Search

Antibiotic resistance genes (ARGs) are an important class of pollutants in the environment. This study investigated the characteristics and ecological effects of ARGs in the Bohai Sea sediments. The results showed that ARGs are widely distributed, and exhibit significant spatial and subtype variations, with absolute abundance following the decreasing order of Liaodong Bay, Laizhou Bay, Bohai Bay, and Bohai Strait. Tetracycline ARGs dominated, comprising 50 % to 62 % of all ARGs, with tetM having the highest abundance at 1.43 × 107 copies/g. Symbiotic network analysis revealed that the phyla Deinococcota, Dadabacteria were serve as the primary likely host of ARGs. The ARGs have a wide range of potential hosts, and bacteria often carry multiple ARGs, enhancing the mobility and ecological niche adaptation of ARGs. This study will provide an important reference for assessing ARGs pollution in semi-enclosed seas. [Display omitted] • ARGs exhibited significant spatial and subtype variations. • TOC and TN significantly influenced 16S rRNA abundance and promoted ARG occurrence and dissemination. • Sediment grain size and silt content affected ARGs by influencing intI 1 abundance. • ARGs have a wide range of potential hosts and have a good mobility and ecological niche adaptation. [ABSTRACT FROM AUTHOR]

Nutrients directly control the level of primary productivity and are crucial for the stability of marine ecosystems. Focusing on the survey results in August 2020 of the Yangtze River Estuary, this study elucidated the distribution characteristics and controlling factors of three nutrients: NO 3 -N, PO 4 -P, SiO 3 -Si. The results showed that the concentrations of NO 3 -N, PO 4 -P, SiO 3 -Si in the study area were generally higher near the shore than far shore, with average concentrations of 11.40, 0.70, and 23.73 μmol/L, respectively. The ocean currents drove the distribution of nutrients, and the transport of CDW and YSCC increased the nutrient levels. The resuspension of sediment caused by factors such as terrain and weather may lead to an abnormal increase in nutrients in the bottom waters. The main controlling factors of the three nutrients were different. NO 3 -N was significantly affected by human activities, PO 4 -P and SiO 3 -Si were mainly affected by natural factors. [Display omitted] • Nutrient characteristics driven by multiple factors is explored in the Yangtze River Estuary. • The nutrient concentrations are generally higher in nearshore and bottom waters. • The ocean currents drive the distribution of the three nutrients NO 3 -N, PO 4 -P, SiO 3 -Si. • The main controlling factors of the three nutrients are quite different. [ABSTRACT FROM AUTHOR]

The process of atmospheric organic carbon (OC) entering the ocean through wet deposition plays a crucial role in the global carbon cycle. To gain insights into the biogeochemical dynamics of OC at the land-sea margin, we conducted an extensive four-year investigation on precipitation OC in Jiaozhou Bay (JZB). The results showed that the volume-weighted mean concentration of particulate OC (POC) and dissolved OC (DOC) in precipitation were 0.38 and 2.06 mg C L−1 with an average wet deposition flux of OC for 2666.5 mg C m−2 yr−1. The source of POC in precipitation is predominantly by the C3 plant emission and burning and fossil fuel combustion. Wet deposition contributed 986.6 t yr−1 of OC of which 506.3 t yr−1 of bioavailable DOC, which could have significant implications for carbon cycle in the JZB. This study could enhance the understanding of the marine atmospheric OC in coastal areas. [Display omitted] • Long-term observation of DOC and POC in wet deposition in an urbanized coastal bay • Source apportionment of OC in precipitation in Jiaozhou Bay (JZB) • The atmospheric environment of JZB has showed a gradual improvement in terms of OC. • Wet deposition contributed JZB with sizeable amounts of bioavailable and inert OC. [ABSTRACT FROM AUTHOR]

