Organochlorine Pesticides in the Han River, Korea

Sang Hee Hong, Donghao Li, and Jae Ryoung OH

1. Introduction

Organochlorine pesticides are one of the most persistent, ubiquitous, and toxic pollutants in estuarine and marine ecosystem.  Their high bioaccumulation potential and harmful biological effects have aroused global concern about ecological disturbance since the 1960s and they have been determined in various environmental media [1, 2, 3].

Organochlorin pesticides contamination of estuarine and marine waters is closely linked to anthropogenic activities [4].  Organochlorine pesticides mainly enter the aquatic environment through agricultural and domestic application.

Unlike metals, there are no known natural sources of some organochlorine compounds such as PCBs and synthetic pesticides (e.g., DDT).  Their occurrence in the environment is therefore entirely the consequence of their production and use by man, principally on land.  Some organic contaminants do however have natural sources.  For example, certain PAHs can be produced during combustion (e.g., in forest fires).

Organic contaminants such as PCBs are highly stable and degrade only very slowly in the environment.  Their widespread occurrence coupled with their persistence has led to concern over the possibility that these compounds may accumulate in more vulnerable compartments of the marine environment, such as in marine mammals, including seals.

As with metals, trace organic contaminants are subject to a variety of processes that influence their occurrence in the environment.  Many of the compounds have low solubility in seawater and show a high affinity for adsorption onto sediments; once adsorbed their dispersion pattern will follow that of the sediment [5].  Sediment movements are in turn affected by, e.g., tidal energy and such physical characteristics as grain size.  These and other factors, including subtle differences in the behaviour of individual PCB congeners, necessitate a careful interpretation of basic information on concentrations.

As far as matrix is concerned, it is known that surface sediments are the ultimate sink for most contaminants.  Therefore, the study of their contaminant content is an important indicator for pollution studies.

Even though it is not high, some pesticides which were banned because of their toxicity and persistence in the late 1960s and early 1970s (Table 1) were still found in the environment of Korea.

Table 1.  Regulation of EDCs in Korea

EDCs	Related Act	Regulation	Year
Aldrin	Toxic Chemicals Control Act	Limited Usage
	Agrochemicals Management Act	Banned	1969
Dieldrin	Toxic Chemicals Control Act	Limited Usage
	Agrochemicals Management Act	Banned	1970
Endrin	Toxic Chemicals Control Act	Limited Usage
	Agrochemicals Management Act	Banned	1969
Chlordane	Toxic Chemicals Control Act	Limited Usage
	Agrochemicals Management Act	Banned	1969
Heptachlor	Toxic Chemicals Control Act	Limited Usage
	Agrochemicals Management Act	Emulsion: Banned	1970
		Powder: Banned	1979
DDT	Toxic Chemicals Control Act	Banned	1991
	Agrochemicals Management Act	Wettable: Banned	1969
		Emulsion: Banned	1971

2. Sampling procedure

2.1. Selection of locations

The Han River is the biggest in the South Korea on the basis of the amount of flowing water which starts from the Mt. Taebaek and flows into the Gyonggi Bay. It is 497.25km long and covers 26,018km square area, and it is the fourth largest river in Korea (including the northern part of Korea). The main flow of the Han River is made at the junction of the north-Han River and the south-Han River in Gyonggi Province. The city of Seoul and Gyonggi Province depend entirely on the Han River for its supply of water. The South and North Han Rivers merge at Yangsuri to form the largest river in the country, the Han River, which flows through the heart of Seoul and empties into the Yellow Sea.

Riverine and coastal water sampling sites were selected according to the following criteria:

· The site shall be outside the zone of initial dilution of a dumpsite or point-source discharge, and easy to access

· The water sites will coincide with historical monitoring sites (i.e., on-going Korea Ministry of Environment Endocrine Disruptors Monitoring Program) when feasible and all other criteria are met.

Sampling sites of water are shown in Fig. 1 and 2.

Fig. 1.  Sampling site of water in Korea

Fig. 2.  Sampling sites of Korea

2.Sampling Procedures

2.1. Sampling Procedures

Water samples were collected by using pre-cleaned one liter glass bottles with teflon-lined caps.  Duplicate samples were collected from each sampling sites.  The sampling personnel wore rubber gloves during sampling.  The personnel put the bottle under the surface of the water as it is closed and open it till it becomes a half full.  Close the bottle and take it out.  Shake the bottle 10 seconds and discard water from the bottle.  Put the bottle under the surface of the water as it is closed again and open it till it becomes full.  Close the bottle and take it out.  Open the cap and add surrogate standards to the sample.  Store the sample in the room temperature and ship back to the laboratory as soon as possible.  If it is not possible to analyze the sample immediately, extract the sample with solvent.

