Nutrient regeneration mediated by extracellular enzymes in water column and interstitial water through a microcosm experiment

2019 ◽  
Vol 670 ◽  
pp. 982-992 ◽  
Author(s):  
Chunlei Song ◽  
Xiuyun Cao ◽  
Yiyong Zhou ◽  
Maurizio Azzaro ◽  
Luis Salvador Monticelli ◽  
...  
Keyword(s):  
Water Column ◽  
Extracellular Enzymes ◽  
Interstitial Water ◽  
Nutrient Regeneration ◽  
Microcosm Experiment

An Overview of Dynamics and Biotoxicity of Metals in the Freshwater Environment

1993 ◽  
Vol 28 (1) ◽  
pp. 1-6 ◽  
Author(s):  
P.M. Huang
Keyword(s):  
Water Column ◽  
Interstitial Water ◽  
Dynamic Equilibrium ◽  
Kinetic Studies ◽  
Integrated Approach ◽  
Freshwater Ecosystem ◽  
Overlying Water ◽  
Freshwater Environment ◽  
Particulate Materials ◽  
The Impact

Abstract The toxic metals, including metalloids, in the freshwater ecosystem are largely associated with surficial sediments and suspended particulate materials. These metals are in dynamic equilibrium with interstitial water and the overlying water column. The bioavailability and toxicity of metals in the freshwater environment are influenced by their speciation and dynamics. Our current understanding of the nature of metal partitioning in particulate materials, interstitial water and the overlying water column is quite limited because of the limitations of the metal fractionation methods and difficulties in obtaining thermodynamic information which approaches the realities in streams, rivers and lakes. Little is known about the in situ metal dynamics. Kinetic studies of metal reactions, thus, warrant in-depth research for years to come. Besides inorganic and organic colloids, microbes contribute to metal transformations. The impact of the interactions of microbes with minerals and organic components on the dynamics and biotoxicity of metals merits attention. Over the last decade, there has been much research on the development of hydrochemical models for better understanding and predicting metal transport in the freshwater system, yet little research has been focused on how well they describe field data. The supply of biologically available metals in the freshwater environment is governed by a series of physical, physicochemical, biochemical and biological processes. To date, there are very few studies on the subject in which an integrated approach has been taken. The roles of these interacting processes in affecting metal dynamics and their impacts on freshwater toxicology deserve increasing attention.

scholarly journals Peru upwelling plankton respiration: calculations of carbon flux, nutrient retention efficiency and heterotrophic energy production

2014 ◽  
Vol 11 (11) ◽  
pp. 16177-16206 ◽  
Author(s):  
T. T. Packard ◽  
N. Osma ◽  
I. Fernández-Urruzola ◽  
L. A. Codispoti ◽  
J. P. Christensen ◽  
...  
Keyword(s):  
Water Column ◽  
Depth Profile ◽  
Carbon Flux ◽  
Energy Production ◽  
Nutrient Retention ◽  
Euphotic Zone ◽  
Nutrient Regeneration ◽  
Retention Efficiency ◽  
High Productivity ◽  
Water Column Respiration

Abstract. Oceanic depth profiles of plankton respiration are described by a power function, RCO2 = (RCO2)0(z/z0)b similar to the vertical carbon flux profile. Furthermore, because both ocean processes are closely related, conceptually and mathematically, each can be calculated from the other. The exponent (b), always negative, defines the maximum curvature of the respiration depth-profile and controls the carbon flux. When b is large, the C flux (FC) from the epipelagic ocean is low and the nutrient retention efficiency (NRE) is high allowing these waters to maintain high productivity. The opposite occurs when b is small. This means that the attenuation of respiration in ocean water columns is critical in understanding and predicting both vertical FC as well as the capacity of epipelagic ecosystems to retain their nutrients. The NRE is a new metric defined as the ratio of nutrient regeneration in a seawater layer to the nutrients introduced into that layer via FC. A depth-profile of FC is the integral of water column respiration. This relationship facilitates calculating ocean sections of FC from water column respiration. In a FC section across the Peru upwelling system we found a FC maximum extending down to 400 m, 50 km off the Peru coast. Finally, coupling respiratory electron transport system activity to heterotrophic oxidative phosphorylation promoted the calculation of an ocean section of heterotrophic energy production (HEP). It ranged from 250 to 500 J d−1 m−3 in the euphotic zone, to less than 5 J d−1 m−3 below 200 m on this ocean section.