To exploit the resolving ability of rare earth element and yttrium (REY) in resuspension binary mixing model, and discover potential new REY-related resuspension proxy, this preliminary research studied the geochemical signature of REY in different Jiaozhou Bay samples including surficial/core sediments and settling trap-collected particles. Close quantitative relation for bulk concentration in particles, sediments and fine-grained fraction of major river sediments around the Yellow Sea, approved the priority contribution of catchment detrital materials. Moreover, common characteristics occurred for compartment-specific partitioning REY signatures in six operated-defined fractions, and multiple REY normalization pattern indexes (i.e. Y/Ho divergence, and Ce/Eu anomalies). All constrain the application of REY in resuspension discrimination of marginal shallow seas. However, linearity with different slopes and intercepts were plotted for the MREE bulge index versus HREE/LREE figure in reducible amorphous Fe-oxides fraction, which could provide new discrimination perceptions. • The geochemistry of rare earth element and yttrium were evaluated. • Catchment detrital material is responsible for sinking particle and sediment. • Common features occur for specific partitioning REY signatures and indices. • New separated distribution of MREE bulge versus HREE/LREE was discovered. [ABSTRACT FROM AUTHOR]

Nutrients distribution and influencing factors in three seamount areas named Y3, M2 and C4 of the Tropical Western Pacific Ocean (TWPO) were investigated. Nutrients showed obvious uplifts around the three seamounts, consistent with the uplifts of isotherms and isohalines, indicating the existence of a bottom-up process of nutrients. Meanwhile, compared with the stations away from seamount and the reference stations in the TWPO, nutrients concentrations around seamount were much higher. Among the three seamounts, the average nutrients concentrations were highest in Y3, while they were lowest in C4. Moreover, compared with the obvious nitrogen limitation in Y3 and M2, the N:P (13.5:1) and Si:N (6.1:1) were closed to the Redfield ratio. The current-seamount interaction was the determining influencing factor on nutrients distribution, causing the hydrology dynamic changes such as uplifts and Taylor column. Meanwhile, T and S also affected nutrients distribution, especially nutrients and T showed significant negative correlations. • It is the first study to describe the environment and nutrients distribution systematically in the seamount. • Seamount could enhance the nutrients concentrations around it. • The nutrients concentrations and structures are different among the three seamount areas. [ABSTRACT FROM AUTHOR]

Abstract A total of 14 phthalate esters (PAEs) were analysed by gas chromatography–mass spectrometry (GC–MS) to better understand its occurrence and distribution in seawater samples of M2 seamount in the Tropical Western Pacific Ocean (TWPO). The concentrations of ΣPAEs in the seawater ranged from 12.13 ng L−1 to 60.69 ng L−1 (av. 28.86 ng L−1), dominated by dibutyl phthalate (DBP), di(2‑ethylhexyl) phthalate (DEHP) and diisobutyl phthalate (DiBP). ΣPAEs concentrations in the southwest of the seamount were lower than those in the northeast, with the minima appearing above the seamount summit. Current-seamount interaction was reckoned to be the principal driving factors in the distribution of PAEs. DEHP posed a medium risk in seawater, suggesting that marine plastic pollution has become an urgent environmental issue that calls for more attention and actions. Microplastics leaching and atmospheric deposition might be the potential sources of PAEs. Highlights • 14 PAEs were determined in the seamount area of the Tropical Western Pacific Ocean. • DBP, DEHP and DiBP were the dominate PAE congeners. • Current-seamount interaction was the main driving factors in the distribution. • DEHP posed a medium risk to aquatic organisms in TWPO. • Microplastics leaching and atmospheric deposition might be the potential sources. [ABSTRACT FROM AUTHOR]

