Interaction of heavy metals and pyrene on their fates in soil and tall fescue (Festuca arundinacea).

90-Day growth chamber experiments were performed to investigate the interactive effect of pyrene and heavy metals (Cu, Cd, and Pb) on the growth of tall fescue and its uptake, accumulation, and dissipation of heavy metals and pyrene. Results show that plant growth and phytomass production were impacted by the interaction of heavy metals and pyrene. They were significantly decreased with heavy metal additions (100-2000 mg/kg), but they were only slightly declined with pyrene spiked up to 100 mg/kg. The addition of a moderate dosage of pyrene (100 mg/kg) lessened heavy metal toxicity to plants, resulting in enhanced plant growth and increased metal accumulation in plant tissues, thus improving heavy metal removal by plants. In contrast, heavy metals always reduced both plant growth and pyrene dissipation in soils. The chemical forms of Cu, Cd, and Pb in plant organs varied with metal species and pyrene addition. The dissipation and mineralization of pyrene tended to decline in both planted soil and unplanted soils with the presence of heavy metals, whereas they were enhanced with planting. The results demonstrate the complex interactive effects of organic pollutants and heavy metals on phytoremediation in soils. It can be concluded that, to a certain extent, tall fescue may be useful for phytoremediation of pyrene-heavy metal-contaminated sites. Further work is needed to enhance methods for phytoremediation of heavy metal-organics co-contaminated soil.

Biodegradation of decabromodiphenyl ether (BDE-209) by a metal resistant strain, Bacillus cereus JP12.

A metal resistant bacterial strain, Bacillus cereus JP12, could use decabromodiphenyl ether (BDE-209) as the sole carbon and energy source for growth in mineral salt medium. Under the conditions of pH 6.0, 30°C, 150 rpm and an inoculum of OD600=0.6, more than 88% of the initial BDE-209 (1mg/L) was degraded after 12 days. The addition of appropriate surfactants and additional carbon sources could enhance the biodegradation efficiency of BDE-209. The presence of Cu(2+) (≤ 8 mg/L) and Zn(2+) (≤ 15 mg/L) provided a slight stimulating effect on BDE-209 removal. However, BDE-209 biodegradation efficiency was decreased when adding higher levels of metals due to reduced substrate availability caused by excess metal adsorption into the cell surface. Biosorption of heavy metals by JP12 led to release of light metals such as K(+) and Na(+). A BDE-209 biodegradation pathway was proposed on the basis of metabolite identification.

Bacterial community diversity in a low-permeability oil reservoir and its potential for enhancing oil recovery.

The diversity of indigenous bacterial community and the functional species in the water samples from three production wells of a low permeability oil reservoir was investigated by high-throughput sequencing technology. The potential of application of indigenous bacteria for enhancing oil recovery was evaluated by examination of the effect of bacterial stimulation on the formation water-oil-rock surface interactions and micromodel test. The results showed that production well 88-122 had the most diverse bacterial community and functional species. The broth of indigenous bacteria stimulated by an organic nutrient activator at aerobic condition changed the wettability of the rock surface from oil-wet to water-wet. Micromodel test results showed that flooding using stimulated indigenous bacteria following water flooding improved oil recovery by 6.9% and 7.7% in fractured and unfractured micromodels, respectively. Therefore, the zone of low permeability reservoir has a great potential for indigenous microbial enhanced oil recovery.

Solar wind origin in coronal funnels.

The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by various ions with the force-free magnetic field as extrapolated from photospheric magnetograms to different altitudes. Specifically, we find that Ne7+ ions mostly radiate around 20 megameters, where they have outflow speeds of about 10 kilometers per second, whereas C3+ ions with no average flow speed mainly radiate around 5 megameters. Based on these results, a model for understanding the solar wind origin is suggested.