April 26, 1999, Monday

 

 LENGTH: 1595 words

 

 HEADLINE: Toxin threatens Mekong delta

 

 BYLINE: BY JAMES FAHN / The Nation

 

[This is a corrected version of the original story, which contained some errors in the units used for the mercury findings.]

 

 A THAI-FRENCH research team testing water quality in Vietnam has discovered "extremely high" levels of mercury, a dangerous neurotoxin,at

 several locations in and around the Mekong delta.

 

 The highest levels were recorded in the waters around Vung Tau, a centre for fishing, tourism and offshore petroleum operations located east of

 Ho Chi Minh City, where the dissolved total mercury level was found to be 40 times greater than the standard set for Thailand's coastal waters.

 The Vietnamese government, however, has set far looser standards.

 

 Samples of fresh water from the Bassac River, one of the many rivers that make up the delta, also revealed significant contamination by

 mercury. The highest level in the river was recorded at a site near the city of Can Tho, but mercury was also found further downstream. The

 source of the contamination -- or rather sources, since the two locations are relatively far apart -- are unknown, although attention around Vung

 Tau has focused on the area's petroleum industry, particularly the offshore producers of oil and natural gas.

 

 At first glance, the situation appears to mirror that in Thailand, where there has been concern over mercury contamination for several years now.

 The heavy metal is found naturally in the gas reservoirs under the Gulf of Thailand, and in the "produced water" that is pumped up along with the

 gas from deep underground.

 

 In the past, all the mercury-contaminated waste-water was treated and then discharged into the sea. Some platforms in the Gulf, however, now

 re-inject the produced water back into underground wells. The gas fields offshore of Vung Tau are also known to be contaminated by mercury.

 

 A Vietnamese official has confirmed that Vietsovpetro -- a Russian-Vietnamesejoint venture that runs the petroleum production operation in the

 Bach Ho ("White Tiger") and Rong ("Dragon") fields southeast of Vung Tau -- releases its produced water into the sea after treating it.

 

 But Vietnam is "not anxious" about mercury contamination, the official claimed, because both the gas and the produced water contain only low

 levels of mercury. As in Thailand, there could be other significantsources releasing the heavy metal into the environment, most notably in the

 waste-water discharges from onshore industrial firms.

 

 The latest findings nevertheless indicate that mercury contamination has expanded beyond the Gulf of Thailand and is turning into a regional

 phenomenon. Contamination of the marine food chain could pose a serious public health threat, as mercury poisoning in humans is known to

 cause birth defects, damage to the nervous system, and -- if ingested in sufficient quantities -- ultimately proves fatal.

 

 The report on Vietnam was the result of research carried out by a team of scientists that included Dr Manuwadi Hungspreugs from the faculty of

 marine science at Chulalongkorn University and Dr Daniel Cossa of IFREMER, a marine research institute in Nantes, France. Funding was

 provided by the European Union as part of a broader study on the Mekong delta. The findings were presented in a paper at a conference in

 Chiang Rai last year.

 

 "The [mercury] values found in the Hau [or Bassac] River branch and from stations off the mouth of [the] Saigon River near Vung Tau were

 considerably higher than the others, and there were extremely high total mercury values at one station near Vung Tau and another at Can Tho," the

 authors state. "This set of results showed that more intensive study must be taken on mercury contamination to find out the cause and the

 remedy."

 

 The researchers tested the water for both reactive mercury, a type that easily evaporates into the atmosphere, and dissolved total mercury,

 Manuwadi explained. The analysis was precise, she added, as technicians at IFREMER calculated mercury concentrations down to the level of

 parts per tiillion (pptr). Most of the results found dissolved total mercury levels in and around the Mekong delta to be between 0.9 and 13.5 pptr.

 

 However, the total mercury registered at sample site number two, just offshore of Vung Tau, was an alarming 4,140 pptr, which is well over the

 Thai standard for mercury dissolved in coastal waters, set at 100 pptr. Vietnamese standards are far less strict. They are set at five parts per

 billion (ppb) -- equal to 5,000 pptr -- for bathing and aquaculture areas, and 10 ppb (10,000 pptr) for other marine areas.

 

 A water quality official with Vietnam's National Environment Agency (NEA) acknowledged that the mercury standards for coastal water are low in

 Vietnam. She said they should be changed later this year. The source, who asked not to be named, said that the NEA has tested coastal waters

 for mercury contamination around both Danang and Vung Tau from 1995 to 1998, but she would not reveal the results.