Highlights • Bacteria were a major source of AS and OM in the sediments of the ECS. • In nearshore, the OM was more labile than that in offshore area. • As the algae bloom decline, the OM source transformed from plankton to bacteria. • The settling plankton detritus provided food for benthic bacteria in summer. • The estimation based on Mur showed the important contribution of bacterial OM. Abstract Amino sugars (AS) were investigated to study the source, reactivity and bacterial contribution of organic matters (OM) in surface sediments of the East China Sea (ECS) both in summer and autumn in 2016, within and after the algae bloom, respectively. The content of AS was 0.48–7.23 μmol/(g dw) with a higher concentration in nearshore than that in offshore area and lower concentration in summer than that in autumn, which on average made up 3.65 ± 1.66% of TOC and 4.49 ± 1.98% of TN in the ECS surface sediments. The low average ratio of glucosamine/galactosamine (GlcN/GalN) (1.16 ± 0.15) indicated a major bacterial source of AS pool of the investigated area. Higher GlcN/GalN (1.30 ± 0.15 in summer and 1.21 ± 0.09 in autumn) and muramic acid (Mur) (8.8 ± 3.8 nmol/(mg C) in summer and 20.5 ± 10.3 nmol/(mg C) in autumn) and together with lower GlcN/Mur (29 ± 8 in summer and 16 ± 4 in autumn) content in nearshore than those in offshore area (GlcN/GalN: 1.11 ± 0.14 in summer and 1.09 ± 0.13 in autumn; Mur: 5.2 ± 1.7 nmol/(mg C) in summer and 10.4 ± 5 nmol/(mg C) in autumn; GlcN/Mur: 36 ± 9 in summer and 34 ± 11 in autumn) indicated more plankton detritus and a more labile nature of OM, and also relatively higher fresh bacteria contribution to OM in nearshore area, which was consistent with the higher concentrations of Chl- a in corresponding surface water. The transformation of plankton to bacteria source of OM from summer to autumn was revealed by the increased total hydrolysable amino sugars (THAS) and Mur concentration, C- and N-normalized yield of THAS, and also the decreased ratios of GlcN/GalN and GlcN/Mur in sediments in autumn. The correlation between Mur in sediments and Chl- a in surface water suggested that the real-time settling plankton detritus was one of the major food sources for benthic bacteria in summer but contributed little in autumn. Based on Mur, the relatively fresh bacteria OM contribution to TOC were 13.1% in summer and 28.5% in autumn. In summary, the composition of AS in the ECS surface sediments showed a major bacteria origin of OM and the bioavailability decreased from nearshore to offshore and also from summer to autumn. As the algae bloom decline, the flux of plankton detritus decreased and the OM source transformed from plankton to bacteria. [ABSTRACT FROM AUTHOR]

As a result of the increasing consumption of fossil fuels all over the world, the ongoing global warming caused by rising atmospheric carbon dioxide (CO 2) concentrations has attracted extensive attention. One of the theoretically feasible and promising methods of reducing CO 2 in the atmosphere is to sequester it by forming thermodynamically stable carbonates. Olivine, (Mg, Fe) 2 SiO 4 , is an abundant mineral that can react with CO 2 to form carbonates when deliberately introduced into seawater. However, in addition to increasing the additional uptake of atmospheric CO 2 , it is inevitably accompanied by the release of other elements (e.g. Si, Ca, Mg, Fe and Ni) which could have adverse effects on marine organisms when those elements are at high levels. In this article, the reaction kinetics and mechanisms of olivine dissolution in seawater were introduced, the influencing factors on the olivine dissolution rate under ex situ conditions were highlighted, the possible impacts of the released products on marine organisms (mainly primary producers) and biogeochemical processes controlled by marine organisms were analyzed, and the potential applications to increase marine carbon storage were discussed. Furthermore, the current challenges of olivine application in seawater, such as dissolution reactivity, ecological effects, cost consumption, and future development directions (i.e. life cycle assessment technique and energy recycling approaches) have been highlighted to promote the practical applications of olivine dissolution in enhancing ocean alkalinity and increasing marine carbon sequestration. [Display omitted] • Olivine addition theoretically lowers atmospheric CO 2 by enhancing ocean alkalinity. • Formation of SiO 2 -rich layers is the key factor influencing olivine dissolution rate. • Potential eco-risks and co-benefits of ocean olivine addition (OOA) were analyzed. • Sufficient assessment experiments should be done before practical OOA application. [ABSTRACT FROM AUTHOR]

