1
|
Pilote M, Houle D, Gagnon C, Couture S, Dastoor A, Ryjkov A. Key factors influencing Hg levels and trends in unperturbed oligotrophic temperate and boreal lakes. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 356:124232. [PMID: 38823549 DOI: 10.1016/j.envpol.2024.124232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/15/2024] [Accepted: 05/24/2024] [Indexed: 06/03/2024]
Abstract
Mercury (Hg) is a toxic metal that presents a major risk to ecosystems, biota, human health, and remains a priority concern. In temperate and boreal lakes Hg and methylmercury (MMHg) are expected to vary as a function of atmospheric Hg deposition, lake water chemistry, catchment characteristics and climate variables. The aim of this study was to quantify Hg and MMHg in unperturbed oligotrophic lakes and to identify the factors controlling their distribution. We first hypothesized that lake Hg (and MMHg to lesser extent) spatial variations are linked to atmospheric deposition, catchment characteristics, and terrestrial exportation of dissolved organic carbon (DOC). We secondly examined if lake Hg concentrations have followed the decrease in atmospheric Hg emission observed between the mid-1990s to the end-2010s. We found that overall, atmospheric Hg has little impact on lake Hg and MMHg concentrations, which are both primarily influenced by DOC input originating from the forest catchment. The relationship between DOC and Hg differed between the spring and the fall, with a Hg-to-DOC ratio twice as high in spring. This seems related to snowmelt input of Hg (with a relatively reduced input of DOC) or the internal lake build-up of Hg during the ice-covered period. Of the 10 lakes intensively visited over a 20-year period, only 3 showed significant lake Hg decreases despite significant negative trends in atmospheric Hg concentrations, suggesting a lag between atmospheric and surface water temporal trends. Overall, terrestrial catchments retain around 80% of atmospheric Hg implying that large Hg pools have been built up in soils in the last decades. As such, the reduction of atmospheric Hg alone will not necessarily result in Hg decreases in lakes, since the Hg concentrations may be modulated by DOC export trends and catchment characteristics. This stresses the need to improve our understanding of the processes governing Hg transfers from catchments into lakes.
Collapse
Affiliation(s)
- M Pilote
- Environment and Climate Change Canada, Water Science and Technology, Aquatic Contaminants Research Division, 105 McGill Street, Montreal, Qc, H2Y 2E7, Canada.
| | - D Houle
- Environment and Climate Change Canada, Water Science and Technology, Aquatic Contaminants Research Division, 105 McGill Street, Montreal, Qc, H2Y 2E7, Canada
| | - C Gagnon
- Environment and Climate Change Canada, Water Science and Technology, Aquatic Contaminants Research Division, 105 McGill Street, Montreal, Qc, H2Y 2E7, Canada
| | - S Couture
- Environment and Climate Change Canada, Water Science and Technology, Aquatic Contaminants Research Division, 105 McGill Street, Montreal, Qc, H2Y 2E7, Canada
| | - A Dastoor
- Environment and Climate Change Canada, Atmospheric Science and Technology, Air Quality Research Division, 2121 route Transcanadienne, Dorval, Qc, H9P 1J3, Canada
| | - A Ryjkov
- Environment and Climate Change Canada, Atmospheric Science and Technology, Air Quality Research Division, 2121 route Transcanadienne, Dorval, Qc, H9P 1J3, Canada
| |
Collapse
|
2
|
Sharma S, Sharma R, Sahu SK, Kota SH. Transboundary sources dominated PM 2.5 in Thimphu, Bhutan. INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY : IJEST 2021; 19:5649-5658. [PMID: 34226828 PMCID: PMC8243619 DOI: 10.1007/s13762-021-03505-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 06/02/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
This study estimates the potential source regions contributing to PM2.5 in the capital city of Thimphu, Bhutan, during the years 2018-2020 using the ground-based data, followed by the HYSPLIT back trajectory analysis. The average PM2.5 concentration in the entire study period was 32.47 µg/m3 which is three times of the World Health Organization recommended limit of 10 µg/m3. Less than half of the days in pre-monsoon (43.47%) and post-monsoon (46.41%), and no days in winter were within the 24-h average WHO guideline of 25 μg/m3. During the COVID-19 lockdown imposed from August 11 to September 21 in Bhutan, only a marginal reduction of 4% in the PM2.5 concentrations was observed, indicating that nonlocal emissions dominate the PM2.5 concentrations in Thimphu, Bhutan. Most back trajectories in the analysis period were allocated to south or south-west sector. India was the major contributor (~ 44%), followed by Bangladesh (~ 19%), Bhutan itself (~ 19%) and China (~ 16%). This study confirms that there are significant contributions from transboundary sources to PM2.5 concentrations in Thimphu, Bhutan, and the elevated PM2.5 concentrations need to be tackled with appropriate action plans and interventions.
