Total petroleum hydrocarbons and heavy metals in the surface sediments of Bohai Bay, China: long-term variations in pollution status and adverse biological risk.

Surface sediments collected from 2001 to 2011 were analyzed for total petroleum hydrocarbons (TPH) and five heavy metals. The sediment concentration ranges of TPH, Zn, Cu, Pb, Cd and Hg were 6.3-535 µg/g, 58-332 µg/g, 7.2-63 µg/g, 4.3-138 µg/g, 0-0.98µg/g, and 0.10-0.68 µg/g, respectively. These results met the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. However, based on the effects range-median (ERM) quotient method, the calculated values for all of the sampling sites were higher than 0.10, suggesting that there was a potential adverse biological risk in Bohai Bay. According to the calculated results, the biological risk decreased from 2001 to 2007 and increased afterwards. High-risk sites were mainly distributed along the coast. This study suggests that anthropogenic influences might be responsible for the potential risk of adverse biological effects from TPH and heavy metals in Bohai Bay.

[Carbon storage of Pinus thunbergii and Robinia pseudoacacia plantations on Nanchangshan Island, Changdao County of Shandong Province, China].

Using indigenous tree species to transform large area pure plantations has been an effective close-to-nature forest management mode in China islands. By using the biomass allometric equation and combined with the investigation data from sampling plots, the carbon storage of the dominant species Pinus thunbergii and Robinia pseudoacacia in the plantations on the Nanchangshan Island of Miaodao Archipelago in Changdao County of Shandong Province was estimated. The average carbon storage in the arbor layer of P. thunbergii and R. pseudoacacia plantations was 56.81 and 37.26 t x hm(-2), respectively, being higher than the average carbon stock (27.62 t x hm(-2)) of tree plantations in Shandong Province. Slope aspect and stand density were the important environmental and biological factors affecting the tree's carbon stock in the Island, respectively. There was no significant correlation between the average cumulative rate of biomass in the arbor layer of P. thunbergi plantation and the stand age. The P. thunbergii with good carbon sequestration function could be an ideal tree species on Nanchangshan Island.

PAHs distribution in sediments associated with gas hydrate and oil seepage from the Gulf of Mexico.

Six sediment samples collected from the Gulf of Mexico were analyzed. Total concentrations of the PAHs ranged from 52 to 403 ng g(-1) dry weight. The lowest PAH concentration without 5-6 rings PAHs appeared in S-1 sample associated with gas hydrate or gas venting. Moreover, S-1 sample had the lowest organic carbon content with 0.85% and highest reduced sulfur level with 1.21% relative to other samples. And, analysis of the sources of PAHs in S-1 sample indicated that both pyrogenic and petrogenic sources, converserly, while S-8, S-10 and S-11 sample suggested petrogenic origin. The distribution of dibenzothiophene, fluorine and dibenzofuran and the maturity parameters of triaromatic steranes suggested that organic matters in S-1 sample were different from that in S-8, S-10 and S-11 sample. This study suggested that organic geochemical data could help in distinguish the characteristic of sediment associated with gas hydrate or with oil seepage.