Abstract The spatial and temporal dynamics of both dissolved and particulate nutrients were studied during 2015–2016 in the Jiaozhou Bay (JZB), a deeply anthropogenic impact ecosystem in China. The dissolved inorganic nutrients was mainly from the wastewater and riverine inputs which is demonstrated from the negative correlation between nutrients with salinity and their higher levels distribution observed in the northeastern and/or northwestern JZB, where mainly received industrial and agricultural source run-off, respectively. The high levels of dissolved and particulate organic pools were also observed in the same area but have autochthonous sources besides terrestrial input, which lead to their higher concentrations in autumn during phytoplankton bloom. The composition of DIN has been changed with the major component from NH 4 + to NO 3 -, which probably due to the controlling load of NH 4 + but no limitation of NO 3 - by human intervention. The average annual DIN/DIP ratio increased by one time but SiO 3 2-/DIN ratio has no obvious variation over the past decade, which indicated that the potential limiting nutrient for phytoplankton growth has been converted from silicon to phosphorus in JZB. Additional, more prone to partition into POC but not DOC pools of organic carbon were found during the phytoplankton bloom in autumn due to the nutrient-rich, diatom dominated condition and both DOP and POP may be the potential P source and can relieve P limitation to some extent during the same time. Nutrient budgets calculation also demonstrated that riverine input and wastewater discharge are major sources of dissolved nitrogen and phosphorus, while silicate were mainly came from submarine fresh groundwater discharge. The mixing flow transported large amounts of nutrients from JZB to the Yellow Sea. Meanwhile, the net ecosystem metabolism and nitrogen metabolism calculation showed the whole ecosystem was heterotrophic and a net nitrogen fixation in JZB. Highlights • The composition of DIN in JZB has been changed with the major component from NH 4 + to NO 3 -. • The proportions of DON and DOP to TDN and TDP has increased obviously over the past decade. • The potential limiting nutrient for phytoplankton growth has been converted from silicon to phosphorus in JZB. • An annual nutrients budget including submarine fresh groundwater discharge is proposed. • JZB is net heterotrophic (57 ×107 mol C/yr) and net nitrogen fixation (74 ×106 mol/yr) on annual basis. [ABSTRACT FROM AUTHOR]

Abstract Sediment geochemical characteristics were analyzed to assess how anthropogenic activities affected the Daya Bay, a subtropics bay adjacent to the most economically developed region of China. Vertical profiles of heavy metal contents and their enrichment factors indicated the development of Daya Bay environment in the past 100 years basically experienced three stages, which were closely consistent with the economic development. Before 1980s, the concentration of heavy metals was basically at the background level. Contamination of metals, particularly for Cr, Ni, Cu, Zn, Cd, and Pb, generally began in mid-1980s and became serious in 2000s. However, after late-2000s, the sediment quality had been radically improved. Heavy metals in nearshore sediment of Daya Bay were all closely related with import of anthropogenic and/or terrestrial material, whereas those in offshore were likely to be related with joint influence from the anthropogenic activities and the natural processes. Highlights • The evolution of Daya Bay environment in the past 100 years basically experienced three stages. • Before 1980s there was no record of heavy metals pollution. • Contamination of metals generally began in mid-1980s and became very serious in 2000s. • After late-2000s the sediment quality had been radically improved. • Contributions of anthropogenic and natural metals in sediment varied with heavy metal types and regional position. [ABSTRACT FROM AUTHOR]

