ng/g) in sediment were reported by Lee et al. . γ-HCH, among HCH isomers was the most abundant in sediment and water. Insecticides containing HCHs are used in agriculture as well as for eradicating mites and lice in human and animals .
DDTs in the water and sediment
DDT and HCH composition
Seasonal distribution of DDT and HCH
HCHs and DDTs seasonal distribution in eight stations in water of Bertam and Telom rivers-2011-Cameron Highlands-Malaysia
HCHs and DDTs seasonal distribution in eight stations in surface sediment of Bertam and Telom rivers-2011-Cameron Highlands-Malaysia
HCH isomers frequency and α/γ ratio
The slight differeces in the dry and wet seasons for HCH isomers sequence (table 3 and 4) could be resulted of the effect of rainfall or different pattern of pesticide usage.An increase in α-HCH in the wet season in the water samples especially at the Taman Sedia and Golf course stations, maybe due to the soil erosion at the nearby agricultural areas with previous usage of technical HCH.
γ,β and δ-HCH isomers were detected in most of the water and sediment samples, whereas α-HCH was below the detection level in the majority of the samples (Figure 4). Better transportation of α-HCH than the other isomers and stopping the use of technical may explain this observation. β-HCH, the most persistent isomer of HCH because of its lower vapour pressure, was found to be in higher concentration than other isomers in two of the stations. The level of β-HCH (ranged from 0.916 to 9.713 ng/L) detected at the lower most station, which is the lake of Habu, revealed that most HCHs came from older residues indicating the cumulative effect which appeared in the most persistent isomer of β-HCH at the last station. In contrast, δ-HCH was found most frequently in sediment after γ-HCH.
γ-HCH also known as lindane, has been banned for agriculture use in Malaysia since the last 10 years, was the most predominant isomer found in 75% of the stations. Generally, the most common isomers of HCHs in environment are γ,β and α-HCH, however, γ-HCH and δ-HCH were the most prevalent isomers detected in the most stations in current study. Similar results were reported by Zhou et al.  for Qiantang River and Kuranchie-Mensah  for Densu River basin.
DDT metabolites frequency and (DDE + DDD)/ DDT ratio
HCHs and DDTs distribution has closely involved in various main parameters. Beyond the HCHs and DDTs chemical characterizations, the features of environmental circumstances exceed one or more of these parameters in importance. First Malaysia with the features of a tropical and developing country and second Cameron Highland as a forest, massive agricultural, rural, and tourist region and third the times gone by usage of OCPs and finally, the policy of the country to reduce DDTs and HCHs all together make the most pieces of DDTs and HCHs distribution puzzle in the area.
The rainfall pattern caused to produce more HCHs and DDTs from soil erosion from the contaminated area of the past and fairly new usage, mostly in wet season.
γ-HCH and DDE were the most often found components which come from both historical applications and new inputs as well.
The study confirmed degradation of the DDT along the river in the all stations. The degradation to DDE and DDD were 50:50 in dry season meanwhile during the wet season the value of DDE is more, resulting from aerobic degradation of DDT.
HCHs and DDTs residues near and tourist and agricultural activity sites were higher than the other sites far from point source pollutions in the water, even in the sediment samples. The spatial distributions of HCHs in water and sediment were not similar, which reflected in reduced HCHs transportation rate in sediment in comparison with water. The results in this study show no obvious correlation between HCHs residue in the water and sediment, but moderate and even good correlation for gamma HCH at stations closer to pollution sources. Thus, modelling for the HCH residues is complicated due to the historical applications, unknown point sources and the distance from source of pollution in addition to metrological, topological and hydrological specifications of the area. Moreover, it is quite possible to find gamma HCH residue in sheltered cultivation crops, which should be investigated further.
