China collaborates with Norway to address prevalence and spread of mercury

Highly skilled basic science researchers from China are pooling their talents with analytical environmental researchers from Norway - and their findings are making their mark on Chinese environmental policy.

Since the early 1990s, Norwegian Thorbjørn Larssen has been collaborating with Chinese students and researchers to map pollutants and their environmental impacts in China. The key research questions he and his Chinese colleagues have been investigating all these years relate to the prevalence and spread of mercury.

Their research has paid off with findings that have helped to convince Chinese authorities to cooperate actively within the UN Environment Programme (UNEP) on developing a global cooperation agreement on mercury waste.

Alarming mercury exposure

"It turns out the Chinese are most exposed to mercury when eating rice," explains Professor Larssen, "in contrast to Norwegians, who ingest nearly all their mercury through fish."

Methylation of mercury in nature and its subsequent uptake in the food chain are the common denominators of Chinese and Norwegian mercury exposure. Inorganic mercury converts to methylmercury under certain environmental conditions in wetlands such as Norway's marshes and China's rice fields. Methylmercury - a far more toxic compound than inorganic mercury - can be absorbed by, and accumulate in, living organisms such as fish and rice.

"It has long been known that methylmercury can form in Norwegian marshes and lake sediments and be taken up by fish. But our discovery - that methylation occurs in rice fields as well, and is thus the primary pathway of exposure for people eating rice - is new," says Professor Larssen, Senior Research Scientist at the Norwegian Institute for Water Research (NIVA) and Adjunct Professor in Environmental Chemistry at the University of Oslo.

Complementing strengths

Thorbjørn Larssen has only good things to say about the cooperative effort and knowledge sharing between Chinese and Norwegian researchers.

"Chinese researchers are leaders in some of the classical research disciplines. For instance, their research groups have a strong tradition in chemical analysis of pollutants. One reason for this is that China spends a great deal on infrastructure and advanced instruments. In this respect we could learn a lot from them," says Professor Larssen.

"But the Chinese educational system does not teach critical thinking to pupils and students to the extent we do in Norway. Here, they have something to learn from us."

Billions are affected

"In our projects we have studied conditions in inland China, so we are quite certain that our findings apply to hundreds of millions of inland Chinese. But if it's true that rice is also the main pathway of mercury exposure in the other Asian countries where people eat rice three times a day, there are billions of people being exposed to the substance by this means."

Disrupts foetal development

Even low levels of mercury exposure have been shown to affect the human foetus. Data from studies in the Faroe Islands indicate that development of the foetal nervous system is somewhat delayed if the mother has ingested moderate amounts of mercury.

"The difference in development rate is not that great, so this is not very dangerous at the levels most individuals ingest through a normal diet. But on the scale of an entire society, high mercury exposure can mean losing some of the most brilliant minds."

Nevertheless, he does not worry excessively for the average Chinese:
"Most mainland Chinese are exposed to less mercury than are most Norwegians. Our team, however, works in particularly polluted mining areas where there truly is cause for concern."

High price for experience

Although little of the heavy industry on mainland Norway pollutes much today, highly polluting industrial activities were rampant just a few decades ago. For example, industrial methods at the zinc works in Odda (75 km inland of Bergen) turned nearby Sørfjord into one of the world's most polluted fjords. Today, by contrast, Odda's zinc production is one of the world's least polluting. Nevertheless, mercury concentrations remain high in the fjord's innermost recesses, and cautions against excessive consumption of fish and shellfish from the area still stand.

"This case from Norway's industrial past has equipped environmental researchers and politicians with valuable experience that is extremely relevant for China now, such as: How did we solve the technical and political problems of mercury discharge? How did the Norwegian authorities work: with or against the industry? And how did Norwegians deal with the problem of a polluting company that formed a cornerstone of the local community?"

Practical training, simple measures

Working with public Chinese research institutes, Dr Larssen and his colleagues have mapped the actual concentrations of mercury in the environment. They have given uncomplicated training to scientists and environmental management authorities alike on how to collect, interpret, analyse and communicate data.

"Through learning by doing, the authorities have understood that it is possible to accomplish something. In fact, the Chinese have an enormous potential to reduce discharges by implementing some simple yet highly effective countermeasures," asserts Professor Larssen. 

"For instance, they have many slag piles from current or previous mercury production. These seep, and it is tremendously costly to move the piles and encapsulate them to remove the contamination completely. But we have shown them how they can mitigate the problem using straightforward, affordable measures."

"Firstly, they can reduce the seeping from the slag piles to some extent. They can also construct dams downstream, before the mercury enters a river. And they can get local farmers to avoid the common practice of growing rice immediately downstream from the slag piles. Much of the polluted water currently runs straight into the rice fields. If instead the farmers were to receive a little support to grow corn there, for instance, this would reduce exposure a great deal. Corn absorbs very little mercury," explains the professor, "whereas rice growing in water where mercury methylation is occurring takes up a lot of it."

Research influences policy

After a long process of building trust and establishing contacts, the professor and his Chinese research colleagues are now working to raise knowledge and awareness among the Chinese authorities about mercury and other pollutants.

"Through the course of the four-year project period, the Chinese authorities have come to understand the need to act. Now they are cooperating within UNEP to develop a global cooperation agreement on mercury waste. This is excellent progress, and China now has one of the largest and most active delegations in the negotiations for the upcoming Mercury Convention," says Professor Larssen. The goal is to have drafted a wording by 2013.

"This process is incredibly important for China and the rest of the world. Over the next three years, the country will be collecting large amounts of data to assess the situation and the problems and opportunities this superpower has to reduce its discharges."