Abstract Reconstructing heavy metal historical trends are essential for better understanding anthropogenic impact on marine ecosystems. In this work, the ecological risk and sources of Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb in Jiaozhou Bay were studied and the anthropogenic metal emissions was also quantified. The ecological risk was mainly caused by Cd, As and Cu, which presented an increasing trend with increased anthropogenic activities since the 1950s. The statistical analysis show that Cr, Mn, Ni, Cu and Zn were primarily from natural sources. Cadmium and Mn might originate from both natural and anthropogenic sources. Arsenic and Pb were sourced from agricultural activities and atmospheric precipitation, respectively. The anthropogenic flux of Cr, Mn, Ni, Cu, Zn, As, Cd and Pb were 138, 586, 63, 66, 161, 35, 0.31 and 44 mg/m2/a since the 1950s. Over 40.0% of Cu and As were quantified from anthropogenic emissions since the 1950s. Highlights • Jiaozhou Bay sediments reflected regional anthropogenic metal emissions. • Anthropogenic source heavy metals present an increasing trend since 1950s. • Risk contribution ratios of Cd, As and Cu were 48.8%, 20.8% and 9.3%, respectively. • Over 40% of Cu and As were quantified from anthropogenic source since the 1950s. [ABSTRACT FROM AUTHOR]

We sampled the surface sediments of the East China Sea shelf (ECSS) in spring and autumn, 2014, and analyzed the biogenic element concentrations and stable carbon (δ 13 C) and nitrogen (δ 15 N) isotopic compositions to study the distribution and seasonal variations of sedimentary organic matter (OM). The average concentrations of TOC, TN and OP in autumn decreased obviously compared with those in spring. The increase of δ 15 N values in autumn indicated the priority utilization of 14 N by bacterial decomposition activity. The values of δ 13 C were used to trace organic matter sources. The estimated percentages for terrestrial OM were in the range of 0–34.6%. They generally decreased seaward in nearshore areas, indicating the decrease of terrigenous influence. There was an obvious tongue-shaped region with relatively low percentages of terrestrial OM (<12%) in the northern part of the ECSS, which may be a reflection of the intrusion pathway of the outer seawater. [ABSTRACT FROM AUTHOR]

To identify sources and evaluate ecological risks of heavy metals in sediments of Jiaozhou Bay, contents and chemical fractions of Cd, Cr, Cu, Pb, Zn, Ni, Sb and Sn were studied. Results suggested that higher metal contents appeared at inner bay and near marine dumping area. Labile fractions of heavy metals accounted for 0.5–77% (~36%) of total contents indicating their significant anthropogenic sources. The enrichment levels of Cd and Sb were relatively higher. Cu, Ni, Cd and Zn were at low to medium risks. Cr, Pb, Sn and Sb were at no or low risks. Total contents of heavy metals were mainly controlled by natural sources, while anthropogenic inputs were important sources of labile fractions of heavy metals in sediments of Jiaozhou Bay with industrial and domestic activities as main contributors for Cu, Pb, Zn, Cr, Ni and Sn, and agricultural activities for Cd and regional coal combustion for Sb. [ABSTRACT FROM AUTHOR]

Total contents and chemical speciation of Co, Ni, Cu, Ga, Mo, Cd, In, Sn, Sb, V, W, Tl, Bi and U in size-fractionated (< 32, 32–63 and > 63 μm) core sediments from Jiaozhou Bay were investigated to reveal their responses to anthropogenic activities. Metal contents showed a decreasing trend with increasing grain sizes. However, the loadings of metal fraction on < 32, 32–63 and > 63 μm grain sizes were 16%, 47% and 37%, respectively. Anthropogenic fluxes and enrichment factors of metals in > 63 μm fraction were closely linked to anthropogenic activities, with an obvious increase in upper 27 cm (1998–2015) and a slight decrease in 2009 year. Metals (especially for Cd, Co, Cu and Ni) in > 63 μm fraction were more easily released, with the highest percentage of acid soluble form and lowest residual form. Thus, the size fraction of > 63 μm cannot be ignored. [ABSTRACT FROM AUTHOR]

