英语文摘:Surface ocean mercury levels triple as human activities increase

LONDON, Aug. 7 (Xinhua) -- Mercury levels in the ocean have more than tripled in some regions as a result of human activities, a new report published in this week's Nature magazine showed.

Mercury is a toxic trace metal that accumulates in aquatic organisms. Its emissions to the environment have increased significantly as a result of activities such as mining and fossil fuel combustion.

Estimates of the amount of mercury that have reached the ocean as a result of anthropogenic perturbations remain uncertain, and are largely based on model studies, owing to a lack of appropriate historical data.

The new study by American researchers from Woods Hole Oceanographic Institution, presents an observation-based estimate of the total amount of anthropogenic mercury in the global ocean.

They report oceanographic measurements of total dissolved mercury and related parameters from several recent expeditions to the Atlantic, Pacific, Southern and Arctic oceans.

Their findings suggest that human disturbances to the global mercury cycle have led to an approximately 150 percent increase in the amount of mercury in thermocline waters and have more than tripled the mercury content of surface waters since the beginning of the Industrial Revolution, with almost two-thirds of the mercury residing in water shallower than 1,000 meters.

According to the researchers, this information may add to our understanding of the processes and the depths at which inorganic mercury is converted into toxic methyl mercury, and subsequently incorporated into marine food webs.