scholarly journals Dissolved Organic Carbon Loading Stimulates Sediment Phosphorus Mobilization and Release: Preliminary Evidence From Xiangshan Port, East China Sea

2022 ◽  
Vol 9 ◽  
Author(s):  
Xu-Meng Dong ◽  
Shuo-Nan Ma ◽  
Hai-Jun Wang ◽  
Yuan-Yuan Li ◽  
Yan Li ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Large Scale ◽  
Preliminary Evidence ◽  
Tight Coupling ◽  
Overlying Water ◽  
P Release ◽  
Large Scale Field ◽  
P Mobilization ◽  
Labile P

Increasing concentrations of dissolved organic carbon (DOC) have been observed in coastal ecosystems worldwide over the past decade, and tight coupling of the carbon (C) and phosphorus (P) biogeochemical cycle has been recognized in aquatic ecosystems. However, there is still no consensus regarding the potential effects of DOC loading on sediment P release. In a 2-month mesocosm experiment, we tested the effects of DOC enrichment on sediment P release in six glass aquariums. Two treatments were set: Control (without sodium acetate (Na(CH3COO)) addition) and Na(CH3COO) addition (equivalent to 5 mg C L−1). The results showed the following: 1) DOC loading stimulated sediment P mobilization and release, as indicated by increases in the labile P recorded for 7-cm-deep sediment using diffusive gradients in thin films, the flux of P across the sediment–water interface, and the total P concentrations in the overlying water; and 2) stimulated alkaline phosphatase activity, increased P-solubilizing bacteria proportion, and decreased dissolved oxygen concentration were likely the primary mechanisms behind the DOC-stimulated sediment P mobilization and release. These results provide insight into the promotion of sediment P release induced by C addition. Further studies investigating the quantitative relationships between DOC loadings and P release are needed to fully elucidate the coupled roles of C and P, especially those based on large-scale field investigations with broader C forms and loadings.

scholarly journals Dissolved organic carbon dynamics in a UK podzolic moorland catchment: linking storm hydrochemistry, flow path analysis and sorption experiments

2012 ◽  
Vol 9 (6) ◽  
pp. 2159-2175 ◽  
Author(s):  
M. I. Stutter ◽  
S. M. Dunn ◽  
D. G. Lumsdon
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Preliminary Evidence ◽  
Soil Conditions ◽  
Dry Period ◽  
Flow Paths ◽  
Antecedent Conditions ◽  
Doc Concentration ◽  
Mineral Soils

Abstract. Better knowledge of spatial and temporal delivery of dissolved organic carbon (DOC) in small catchments is required to understand the mechanisms behind reported long-term changes in C fluxes from some peatlands. We monitored two storms with contrasting seasons and antecedent conditions in a small upland UK moorland catchment. We examined DOC concentrations and specific UV absorbance (SUVA at 285 nm), together with solute concentrations required to undertake end-member mixing analyses to define dominant flow paths contributing to streamflow. This was combined with laboratory soil-solution equilibrations. We aimed to resolve how seasonal biogeochemical processing of DOC and flowpath changes in organo-mineral soils combine to affect DOC exported via the stream. An August storm following a dry period gave maximum DOC concentration of 10 mg l−1. Small DOC:DON ratios (16–28) and SUVA (2.7–3.6 l mg−1 m−1) was attributed to filtration of aromatic compounds associated with up to 53% B horizon flow contributions. This selective filtration of high SUVA DOC was reproduced in the experimental batch equilibration system. For a November storm, wetter antecedent soil conditions led to enhanced soil connectivity with the stream and seven times greater DOC stream-load (maximum concentration 16 mg l−1). This storm had a 63% O horizon flow contribution at its peak, limited B horizon buffering and consequently more aromatic DOC (SUVA 3.9–4.5 l mg−1 m−1 and DOC:DON ratio 35–43). We suggest that simple mixing of waters from different flow paths cannot alone explain the differences in DOC compositions between August and November and biogeochemical processing of DOC is required to fully explain the observed stream DOC dynamics. This preliminary evidence is in contrast to other studies proposing hydrological controls on the nature of DOC delivered to streams. Although our study is based only on two storms of very different hydrological and biogeochemical periods, this should promote wider study of DOC biogeochemical alteration in headwaters so that this be better incorporated in modelling to predict the impacts of changes in DOC delivery to, and fate in, aquatic systems.