Collapse
Affiliation(s)
- S. Sharma
- Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016 India
| | - R. Sharma
- Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016 India
| | - S. K. Sahu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084 China
| | - S. H. Kota
- Department of Civil Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016 India
| |
Collapse
|
3
|
Janssen SE, Riva-Murray K, DeWild JF, Ogorek JM, Tate MT, Van Metre PC, Krabbenhoft DP, Coles JF. Chemical and Physical Controls on Mercury Source Signatures in Stream Fish from the Northeastern United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:10110-10119. [PMID: 31390861 DOI: 10.1021/acs.est.9b03394] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Streams in the northeastern U.S. receive mercury (Hg) in varying proportions from atmospheric deposition and legacy point sources, making it difficult to attribute shifts in fish concentrations directly back to changes in Hg source management. Mercury stable isotope tracers were utilized to relate sources of Hg to co-located fish and bed sediments from 23 streams across a forested to urban-industrial land-use gradient within this region. Mass-dependent isotopes (δ202Hg) in prey and game fish at forested sites were depleted (medians -0.95 and -0.83 ‰, respectively) in comparison to fish from urban-industrial settings (medians -0.26 and -0.38 ‰, respectively); the forested site group also had higher prey fish Hg concentrations. The separation of Hg isotope signatures in fish was strongly related to in-stream and watershed land-use indicator variables. Fish isotopes were strongly correlated with bed sediment isotopes, but the isotopic offset between the two matrices was variable due to differing ecosystem-specific drivers controlling the extent of MeHg formation. The multivariable approach of analyzing watershed characteristics and stream chemistry reveals that the Hg isotope composition in fish is linked to current and historic Hg sources in the northeastern U.S. and can be used to trace bioaccumulated Hg.
Collapse
Affiliation(s)
- Sarah E Janssen
- United States Geological Survey, Upper Midwest Water Science Center , Middleton , Wisconsin 53562 , United States
| | - Karen Riva-Murray
- United States Geological Survey, New York Water Science Center , Troy , New York 12180 , United States
| | - John F DeWild
- United States Geological Survey, Upper Midwest Water Science Center , Middleton , Wisconsin 53562 , United States
| | - Jacob M Ogorek
- United States Geological Survey, Upper Midwest Water Science Center , Middleton , Wisconsin 53562 , United States
| | - Michael T Tate
- United States Geological Survey, Upper Midwest Water Science Center , Middleton , Wisconsin 53562 , United States
| | - Peter C Van Metre
- United States Geological Survey, Texas Water Science Center Austin , Texas 78754 , United States
| | - David P Krabbenhoft
- United States Geological Survey, Upper Midwest Water Science Center , Middleton , Wisconsin 53562 , United States
| | - James F Coles
- United States Geological Survey, New England Water Science Center Northborough , Massachusetts 01532 , United States
| |
Collapse
|
4
|
Zhou H, Zhou C, Hopke PK, Holsen TM. Mercury wet deposition and speciated mercury air concentrations at rural and urban sites across New York state: Temporal patterns, sources and scavenging coefficients. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 637-638:943-953. [PMID: 29763876 DOI: 10.1016/j.scitotenv.2018.05.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 04/12/2018] [Accepted: 05/04/2018] [Indexed: 06/08/2023]
Abstract
Measurements of ambient speciated mercury (Hg) concentrations and Hg wet deposition were made at two urban sites (Bronx, NY and Rochester, NY) and one rural site (Potsdam, NY) in New York State in 2013 and 2014 to: 1) determine the factors influencing Hg wet deposition concentrations, 2) identify the contribution of gaseous oxidized Hg (GOM) and particulate bound Hg (PBM) scavenging to Hg wet deposition concentrations, and 3) identify potential source areas associated with high concentration events. The Bronx had the highest mean gaseous elemental Hg (GEM) and GOM concentrations, Rochester had the highest mean PBM and the lowest GOM concentrations, and