scholarly journals Effects of temperature and organic pollution on nutrient cycling in marine sediments

2015 ◽  
Vol 12 (15) ◽  
pp. 4565-4575 ◽  
Author(s):  
C. Sanz-Lázaro ◽  
T. Valdemarsen ◽  
M. Holmer
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Nutrient Cycling ◽  
Water Column ◽  
Temperature Rise ◽  
Nutrient Release ◽  
Organic Pollution ◽  
Coastal Sediments ◽  
Effect Of Temperature ◽  
Climate Change Scenarios

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems. In these systems sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, increased linearly with temperature and were significantly higher under organic pollution than under nonpolluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and it was significantly higher in organic polluted compared to nonpolluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible for this behavior. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at a temperature rise > 6 °C could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.

scholarly journals Effects of global climate change and organic pollution on nutrient cycling in marine sediments

2015 ◽  
Vol 12 (1) ◽  
pp. 21-49
Author(s):  
C. Sanz-Lázaro ◽  
T. Valdemarsen ◽  
M. Holmer
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Nutrient Cycling ◽  
Water Column ◽  
Temperature Rise ◽  
Nutrient Release ◽  
Organic Pollution ◽  
Coastal Sediments ◽  
Effect Of Temperature ◽  
Climate Change Scenarios

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems, where sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios especially when the interactions among drivers may not be just additive. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, and increased linearly with temperature and were significantly higher under organic pollution than under non-polluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and was significantly higher in organic polluted compared to non-polluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible of this behaviour. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at temperature rise >6 ° could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.

scholarly journals Elevated temperature and browning increase dietary methylmercury, but decrease essential fatty acids at the base of lake food webs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pianpian Wu ◽  
Martin J. Kainz ◽  
Fernando Valdés ◽  
Siwen Zheng ◽  
Katharina Winter ◽  
...  
Keyword(s):  
Climate Change ◽  
Fatty Acids ◽  
Organic Matter ◽  
Food Webs ◽  
Essential Fatty Acids ◽  
Trophic Levels ◽  
Climate Change Scenarios ◽  
Essential Nutrients ◽  
Aquatic Food Webs ◽  
Aquatic Food

AbstractClimate change scenarios predict increases in temperature and organic matter supply from land to water, which affect trophic transfer of nutrients and contaminants in aquatic food webs. How essential nutrients, such as polyunsaturated fatty acids (PUFA), and potentially toxic contaminants, such as methylmercury (MeHg), at the base of aquatic food webs will be affected under climate change scenarios, remains unclear. The objective of this outdoor mesocosm study was to examine how increased water temperature and terrestrially-derived dissolved organic matter supply (tDOM; i.e., lake browning), and the interaction of both, will influence MeHg and PUFA in organisms at the base of food webs (i.e. seston; the most edible plankton size for zooplankton) in subalpine lake ecosystems. The interaction of higher temperature and tDOM increased the burden of MeHg in seston (< 40 μm) and larger sized plankton (microplankton; 40–200 μm), while the MeHg content per unit biomass remained stable. However, PUFA decreased in seston, but increased in microplankton, consisting mainly of filamentous algae, which are less readily bioavailable to zooplankton. We revealed elevated dietary exposure to MeHg, yet decreased supply of dietary PUFA to aquatic consumers with increasing temperature and tDOM supply. This experimental study provides evidence that the overall food quality at the base of aquatic food webs deteriorates during ongoing climate change scenarios by increasing the supply of toxic MeHg and lowering the dietary access to essential nutrients of consumers at higher trophic levels.

scholarly journals ESTIMATION OF PHOSPHORUS AND NITROGEN RELEASED BY THE BREEDING OF OREOCHROMIS NILOTICUS IN CAGES IN THE TOHO AND TODOUGBA LAGOONS(SOUTHER BENIN) BETWEEN 2017 AND 2020

2021 ◽  
Vol 9 (11) ◽  
pp. 422-430
Author(s):  
Achoh Mardochee Ephraim ◽  
◽  
Agadjihouede Hyppolite ◽  
Gangbe Luc ◽  
Aizonou Romaric ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Oreochromis Niloticus ◽  
Nutrient Release ◽  
Laboratory Analysis ◽  
The Other ◽  
Production Data ◽  
Nitrogen Concentrations ◽  
High Production

