Dissolved nutrients and organic particulates in water flowing over coral reefs at Lizard Island

1983 ◽  
Vol 34 (6) ◽  
pp. 835 ◽  
Author(s):  
CJ Crossland ◽  
DJ Barnes
Keyword(s):  
Organic Carbon ◽  
Coral Reefs ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Dissolved Nutrients ◽  
Reef Complex ◽  
Nutrient Levels ◽  
Lizard Island ◽  
Nitrogen Phosphorus ◽  
Benthic Zone

Concentrations of dissolved nutrients and organic particulates were measured in seawater flowing across the windward and leeward reef flats of the lagoonal reef complex at Lizard Island. Measurements were made during the day, at night, and at various stages of the tide over a period of several weeks. The reef complex, as a whole, did not consume or export statistically significant amounts of inorganic nitrogen, phosphorus, silicate, organic nitrogen or organic carbon. Depletion or elevation of nutrient levels in one benthic zone appeared to be balanced by production or consumption in downstream zones.

scholarly journals Soil organic carbon dynamics under long-term fertilizations in arable land of northern China

2009 ◽  
Vol 6 (4) ◽  
pp. 6539-6577 ◽  
Author(s):  
W. J. Zhang ◽  
X. J. Wang ◽  
M. G. Xu ◽  
S. M. Huang ◽  
H. Liu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Cropping Systems ◽  
Inorganic Nitrogen ◽  
Northern China ◽  
Double Cropping ◽  
Conversion Rates ◽  
Warm Temperate ◽  
Nitrogen Phosphorus

Abstract. Soil organic carbon (SOC) data were collected from six long-term experiment sites in the upland of northern China. Various fertilization (e.g. inorganic fertilizations and combined inorganic-manure applications) and cropping (e.g. mono- and double-cropping) practices have been applied at these sites. Our analyses indicate that long-term applications of inorganic nitrogen-phosphorus (NP) and nitrogen-phosphorus-potassium (NPK) result in a significant increase in SOC at the sites with the double-cropping systems. The applications of inorganic NP and/or NPK combined with manure lead to a significantly increasing trend in SOC content at all the sites. However, the application of NPK with crop residue incorporation can only increase SOC content in the warm-temperate areas with the double-cropping systems. Regression analyses suggest that soil carbon sequestration responds linearly to carbon input at all the sites. Conversion rates of carbon input to SOC decrease significantly with an increase of annual accumulative temperature or precipitation, showing lower rates (6.8%–7.7%) in the warm-temperate areas than in the mid-temperate areas (15.8%–31.0%).

scholarly journals Modelling carbon overconsumption and the formation of extracellular particulate organic carbon

2007 ◽  
Vol 4 (4) ◽  
pp. 433-454 ◽  
Author(s):  
M. Schartau ◽  
A. Engel ◽  
J. Schröter ◽  
S. Thoms ◽  
C. Völker ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Organic Nitrogen ◽  
Dissolved Inorganic Carbon ◽  
Inorganic Nitrogen ◽  
C:N Ratio ◽  
Algal Growth ◽  
Phytoplankton Growth ◽  
Maximum Likelihood Estimates ◽  
Model Parameters

Abstract. During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by phytoplankton is exuded in the form of dissolved organic carbon (DOC), which can be transformed into extracellular particulate organic carbon (POC). A major fraction of extracellular POC is associated with carbon of transparent exopolymer particles (TEP; carbon content = TEPC) that form from dissolved polysaccharides (PCHO). The exudation of PCHO is linked to an excessive uptake of DIC that is not directly quantifiable from utilisation of dissolved inorganic nitrogen (DIN), called carbon overconsumption. Given these conditions, the concept of assuming a constant stoichiometric carbon-to-nitrogen (C:N) ratio for estimating new production of POC from DIN uptake becomes inappropriate. Here, a model of carbon overconsumption is analysed, combining phytoplankton growth with TEPC formation. The model describes two modes of carbon overconsumption. The first mode is associated with DOC exudation during phytoplankton biomass accumulation. The second mode is decoupled from algal growth, but leads to a continuous rise in POC while particulate organic nitrogen (PON) remains constant. While including PCHO coagulation, the model goes beyond a purely physiological explanation of building up carbon rich particulate organic matter (POM). The model is validated against observations from a mesocosm study. Maximum likelihood estimates of model parameters, such as nitrogen- and carbon loss rates of phytoplankton, are determined. The optimisation yields results with higher rates for carbon exudation than for the loss of organic nitrogen. It also suggests that the PCHO fraction of exuded DOC was 63±20% during the mesocosm experiment. Optimal estimates are obtained for coagulation kernels for PCHO transformation into TEPC. Model state estimates are consistent with observations, where 30% of the POC increase was attributed to TEPC formation. The proposed model is of low complexity and is applicable for large-scale biogeochemical simulations.