Potsdam had the lowest mean GEM and PBM concentrations. The annual volume weighted mean (VWM) Hg concentrations and Hg wet deposition fluxes in the Bronx, Rochester, and Potsdam were significantly different with mean values of 10.3 ± 8.16, 10.2 ± 9.06, and 5.07 ± 1.79 ngL-1 and 8.45 ± 0.64, 6.65 ± 0.21, and 5.25 ± 0.49 μg/m2 year-1, respectively. Hg wet deposition flux and precipitation depth were positively correlated at all three sites as were Hg concentration in precipitation and weekly GOM concentrations at the Bronx and Potsdam sites. Scavenging coefficients (SC) of 680, 630, 850 for GOM and 410, 320, and 410 for PBM at Bronx, Rochester, and Potsdam, respectively, suggest GOM is responsible for most of the scavenged Hg. Measured GOM and PBM concentrations were relatively constant before precipitation events and Hg concentrations in precipitation did not vary significantly during precipitation events implying the scavenging process mainly occurred in clouds. VWM Hg concentrations, monthly accumulated Hg flux, and SCs for GOM and PBM were higher at the urban sites and significantly different for non-snow and snow events. Local sources appeared more important at the rural site while regional sources affected high urban concentrations.
Collapse
Affiliation(s)
- Hao Zhou
- Center for Air Resources Engineering and Science, Clarkson University, Potsdam 13699, NY, United States
| | - Chuanlong Zhou
- Department of Civil and Environmental Engineering, Clarkson University, Potsdam 13699, NY, United States
| | - Philip K Hopke
- Center for Air Resources Engineering and Science, Clarkson University, Potsdam 13699, NY, United States; Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester 14642, NY, United States.
| | - Thomas M Holsen
- Department of Civil and Environmental Engineering, Clarkson University, Potsdam 13699, NY, United States
| |
Collapse
|
5
|
Holmes CD, Krishnamurthy NP, Caffrey JM, Landing WM, Edgerton ES, Knapp KR, Nair US. Thunderstorms Increase Mercury Wet Deposition. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:9343-50. [PMID: 27464305 DOI: 10.1021/acs.est.6b02586] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Mercury (Hg) wet deposition, transfer from the atmosphere to Earth's surface by precipitation, in the United States is highest in locations and seasons with frequent deep convective thunderstorms, but it has never been demonstrated whether the connection is causal or simple coincidence. We use rainwater samples from over 800 individual precipitation events to show that thunderstorms increase Hg concentrations by 50% relative to weak convective or stratiform events of equal precipitation depth. Radar and satellite observations reveal that strong convection reaching the upper troposphere (where high atmospheric concentrations of soluble, oxidized mercury species (Hg(II)) are known to reside) produces the highest Hg concentrations in rain. As a result, precipitation meteorology, especially thunderstorm frequency and total rainfall, explains differences in Hg deposition between study sites located in the eastern United States. Assessing the fate of atmospheric mercury thus requires bridging the scales of global transport and convective precipitation.
Collapse
Affiliation(s)
- Christopher D Holmes
- Department of Earth, Ocean, and Atmospheric Science, Florida State University , Tallahassee, Florida 32306, United States
| | - Nishanth P Krishnamurthy
- Department of Earth, Ocean, and Atmospheric Science, Florida State University , Tallahassee, Florida 32306, United States
| | - Jane M Caffrey
- Center for Environmental Diagnostics and Bioremediation, University of West Florida , Pensacola, Florida 32514, United States
| | - William M Landing
- Department of Earth, Ocean, and Atmospheric Science, Florida State University , Tallahassee, Florida 32306, United States
| | - Eric S Edgerton
- Atmospheric Research & Analysis, Inc. , Cary, North Carolina 27513, United States
| | - Kenneth R Knapp
- National Centers for Environmental Information, National Oceanic and Atmospheric Administration , Asheville, North Carolina 28801, United States
| | - Udaysankar S Nair
- Department of Atmospheric Science, University of Alabama , Huntsville, Alabama 35805, United States
| |
Collapse
|