Nutrient cycle

Summary

A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic. Mineral cycles include the carbon cycle, sulfur cycle, nitrogen cycle, water cycle, phosphorus cycle, oxygen cycle, among others that continually recycle along with other mineral nutrients into productive ecological nutrition. Outline The nutrient cycle is nature's recycling system. All forms of recycling have feedback loops that use energy in the process of putting material resources back into use. Recycling in ecology is regulated to a large extent during the process of decomposition. Ecosystems employ biodiversity in the food webs that recycle natural materials, such as mineral nutrients, which includes water. Recycling in natural systems is one of the many ecosystem services that sustain and contribute to the well-being of h

Official source

https://en.wikipedia.org/wiki/Nutrient_cycle

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related publications (59)

Related publications

Related people (10)

Related people

Related units (7)

Related units

Related concepts (57)

Related concepts

Related courses (16)

Related courses

Related lectures (20)

Related lectures

Related publications (59)

Surface-groundwater interactions in intermittent rivers and ephemeral streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES. We combine a review of theIRES biogeochemistry literature with concepts of IRES hydrogeomorphology to: (i) outline common distinctions among hydrological states in IRES; (ii) use these distinctions, together with considerations of carbon, nitrogen, and phosphorus cycles within IRES, to predict the relative potential for biogeochemical processing across different reach-scale processing zones (flowing water, fragmented pools, hyporheic zones, groundwater, and emerged sediments); and (iii) explore the potential spatial and temporal variability of carbon and nutrient biogeochemical processing across entire IRES networks. Our approach estimates the greatest reach-scale potential for biogeochemical processing when IRES reaches are fragmented into isolated surface water pools, and highlights the potential of relatively understudied processing zones, such as emerged sediments. Furthermore, biogeochemical processing in fluvial networks dominated by IRES is likely more temporally than spatially variable. We conclude that biogeochemical research in IRES would benefit from focusing on interactions between different nutrient cycles, surface-groundwater interactions in non-flowing states, and consideration of fluvial network architecture. Our conceptual framework outlines opportunities to advance studies and expand understanding of biogeochemistry in IRES.

2021

Influence of Microplastics on Microbial Structure, Function, and Mechanical Properties of Stream Periphyton

Renata Behra, Kristin Schirmer, Ahmed Tlili

Periphyton is a freshwater biofilm composed of prokaryotic and eukaryotic communities that occupy rocks and sediments, forming the base of the food web and playing a key role in nutrient cycling. Given the large surface that periphyton comprises, it may also act as a sink for a diverse range of man-made pollutants, including microplastics (MP). Here we investigated the effect of 1-4 mu m and 63-75 mu m sized, spherical polyethylene MP with native and ultraviolet (UV)-weathered surface on developing natural stream periphyton communities over 28 days. In order to ensure proper particle exposure, we first tested MP suspension in water or in water containing either Tween 80, extracellular polymeric substances - EPS, fulvic acids, or protein. We found the extract of EPS from natural periphyton to be most suitable to create MP suspensions in preparation of exposure. Upon exposure, all tested types of MP were found to be associated with the periphyton, independent of their size and other properties. While biomass accrual and phenotypic community structure of the photoautotrophs remained unchanged, the prokaryotic and eukaryotic communities experienced a significant change in composition and relative abundances. Moreover, alpha diversity was affected in eukaryotes, but not in prokaryotes. The observed changes were more prominent in periphyton exposed to UV-treated as compared with native surface MP. Mechanical properties, as assessed by compression rheology, showed that MP-exposed periphyton had longer filamentous streamers, higher stiffness, lower force recovery and a higher viscoelasticity than control periphyton. Despite the observed structural and mechanical changes of periphyton, functional parameters (i.e., photosynthetic yield, respiration and nutrient uptake efficiencies) were not altered by MP, indicating the absence of MP toxicity, and suggesting functional redundancy in the communities. Together, our results provide further proof that periphyton is a sink for MP and demonstrate that MP can impact local microbial community composition and mechanical properties of the biofilms. Consequences of these findings might be a change in dislodgement behavior of periphyton, a propagation through the food chains and impacts on nutrient cycling and energy transfer. Hence, taking the omnipresence, high persistence and material and size diversity of MP in the aquatic environment into account, their ecological consequences need further investigation.

FRONTIERS MEDIA SA2022

Comparison of two carbon-nitrogen regulatory models calibrated with mesocosm data

Shubham Krishna

Marine phytoplankton can regulate their stoichiometric composition in response to variations in the availability of nutrients, light and the pH of seawater. Varying elemental composition of photoautotrophs affects several important ecological and biogeochemical processes, e.g., primary and export production, nutrient cycling, calcification, and grazing. Here we compare two plankton ecosystem models that consider regulatory mechanisms of cellular carbon and nitrogen, driving the physiological acclimation of photoautotrophs. The Carbon:Nitrogen Regulated Ecosystem Model (CN-REcoM) and the optimality-based model (OBM) differ in their representation of phytoplankton dynamics, i.e. nutrient acquisition, synthesis of chlorophyll a, and growth. All other model compartments (zooplankton, detritus, dissolved inorganic and organic matter) and processes (grazing, aggregation, remineralisation) remain identical in both models. We assess the skills of the two models against data from an ocean acidification mesocosm experiment with three CO2 treatments. Neither model accounts for any carbon dioxide (CO2) effects explicitly. Instead, we assimilate data of the different CO2 treatments separately into the models. Thereby we aim at identifying optimal model parameter values that might correlate with differences in CO2 conditions. For the OBM, optimal parameter estimates of Q(min) (subsistence N:C ratio) and V-C(0) (maximum potential photosynthesis rate of photoautotrophs) turned out to be higher for mesocosms exposed to high CO2 compared to those with low CO2 concentrations. By contrast, a similar correlation is not observed for the CN-REcoM. A possible physiological interpretation of higher estimates of Q(min), and V-C(0) according to the OBM is that phytoplankton may experience environmental stress under more acidic conditions, and hence must invest more energy/resources for maintaining basic cellular functions. Our data assimilation reveals that the parameters of the OBM are better constrained by the data than those of the CN-REcoM. Furthermore, the OBM is better able than CN-REcoM to reproduce data that were not used for parameter optimization.

2019