Fate and Transport of Pollutants in the Environment

Introduction

Air emission and water discharge introduce anthropogenic pollutants into the environment. The physical, chemical and biological transformations of pollutants in atmospheric and aquatic environments play a critical role in their toxicity and contamination pathways that render health, welfare and ecological effects. Sophisticated analytical and modeling tools are required to understand the complex interactions between the released pollutants and natural constituents. These understandings form the basis for policy making and environmental protection pertinent to water and air quality.

Dr. Lin’s Environmental Modeling & Assessment Laboratory develops, evaluates and applies first-principle and statistical models to determine the causes of pollution events, to delineate pollutant source-receptor relationship, and to understand the global biogeochemical cycling of persistent pollutants.

Model Development & Evaluation

Atmospheric & aquatic models are mathematical representations of concurring processes in the natural environment. The parameterization and formulation allow scientific analysis of complicated interactions and serve as predictive tools for pollution events after rigorous model validation ad evaluation.

                  Chemical cycling of mercury in the natural environment

                              Chemical cycling of mercury in the natural environment

Lin C.-J., Singhasuk P., Pehkonen S. O. “Atmospheric Chemistry of mercury,” inEnvironmental Chemistry and Toxicology of Mercury, (Eds.) G. Liu et al., John Wiley & Sons, Inc., New York, USA, 2011.

Source Apportionment of Pollutants

An important task in environmental assessment is to identify the emission sources and determine their relative contribution to the pollution. Such apportionments provide valuable data for policy makers to formulate strategies for water and air quality management. Using first-principle models, the emission from a specific source can be isolated and the source contribution to a pollution scenario can be calculated. Based on the source strength,  the  required degree of emission reduction to attain air/water quality goals are then estimated.

                   Relative strength of contributing emission source categories

                                        Relative strength of contributing emission source categories

Lin C.-J., Shetty S., Pongprueksa P., et al. “Source Attribution for Mercury Deposition in the Contiguous US.” Journal of Air & Waste Management Ass., 62, (1), 52-63, 2012.

Intercontinental Transport of Pollutants

Long-lived air pollutants (e.g., mercury & toxic organics) are persistent in the environment and subject to long-range transport at regional and global scales. Under favorable meteorological conditions, transport of air pollutants from East Asia to North America take 7-10 days. Such events can be simulated using atmospheric circulation models coupled with chemistry modules describing air dispersion & chemical transformation.

        Long-range transport of air pollutants across the Pacific Ocean

                            Long-range transport of air pollutants across the Pacific Ocean

Lin C.-J., Pan L., Pongprueksa P., et al. “Estimating Mercury Emission Outflow from East Asia Using CMAQ-Hg.” Atmospheric Chemistry and Physics, 10, (4), 1853-1864,2010.

Biogeochemical Cycling 

Pollutants undergo regional & global cycling via biogeochemical processes that distribute the pollutant in different environmental compartments (soil, air, water, biomass, etc.). Using process model coupled with stable isotopic tracing techniques, the translocation and accumulation of pollutants can be confidently determined.

                  Schematics of pollutant cycling in forest ecosystems

                               Schematics of pollutant cycling in forest ecosystems

Cui L., Feng X., Lin C.-J., et al. “Accumulation & Translocation of 198Hg in Vegetation.”Environmental Toxicology & Chemistry , 33, 334-340, 2014.