Effects of carbon and nitrogen supplementation on lignin and cellulose decomposition by a Streptomyces

1981 ◽  
Vol 27 (8) ◽  
pp. 859-863 ◽  
Author(s):  
Maichael J. Barder ◽  
Don L. Crawford
Keyword(s):  
Organic Carbon ◽  
Organic Nitrogen ◽  
Cellulose Degradation ◽  
Inorganic Nitrogen ◽  
White Rot Fungi ◽  
Cellular Growth ◽  
White Rot ◽  
Lignocellulose Degradation ◽  
Cellulose Decomposition ◽  
Ion Effects

Effects of nitrogen source and concentration and organic carbon cosubstrates on lignin and cellulose degradation by Streptomyces badius strain 252 were examined using 14C-labeled substrates prepared from Pseudotsuga menziesii twigs. As compared with white-rot fungi, which do not degrade lignin in the absence of a readily metabolizable carbon cosubstrate, degradation of a milled-wood lignin occurred in a minimal medium, although degradation by S. badius was greatly enhanced when organic nitrogen and an organic carbon cosubstrate were added to the medium. Lignin degradation was greatest in the presence of high levels of organic nitrogen. Further enhancement of lignin and cellulose degradation occurred in a medium containing organic nitrogen supplemented with low levels of NO3−. The specific effects of inorganic nitrogen on lignocellulose degradation by S. badius in an otherwise optimal medium included both enhancement and inhibition of lignin or cellulose degradation depending on the source and concentration of inorganic nitrogen used. These effects were distinctly different from those observed with white-rot fungi and were shown to be specific ion effects on polymer degradation and not simply a salt concentration effect on cellular growth.

Carbon and nitrogen budgets of two Ascidians and their symbiont, Prochloron, in a tropical seagrass meadow

1993 ◽  
Vol 44 (1) ◽  
pp. 173 ◽  
Author(s):  
I Koike ◽  
M Yamamuro ◽  
PC Pollard
Keyword(s):  
Organic Carbon ◽  
Organic Nitrogen ◽  
Carbon Budget ◽  
Seagrass Meadow ◽  
Inorganic Nitrogen ◽  
Host Animal ◽  
Nitrogen Budgets ◽  
Carbon And Nitrogen ◽  
Respiration Rates ◽  
Surrounding Environment

Two species of ascidian, Didemnum molle Herdman and Lissoclinum voeltzkowi Michaelsen, were collected from a Fijian seagrass meadow. The primary production of their symbiont (Prochloron), the inorganic nitrogen metabolism and the filtration rate were measured to assess the nutritional coupling between the symbiont and the host animal. The loss of organic carbon due to the respiration of D. molle (1.1 �g at. C (mg dry wt)-1 day-1) was greater than that supplied through photosynthesis of the Prochloron (0.69 �g at. C (mg dry wt)-1 day,-1). The carbon supplied through filter-feeding appeared to supplement the ascidian's carbon budget. In contrast, organic carbon from the Prochloron of L. voeltzkowi appeared to meet the colony's respiration needs. The nitrogen budgets of both ascidian colonies were estimated from their respiration rates, the nitrogen requirement of the Prochloron, and the uptake of inorganic nitrogen and particulate organic nitrogen uptake from the water column. The nitrogen incorporated from the surrounding environment could contribute to the net nitrogen gain of the colony. However, our estimate of the nitrogen needed by the Prochloron was much greater than that which could be supplied externally. The amount of nitrogen released by the ascidians was also greater than that which could be supplied externally. This suggests that nitrogen is efficiently recycled within the symbiotic Prochloron-ascidian relationship.

scholarly journals Modelling carbon overconsumption and the formation of extracellular particulate organic carbon