 

 Manuwadi explained that her team of researchers might have found even more total mercury present at sample site number one, also near Vung

 Tau. But the sample was thrown out, she said, because the results were so high the technicians were afraid there had been some kind of error in

 the measuring process. At any rate, there was 30 per cent more reactive mercury at sample site one compared to sample site two.

 

 Similar caution was exercised with one of the samples from the Bassac River. "We are very conservative when it comes to reporting this kind of

 data," Manuwadi stressed. "We wanted to be extra careful there were no mistakes involved."

 

 Nevertheless, another sample from the Bassac river near Can Tho also showed an elevated amount of total mercury dissolved in the water: 1,580

 pptr. Vietnam's standards for mercury in fresh water are stricter than those for coastal water: they have been set at 1 ppb (1,000 pptr) at sites

 near inlets for drinking water, and 2 ppb (2,000 pptr) elsewhere, which is equivalent to Thai standards.

 

 Several Vietnamese water experts from Can Tho and Ho Chi Minh City were contacted by The Nation, but all were puzzled about the origins of

 the mercury contamination within the delta. Manuwadi was similarly baffled, but said she was told there is a shipyard and a naval base in the area.

 

 

 Around Vung Tau, meanwhile, attention has generally turned to the petroleum producers, especially given Thailand's experience. "There is a

 probability that the [mercury] contamination could be caused by the produced water from the nearby oil extraction platform off Vung Tau," notes

 the research paper, which adds that a Russian researcher named A Alekseev had found extremely high levels of cadmium in the sediment from

 this area.

 

 In 1996, officials from British Petroleum, which has a joint venture with Norway's Statoil to explore several offshore concessions in Vietnam, told

 The Nation that "a small amount of mercury" was present in the gas found at the Lan Tay field, which is located roughly 400 kilometres southeast

 of Vung Tau but is not yet in operation.

 

 Meanwhile, Malaysia-based Petronas Carigali and Japan's JVPC have recently begun producing oil from other offshore fields north of Bach Ho.

 However, Vietsovpetro's operations in the Bach Ho field are the closest to Vung Tau, about 110 kilometres away, and have been working since

 1984, according to Nguyen Duc Huynh, director of Petro Vietnam's Research and Development Centre for Petroleum Safety and Environment

 (RDCPSE). But, he added, "this problem is not anxious to Vietnam [since the] mercury concentration is not high in [the] gas and [related]

 petroleum wastes".

 

 Petro Vietnam, a state-owned oil firm, is one of the main partners in the Vietsovpetro consortium, which produces both oil and natural gas from

 the Bach Ho field and is now slated to take over operations at the offshore Dai Hung oil field. The other partner is Russia's Petroleum Ministry,

 Nguyen Duc Huynh said.

 

 The official, whose research centre has been carrying out environmental surveys around the Bach Ho field since 1994, claimed that mercury levels

 in the produced water discharged by Vietsovpetro last year was less than 2 ppb. Mercury concentration in the seawater around the platforms is

 less than 1 ppb, he added.

 

 Mercury in the sediment at the gas field, meanwhile, was measured at 90 ppb, slightly over the background level of 70 ppb, according to the

 official. The drilling cuttings dumped into the sea from the platforms contain 360 ppb of mercury, four times over the background level. Barite,

 which is used to prepare drilling muds, is also released into the sea, but contains almost no mercury, he said.

 

 Nguyen Duc Huynh noted that mercury levels in the sediment offshore of Vietnam were far lower than the levels reported around the gas

 production platforms in the Gulf of Thailand, which reach as high as 51 ppm (or 51,000 ppb).

 

 However, the mercury levels found dissolved in Vietnamese water by the EU-funded researchers dwarf anything reported in Thailand, where the

 highest mercury readings revealed by the Pollution Control Department is 480 pptr, measured at the Map Ta Phud industrial port in Rayong in

 February 1996.

 

 Nguyen Thanh Tin, a water quality expert at the Centre of Water Quality and Environment in Ho Chi Minh City, pointed that some factories in Dong

 Nai province, an industrial zone outside the city, use mercury in their production processes. It's possible the heavy metal is being discharged in

 their waste-water and running off into the sea, he said.

 

 The Nation also attempted to contact Dr Nguyen Ngoc Sinh, director-generalof Vietnam's National Environment Agency, but he was unavailable

 for comment.