By Quirin Schiermeier and Yana Balling

A week after around one million cubic meters of red sludge escaped from a Hungarian alumina factory, an analysis commissioned by the environmental group Greenpeace has revealed that more than 50 tonnes of arsenic may have been released as a result of the spill.

The sludge, a by-product of alumina (aluminum oxide) production, has killed at least seven people and contaminated several thousand hectares of land north of Hungary's Lake Balaton on October 4, which escaped contamination. The village of Kolontár and two smaller villages may have to be abandoned completely, and scientists predict that the environment will take years to recover.

The Greenpeace analysis, by Austria's Federal Environment Agency in Vienna, examined the heavy metal content of mud samples collected by campaigners on October 5.

In addition to containing almost twice as much arsenic (110 milligrams per kilogram dry mass) as expected for the red mud resulting from aluminum oxide production, the concentrations of mercury and chromium are also relatively high, says chemist Herwig Schuster, chief Greenpeace campaigner for Central and Eastern Europe. "Because arsenic is readily soluble we might be in for a major groundwater problem," he adds.

Work in progress

The study has met with skepticism from Hungarian chemists, partly because bauxite, the ore from which most aluminum oxide (and ultimately aluminum) is derived, contains neither mercury nor much arsenic. However, Greenpeace says that the findings have been confirmed by an independent laboratory in Hungary. The Hungarian government's own figures--based on samples taken by scientists last week at two sites in the area--are yet to be published.

"It's hard to say what needs to be done as long as we don't know exactly which and how much toxic substances have been released," says Gergely Simon, an environmental chemist for the Hungarian arm of the Clean Air Action Group. He has asked the Hungarian home office to reveal all of the information collected so far on the mud's chemical composition.

János Szépvölgyi, director of the Hungarian Academy of Science's Institute of Materials and Environmental Chemistry in Budapest, is heading up the government effort to analyze soil and water in the area.

"All life is dead," he says. "A two- to five-centimeter-thick layer of caustic mud is covering the soil. The mud needs to be physically collected and removed--this will take a long time."

On the basis of a preliminary analysis, Szépvölgyi says, "We know that the mud contains some 2 percent titanium and 0.5 percent vanadium oxide. But the real problem is dissolved heavy metals, which might enter surface waters and will be taken up by plants."

But preliminary analysis of their samples, he adds, suggests that the content of dissolved arsenic and chromium is manageable. The most contaminated surface water flows are a small creek called Torma and the Marcal river. The Rába river, a tributary of the Danube, is less affected, and contamination in the Danube is almost negligible, says Szépvölgyi.

But he stresses that the findings are preliminary, and that the water quality of all creeks and rivers in the area must be checked regularly.

The analysis, which includes the results of a laboratory analysis of samples taken on Friday by scientists at the Academy's Research Institute for Soils Science and Agricultural Chemistry in Budapest, will be released later this week, says Szépvölgyi.

Water hazard

Schuster says that Greenpeace's figures suggest that the drinking water supplies of at least 100,000 people could be affected by potentially toxic levels, including inhabitants of the city of Györ downstream of the contaminated rivers. Exactly how fast and far the contamination will spread depends on the permeability of local soils--which scientists have not yet assessed.

The Greenpeace findings are surprising, says Tamás Weiszburg, a mineralogist at the Eötvös Loránd University in Budapest, who was not involved in either analysis.

Although small amounts of arsenic in bauxite sludge might have accumulated over time, "If that [Greenpeace] sample is representative there is no question that industrial wastes have been mixed in the basin," says Weiszburg.

Greenpeace also suspects that the leaked basin may have contained toxic waste besides the sludge from aluminum oxide production.

"Environmental standards for old plants in Hungary are lagging far behind the European rules for newly built production facilities," says Schuster. "We don't even know in which year the dam was built and how often it was modified."

Meanwhile, the Hungarian government has warned that there is a real danger of a second toxic spill from the same site. Another dam on the site looks weak, and if it breaks several hundred thousand tonnes of sludge could flood the surrounding land and rivers.

The government said last week that it will have experts from the Geological Institute of Hungary in Budapest re-assess the safety of three more storage sites that together hold about 50 million tonnes of red mud. Some 30 million tonnes are held at Ajka, 12 million tonnes at Almásfüzít and 8 million tonnes at Mosonmagyaróvár. The Almásfüzít and the Mosonmagyaróvár are situated in the immediate vicinity of the river Danube.