scholarly journals The Influence of Dissolved Organic Carbon on the Microbial Community Associated with Tetraselmis striata for Bio-Diesel Production

2020 ◽  
Vol 10 (10) ◽  
pp. 3601
Author(s):  
Sae-Hee Kim ◽  
Jin Ho Kim ◽  
Seung Ho Baek ◽  
Joo-Hwan Kim ◽  
Penelope A. Ajani ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Large Scale ◽  
Food Web Structure ◽  
Bacterial Composition ◽  
Suitable Candidate ◽  
Web Structure ◽  
Tetraselmis Striata ◽  
And Function ◽  
Diesel Production

The green alga Tetraselmis striata is regarded as a suitable candidate microalga for bio-diesel production. Recently, T. striata was cultured near Yeonghueung Island, Korea, in a “marine culturing field”; however, its environmental impacts are not yet studied. We estimated the amount of dissolved organic carbon (DOC) released from T. striata cultivation in the marine culturing field, and we investigated the changes in bacterial composition. Then, we designed and installed a mesocosm for further understanding. From the mesocosm results, the DOC released from the cultivation of T. striata led to changes in bacterial communities, disturbance of the microbial food web structure, rapid depletion of nutrients, and a decrease in dissolved oxygen (DO) and pH. Our novel work demonstrates that large amounts of DOC secreted by large-scale microalgal cultures such as that of T. striata can potentially have a significant impact on the structure and function of the surrounding microbial ecosystem.

Transport of Dissolved Organic Carbon-Derived Natural Colloids from Bed Sediments to Overlying Water: Laboratory Simulations

1993 ◽  
Vol 28 (8-9) ◽  
pp. 139-147 ◽  
Author(s):  
K. T. Valsaraj ◽  
G. J. Thoma ◽  
C. L. Porter ◽  
D. D. Reible ◽  
L. J. Thibodeaux
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Chemical Properties ◽  
Adjustable Parameter ◽  
Brownian Diffusion ◽  
Overlying Water ◽  
Sediment Bed ◽  
Water Diffusivity ◽  
Physico Chemical ◽  
Sediment Diagenesis

Natural colloids are part of the carbon cycle arising from sediment diagenesis. Natural colloids can be quantified as the dissolved organic carbon (DOC) present in the pore-water of sediment beds. In this paper we demonstrate that DOC is mobile in a system in which the dominant transport mechanism is Brownian diffusion. A simple model which assumes constant physico-chemical properties for the DOC adequately predicts the DOC release rate from a sediment bed in a microcosm. A single adjustable parameter, the water diffusivity, is used to fit the model to the experimental data. The experimental diffusivities obtained from the fitted data agree well with previously presented values.

Transport of Dissolved Organic Carbon, Nutrients, and Trace Metals from the Wilson and Blossom Rivers to Smeaton Bay, Southeast Alaska

1984 ◽  
Vol 41 (1) ◽  
pp. 180-190 ◽  
Author(s):  
Susan F. Sugai ◽  
David C. Burrell
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Large Scale ◽  
Nutrient Export ◽  
Drainage Basins ◽  
Southeast Alaska ◽  
Scale Removal ◽  
Reducing Conditions ◽  
Fe And Mn ◽  
Topographical Relief

Regional and seasonal differences in chemical input from the Wilson and Blossom rivers, two pristine, major salmon-producing rivers in southeast Alaska, were examined. For a period of 2 yr, concentrations of dissolved organic carbon, nutrients, Cu, Fe, and Mn in the rivers were determined at approximately monthly intervals and used to calculate export rates. Because of extremely high annual precipitation (400–450 cm) and drainage basins restricted by high topographical relief, the concentrations and export rates of nutrients and Cu are low in the rivers for most of the year. The maximum nutrient export from the Wilson–Blossom system appears to be closely tied to the annual salmon cycle. Iron and Mn export rates from the watersheds are much higher than those for Cu, reflecting solubilization of Fe and Mn under reducing conditions that develop in muskeg ponds during drought periods. The association of metals with organics allows transport of Fe and possibly other metals throughout the fjord system, in contrast with the large-scale removal of metals in or near the river's mouth, as has been observed elsewhere.