Nutrient Cycling and Primary Production in Port Hacking, New South Wales

1978 ◽  
Vol 29 (6) ◽  
pp. 803 ◽  
Author(s):  
BD Scott
Keyword(s):  
Primary Production ◽  
Water Column ◽  
New South ◽  
Heavy Rain ◽  
Sedimentation Rates ◽  
Nutrient Regeneration ◽  
Seasonal Differences ◽  
Salinity Stratification ◽  
South Wales ◽  
Lower Water Column

The changes in the concentrations of nitrate, phosphate and silicate in a marine-dominated estuarine basin are described and related to the changes in the physical properties of the water and the primary production. The consumption of oxygen and nutrient regeneration in the lower water column were directly related to density differences in the lower water column, and to the primary production. The regeneration of nutrients was related to the consumption of oxygen, with seasonal differences in the regeneration of nitrate and silicate. Increased rates of nutrient regeneration during salinity stratification after heavy rain were attributed to increased sedimentation rates.

scholarly journals Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a <sup>13</sup>C pulse-chase experiment

2018 ◽  
Vol 15 (9) ◽  
pp. 2873-2889 ◽  
Author(s):  
Philip M. Riekenberg ◽  
Joanne M. Oakes ◽  
Bradley D. Eyre
Keyword(s):  
Water Column ◽  
Nutrient Availability ◽  
Nutrient Enrichment ◽  
Extracellular Enzymes ◽  
Turnover Time ◽  
Ex Situ ◽  
Nutrient Concentrations ◽  
Organic C ◽  
Storage Products

Abstract. Shallow coastal waters in many regions are subject to nutrient enrichment. Microphytobenthos (MPB) can account for much of the carbon (C) fixation in these environments, depending on the depth of the water column, but the effect of enhanced nutrient availability on the processing and fate of MPB-derived C (MPB-C) is relatively unknown. In this study, MPB was labeled (stable isotope enrichment) in situ using 13C-sodium bicarbonate. The processing and fate of the newly fixed MPB-C was then traced using ex situ incubations over 3.5 days under different concentrations of nutrients (NH4+ and PO43-: ambient, 2× ambient, 5× ambient, and 10× ambient). After 3.5 days, sediments incubated with increased nutrient concentrations (amended treatments) had increased loss of 13C from sediment organic matter (OM) as a portion of initial uptake (95 % remaining in ambient vs. 79–93 % for amended treatments) and less 13C in MPB (52 % ambient, 26–49 % amended), most likely reflecting increased turnover of MPB-derived C supporting increased production of extracellular enzymes and storage products. Loss of MPB-derived C to the water column via dissolved organic C (DOC) was minimal regardless of treatment (0.4–0.6 %). Loss due to respiration was more substantial, with effluxes of dissolved inorganic C (DIC) increasing with additional nutrient availability (4 % ambient, 6.6–19.8 % amended). These shifts resulted in a decreased turnover time for algal C (419 days ambient, 134–199 days amended). This suggests that nutrient enrichment of estuaries may ultimately lead to decreased retention of carbon within MPB-dominated sediments.

scholarly journals Peruvian upwelling plankton respiration: calculations of carbon flux, nutrient retention efficiency, and heterotrophic energy production

