Seasonal Variation in Gross Ecosystem Production, Plant Biomass, and Carbon and Nitrogen Pools in Five High Arctic Vegetation Types

Methylmercury (MeHg) biomagnifies through aquatic food webs resulting in elevated concentrations in fish globally. Stable carbon and nitrogen isotopes are frequently used to determine dietary sources of MeHg and to model its biomagnification. However, given the strong links between MeHg and sulfur cycling, we investigated whether sulfur isotopes (δ34S) would improve our understanding of MeHg concentrations ([MeHg]) in Arctic lacustrine food webs. Delta34S values and total mercury (THg) or MeHg were measured in water, sediments, and biota from six lakes near Resolute Bay, NU, Canada. In two lakes impacted by historical eutrophication, aqueous sulfate δ34S was ∼8‰ more positive than sedimentary δ34S, suggestive of bacterial sulfate reduction in the sediment. In addition, aqueous δ34S showed a significant positive relationship with aqueous [MeHg] across lakes. Within taxa across lakes, [THg] in Arctic char muscle and [MeHg] in their main prey, chironomids, were positively related to their δ34S values across lakes, but inconsistent relationships were found across entire food webs among lakes. Across lakes, nitrogen isotopes were better predictors of biotic [THg] and [MeHg] than δ34S within this dataset. Our results suggest some linkages between Hg and S biogeochemistry in high Arctic lakes, which is an important consideration given anticipated climate-mediated changes in nutrient cycling.

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Seasonal variation in tissue dry biomass and its relative ash and organic carbon and nitrogen content in the freshwater mussel Dreissena polymorpha (Pallas)

Archiv für Hydrobiologie ◽

10.1127/archiv-hydrobiol/127/1993/409 ◽

1993 ◽

Vol 127 (4) ◽

pp. 409-421

Author(s):

Jaap Dorgelo ◽

Michiel H. Kraak

Keyword(s):

Seasonal Variation ◽

Organic Carbon ◽

Nitrogen Content ◽

Dreissena Polymorpha ◽

Freshwater Mussel ◽

Carbon And Nitrogen ◽

Dry Biomass ◽

Carbon And Nitrogen Content

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Carbon and nitrogen pools in Chinese fir and evergreen broadleaved forests and changes associated with felling and burning in mid-subtropical China

Forest Ecology and Management ◽

10.1016/j.foreco.2005.05.030 ◽

2005 ◽

Vol 216 (1-3) ◽

pp. 216-226 ◽

Cited By ~ 58

Author(s):

Yu Sheng Yang ◽

Jianfen Guo ◽

Guangshui Chen ◽

Jinsheng Xie ◽

Ren Gao ◽

...

Keyword(s):

Chinese Fir ◽

Subtropical China ◽

Carbon And Nitrogen ◽

Nitrogen Pools

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Measuring the Labile and Recalcitrant Pools of Carbon and Nitrogen in Forested and Agricultural Soils: A Study under Tropical Conditions

Forests ◽

10.3390/f10070544 ◽

2019 ◽

Vol 10 (7) ◽

pp. 544

Author(s):

Risely Ferraz de Almeida ◽

Joseph Elias Rodrigues Mikhael ◽

Fernando Oliveira Franco ◽

Luna Monique Fonseca Santana ◽

Beno Wendling

Keyword(s):

Agricultural Soils ◽

Soil Surface ◽

Environmental Stability ◽

Management Systems ◽

Human Intervention ◽

Carbon And Nitrogen ◽

Nitrogen Pools ◽

Tropical Conditions ◽

Recalcitrant Carbon ◽

The Impact

Soil organic carbon and nitrogen can be divided into labile and recalcitrant pools according to the time it takes to be cycled. The way in which carbon and nitrogen pools are cycled and distributed between labile and recalcitrant pools can directly relate to soil quality. This paper tested the hypothesis that labile and recalcitrant pools of carbon and nitrogen vary between agricultural soils with different species and fertilization management systems (nitrogen, phosphorus, and potassium need) under tropical conditions. This study aimed to examine the impact of land-uses on stocks and losses of carbon and nitrogen under tropical conditions. We explored labile (soil microbial biomass and labile carbon) and recalcitrant carbon pools (humin, humic acid, and fulvic acid) in forested and agricultural soils, defined as latosol (forest, fertilized pasture, and unfertilized pasture) and cambisol (forest, coast pasture, sugarcane, and silage corn). Forested soil was used as an appropriate use to soil conservation in tropical that presents levels adequate of carbon and nitrogen stocks and biological condition in soil. Results showed that pools of labile and recalcitrant carbon are different on soil layers and the use of soil. Forest use in cambisol and latosol promoted higher labile and recalcitrant pools of carbon and nitrogen due to the greater environmental stability without human intervention. On the other hand, human intervention occurred in fertilized pasture and coast pasture; however, both uses presented similar recalcitrant carbon and nitrogen pools when compared to forested soil on the soil surface due to fertilizer uses and the high volume of the grass root system. Overall, our findings reveal that under tropical conditions, agriculture and forested soil can present similar recalcitrant pools of carbon and nitrogen if agricultural soils are associated with the appropriate fertilizer management. Pasture with adequate fertilization management systems can be used as an alternative to recover degraded areas with low levels of recalcitrant carbon and nitrogen pools.

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