scholarly journals High-resolution characterization of labile phosphorus, iron, and manganese in sediments of different trophic waters in Lake Taihu, China

2017 ◽  
Vol 77 (2) ◽  
pp. 286-295 ◽  
Author(s):  
Liqing Zeng ◽  
Fan Yang ◽  
Changzhou Yan ◽  
Xinhong Wang
Keyword(s):  
High Resolution ◽  
Lake Taihu ◽  
Diffusion Flux ◽  
Trophic Levels ◽  
Overlying Water ◽  
Positive Correlation ◽  
P Release ◽  
Labile Phosphorus ◽  
Apparent Diffusion ◽  
Labile P

Abstract High-resolution combined ZrO-Chelex diffusive gradients in thin film (DGT) probes were arranged to synchronously monitor the characteristics of labile phosphorus (P), iron (Fe), and manganese (Mn) in sediments from regions of varying trophic levels in Lake Taihu, China. Results showed that P release was closely related to the lake region's trophic level. Labile P in sediments and the apparent diffusion flux (Fd) of P were higher in hyper-eutrophic algae-dominated regions than those in macrophyte-algae-dominated and macrophyte-dominated regions, indicating that P released from sediments may be facilitated in eutrophic environments. A positive correlation observed between DGT-labile P and Fe or Mn, which had similar regional spatial distributions to P, showed that reductive dissolution of Fe-Mn (oxyhydr)oxides (FeOOH-MnOOH) in sediments was responsible for internal P release, which was strengthened in eutrophic environments. Ratios of labile Fe or Mn/labile P (LFe/LP and LMn/LP) in sediments in algae-dominated regions showed lower values than those in macrophyte-algae-dominated and macrophyte-dominated regions, further confirming that FeOOH-MnOOH in algae-dominated regions were less able to fix P, which brought higher pollution risks for the overlying water. LFe/LP or LMn/LP also had a significantly positive correlation with Fd, further testament that labile Fe or Mn was much more relevant to the sediment P cycle.

scholarly journals Partial coupling and differential regulation of biologically and photochemically labile dissolved organic carbon across boreal aquatic networks

2014 ◽  
Vol 11 (20) ◽  
pp. 5969-5985 ◽  
Author(s):  
J.-F. Lapierre ◽  
P. A. del Giorgio
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Large Scale ◽  
Natural Waters ◽  
Boreal Lakes ◽  
Aquatic Environments ◽  
Photochemical Degradation ◽  
Landscape Gradients ◽  
Partial Coupling ◽  
Internal Production

Abstract. Despite the rapidly increasing volume of research on the biological and photochemical degradation of DOC (dissolved organic carbon) in aquatic environments, little is known of the large-scale patterns in biologically and photochemically degradable DOC (BDOC and PDOC, respectively) in continental watersheds, and on the links that exist between these two key properties that greatly influence the flow of carbon from continents to oceans. Here we explored the patterns in the concentrations and proportions of BDOC and PDOC across hundreds of boreal lakes, rivers and wetlands spanning a large range of system trophic status and terrestrial influence, and compared the drivers of these two reactive pools of DOC at the landscape level. Using standardized incubations of natural waters, we found that the concentrations of BDOC and PDOC covaried across all systems studied but were nevertheless related to different pools of dissolved organic matter (DOM; identified by fluorescence analyses) in ambient waters. Concentrations of nutrients and protein-like fluorescent DOM (FDOM) explained nearly half of the variation in BDOC, whereas PDOC was exclusively predicted by DOM optical properties, consistent with the photochemical degradability of specific FDOM pools that we experimentally determined. The concentrations of colored DOM (CDOM), which we use here as a proxy of terrestrial influence, almost entirely accounted for the observed relationship between FDOM and the concentrations of both BDOC and PDOC. The concentrations of CDOM and of the putative biolabile fluorescence component shifted from complete decoupling in clear-water environments to strong coupling in darker streams and wetlands. This suggests a baseline autochthonous BDOC pool fueled by internal production that is gradually overwhelmed by land-derived BDOC as terrestrial influence increases across landscape gradients. The importance of land as a major source of both biologically and photochemically degradable DOC for continental watersheds resulted in a partial coupling of those carbon pools in natural freshwaters, despite fundamental contrasts in terms of their composition and regulation.

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