The present study aim to estimate the ratio of aquaculture in the phosphorus and nitrogen concentrations determined in the Toho - Todougba lagoons. For this purpose, the two lagoons were subdivided into 7 stations for the determination of phosphorus and nitrogen concentrations in the water column. Production data from 2017 to 2019 were collected from the Direction of the Ficheries Production and from the literature. Data for 2020 were collected directly from fish farmers. Annual tilapia production was estimated by year and the amounts of phosphorus and nitrogen released from aquaculture are deduced based on the ratio of Montanhini Neto & Ostrensky (2013). The concentration of each of these nutrients was estimated by station and compared to the concentration determined by laboratory analysis of the water. This methodology shows that the amount of phosphorus and nitrogen released to the environment varies from 0.49 mg/L to 0.18 mg/L for phosphorus and from 1.53 mg/L to 0.58 mg/L for nitrogen. The lowest values are obtained in 2020 and differ significantly from the other years (p <0.05). The quantity of phosphorus discharged is higher at the high production stations (Tonon 0.20 mg/L and Lokohoue 0.11 mg/L). Some of this is stored in the sediment. The nitrogen generated by aquaculture is significantly lower than the average determined in water (p <0.05). However, the concentration determined is still related to the amount of organic matter released due to aquaculture. Although aquaculture is not the only source of nutrient release to water, strategies for aquaculture with less nutrient release should be determined.

scholarly journals Decreased Snow Cover Stimulates Under-Ice Primary Producers but Impairs Methanotrophic Capacity

mSphere ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Sarahi L. Garcia ◽  
Anna J. Szekely ◽  
Christoffer Bergvall ◽  
Martha Schattenhofer ◽  
Sari Peura
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Water Column ◽  
Relative Abundance ◽  
Heterotrophic Bacteria ◽  
Methane Emissions ◽  
Boreal Lakes ◽  
Climate Change Scenarios ◽  
Primary Producers ◽  
Microbial Composition

ABSTRACT Climate change scenarios anticipate decreased spring snow cover in boreal and subarctic regions. Forest lakes are abundant in these regions and substantial contributors of methane emissions. To investigate the effect of reduced snow cover, we experimentally removed snow from an anoxic frozen lake. We observed that the removal of snow increased light penetration through the ice, increasing water temperature and modifying microbial composition in the different depths. Chlorophyll a and b concentrations increased in the upper water column, suggesting activation of algal primary producers. At the same time, Chlorobiaceae, one of the key photosynthetic bacterial families in anoxic lakes, shifted to lower depths. Moreover, a decrease in the relative abundance of methanotrophs within the bacterial family Methylococcaceae was detected, concurrent with an increase in methane concentration in the water column. These results indicate that decreased snow cover impacts both primary production and methane production and/or consumption, which may ultimately lead to increased methane emissions after spring ice off. IMPORTANCE Small lakes are an important source of greenhouse gases in the boreal zone. These lakes are severely impacted by the winter season, when ice and snow cover obstruct gas exchange between the lake and the atmosphere and diminish light availability in the water column. Currently, climate change is resulting in reduced spring snow cover. A short-term removal of the snow from the ice stimulated algal primary producers and subsequently heterotrophic bacteria. Concurrently, the relative abundance of methanotrophic bacteria decreased and methane concentrations increased. Our results increase the general knowledge of microbial life under ice and, specifically, the understanding of the potential impact of climate change on boreal lakes.

scholarly journals Mud, microbes, and macrofauna: seasonal dynamics of the iron biogeochemical cycle in an intertidal mudflat

2020 ◽  
Author(s):  
Jacob P. Beam ◽  
Sarabeth George ◽  
Nicholas R. Record ◽  
Peter D. Countway ◽  
David T. Johnston ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Community ◽  
Seasonal Dynamics ◽  
Solid Phase ◽  
Nutrient Release ◽  
Coastal Sediments ◽  
Biogeochemical Cycle ◽  
Intertidal Mudflat ◽  
Iron Cycling ◽  
Natural Ecosystems

