An adsorption and thermodynamic study of ofloxacin on marine sediments

2017 ◽  
Vol 14 (6) ◽  
pp. 350 ◽  
Author(s):  
Wen-Qing Cao ◽  
Jun Song ◽  
Gui-Peng Yang
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Marine Sediments ◽  
Adsorption Process ◽  
Entropy Change ◽  
Natural Seawater ◽  
Organic Carbon Content ◽  
Adsorption Behaviour ◽  
H2o2 Treatment ◽  
Sediment Organic Carbon

Environmental contextOfloxacin, a widely used fluorinated antibiotic, is resistant to biodegradation and hence can accumulate in the environment. A systematic investigation of ofloxacin on marine sediments showed that sediment organic carbon and heterogeneous sites on sediments play important roles in adsorption processes. The results help our understanding of the environmental behaviour and fate of ofloxacin in marine systems. AbstractThe adsorption behaviour of ofloxacin (OFL) on marine sediments treated by different methods was investigated using batch experiments. Three factors (sediment organic carbon content, salinity and temperature) that may affect the adsorption behaviour of OFL were analysed. The equilibrium time for OFL adsorption on marine sediment in natural seawater was ~4–5h. The adsorption of OFL on all sediments with different treatments fitted the Freundlich model well. The adsorption parameter Kf value was in the order of Kf (H2O2 treatment)<Kf (H2O treatment)<Kf (HCl treatment) over the studied concentration range. The adsorption of OFL was influenced not only by the sediment organic carbon content but also by external factors such as salinity of media and temperature. The adsorption was favourably influenced by decreased salinity and temperature of seawater. The adsorption capacity of OFL on marine sediments decreased with an increase of temperature and salinity. The Kf values decreased from 33.73±1.66 to 22.54±1.12(Lkg−1)1/n when the temperature increased from 283 to 313K. The changes in standard Gibbs free energy (ΔG0) and enthalpy (ΔH0) were −6.62±0.34kJmol−1 and −7.58±0.38kJmol−1 respectively, indicating that the adsorption process of OFL was spontaneous and exothermic. The positive value of the entropy change ΔS0 (i.e. 3.38±0.17JK−1mol−1) suggests that the degree of freedom increased during the adsorption process.

scholarly journals Blooms of cyanobacteria in a temperate Australian lagoon system post and prior to European settlement

2016 ◽  
Vol 13 (12) ◽  
pp. 3677-3686 ◽  
Author(s):  
Perran L. M. Cook ◽  
Miles Jennings ◽  
Daryl P. Holland ◽  
John Beardall ◽  
Christy Briles ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Phosphorus Release ◽  
Cyanobacterial Blooms ◽  
Organic Carbon Content ◽  
Lagoon System ◽  
European Settlement ◽  
Current Period ◽  
Sediment Organic Carbon ◽  
Nitrogen Inputs

Abstract. Blooms of noxious N2 fixing cyanobacteria such as Nodularia spumigena are a recurring problem in some estuaries; however, the historic occurrence of such blooms in unclear in many cases. Here we report the results of a palaeoecological study on a temperate Australian lagoon system (the Gippsland Lakes) where we used stable isotopes and pigment biomarkers in dated cores as proxies for eutrophication and blooms of cyanobacteria. Pigment proxies show a clear signal, with an increase in cyanobacterial pigments (echinenone, canthaxanthin and zeaxanthin) in the period coinciding with recent blooms. Another excursion in these proxies was observed prior to the opening of an artificial entrance to the lakes in 1889, which markedly increased the salinity of the Gippsland Lakes. A coincident increase in the sediment organic-carbon content in the period prior to the opening of the artificial entrance suggests that the bottom waters of the lakes were more stratified and hypoxic, which would have led to an increase in the recycling of phosphorus. After the opening of the artificial entrance, there was a  ∼  60-year period with low values for the cyanobacterial proxies as well as a low sediment organic-carbon content suggesting a period of low bloom activity associated with the increased salinity of the lakes. During the 1940s, the current period of re-eutrophication commenced, as indicated by a steadily increasing sediment organic-carbon content and cyanobacterial pigments. We suggest that increasing nitrogen inputs from the catchment led to the return of hypoxia and increased phosphorus release from the sediment, which drove the re-emergence of cyanobacterial blooms.