The behavior of heavy metals in contaminated sediment is of ecological significance considering the change of pH caused by ocean acidification. This study investigated the mobility of Cd, Cu, Ni, Pb, Fe, and Mn under experimental conditions for seawater acidification via enrichment of CO 2 gas at different reaction set-ups. The results indicated that the concerned metals behaved differently in the water compared to the sediment. The heavy metals were considerably transferred from sediment to seawater, and the resultant intensity was controlled by the degree of acidification and the chemical state of specific metals. Moreover, labile fractions of heavy metals in sediments were more susceptible to acidification than other fractions. These findings were observed and confirmed using real-time monitoring conducted via the diffusion gradient technique (DGT). Overall, the results of this study provided new insights into exploring the coupling risk of heavy metals with ocean acidification. • Long-term effects of acidification on heavy metal mobility • Variations in heavy metal distribution patterns in sediment–seawater systems • CO 2 enrichment acidified the pH of the system. • Changes in effective heavy metals were obtained by diffusion gradient technique. [ABSTRACT FROM AUTHOR]

Surface sediments were collected from the main path of Kuroshio Current (KC) off eastern Taiwan (ETW), and laboratory incubation was conducted for the study of the nutrient exchange at the sediment-water interface. Exchange fluxes of NO 3 − -N, NO 2 − -N, NH 4 + -N, PO 4 3 − -P and SiO 3 2 − -Si under simulated site condition were − 0.0866, 0.00146, 0.0634, − 0.00812 and − 0.181 mmol m − 2 d − 1 , respectively. This indicated that sediments in the studied area might act as a source of NO 2 − -N and NH 4 + -N and a sink of NO 3 − -N, PO 4 3 − -P and SiO 3 2 − -Si. Factors affecting nutrient exchange fluxes were studied by changing incubation conditions. Compared with some coastal areas in China, the main path of KC off ETW showed relatively low nutrient exchange fluxes at the sediment-water interface. It could be inferred that the sediment-water exchange of nutrients in the main path of KC off ETW had little influence on the downstream nutrient transportation by KC year-round based on the results of this research. [ABSTRACT FROM AUTHOR]

The radioactivity concentration of 238 U, 232 Th, 226 Ra, 40 K, and 137 Cs in soil samples collected in a coastal wetland of the Southern Laizhou Bay, China were measured. Mean activity concentrations were 54.4 ± 11.7, 57.9 ± 9.7, 28.6 ± 4.3, 542 ± 21, and 10.2 ± 2.9 Bq kg −1 dry weight for 238 U, 232 Th, 226 Ra, 40 K and 137 Cs, respectively. Statistical analyses suggested significant correlations between clay content and 40 K as well as 137 Cs. The radium equivalent activity, the absorbed dose rate in the air at 1 m above the ground surface, and the external hazard index were calculated. The result showed that the radioactivity level in the wetland was in normal range. But sites along the river tended to have higher radiological hazard indexes. The vertical distributions of radionuclides in profiles illustrated some phenomena, such as vertical transport of 238 U, disequilibrium between 238 U and 226 Ra, and change in material sources. [ABSTRACT FROM AUTHOR]

Abstract: Total concentrations, chemical fractions by BCR procedure and enrichment factors of nine potential harmful elements (V, Cr, Co, Ni, Cu, Zn, Mo, Cd and Pb) in surface sediments of the East China Sea (ECS) were investigated. Spatial distributions illustrated that PHEs (potential harmful elements) were mainly from the Changjiang River and the Jiangsu coastal current, except Pb which was influenced by atmospheric input. Sediments in the ECS were moderately polluted with Cd, Pb, Zn and Cu according to their enrichment factors (EFs). Distributions of EFs and labile fractions revealed that anthropogenic Cd and Cu were mainly input though the Changjiang, Pb pollutant was delivered from the Changjiang and atmosphere, while Zn was impacted by terrestrial pollution from the Changjiang and the Hangzhou Bay. Budget calculation showed that the Changjiang contributed 82–90% of PHE influxes. Thirty-eight to 77% of PHEs were buried in sediment, mainly along the inner shelf. [Copyright &y& Elsevier]