AbstractMicroorganisms and burrowing animals exert a pronounced impact on the cycling of redox sensitive metals in coastal sediments. Sedimentary metal cycling is likely controlled by seasonal processes including changes in temperature, animal feeding behavior due to food availability, and availability of organic matter in sediments. We hypothesized that the iron biogeochemical cycle and associated sedimentary microbial community will respond to seasonal changes in a bioturbated intertidal mudflat. In this study, we monitored the spatiotemporal dynamics of porewater and highly reactive solid phase iron with the corresponding prokaryotic and eukaryotic sedimentary microbial communities over one annual cycle from November 2015 to November 2016. Continuous and seasonally variable pools of both porewater Fe(II) and highly reactive iron (FeHR) were observed throughout the season with significant increases of Fe(II) and FeHR in response to increased sediment temperature in summer months. Maximum concentrations of Fe(II) and FeHR were predominantly confined to the upper 5 cm of sediment throughout the season. Iron-oxidizing and -reducing microorganisms were present and stable throughout the season, and exhibited strong depth-dependent stratification likely due to availability of Fe(II) and FeHR pools, respectively. Otherwise, the community was dominated by Deltaproteobacteria, which are involved in sulfur and potentially iron cycling, as well as Gammaproteobacteria and Bacteroidetes. The microbial community was relatively stable throughout the seasonal cycle, but showed strong separation with depth, probably driven by changes in oxygen availability and organic matter. The relative abundance of diatoms revealed a noticeable seasonal signature, which we attribute to spring and fall blooms recorded in the sediments. Macro-, meio, and microfauna were detected throughout the season with some seasonal variations that may influence sedimentary iron transformations by active microbial grazing. The seasonal dynamics of the sedimentary iron cycle are controlled by numerous, interdependent processes, with macrobiota-microbiota relationships and depth stratification comprising primary components. Deciphering these processes in natural ecosystems is essential to understand how they might respond to future environmental perturbations, such as anthropogenic nutrient release to coastal systems.

scholarly journals Diverging responses of high-latitude CO<sub>2</sub> and CH<sub>4</sub> emissions in idealized climate change scenarios

2020 ◽  
Author(s):  
Philipp de Vrese ◽  
Tobias Stacke ◽  
Thomas Kleinen ◽  
Victor Brovkin
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Global Warming ◽  
21St Century ◽  
High Latitude ◽  
Climate Change Scenarios ◽  
Climate Scenarios ◽  
Soil Co2 ◽  
Linear Dependency ◽  
Soil Co2 Emissions

Abstract. The present study investigates the response of the high latitude's carbon cycle to in- and decreasing atmospheric greenhouse gas (GHG) concentrations in idealized climate change scenarios. For this, we use an adapted version of JSBACH – the land-surface component of the Max-Planck-Institute for Meteorology's Earth system model (MPI-ESM) – that accounts for the organic matter stored in the permafrost-affected soils of the high northern latitudes. To force the model, we use different climate scenarios that assume an increase in GHG concentrations, following the Shared Socioeconomic Pathway 5, until peaks in the years 2025, 2050, 2075 or 2100, respectively. The peaks are followed by a decrease in atmospheric GHGs that returns the concentrations to the levels at the beginning of the 21st century. We show that the soil CO2 emissions exhibit an almost linear dependency on the global mean surface temperatures that are simulated for the different climate scenarios. Here, each degree of warming increases the fluxes by, very roughly, 50 % of their initial value, while each degree of cooling decreases them correspondingly. However, the linear dependency does not mean that the processes governing the soil CO2 emissions are fully reversible on short timescales, but rather that two strongly hysteretic factors offset each other – namely the vegetation's net primary productivity and the availability of formerly frozen soil organic matter. In contrast, the soil methane emissions show almost no increase with rising temperatures and they are consistently lower after than prior to a peak in the GHG concentrations. Here, the fluxes can even become negative and we find that methane emissions will play only a minor role in the northern high latitudes' contribution to global warming, even when considering the gas's high global warming potential. Finally, we find that the high-latitude ecosystem acts as a source of atmospheric CO2 rather than a sink, with the net fluxes into the atmosphere increasing substantially with rising atmospheric GHG concentrations. This is very different to scenario simulations with the standard version of the MPI-ESM in which the region continues to take up atmospheric CO2 throughout the entire 21st century, confirming that the omission of permafrost-related processes and the organic matter stored in the frozen soils leads to a fundamental misrepresentation of the carbon dynamics in the Arctic.

scholarly journals VOLUME AND HEAT TRANSPORTS ANALYSIS IN THE SOUTH ATLANTIC BASIN RELATED TO CLIMATE CHANGE SCENARIOS

2015 ◽  
Vol 33 (2) ◽  
Author(s):  
Lívia Maria Barbosa Sancho ◽  
Luiz Paulo De Freitas Assad ◽  
Luiz Landau
Keyword(s):  
Climate Change ◽  
Fluid Dynamics ◽  
Water Column ◽  
Heat Transport ◽  
South Atlantic ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Climate Change Scenarios ◽  
Geophysical Fluid Dynamics ◽  
Zonal Section ◽  
Advective Heat Transport