2007 ◽  
Vol 4 (1) ◽  
pp. 13-67 ◽  
Author(s):  
M. Schartau ◽  
A. Engel ◽  
J. Schröter ◽  
S. Thoms ◽  
C. Völker ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Organic Nitrogen ◽  
Dissolved Inorganic Carbon ◽  
Inorganic Nitrogen ◽  
C:N Ratio ◽  
Algal Growth ◽  
Phytoplankton Growth ◽  
Maximum Likelihood Estimates ◽  
Model Parameters

Abstract. During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by phytoplankton is exuded in the form of dissolved organic carbon (DOC), which can be transformed into extracellular particulate organic carbon (POC). A major fraction of extracellular POC is associated with carbon of transparent exopolymer particles (TEP; carbon content = TEPC) that form from dissolved polysaccharides (PCHO). The exudation of PCHO is linked to an excessive uptake of DIC that is not directly quantifiable from utilisation of dissolved inorganic nitrogen (DIN), called carbon overconsumption. Given these conditions, the concept of assuming a constant stoichiometric carbon-to-nitrogen (C:N) ratio for estimating new production of POC from DIN uptake becomes inappropriate. Here, a model of carbon overconsumption is analysed, combining phytoplankton growth with TEPC formation. The model describes two modes of carbon overconsumption. The first mode is associated with DOC exudation during phytoplankton biomass accumulation. The second mode is decoupled from algal growth, but leads to a continuous rise in POC while particulate organic nitrogen (PON) remains constant. While including PCHO coagulation, the model goes beyond a purely physiological explanation of building up carbon rich particulate organic matter (POM). The model is validated against observations from a mesocosm study. Maximum likelihood estimates of model parameters, such as nitrogen- and carbon loss rates of phytoplankton, are determined. The optimisation yields results with higher rates for carbon exudation than for the loss of organic nitrogen. It also suggests that the PCHO fraction of exuded DOC was 63±20% during the mesocosm experiment. Optimal estimates are obtained for coagulation kernels for PCHO transformation into TEPC. Model state estimates are consistent with observations, where 30% of the POC increase was attributed to TEPC formation. The proposed model is of low complexity and is applicable for large-scale biogeochemical simulations.

Predicting particulate pools of nitrogen, phosphorus and organic carbon in lakes

2007 ◽  
Vol 69 (4) ◽  
pp. 484-494 ◽  
Author(s):  
Andreas C. Bryhn ◽  
Dag O. Hessen ◽  
Thorsten Blenckner
Keyword(s):  
Organic Carbon ◽  
Nitrogen Phosphorus

scholarly journals Turbid Coral Reefs: Past, Present and Future—A Review

Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 251
Author(s):  
Adi Zweifler (Zvifler) ◽  
Michael O’Leary ◽  
Kyle Morgan ◽  
Nicola K. Browne
Keyword(s):  
Climate Change ◽  
Coral Reef ◽  
Coral Reefs ◽  
Environmental Change ◽  
Scientific Literature ◽  
Conservation Status ◽  
Climate Change Impacts ◽  
Geographic Range ◽  
Reef Complex ◽  
Sediment Input

Increasing evidence suggests that coral reefs exposed to elevated turbidity may be more resilient to climate change impacts and serve as an important conservation hotspot. However, logistical difficulties in studying turbid environments have led to poor representation of these reef types within the scientific literature, with studies using different methods and definitions to characterize turbid reefs. Here we review the geological origins and growth histories of turbid reefs from the Holocene (past), their current ecological and environmental states (present), and their potential responses and resilience to increasing local and global pressures (future). We classify turbid reefs using new descriptors based on their turbidity regime (persistent, fluctuating, transitional) and sources of sediment input (natural versus anthropogenic). Further, by comparing the composition, function and resilience of two of the most studied turbid reefs, Paluma Shoals Reef Complex, Australia (natural turbidity) and Singapore reefs (anthropogenic turbidity), we found them to be two distinct types of turbid reefs with different conservation status. As the geographic range of turbid reefs is expected to increase due to local and global stressors, improving our understanding of their responses to environmental change will be central to global coral reef conservation efforts.

scholarly journals Biodegradability of dissolved organic carbon in the Yukon River and its tributaries: Seasonality and importance of inorganic nitrogen

2012 ◽  
Vol 26 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
K. P. Wickland ◽  
G. R. Aiken ◽  
K. Butler ◽  
M. M. Dornblaser ◽  
R. G. M. Spencer ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Inorganic Nitrogen ◽  
Yukon River
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