eGEOTRACES

Factsheet #3: Mercury

Mercury (Hg) is emitted to the environment through natural and anthropogenic sources. Natural sources of Hg include mainly volcanoes, hydrothermal events, rock weathering, and soil and vegetation emissions (including natural forest fires). Anthropogenic sources of Hg include mainly coal combustion, smelting of metals, gold and silver mining, and chloralkali production using mercury or mercury compounds, and all human combustion processes. Since the industrial revolution anthropogenic mercury inputs exceed natural inputs by at least a factor of five

The UNEP Minamata Convention was ratified in August 2017 and aims to protect human health from mercury exposure by reducing anthropogenic, inorganic, mercury emissions. The most toxic and biomagnifying mercury species, methylmercury, is not emitted from anthropogenic or natural sources, but produced in the ocean from inorganic mercury.

Atlas

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Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Shedding light on Arctic Mercury

New research is now shining a light on mercury cycling on the Arctic shelf.

Linear correlation between Dissolved Gaseous Mercury and Dissolved Inorganic Carbon opens new modelling perspectives

Živković and his colleagues led a close study of the mercury speciation along the 40°S GEOTRACES section.

Mercury stable isotopes constrain atmospheric pathways to the ocean

The study’s results hold promise that the implementation of anti-pollution measures under the Minamata Convention will likely result in a faster decrease of oceanic mercury levels than previously thought.

Loss of old Arctic sea ice increases methylmercury concentrations

Researchers from the SCRIPPS, the Stockholm Natural Museum and the Mediterranean Institute of Oceanography show the importance of sea ice composition on methylmercury budgets

Precise estimate of the mercury export from the Arctic to the Atlantic Ocean

Using new observations acquired during GEOTRACES Arctic cruises, a refined arctic mercury budget has been established

Arctic mercury export flux with marine particles higher than anticipated

In the ocean, the residence time of mercury (Hg), is largely driven by two removal mechanisms: evasion to the atmosphere and downward export flux with settling particles. The later was […]

Want to learn more?

Watch the talk of Dr. Katlin Bowman “Mercury biogeochemistry in the Arctic Ocean” given as part of the webinar series “Breaking the Ice Ceiling” organized by a coalition of institutions including The Arctic Institute, Women in Polar Sciences, and Women of the Arctic:

Factsheet #2: Dissolved lead

Lead (Pb) occurs naturally in the environment as a trace element. Lead major natural sources include volcanoes and weathering of rocks. Human activities, including mining, coal combustion, addition to gasoline and waste incineration, have greatly increased the distribution and abundance of lead in the environment. Increased usage and then phasing-out of leaded-petrol since the mid-70s yielded a decrease of this contamination.

Lead can enter the ocean by atmospheric deposition and fluvial freshwaters are common to other trace metals. Therefore, lead provides a proxy of trace metal inputs to the ocean. Isotopic ratios of Pb can be applied to determining the source material (ie. gasoline, coal) or the source location (ie. Asia, North America) of Pb inputs.

By measuring lead concentrations and isotopes GEOTRACES scientists reveal for the first time that natural lead can be detected again in the surface water of the North Atlantic. Indeed, significant proportions of up to 30–50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters off the Sahara. This clearly reflects the success of the global effort to reduce anthropogenic Pb emissions. Indeed, the increased usage and then phasing-out of leaded petrol since the mid-70s yielded a decrease in this pollution.

Atlas

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Atlantic Ocean:

Indian Ocean:

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Shedding light on Arctic Mercury

New research is now shining a light on mercury cycling on the Arctic shelf.

Linear correlation between Dissolved Gaseous Mercury and Dissolved Inorganic Carbon opens new modelling perspectives

Živković and his colleagues led a close study of the mercury speciation along the 40°S GEOTRACES section.

Mercury stable isotopes constrain atmospheric pathways to the ocean

The study’s results hold promise that the implementation of anti-pollution measures under the Minamata Convention will likely result in a faster decrease of oceanic mercury levels than previously thought.

Loss of old Arctic sea ice increases methylmercury concentrations

Researchers from the SCRIPPS, the Stockholm Natural Museum and the Mediterranean Institute of Oceanography show the importance of sea ice composition on methylmercury budgets

Precise estimate of the mercury export from the Arctic to the Atlantic Ocean

Using new observations acquired during GEOTRACES Arctic cruises, a refined arctic mercury budget has been established

Arctic mercury export flux with marine particles higher than anticipated

In the ocean, the residence time of mercury (Hg), is largely driven by two removal mechanisms: evasion to the atmosphere and downward export flux with settling particles. The later was […]

Factsheet #1: Dissolved Iron

Phytoplankton which lives at the surface of the oceans is responsible of half of the Earth oxygen production, through photosynthesis. In addition, it is fixing dissolved carbon (CO2) of atmospheric origin as solid particles which, when dying, are falling as detritus in the abyss and the sediment. This mechanism called the “Biological Carbon Pump” is an important sink for the anthropogenic CO2. Understanding the processes leading to phytoplankton development is thus a major issue for present-day climate modelling and the prediction of our future climate.

Iron (as other trace metals) is essential for the photosynthesis success of most of the phytoplanktonic species. However, its abundance in the marine waters is extremely low and its absence is limiting the phytoplankton development in roughly half of the world’s oceans. This led to the development of studies of artificial ocean iron fertilization, the hypothesis being that stimulating photosynthesis will improve the capacity of the ocean to absorb CO2. However, thanks to studies on the iron distribution and fate it is now proved that artificial ocean iron fertilization will never produce the expected result as photosynthesis continues to be limited due to the complexity of processes at play in surface waters. Such results prevent wasting money in useless operations.

Thus, to understand the carbon pump functioning or to test geoengineer’s hypothesis, studying the oceanic iron cycle is essential. This includes: understanding the iron sources to the ocean, its sinks, its distribution, etc. GEOTRACES is elucidating these questions, as well as, producing high-quality data and representing it on an electronic Atlas that helps to easily convey the information.

Find below a summary of main GEOTRACES findings and products on iron research:

Atlas

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Atlantic Ocean:

Pacific Ocean:

3D scenes showing the distribution of dissolved iron in the Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high concentrations of dissolved iron. The diversity of hydrothermal iron inputs is identified along Mid Oceanic Ridges in the two basins. Important release of dissolved iron from the sediments are indicated along the African, South American, Asian and Peruvian coasts.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on iron research:

Shedding light on Arctic Mercury

New research is now shining a light on mercury cycling on the Arctic shelf.

Linear correlation between Dissolved Gaseous Mercury and Dissolved Inorganic Carbon opens new modelling perspectives

Živković and his colleagues led a close study of the mercury speciation along the 40°S GEOTRACES section.

Mercury stable isotopes constrain atmospheric pathways to the ocean

The study’s results hold promise that the implementation of anti-pollution measures under the Minamata Convention will likely result in a faster decrease of oceanic mercury levels than previously thought.

Loss of old Arctic sea ice increases methylmercury concentrations

Researchers from the SCRIPPS, the Stockholm Natural Museum and the Mediterranean Institute of Oceanography show the importance of sea ice composition on methylmercury budgets

Precise estimate of the mercury export from the Arctic to the Atlantic Ocean

Using new observations acquired during GEOTRACES Arctic cruises, a refined arctic mercury budget has been established

Arctic mercury export flux with marine particles higher than anticipated

In the ocean, the residence time of mercury (Hg), is largely driven by two removal mechanisms: evasion to the atmosphere and downward export flux with settling particles. The later was […]

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved iron:

Rechercher