ABSTRACT. This study evaluates how climate change might affect advective heat and volume transports in the South Atlantic Basin based on Intergovernmental Panel on Climate Change (IPCC) A1FI and B1 climate change scenarios projections. Using the Climatic Model 2.1 (CM2.1) results that were developed by the Geophysical Fluid Dynamics Laboratory (GFDL), integrated on the water column, analyses were conducted through two meridional sections and one zonal section of the study area (between 25◦S-70◦S and 70◦W-20◦E). The annual mean time series were analyzed using historical 100-year climate change scenarios. The analyses of the climate change experiment parameters were compared with those of the H2 climate scenario. The volume transport (VT) through the water column weakened of about 5% in average and the advective heat transport (HT) increased of about 22% at the Drake and Africa-Antarctic (AF-AA) passages at the end of the experiments. For the zonal section at 25◦S, direction oscillations were observed in the integrated VT through the water column due to velocity intensity variations of the water masses and a decrease of about 22% in the HT was observed. Thus, it was observed a decrease in the water and heat supplies at 25◦S due to the Drake and AF-AA VT behavior, which may alter deep circulation patterns.Keywords: water column analysis, advective heat transport, flow direction, Drake Passage, Africa-Antarctic passage.RESUMO. Baseado nas projeções dos cenários de mudanças climáticas A1FI e B1 do Painel Intergovernamental de Mudanc¸as Climáticas (IPCC), esse estudo avalia como as mudanças climáticas podem impactar os transportes advectivos de calor e volume na bacia do Atlântico Sul. Através de resultados gerados pelo Modelo Climático 2.1 (CM2.1) desenvolvido pelo Geophysical Fluid Dynamics Laboratory (GFDL), foram feitas análises através de duas seções meridionais e uma seção zonal na área de estudo (entre 25◦S-70◦S e 70◦W-20◦E) integradas na coluna d’água. Foram analisados campos prognósticos médios anuais referentes a experimentos com 100 anos de duração. As análises dos parâmetros dos experimentos de mudanças climáticas foram realizadas em comparação com o experimento clima (H2). O transporte de volume (TV) integrado na coluna d’água enfraqueceu aproximadamente 5%, enquanto o transporte advectivo de calor (TC) aumentou em torno de 22% no Drake e na Passagem África-Antártida (AF-AA) ao final dos experimentos. Para a seção em 25◦S, foram observadas oscilações de direção do fluxo devido a variações na intensidade das velocidades das massas d’água com um enfraquecimento médio de 22% para o TC. Adicionalmente, foi observada uma diminuição no suprimento de água em 25◦S devido ao comportamento do TV das demais seções, o que pode alterar os padrões de circulação profunda.Palavras-chave: análise na coluna d’água, transporte advectivo de calor, direção do fluxo, Passagem de Drake, passagem África-Antártida.

Seasonal and Long-Term Changes to Pavement Life Caused by Rising Temperatures from Climate Change

2019 ◽  
Vol 2673 (6) ◽  
pp. 267-278 ◽  
Author(s):  
Jayne F. Knott ◽  
Jo E. Sias ◽  
Eshan V. Dave ◽  
Jennifer M. Jacobs
Keyword(s):  
Climate Change ◽  
Temperature Rise ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Climate Change Scenarios ◽  
Top Down ◽  
Bottom Up ◽  
Pavement Damage ◽  
The Impact

Pavements are vulnerable to reduced life with climate-change-induced temperature rise. Greenhouse gas emissions have caused an increase in global temperatures since the mid-20th century and the warming is projected to accelerate. Many studies have characterized this risk with a top-down approach in which climate-change scenarios are chosen and applied to predict pavement-life reduction. This approach is useful in identifying possible pavement futures but may miss short-term or seasonal pavement-response trends that are essential for adaptation planning. A bottom-up approach focuses on a pavement’s response to incremental temperature change resulting in a more complete understanding of temperature-induced pavement damage. In this study, a hybrid bottom-up/top-down approach was used to quantify the impact of changing pavement seasons and temperatures on pavement life with incremental temperature rise from 0 to 5°C at a site in coastal New Hampshire. Changes in season length, seasonal average temperatures, and temperature-dependent resilient modulus were used in layered-elastic analysis to simulate the pavement’s response to temperature rise. Projected temperature rise from downscaled global climate models was then superimposed on the results to determine the timing of the effects. The winter pavement season is projected to end by mid-century, replaced by a lengthening fall season. Seasonal pavement damage, currently dominated by the late spring and summer seasons, is projected to be distributed more evenly throughout the year as temperatures rise. A 7% to 32% increase in the asphalt-layer thickness is recommended to protect the base and subgrade with rising temperatures from early century to late-mid-century.

