Gas Phase Hydrogenated and Deuterated Fullerene Cations

H/D accretion,especially onto ionized fullerenes,is expected to be very efficient in space.In this work,we study hydrogenated and deuterated fullerene cations and their photodissociation behavior in the gas phase.The experimental results show that hydrogenated fullerene cations(i.e.,[C_(60)H_(n)]^(+)and[C_(70)H_(n)]^(+),n up to 30)and deuterated fullerene cations(i.e.,[C_(60)D_(n)]^(+)and[C_(70)D_(n)]^(+),n up to 21)are formed efficiently through the ion-atom collision reaction pathway.Upon irradiation,the hydrogenated and deuterated fullerene cations dissociate into fullerene cations and H/H_(2)or D/D_(2)species.The structures of the newly formed hydrogenated and deuterated fullerene cations(C_(58)and C_(60))and the bonding energies for these reaction pathways are investigated by means of quantum chemical calculations.The competition between hydrogenation and dehydrogenation is confirmed,and the hydrogenation-to-dehydrogenation ratio in the accretion processes in the gas phase is determined.We infer that the proportion of accreted hydrogen and deuterium atoms on the surface of fullerenes is similar to that of hydrogen and deuterium atoms in the interstellar environment where these fullerenes are located,especially when the interstellar environments are similar to our experimental conditions,i.e.,the hot environment.

Distribution, bioaccumulation, trophic transfer and risk assessment of trace elements in fish from a typical shallow outflow lake basin, China

Fish are important food sources for humans,and the availability of appropriate amount of trace elements(TEs)plays a crucial role in fish growth.Currently,due to large volumes of sewage discharge,high levels of certain elements are present in aquatic environments,and these elements accumulate in fish and potentially affect human health.In this study,the distribution and bioaccumulation capacity of trace elements in six dominant fish species from Chaohu Lake(China)were analyzed.The results showed that the bioaccumulation capacity of fish for Zn was greater than other TEs.And the source of the TEs in the fish were explored along with the concentration of the TEs in the aquatic environment,which indicated that TEs in fish were mainly obtained through ingestion and indirectly affected by the industrial activities in the basin.Additionally,stable carbon and nitrogen isotopes were used to classify the trophic levels and explore the biological magnification of TEs of the fish.It was found that Sb and Sr showed biomagnification with the increase of trophic level of fish.Based on the above analyses,the environmental biogeochemical cycle model of TEs in the lake was distinguished and established,which can offer valuable insights for sustainable fishery management in the downstream Yangtze River Delta ecosystem.

Spatial distribution and pollution assessment of heavy metals in urban soils from southwest China

To identify the concentrations and sources of heavy metals, and to assess soil environmental quality, 63 soil samples were collected in Yibin City, Sichuan Province, China. Mean concentrations of As, Pb, Zn, and Cu were 10.55, 61.23, 138.88 and 56.35 mg/kg, respectively. As concentrations were comparable to background values, while Pb, Zn, and Cu concentrations were higher than their corresponding background values. Industrial areas exhibited the highest concentrations of As, Pb, Zn, and Cu, while the lowest concentrations occurred in parks. Statistical analysis was performed and two cluster groups of metals were identified with Pb, Zn, and Cu in one group and As in the other. Spatial distribution maps indicated that Pb, Zn, and Cu were mainly controlled by anthropogenic activities, whereas As could be mainly accounted for by soil parent materials. Pollution index values of As, Pb, Zn, and Cu varied in the range of 0.24-1.93, 0.66-7.24, 0.42-4.19, and 0.62-5.25, with mean values of 0.86, 1.98, 1.61, and 1.78, respectively. The integrated pollution index （IPI） values of these metals varied from 0.82 to 3.54, with a mean of 1.6 and more than 90% of soil samples were moderately or highly contaminated with heavy metals. The spatial distribution of IPI showed that newer urban areas displayed relatively lower heavy metal contamination in comparison with older urban areas.

Mantle geochemistry: Insights from ocean island basalts

The geochemical study of the Earth's mantle provides important constraints on our understanding of the formation and evolution of Earth, its internal structure, and the mantle dynamics. The bulk Earth composition is inferred by comparing terrestrial mantle rocks with chondrites, which leads to the chondritic Earth model. That is, Earth has the same relative proportions of refractory elements as that in chondrites, but it is depleted in volatiles. Ocean island basalts(OIB) may be produced by mantle plumes with possible deep origins; consequently, they provide unique opportunity to study the deep Earth. Isotopic variations within OIB can be described using a limited number of mantle endmembers, such as EM1, EM2 and HIMU, and they have been used to decipher important mantle processes. Introduction of crustal material into the deep mantle via subduction and delamination is important in generating mantle heterogeneity; however, there is active debate on how they were sampled by mantle melting, i.e.,the role of olivine-poor lithologies in the OIB petrogenesis. The origin and location of high 3He/4He mantle remain controversial,ranging from unprocessed(or less processed) primitive material in the lower mantle to highly processed materials with shallow origins, including ancient melting residues, mafic cumulates under arcs, and recycled hydrous minerals. Possible core-mantle interaction was hypothesized to introduce distinctive geochemical signatures such as radiogenic 186 Os and Fe and Ni enrichment in the OIB. Small but important variations in some short-lived nuclides, including 142 Nd, 182 W and several Xe isotopes, have been reported in ancient and modern terrestrial rocks, implying that the Earth's mantle must have been differentiated within the first 100 Myr of its formation, and the mantle is not efficiently homogenized by mantle convection.

Re-Os isotope geochemistry of three Chinese chondrites

Three Chinese ordinary chondrites,including Jilin (H5),Boxian (LL3.8) and Lujiang (LL6),have been studied for their Re and Os abundances and Os isotopic composition in whole-chondrite samples,separated magnetic and nonmagnetic fractions,and nodules. The results indicate that the Re and Os abundances of the whole-chondrite samples are in the ranges of corresponding H-and LL-Groups,respectively. The Re and Os abundances of magnetic fraction from Boxian and Lujiang are within the range of high-Os ⅡAB and ⅢAB irons,whereas those of nonmagnetic fractions of Boxian and Lujiang are lower than the whole-chondrite values. The Re and Os abundances of nodules in Jilin are in the range of the LL-Group. 187Re/188Os and 187Os/188Os ratios of the three whole chondrites are in the range of ordinary chondrites which locate around the isochron of ⅡAB+ⅢAB irons. 187Re/188Os and 187Os/188Os ratios of the magnetic and nonmagnetic fractions from Boxian have a larger difference. The nonmag-netic fraction of Lujiang may contain a recent addition of Re,which causes deviation of the 187Re/188Os ratio from the irons isochron. The Re and Os abundances of nodules in Jilin are lower than those of the whole-chondrite,but their 187Os/188Os ratios are higher than that of the whole chondrite.