Session Title :

Defining "natural" and "anthropogenic" mercury impacts

Synopsis :

This session will include presentations that discuss emissions of mercury to the atmosphere from different sources (anthropogenic, geogenic, aquatic, terrestrial). Presentations will cover emissions inventories, archives of historical impact, terrestrial and ocean emissions and global modeling. The goal of this session is to develop a consistent definition of natural and anthropogenic mercury sources.

Description :

Humans have been releasing mercury to the environment since antiquity, resulting in a significant accumulation in the ocean, atmosphere, and terrestrial ecosystems. Anthropogenic mercury emitted to the atmosphere is subsequently deposited and can be re-emitted, effectively prolonging the residence time of this mercury in the environment. In the same manner, mercury released to surface terrestrial and aquatic ecosystems will actively cycle with the atmosphere before being sequestered in stable, longer-lived pools. This re-emitted component of anthropogenic mercury is referred to as legacy mercury and potentially makes up a substantial fraction of present-day emissions. The full extent to which legacy anthropogenic mercury impacts present-day biogeochemical cycling is poorly understood. And because legacy emissions and environmental fate are so poorly characterized, estimating natural emissions is confounded.

Goals & Objectives

This session will focus on achieving a better understanding of the global budget of natural and legacy anthropogenic emissions, and how past releases influence the global cycling of mercury we observe today. The emphasis will be on global biogeochemical cycling, with complementary regional and local perspectives. Specific goals of the session include:

• Estimates of natural and legacy anthropogenic mercury emissions, at present-day and over historical timescales, developed in concert with estimates of primary anthropogenic emissions.
• Quantifying releases of anthropogenic mercury from products and processes to aquatic and terrestrial ecosystems.
• A better understanding of how mercury (of anthropogenic or natural origin) propagates between the atmosphere, ocean, and terrestrial ecosystems.
• A better understanding of how past releases of mercury influence present-day distributions in the environment.

Importance to conference attendees

One of the critical tasks of the UNEP legally binding instrument on mercury is to regulate anthropogenic releases to the environment. Fundamental to this task is having an adequate quantitative understanding of natural and anthropogenic sources of mercury and their impact on mercury cycling. Our session will provide a forum for state-of-the-science observations and modeling of mercury sources. The session is relevant to the broader mercury community by including speakers from the aquatic, terrestrial, and atmospheric perspectives.