2.2. Condition during the sample collection

The weather was fine during water sampling in August , 2002.  Most sampling dates in February, 2003 were sunny and air temperature was mild.

2.3. Sample preparation and analysis

The preparations of water samples for analysis of persistent organochlorine pesticides were in accordance with a little modified standard operating procedures of UNU.

2.3.1. Water preparation

Briefly, 1 liter of water sample, after adding surrogate compounds, was extracted by 50 mL dichloromethane. Extracted solvent was then dehydrated by passing through anhydrous sodium sulfate and then concentrated to approximately 1 mL. The clean up was carried out with silica gel column chromatography.  GC internal standard was added and injected into a gas chromatograph-electron capture detector(GC-uECD) for quantification  and gas chromatograph-mass spectrometer (GC-MS) for confirmation.

Target compounds were quantified by HP6890 GC-mECD and were confirmated by Shimadzu GC/MS-QP2010. The GC column employed for GC-uECD was DB-5 fused silica capillary column (0.25 mm x 30 m) coated with 100% dimethylpolysiloxane at 0.25 um film thickness.   DB-1 fused silica capillary column (0.32 mm x 30 m) coated with 100% dimethylpolysiloxane at 0.25 um film thickness was used for Shimadzu GC/MS-QP2010.

3.  Analytical Results

3.1. Organochlorine pesticides in the Han River in August, 2002

Wide ranges of concentration of organochlorine pesticides were detected in August, with total organochlorine pesticides concentrations ranging from 0.84 to 10.66 ng/L. The highest total organochlorine pesticides concentration detected was at St. 6 (10.66 ng/L).

The individual organochlorine pesticides concentrations in this region ranged from ND to 4.53 ng/L. a-, b-, and g-HCH were present in all the samples.   Endosulfan sulfate, p,p’-DDE, p,p’-DDD were detected in 7 samples out of 8.  d-HCH, g-chlordane, heptachlor epoxide, dieldrin, endrin and p,p’-DDT were present in some samples.  Other organochlorine pesticides, such as a-chlordane and heptachlor appeared sporadically. The highest amounts of individual organochlorine pesticides were b-HCH (4.53 ng/L) and g-HCH (4.02 ng/L) recorded at St. 7 and St. 6, respectively.

St. 4, 6, 7 and 8 are more contaminated than the other sampling stations in the Han River.  This is probably due to input of sewage from mega city Seoul.  Among the eight locations, St. 6 which is very near to the large paddy field was more contaminated than the other locations; the lowest concentration was recorded in St. 1 (see Table 2). St. 7 where the Han River and the Imjin River which flows from North Korea merge also showed high level of organochlorine pesticides.

The mean and concentration ranges at eight locations are shown in the Table 2 below.

Table 2. Mean and Concentration Ranges of OCPs in the Han River in August 2002 (ng/L).

OCPs	Min	Max	Mean	Standard Deviation
a-HCH	0.03	1.59	0.52	0.63
β-HCH	0.01	4.53	1.45	1.65
γ-HCH	0.07	4.02	1.42	1.58
δ-HCH	ND	0.33	0.11	0.12
a-chlordane	ND	0.04	0.02	0.01
γ-chlordane	ND	0.15	0.08	0.07
Heptachlor	ND	0.05	0.04	0.02
Heptachlor epoxide	ND	0.10	0.07	0.04
Aldrin	ND	0.05	0.05	0.02
Dieldrin	ND	2.03	0.79	0.88
Endrin	ND	0.43	0.20	0.15
endosulfan sulfate	ND	0.24	0.11	0.08
p,p'-DDE	ND	0.41	0.15	0.14
p,p'-DDD	ND	0.75	0.23	0.27
p,p'-DDT	ND	1.17	0.35	0.41
Total	0.84	10.66	4.85	3.53

See the Appendix Table 2A for details on site-specific levels

3.2. Organochlorine pesticides in the Han River in February, 2003

Wide ranges of concentration of organochlorine pesticides were detected in February, 2003 as well, with total organochlorine pesticides concentrations ranging from 0.54 (St. 1) to 7.22 ng/L (St. 7). The highest total organochlorine pesticides concentrations detected was at St. 7 (7.22 ng/L).

The individual organochlorine pesticides concentrations in this region ranged from ND to 4.48 ng/L. b-, and g-HCH, endosulfan sulfate, p,p’-DDE, p,p’-DDD were present in all the samples.   a-HCH , p,p’-DDT were detected in 7 samples out of 8.  δ-HCH, a- chlordane, heptachlor epoxide, and endrin were present in some samples.  Other organochlorine pesticides, such as g-chlordane, heptachlor, and dieldrin appeared sporadically.

