Species-specific isotope tracking of mercury uptake and transformations by pico-nanoplankton in an eutrophic lake

Abstract. The exchange of gaseous elemental mercury, Hg(0), between the atmosphere and terrestrial surfaces remains poorly understood mainly due to difficulties in measuring net Hg(0) fluxes on the ecosystem scale. Emerging evidence suggests foliar uptake of atmospheric Hg(0) to be a major deposition pathway to terrestrial surfaces. Here, we present a bottom-up approach to calculate Hg(0) uptake fluxes to aboveground foliage by combining foliar Hg uptake rates normalized to leaf area with species-specific leaf area indices. This bottom-up approach incorporates systematic variations in crown height and needle age. We analyzed Hg content in 583 foliage samples from six tree species at 10 European forested research sites along a latitudinal gradient from Switzerland to northern Finland over the course of the 2018 growing season. Foliar Hg concentrations increased over time in all six tree species at all sites. We found that foliar Hg uptake rates normalized to leaf area were highest at the top of the tree crown. Foliar Hg uptake rates decreased with needle age of multiyear-old conifers (spruce and pine). Average species-specific foliar Hg uptake fluxes during the 2018 growing season were 18 ± 3 µg Hg m−2 for beech, 26 ± 5 µg Hg m−2 for oak, 4 ± 1 µg Hg m−2 for pine and 11 ± 1 µg Hg m−2 for spruce. For comparison, the average Hg(II) wet deposition flux measured at 5 of the 10 research sites during the same period was 2.3 ± 0.3 µg Hg m−2, which was 4 times lower than the site-averaged foliar uptake flux of 10 ± 3 µg Hg m−2. Scaling up site-specific foliar uptake rates to the forested area of Europe resulted in a total foliar Hg uptake flux of approximately 20 ± 3 Mg during the 2018 growing season. Considering that the same flux applies to the global land area of temperate forests, we estimate a foliar Hg uptake flux of 108 ± 18 Mg. Our data indicate that foliar Hg uptake is a major deposition pathway to terrestrial surfaces in Europe. The bottom-up approach provides a promising method to quantify foliar Hg uptake fluxes on an ecosystem scale.

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Phytoplankton nutrient limitation in a polymictic eutrophic lake: community versus species-specific responses

Fundamental and Applied Limnology / Archiv für Hydrobiologie ◽

10.1127/1863-9135/2007/0169-0057 ◽

2007 ◽

Vol 169 (1) ◽

pp. 57-68 ◽

Cited By ~ 21

Author(s):

D. F. Burger ◽

D. P. Hamilton ◽

J. A. Hall ◽

E. F. Ryan

Keyword(s):

Nutrient Limitation ◽

Eutrophic Lake ◽

Species Specific

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A bottom-up quantification of foliar mercury uptake fluxes across Europe

10.5194/bg-2020-289 ◽

2020 ◽

Author(s):

Lena Wohlgemuth ◽

Stefan Osterwalder ◽

Carl Joseph ◽

Ansgar Kahmen ◽

Günter Hoch ◽

...

Keyword(s):

Leaf Area ◽

Tree Species ◽

Growing Season ◽

Deposition Flux ◽

Foliar Uptake ◽

Bottom Up ◽

Needle Age ◽

Uptake Rates ◽

Mercury Uptake ◽

Species Specific

Abstract. The exchange of gaseous elemental mercury, Hg(0), between the atmosphere and terrestrial surfaces remains poorly understood mainly due to difficulties in measuring net Hg(0) fluxes on the ecosystem scale. Emerging evidence suggests foliar uptake of atmospheric Hg(0) to be a major deposition pathway to terrestrial surfaces. Here, we present a bottom-up approach to calculate Hg(0) uptake fluxes to aboveground foliage by combining foliar Hg uptake rates normalized to leaf area with species-specific leaf area indices. This bottom-up approach incorporates systematic variations in crown height and needle age. We analyzed Hg content in 583 foliage samples from six tree species at 10 European forested research sites along a latitudinal gradient from Switzerland to Northern Finland over the course of the 2018 growing season. Foliar Hg concentrations increased over time in all six tree species at all sites. We found that foliar Hg uptake rates normalized to leaf area were highest at the top of the tree crown. Foliar Hg uptake rates decreased with needle age of multi-year old conifers (spruce and pine). Average species-specific foliar Hg uptake fluxes during the 2018 growing season were 18 ± 3 µg Hg m−2 for beech, 26 ± 5 µg Hg m−2 for oak, 4 ± 1 µg Hg m−2 for pine and 11 ± 1 µg Hg m−2 for spruce. For comparison, the average Hg(II) wet deposition flux measured at 5 of the 10 research sites during the same period was 2.3 ± 0.3 µg Hg m−2, which was four times lower than the site-averaged foliar uptake flux of 10 ± 3 µg Hg m−2. Scaling up site-specific foliar uptake rates to the forested area of Europe resulted in a total foliar Hg uptake flux of approximately 20 ± 3 Mg during the 2018 growing season. Considering that the same flux applies to the global land area of temperate forests, we estimate a foliar Hg uptake flux of 108 ± 18 Mg. Our data indicate that foliar Hg uptake is a major deposition pathway to terrestrial surfaces in Europe. The bottom up approach provides a promising method to quantify foliar Hg uptake fluxes on an ecosystem scale.

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Impact of hypolimnetic oxygenation on profundal macroinvertebrates in a eutrophic lake in central Alberta. II. Changes in Chironomus spp. abundance and biomass

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f97-123 ◽

1997 ◽

Vol 54 (9) ◽

pp. 2170-2181 ◽

Cited By ~ 11

Author(s):

W P Dinsmore ◽

E E Prepas

Keyword(s):

Dissolved Oxygen ◽

Eutrophic Lake ◽

Minor Importance ◽

Fish Food ◽

Anoxic Conditions ◽

South Basin ◽

Hypolimnetic Oxygenation ◽

Species Specific ◽

Oxygen Concentrations

Effects of hypolimnetic oxygenation on profundal (15-25 m depth) Chironomus spp. in double-basined Amisk Lake were studied from 1988 to 1991. Responses were species specific. Mean densities and biomasses of C. anthracinus at 25 m increased 55- and 109-fold, respectively, in the treated north basin over the study period. Densities also increased in the reference south basin, but mean larval weights and biomasses were significantly lower than in the treated basin (P < 0.001). Anoxic conditions in the hypolimnion (dissolved oxygen concentrations <1 mg ·L-1), rather than low hypolimnetic temperatures, appeared to limit C. anthracinus distribution in Amisk Lake. Major changes in C. anthracinus abundance were not apparent until 2 years after the treatment commenced. Densities and biomasses of C. cucini were higher in the reference basin than in the treated basin of Amisk Lake. Densities of the C. decorus and C. plumosus groups increased in the treated basin but remained of minor importance. In comparison, densities of the C. cucini and C. plumosus groups at 25 m in the reference south basin of nearby Baptiste Lake declined over the study period. Increased profundal Chironomus spp. abundance in Amisk Lake suggested an increase in potential fish food.

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Electron Microscopy in the Study of Natural Phytoplankton Assemblages

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119831 ◽

1985 ◽

Vol 43 ◽

pp. 620-623

Author(s):

Linda Sicko-Goad

Keyword(s):

Electron Microscopy ◽

Aquatic Environment ◽

Size Range ◽

Physical Parameters ◽

Specific Information ◽

Phytoplankton Assemblages ◽

Phytoplankton Productivity ◽

Ecosystem Effects ◽

Time Of Year ◽

Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

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