Heavy metal pollution in intertidal sediments from Quanzhou Bay, China

The concentrations of eight heavy metals （Cu, Zn, Pb, Cd, Cr, Ni, Hg, and As） in the intertidal surface sediments from Quanzhou Bay were determined to evaluate their levels and spatial distribution due to urbanization and economic development of Quanzhou region, southeast China. The ranges of the measured concentrations in the sediments are as follows： 24.8-119.7 mg/kg for Cu, 105.5-241.9 mg/kg for Zn, 34.3-100. 9 mg/kg for Pb, 0.28-0. 89 mg/kg for Cd, 51.1-121.7 mg/kg for Cr, 16.1-45.7 mg/kg for Ni, 0.17-0.74 mg/kg for Hg, and 17.7-30.2 mg/kg for As. The overall average concentrations of above metals exceed the primary standard criteria but meet the secondary standard criteria of the Chinese National Standard of Marine Sediment Quality. Several contents of Cu and Hg exceed the secondary standard criteria at some stations. The results of geoaccumulation index （Igeo） show that Cd causes strong pollution in most of the study area. There are no significant correlations among most of these heavy metals, indicating they have different anthropogenic and natural sources. Some locations present severe pollution by heavy metals depending on the sources, of which sewage outlets, aquatic breeding, and commercial ports are the main sources of contaminants to the area.

Characterization of uncultivated magnetotactic bacteria from the sediments of Yuehu Lake, China

Marine magnetotactic bacteria were collected from the intertidal sediments of Yuehu Lake（China）, where their abundance reached 103–104 ind./cm3. Diverse morphotypes of magnetotactic bacteria were observed, including cocci and oval, vibrio-, spirillum-, rod-, elliptical-, handle- and bar-shaped forms. The magnetococci were the most abundant, and had flagella arranged in parallel within a bundle. The majority of magnetosomes were arranged in one, two or multiple chains, although irregular arrangements were also evident. All the results of high-resolution transmission electron microscopy（HRTEM） analysis show that magnetosome crystals were composed of Fe3O4, and their morphology was specific to particular cell morphotypes. By the 16 S r RNA gene sequence analysis, we found fourteen operational taxonomic units（OTUs） which were related to magnetotactic bacteria. Among these, thirteen belonged to the Alphaproteobacteria and one to the Gammaproteobacteria.Compared with known axenic and uncultured marine magnetotactic bacteria, the 16 S r RNA gene sequences of most magnetotactic bacteria collected from the Yuehu Lake exhibited sequence identities ranging from 90.1% to96.2%（〈97%）. The results indicate that microbial communities containing previously unidentified magnetotactic bacteria occur in the Yuehu Lake.

Degradation kinetics and products of triazophos in intertidal sediment

This work presents taboratory studies on the degradation of triazophos in intertidat sediment. The overall degradations were found to follow the first-order decay model. After being incubated for 6 d, the percentage of degradations of triazophos in unsterilized and sterilized sediments were 94.5% and 20.5%, respectively. Between the temperatures of 15℃ and 35℃, the observed degradation rate constant（kob,d） enhanced as the incubation temperature increased. Triazophos in sediment degraded faster under aerobic condition than under anaerobic one. The water content of sediment had little influence on the degradation when it was in the range of 50%-100%. The values of kobsd decreased with increasing initial concentration of triazophos in sediment, which could result from the microorganism inhibition by triazophos. Four major degradation products, o, o-diethyl phosphorothioic acid, monoethyl phosphorothioic acid, phosphorothioic acid, and 1-phenyl-3-hydroxy-1, 2,4-triazole, were tentatively identified as their corresponding trimethylsilyl derivatives with a gas chromatography-mass spectrometer. The possible degradation pathway of triazophos in intertidal sediment was proposed. The results revealed that triazophos in intertidal sediment was relatively unstable and coutd be easily degraded.

Release of Mercury from Intertidal Sediment to Atmosphere in Summer and Winter

The release of mercury from intertidal sediment to atmosphere was studied based on the simulated experiment. The experiment samples were collected from the Haibo Estuary (S1) and the Licun Estuary (S2) of the Jiaozhou Bay in China,which are seriously polluted with mercury. The results show that the mercury in sediment releases rapidly to atmosphere under solar radiation. After 8 hours of solar radiation,mercury concentrations decrease from 5.62 μg/g and 2.92 μg/g to 2.34 μg/g and 1.39 μg/g in S1 and S2 sediments respectively in summer,and decrease from 5.62 μg/g and 2.92 μg/g to 4.58 μg/g and 2.13 μg/g respectively in winter. The mercury species in the sediment change markedly under solar radiation. The concentrations of mercury bound to organic matter decrease significantly from 2.73 μg/g to 0.31 μg/g in S1 and from 2.07 μg/g to 0.31 μg/g in S2,and the released mercury mainly comes from mercury bound to organic matter. Mercury flux shows distinguishing characteristic of diurnal change,and it increases rapidly in the morning with the rising of solar radiation intensity,but decreases in the afternoon. The mercury flux increases with sediment temperature and solar radiation intensity. The rapid release of mercury in intertidal sediment plays an important role in the regional mercury cycle.

Complete genome analysis of bacteriochlorophyll acontaining Roseicitreum antarcticum ZS2-28^(T)reveals its adaptation to Antarctic intertidal environment

Aerobic anoxygenic phototrophic bacteria(AAPB)are photoheterotrophic prokaryotes able to use both light and dissolved organic matter as energy sources.Roseicitreum antarcticum ZS2-28^(T)was isolated from intertidal sediment in the Larsemann Hills,Princess Elizabeth Land,Antarctica,and was able to produce bacteriochlorophyll a.It is the type strain of the sole species within the genus Roseicitreum.The complete genome sequence of the bacterium was determined using Illumina HiSeq X and PacBio RSII systems.The genome of R.antarcticum ZS2-28^(T)was 4253095 bp and consisted of one chromosome and four plasmids.A number of genes related to the bacteriochlorophyll a production,photosynthetic reaction,cold adaptation,salt adaptation,ultra-violet resistance and DNA damage repairing were found in the genome.In addition to genomic islands and typeⅣsecretion systems,genes related to gene transfer agents were detected in the genome of R.antarcticum ZS2-28^(T),suggesting that this bacterium can adapt to its environment by acquiring exogenous nucleic acids.The annotated complete genome sequence provides genetic insights into the environmental adaptation and ecological function of R.antarcticum ZS2-28^(T)in Antarctic coastal area.

Two new marine benthic diatom species of Hippodonta(Bacillariophyceae)from the coast of China:H.nanjiensis sp.nov.and H.qingdaoensis sp.nov.

The diversity and distribution of Hippodonta species on the coast of China are largely unknown due to limited investigations.In this paper,we report the detailed morphology and ultrastructure of two new species:H.nanjiensis sp.nov.,collected from intertidal sandy sediments of Nanji Islands,the East China Sea and H.qingdaoensis sp.nov.,collected from intertidal sandy sediments of the No.1 Bathing Beach in Qingdao City,the Yellow Sea.Both species occur mainly in the middle part of the intertidal zone.H.nanjiensis possesses a unique large round central area.H.qingdaoensis differs from congeners in having a unique stria pattern,wherein the areolae in the middle transapical striae are less developed or absent on the primary side of the valve,and two areolae per stria are apparent under light microscopy(LM).This study expands our knowledge of Hippodonta diversity and distribution on the coast of China.