scholarly journals Distribution of Archaeal and Bacterial communities in a subtropical reservoir

2015 ◽  
Vol 27 (4) ◽  
pp. 411-420 ◽  
Author(s):  
Laís Américo Soares ◽  
André Cordeiro Alves Dos Santos ◽  
Iolanda Cristina Silveira Duarte ◽  
Emiliana Manesco Romagnoli ◽  
Maria do Carmo Calijuri
Keyword(s):  
Organic Matter ◽  
Nutrient Cycling ◽  
Microbial Communities ◽  
Water Column ◽  
Bacterial Communities ◽  
Aquatic Ecosystems ◽  
Metabolic Plasticity ◽  
Environmental Process ◽  
Ecological Importance ◽  
The Relationship

Abstract Aim: Microbial communities play a central role in environmental process such as organic matter mineralization and the nutrient cycling process in aquatic ecosystems. Despite their ecological importance, variability of the structure of archaeal and bacterial communities in freshwater remains understudied. Methods In the present study we investigated the richness and density of archaea and bacteria in the water column and sediments of the Itupararanga Reservoir. We also evaluated the relationship between the communities and the biotic and abiotic characteristics. Samples were taken at five depths in the water column next to the dam and three depths next to the reservoir entrance. Results PCR-DGGE evaluation of the archaeal and bacterial communities showed that both were present in the water column, even in oxygenated conditions. Conclusions The density of the bacteria (qPCR) was greater than that of the archaea, a result of the higher metabolic plasticity of bacteria compared with archaea.

scholarly journals Diverging responses of high-latitude CO<sub>2</sub> and CH<sub>4</sub> emissions in idealized climate change scenarios

2021 ◽  
Vol 15 (2) ◽  
pp. 1097-1130
Author(s):  
Philipp de Vrese ◽  
Tobias Stacke ◽  
Thomas Kleinen ◽  
Victor Brovkin
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Global Warming ◽  
High Latitude ◽  
Climate Change Scenarios ◽  
Climate Scenarios ◽  
Soil Co2 ◽  
Soil Co2 Emissions ◽  
Net Fluxes ◽  
Global Mean

Abstract. The present study investigates the response of the high-latitude carbon cycle to changes in atmospheric greenhouse gas (GHG) concentrations in idealized climate change scenarios. To this end we use an adapted version of JSBACH – the land surface component of the Max Planck Institute for Meteorology Earth System Model (MPI-ESM) – that accounts for the organic matter stored in the permafrost-affected soils of the high northern latitudes. The model is run under different climate scenarios that assume an increase in GHG concentrations, based on the Shared Socioeconomic Pathway 5 and the Representative Concentration Pathway 8.5, which peaks in the years 2025, 2050, 2075 or 2100, respectively. The peaks are followed by a decrease in atmospheric GHGs that returns the concentrations to the levels at the beginning of the 21st century, reversing the imposed climate change. We show that the soil CO2 emissions exhibit an almost linear dependence on the global mean surface temperatures that are simulated for the different climate scenarios. Here, each degree of warming increases the fluxes by, very roughly, 50 % of their initial value, while each degree of cooling decreases them correspondingly. However, the linear dependence does not mean that the processes governing the soil CO2 emissions are fully reversible on short timescales but rather that two strongly hysteretic factors offset each other – namely the net primary productivity and the availability of formerly frozen soil organic matter. In contrast, the soil methane emissions show a less pronounced increase with rising temperatures, and they are consistently lower after the peak in the GHG concentrations than prior to it. Here, the net fluxes could even become negative, and we find that methane emissions will play only a minor role in the northern high-latitude contribution to global warming, even when considering the high global warming potential of the gas. Finally, we find that at a global mean temperature of roughly 1.75 K (±0.5 K) above pre-industrial levels the high-latitude ecosystem turns from a CO2 sink into a source of atmospheric carbon, with the net fluxes into the atmosphere increasing substantially with rising atmospheric GHG concentrations. This is very different from scenario simulations with the standard version of the MPI-ESM, in which the region continues to take up atmospheric CO2 throughout the entire 21st century, confirming that the omission of permafrost-related processes and the organic matter stored in the frozen soils leads to a fundamental misrepresentation of the carbon dynamics in the Arctic.

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