Study area and sampling intervals
Stations coordination and mean of physicochemical characteristics of water and particle size of sediment samples
Particle size sediment
N 04 32 998
E 101 24 666
N 04 35 329
E 101 25 022
N 04 29 225
E 101 23 065
N 04 28.900
E 101 22.230
N 04 28 580
E 101 22 885
N 04 28 467
E 101 23 045
N 04 25 871
E 101 23 275
N 04 26 565
E 101 23 280
The ampoule of mixed of organochlorine pesticide standards consisted of α-HCH, β-HCH, γ-HCH, δ-HCH, 4,4′DDT, 4,4′DDE, 4,4′DDD was obtained from the Supelco (Belle–Fonte, USA). The stock solution (200 ppm) of mixed OCPs was prepared in 10 mL n-hexane. Fresh working standard solutions containing a mixture of the mixed of OCP, surrogates (2, 4, 5, 6-tetrachloro-m-xylene & decachlorobiphenyl) and the internal standard component (pentachloronitrobenzene( was prepared by stepwise dilution of the stock solution with range 1.95, 3.91, 7.81, 15.63, 31.25 and 62.5 μg L-1. The sediment samples were collected with a Peterson grab sampler to depth of about 5cm. The sediment samples were wrapped in aluminium foil and stored at 4°C until analysis. 250 g of the sediment was collected from each station to determine particle size. Water samples were collected in glass bottles. The samples were kept at 4°C prior extraction process. A multi-parameter portable device (YSI) was used for onsite measurements of temperature, electrical conductivity, total dissolved solids, salinity and turbidity of the rivers. Organic free water was prepared by passing distilled water through a filter bed containing about 250 g of activated carbon [55, 56] and stored in a cleaned narrow-mouth bottle with teflon septa and screw cap. All the glassware was rinsed with an analytical n-hexane before use. All the solvents which were used for extraction, cleanup and enhancement were pesticide grade. The anhydrous sodium sulphate was purified by heating at 400°C for 4 hrs. The florisil (PR Grade) was used for cleanup in an activated form .
A gas chromatograph mass spectrometer (GC/MS) analyses were performed on an Agilent 7890A gas chromatograph (GC) directly coupled to the mass spectrometer system (MS) of an Agilent 5975C inert MSD with a triple-axis detector to confirm the order of components. Method Detection Limit (MDL) was found by carrying on a laboratory fortified blank as a real sample. The values for MDL were found between 0.003 and 0.006 μg/L, and Method Quantification Level (MQL) was found between 0.008 and 0.015 μg/L and 0.002 and 0.004 μg/g for water and sediment, respectively. The internal standard concentration was kept constant in all solutions as 100 μg/L. Relative response factor was applied to quantify data. Percentage recoveries were verified by the surrogate component. Surrogate standards were added to each sample to monitor the extraction performance and matrix effects. A recovery value between 75 to 125 percent was considered to quantification and 65 to 135 percent for qualification as well. The concentrations of OCPs were not modified by the recovery ratios of the surrogates. Every sample were analysed in triplicate and the average amount was applied in data analysing.
The sediment water content was determined by oven drying of about 25 g of wet sediment for 12 h at 105°C. A series of mesh sieves ranged from 0.0125 to 64 mm were applied to determine particle size of the sediment samples. 10.00 g of air dried grounded homogenised sediment sample mixed with 10 g of anhydrous sodium sulphate, which was spiked with 1mL of 0.160 ppm surrogate solutions were extracted with 300 mL n-hexane/acetone 50:50 for six hours in a soxhlet extractor. The extracted volume was reduced by a rotovap to about five mL. This reduced extracted volume was loaded on to the cleanup column filled by 20 g of activated florisil. The cleanup column was eluted three times with 65 mL of n-hexane, 45 mL of 70:30 n-hexane/dichloromethane and 55 mL of dichloromethane. The cleaned up solution was concentrated by evaporating from solvent by use of a rotovap. This solution was further concentrated to 2 mL by a stream of nitrogen. 1 μL litre of the concentrated solution was spiked with 1 μL 100 ppm of internal standard exactly before an injection into the GC-ECD.
1000 mL of water sample which it was spiked with 1 mL of 0.080 ppm surrogate solution and added 5 mL methanol was passed through a 6 mL capacity C18 cartridge. The cartridge was optimized with 5 mL ethyleacetate, 5 mL dichloromethane, 10 mL methanol and 10 mL organic free water before use. And it was eluted by 5 mL ethyleacetate and 5 mL dichloromethane. This eluted solution was concentrated by a stream of nitrogen to 1 mL. 1 μL of the concentrated solution was spiked with 1 μL of 100 ppm internal standard exactly before an injection to the GC-ECD.
A Varian chromopack CP-3800 Gas Chromatograph was applied to analyse the OCP in the samples. The instrument was equipped with a 63Ni electron capture detector and a 30 m × 0.32 mm i.d (0.25 μm film thickness) HP-5ms fused silica capillary column. Nitrogen gas was used as the carrier gas at 1.5 mL/min. The oven temperature was kept at 90°C for 1 minute and increased to 170°C at a rate of 3.5°C/min and then to 280°C at a rate of 5°C/min. The injector and detector temperatures were adjusted at 250 and 300°C respectively. 1 μL of each sample was injected to the GC-ECD for separation and quantitative analysis.
The authors thank the ALIR-UKM staff and En Man Ghani for technical assistance in running the GC. Part of the project is financed by OUP grant of UKM-OUP-NBT-29-152/2011
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