Similar to August 2002, St. 5, 6, 7 and 8 are more contaminated than the other sampling stations in the Han River.  But St. 4 showed quite low concentration compare to August 2002. 

Among the eight locations, St. 6 which is very near to the large paddy field was more contaminated than the other locations; the lowest concentration was recorded in St. 1 (see Table 3). St. 7 showed highest level of organochlorine pesticides; the lowest concentration was recorded in St. 1 (see Table 3).

The mean and concentration ranges at eight locations are shown in the Table 3 below.

The highest amounts of individual organochlorine pesticides were b-HCH (4.48 and 3.06 ng/L) recorded at St. 7 and St. 8, respectively.

Table 3. Mean and Concentration Ranges of OCPs in the Han River in February 2003 (ng/L).

OCPs	Min	Max	Mean	Standard Deviation
a-HCH	ND	0.58	0.26	0.19
β-HCH	0.05	4.48	1.20	1.67
γ-HCH	0.06	2.87	1.13	1.08
δ-HCH	ND	0.09	0.04	0.03
a-chlordane	ND	0.03	0.02	0.01
γ-chlordane	ND	0.15	0.11	0.07
Heptachlor	ND	0.03	0.02	0.01
Heptachlor epoxide	ND	0.07	0.04	0.03
Aldrin	ND	0.00	ND	0.00
Dieldrin	ND	0.09	0.07	0.04
Endrin	ND	0.36	0.17	0.13
endosulfan sulfate	0.01	0.40	0.13	0.12
p,p'-DDE	0.02	0.28	0.09	0.09
p,p'-DDD	0.01	0.43	0.13	0.14
p,p'-DDT	ND	0.25	0.07	0.08
Total	0.54	7.22	3.19	2.25

See the Appendix Table 3A for details on site-specific levels

3.3. Summary of Results

In most of the water samples, concentrations of organochlorine pesticides were low. 

The total organochlorine pesticide concentrations ranged from 0.84 (St. 1) to 10.66 ng/L (St. 6) in August, 2002 and concentrations ranging from 0.54 (St. 1) to 7.22 ng/L (St. 7) in February, 2003.

b- and g-HCH were present in all the samples. a-HCH, endosulfan sulfate, p,p’-DDE, p,p’-DDD, and p,p’-DDT were present in most samples.  Aldrin and heptachlor were scarcely detected.

Results from this study illustrate the extent of pollution of these undesirable compounds and despite the relatively small size of the overall sampling area, there was considerable variation in the concentration levels from the sites.

It seems that sewage input from Seoul influence the high level of organochlorine pesticides in St. 4, 5, 6, 7 and 8. 

Most organochlorine pesticides were banned about 30 years ago, but because of their persistence in the environment and can be long-range transported by air, they are still detected in the waters of Korea.  So the presence of organochlorine pesticides in Korean waters is probably partly a function of their use in neighbouring countries, including China and North Korea.  There does not appear to be any noticeable trend in the levels of the pollutants detected at various sampling locations.

3.4. Summary of Quality Assurance and Control Measurements

The calibration curve was constructed with a linearity of 0.99(GC-MS). Extraction was performed using a little modified UNU procedure.  The performance of the analytical method was additionally evaluated by replicate analyses of three Standard Reference Materials (SRMs), which were supplied by Shimadzu Co. Ltd.  (Table 4A-6A).

4. Method Detection Limit (MDL)

The method detection limit was determined following the procedures outlined in Federal Register [7].  The MDL for an analyte is established by performing seven replicate analyses of the analyte at a low concentration. The statistical manipulation of this data results in an estimate of the standard deviation (sigma) of its measurement above the corresponding blank response. An MDL set at 3sigma theoretically, would result in only about a 1 percent chance of a false positive, assuming a normal distribution of concentrations at the MDL.  MDL of organochlorine pesticides induced from S/N ration of GC-MS and GC-ECD is shown in Table 7A.

4.  Problems Encountered

We encountered no major problems in the use of the stipulated procedures in this monitoring programme.

5.  Conclusions

Monitoring studies of Korean waters indicate the presence of organochlorine micropollutants of environmental and toxicological interest, among which the organochlorine pesticides play an important role.  Levels of organochlorine pesticides measured can be said to be in the quite low range. This is not surprising, as most organochlorine pesticides were prohibited to use in Korea in the late 1960’s and early 1970’s.  However, these organochlorine pesticides have been detected because they are persistent in the environment and atmospheric deposition could be the source of entry to our environment. In order to understand the fate of these compounds, it is necessary to continue to monitor their presence to elucidate the distribution and behavior of these compounds in various environmental compartments in the Korea context, and compare data with its neighbouring countries like North Korea, China and Japan.

[5] References

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[7] Federal Register (1984), vol. 49, No. 209:198-199.