Abstract: The distributions, annual sedimentation and atmospheric deposition flux of heavy metals have been studied in sediments of the South Yellow Sea (SYS), in order to evaluate their levels and pollution status. The higher concentrations of heavy metals were generally found in the central part of the SYS, which may be associated with the organic matters due to their high affinity to the metals. According to the calculated enrichment factor (EF) of the studied metals, Cd in the sediments posed a high risk to local environments, while Mn, Hg, Pb and Zn were at moderate risk levels. Sedimentation fluxes study in the SYS showed that most heavy metals were deposited in the Chinese offshore. Annual dry deposition flux of these metals indicated that the particulate heavy metals deposition via atmosphere also play an important role in biogeochemical cycles in the SYS. [Copyright &y& Elsevier]

Sediment geochemical technique was employed to assess how the sediment records reflect the environmental changes of Jiaozhou Bay, a semi-enclosed bay adjacent to Qingdao, China. In the past hundred years, Jiaozhou Bay has been greatly impacted by human interventions. A dated core sediment by 210Pb chronology was analyzed for trace metals including Li, Cd, Cr, Pb, Cu, Ni, Co, Zn together with C, N, P and BSi. Based on the research, the development of Jiaozhou Bay environment in the past hundred years can be divided into three stages: (1) before the 1980s characterized by relatively low sedimentation rate, weak heavy metal pollution and scarce eutrophication; (2) from the 1980s to 2000, accelerating in the 1990s, during which high sedimentation rates, polluted by heavy metals and the frequent occurrence of red tide; (3) after 2000, the period of the improvement of environment, the whole system has been meliorated including the heavy metal pollution and hypernutrification. [Copyright &y& Elsevier]

Abstract: The modulation of carrageenan oligosaccharides from Kappaphycus striatum on the immune system in S180-bearing mice was investigated. The mice inoculated with S180 cell suspension were treated p.o. with carrageenan oligosaccharides (50, 100 and 200μg/g) for 14 days. The effects of carrageenan oligosaccharides on transplantable tumors and macrophage phagocytosis, quantitative hemolysis of sheep red blood cells (QHS), lymphocyte proliferation, the activity of natural killer cells (NK), production of interleukin-2 (IL-2) and tumor necrosis factor-α (TNF-α) were studied. Carrageenan oligosaccharides could significantly inhibit the growth of transplantable sarcoma S180 and increase macrophage phagocytosis, the form of antibody secreted by spleen cells, spleen lymphocyte proliferation, NK cells activity, serumal IL-2 and TNF-α level in S180-bearing mice. Considering all these results, it is suggested that carrageenan oligosaccharides exert their antitumor effect by promoting the immune system. [Copyright &y& Elsevier]

Abstract: Antioxidant activity of κ-carrageenan oligosaccharides (OM) and their chemical modification derivatives was investigated employing various established in vitro systems, such as reducing power, iron ion chelation, and total antioxidant activity using β-carotene–linoleic acid system. The oversulfated (SD), lowly (LAD), and highly acetylated derivatives (HAD) in reducing power assay, the phosphorylated derivative (PD) in metal chelating assay, and oversulfated and phosphorylated derivatives in total antioxidant activity assay exhibited antioxidant activity higher than that of carrageenan oligosaccharides. The results indicated that the chemical modification of carrageenan oligosaccharides can enhance their antioxidant activity in vitro. The protective effects of the carrageenan oligosaccharides and their chemically modified derivatives against H2O2 and UVA (long-wave ultraviolet radiation) induced oxidative damage on rat thymic lymphocyte were investigated by measuring cell viability via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Thymic lymphocyte exposure to H2O2 and UVA, a marked reduction in cell survival was observed, which was significantly prevented by carrageenan oligosaccharides and their derivatives (preincubated for 2h) at 66.7–2000μg/mL. But both the carrageenan oligosaccharides and their different derivatives showed the similar protective effects on intracellular level. Taken together, these results suggest that carrageenan oligosaccharides and their derivatives show relevant antioxidant activity both in vitro and in a cell system. [Copyright &y& Elsevier]