Anaerobic microbial Fe(II) oxidation and Fe(III) reduction in coastal marine sediments controlled by organic carbon content

2016 ◽  
Vol 18 (9) ◽  
pp. 3159-3174 ◽  
Author(s):  
Katja Laufer ◽  
James M. Byrne ◽  
Clemens Glombitza ◽  
Caroline Schmidt ◽  
Bo Barker Jørgensen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Marine Sediments ◽  
Organic Carbon Content ◽  
Coastal Marine Sediments ◽  
Coastal Marine

scholarly journals Assessing the potential of amino acid δ<sup>13</sup>C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

2015 ◽  
Vol 12 (2) ◽  
pp. 1613-1651 ◽  
Author(s):  
T. Larsen ◽  
L. T. Bach ◽  
R. Salvatteci ◽  
Y. V. Wang ◽  
N. Andersen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Organic Carbon ◽  
Primary Production ◽  
Carbon Content ◽  
Marine Sediments ◽  
Growth Conditions ◽  
Marine Diatom ◽  
Organic Carbon Content ◽  
Amino Acid Synthesis

Abstract. Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles, and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing biosynthetic origin of amino acid carbon skeletons, based on natural occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions; and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results underscore that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e. isoleucine, lysine, leucine and tyrosine), bacterial derived amino acids ranged from 10–15% in the sediment layers from the last 5000 years to 35% during the last glacial period. The larger bacterial fractions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to a substantially larger degree than suggested by changes in total organic nitrogen and carbon content. Taken together, these culturing and sediment studies suggest that δ13CAA patterns in sediments represent a novel proxy for understanding both primary production sources, as well as direct bacterial role in the ultimate preservation of sedimentary organic matter.

scholarly journals Blooms of cyanobacteria in a temperate Australian lagoon system post and prior to European settlement

2015 ◽  
Vol 12 (22) ◽  
pp. 18829-18853
Author(s):  
P. L. M. Cook ◽  
M. Jennings ◽  
D. P. Holland ◽  
J. Beardall ◽  
C. Briles ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Phosphorus Release ◽  
Cyanobacterial Blooms ◽  
Organic Carbon Content ◽  
Lagoon System ◽  
European Settlement ◽  
Current Period ◽  
Sediment Organic Carbon ◽  
Nitrogen Inputs

Abstract. Blooms of noxious N2 fixing cyanobacteria such as Nodularia spumigena are a recurring problem in some estuaries. Here we report the results of a palaeoecological study on a temperate Australian lagoon system (The Gippsland Lakes) where we used stable isotopes and pigment biomarkers in dated cores as proxies for eutrophication and blooms of cyanobacteria. Pigment proxies show a clear signal, with an increase in cyanobacterial pigments (echinenone, canthaxanthin and zeaxanthin) in the period coinciding with recent blooms. Another excursion in these proxies was observed prior to the opening of an artificial entrance to the lakes in 1889, which markedly increased the salinity of the Gippsland Lakes. A coincident increase in the sediment organic carbon content in the period prior to the opening of the artificial entrance suggests the bottom waters of the lakes were increasingly stratified and hypoxic, which would have led to an increase in the recycling of phosphorus. After the opening of the artificial entrance there was a ~ 60 year period with low values for the cyanobacterial proxies as well as a low sediment organic carbon content suggesting a period of low bloom activity associated with the increased salinity of the lakes. During the 1940s, the current period of re-eutrophication commenced as indicated by a steadily increasing sediment organic carbon content and cyanobacterial pigments. We suggest increasing nitrogen inputs from the catchment led to the return of hypoxia and increased phosphorus release from the sediment, which drove the re-emergence of cyanobacterial blooms.

scholarly journals Recent variations in sediment organic carbon content in Lake Soyang (Korea)

Limnology ◽  
2005 ◽  
Vol 6 (2) ◽  
pp. 139-139 ◽  
Author(s):  
Boo-Keun Khim ◽  
Hee Mdn Jung ◽  
Daekyo Cheong
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Organic Carbon Content ◽  
Sediment Organic Carbon
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