2015 ◽  
Vol 12 (9) ◽  
pp. 2641-2654 ◽  
Author(s):  
T. T. Packard ◽  
N. Osma ◽  
I. Fernández-Urruzola ◽  
L. A. Codispoti ◽  
J. P. Christensen ◽  
...  
Keyword(s):  
Water Column ◽  
Depth Profile ◽  
Carbon Flux ◽  
Energy Production ◽  
Nutrient Retention ◽  
Euphotic Zone ◽  
Nutrient Regeneration ◽  
Retention Efficiency ◽  
High Productivity ◽  
Water Column Respiration

Abstract. Oceanic depth profiles of plankton respiration are described by a power function, RCO2 = (RCO2)0 (z/z0)b, similar to the vertical carbon flux profile. Furthermore, because both ocean processes are closely related, conceptually and mathematically, each can be calculated from the other. The exponent b, always negative, defines the maximum curvature of the respiration–depth profile and controls the carbon flux. When |b| is large, the carbon flux (FC) from the epipelagic ocean is low and the nutrient retention efficiency (NRE) is high, allowing these waters to maintain high productivity. The opposite occurs when |b| is small. This means that the attenuation of respiration in ocean water columns is critical in understanding and predicting both vertical FC as well as the capacity of epipelagic ecosystems to retain their nutrients. The ratio of seawater RCO2 to incoming FC is the NRE, a new metric that represents nutrient regeneration in a seawater layer in reference to the nutrients introduced into that layer via FC. A depth profile of FC is the integral of water column respiration. This relationship facilitates calculating ocean sections of FC from water column respiration. In an FC section and in a NRE section across the Peruvian upwelling system we found an FC maximum and a NRE minimum extending down to 400 m, 50 km off the Peruvian coast over the upper part of the continental slope. Finally, considering the coupling between respiratory electron transport system activity and heterotrophic oxidative phosphorylation promoted the calculation of an ocean section of heterotrophic energy production (HEP). It ranged from 250 to 500 J d−1 m−3 in the euphotic zone to less than 5 J d−1 m−3 below 200 m on this ocean section.

scholarly journals Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: A <sup>13</sup>C pulse-chase experiment

2017 ◽  
Author(s):  
Philip M. Riekenberg ◽  
Joanne M. Oakes ◽  
Bradley D. Eyre
Keyword(s):  
Water Column ◽  
Nutrient Availability ◽  
Extracellular Enzymes ◽  
Turnover Time ◽  
Ex Situ ◽  
Nutrient Concentrations ◽  
Organic C ◽  
Storage Products ◽  
And Storage

Abstract. Shallow coastal waters in many regions are subject to nutrient over-enrichment. Microphytobenthos (MPB) can account for much of the carbon (C) fixation in these environments, depending on the depth of the water column, but the effect of enhanced nutrient availability on the processing and fate of MPB-derived C is relatively unknown. In this study, MPB were labeled (stable isotope enrichment) in situ using 13C-sodium bicarbonate. The processing and fate of the newly-fixed MPB-C was then traced using ex situ incubations over 3.5 d under different concentrations of nutrients (NH4+ and PO43−: ambient, 2× ambient, 5× ambient, and 10× ambient). After 3.5 d, sediments incubated with increased nutrient concentrations (amended treatments) had increased loss of 13C from sediment organic matter as a portion of initial uptake (95 % remaining in ambient vs 79–93 % for amended treatments) and less 13C in MPB (52 % ambient, 26–49 % amended), most likely reflecting increased turnover of MPB-derived C supporting increased production of extracellular enzymes and storage products. Loss of MPB-derived C to the water column via dissolved organic C was minimal regardless of treatment (0.4–0.6 %). Loss due to respiration was more substantial, with effluxes of dissolved inorganic C increasing with additional nutrient availability (4 % ambient, 6.6–19.8 % amended). These shifts resulted in a decreased turnover time for algal C (419 d ambient, 134–199 d amended). This suggests that nutrient enrichment of estuaries may ultimately lead to decreased retention of carbon within MPB-dominated sediments.

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