Environmental risk assessment of genetically engineered herbicide-tolerant Zoysia japonica

Herbicide-tolerant Zoysia grass (Zoysia japonica Steud.) has been generated previously through Agrobacterium tumefaciens-mediated transformation. The genetically modified (GM) Zoysia grass survived Basta spraying and grew to maturity normally while the wild-type (WT) grass stopped growing and died. GM Zoysia grass will permit more efficient weed control for various turf grass plantings such as home lawns, golf courses, and parks. We examined the environmental/biodiversity risks of herbicide-tolerant GM Zoysia before applying to regulatory agencies for approval for commercial release. The GM and WT Zoysia grass' substantial trait equivalence, ability to cross-pollinate, and gene flow in confined and unconfined test fields were selectively analyzed for environmental/biodiversity effects. No difference between GM and WT Zoysia grass in substantial traits was found. To assess the potential for cross-pollination and gene flow, a non-selective herbicide, Basta, was used. Results showed that unintended cross-pollination with and gene flow from GM Zoysia grass were not detected in neighboring weed species examined, but were observed in WT Zoysia grass (on average, 6% at proximity, 1.2% at a distance of 0.5 m and 0.12% at a radius of 3 m, and 0% at distances over 3 m). On the basis of these initial studies, we conclude that the GM Zoysia grass generated in our laboratory and tested in the Nam Jeju County field does not appear to pose a significant risk when cultivated outside of test fields.     

Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea

We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n?=?5,682, 18–96 years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60 μg/L (95 % CI?=?1.57–1.62 μg/L) and 2.87 μg/dL (95 % CI?=?2.84–2.90 μg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2 km of an abandoned metal mine (n?=?3,165, BCL?=?1.87 μg/L, BLL?=?2.91 μg/dL) compared to people living more than 2 km away (n?=?2,517, BCL?=?1.31 μg/L, BLL?=?2.82 μg/dL; P?<?0.0001) and to the general population values reported in the literature.     

Arsenic speciation and accumulation in evapoconcentrating waters of agricultural evaporation basins

To sustain agricultural productivity, evaporation basins (or ponds) have been widely used for the disposal of agricultural drainage in areas requiring subsurface drainage in the San Joaquin Valley of California, USA. The drainage water contains elevated concentration of trace elements including selenium (Se) and arsenic (As). Unlike Se, little information is available about As, a potentially high risk element. The objective of this study was to characterize the chemical behavior of As and acquire data for better understanding of biogeochemical processes and conditions affecting As fate in evaporation ponds. The study site was a 726 ha evaporation basin facility (containing 10 cells with water flowing in series) in the hydrologically closed Tulare Basin of California. We examined water chemistry, As concentration and speciation along the water flow path between cells as well as within the cells. Arsenic concentrations in the water increased linearly with Cl(-), a conservative ion from evapoconcentration. Reduced As species as arsenite [As(III)] and organic arsenic (org-As) also increased with increases in Cl(-) and salinity. Water samples with elevated EC (i.e., towards the end of flow path) had high dissolved organic matter, low dissolved oxygen, and elevated sulfide concentrations, indicating the development of reducing conditions. We hypothesize that such changes could facilitate the reduction of arsenate [As(V)] to As(III) and org-As. Elevated As in sediment profiles indicate a solid phase sink mechanism, but not significant enough to remove and reduce As concentrations in the water columns. These findings help us better define the processes that affect As in drainage facilities and contribute to our understanding of how As behaves in other regions of the world that have similar climatic and hydrogeochemical conditions.     

Photodegradation of alachlor with the TiO(2) film immobilised on the glass tube in aqueous solution

Alachlor photodegradation was performed using TiO(2), which was synthesized by a modified sol-gel method. The thickness of a TiO(2) film immobilised by a 5-time dip-coating was 174 nm and the average diameter of TiO(2) particles was about 10-15 nm in SEM images. The crystal structure of a TiO(2) film calcinated at 300 degrees C for 1 h was observed as a typical anatase type. The stability of a TiO(2) film by a modified sol-gel method was 4% better than TiO(2) by a typical sol-gel method.The removal rate of alachlor with both Fe(3+) and UV radiation in the absence of TiO(2) was 0.28 mg/l/h in 10 h and the removal rate of alachlor with Fe(3+)/UV in the presence of TiO(2) was 0.32 g/l/h, which was higher by 14% than that with Fe(3+)/UV system. TOC concentration during the alachlor degradation with both TiO(2) and UV radiation in the absence of added Fe(3+) decreased from 100%, through 81% and 51%, to 44% with time elapses of 4, 8, and 10 h, respectively, while TOC concentration with both added Fe(3+) and UV radiation in the absence of TiO(2) decreased from 100% to 70% in 10 h.     

CuCl2-catalyzed PCDD/F formation and congener patterns from phenols

Homologue and isomer patterns of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) in CuCl2-catalyzed formation were studied in an isothermal flow reactor using a distribution of 20 phenols as measured in municipal waste incinerator (MWI) exhaust gases. A mixture of 20 phenols was synthesized and used as reactants for this study because phenols are known to be key precursors in the formation of PCDD/F. Experiments were conducted at 400 degrees C. The 92% of nitrogen (N2) and 8% of oxygen (O2) were used as a carrier gas. PCDD/F homologue and isomer patterns with dibenzo-p-dioxin (DD) and dibenzofuran (DF) were obtained from a mixture of 20 phenols. DF+PCDF formation was favored over DD+PCDD formation. The major homologue groups formed were non-chlorinated DD and DF, and PCDD/F homologue fraction decreased with the degree of chlorination. PCDD/F homologue and isomer distributions were almost constant. Phenol and lower chlorinated phenols present in high amount played an important role in PCDD/F congener distributions. The results presented here can be used as characteristics or fingerprints for homologue and isomer patterns of PCDD/F formation attribution in CuCl2-catalyzed reaction from phenols.     

Chlorination of dibenzofuran and dibenzo-p-dioxin vapor by copper (II) chloride

Dibenzofuran (DF) is formed from phenol and benzene in combustion gas exhaust streams prior to particle collection equipment. Subsequent chlorination at lower temperatures on particle surfaces is a potential source of chlorinated dibenzofuran (CDF). Gas streams containing 8% O₂ and approximately 0.1% DF vapor were passed through particle beds containing copper (II) chloride (0.5% Cu, mass) at temperatures ranging from 200 to 400 °C to investigate the potential for CDF formation during particle collection. Experiment duration was sufficient to provide an excess amount of DF (DF/Cu=3). The efficiency of DF chlorination by CuCl₂ and the distribution of CDF products were measured, with effects of temperature, gas velocity, and experiment duration assessed. Results of a more limited investigation of dibenzo-p-dioxin (DD) chlorination by CuCl₂ to form chlorinated DD (CDD) products are also presented.The efficiency of DF/DD chlorination by CuCl₂ was high, both in terms of CuCl₂ utilization and DF/DD conversion. Total yields of Cl on CDF/CDD products of up to 0.5 mole Cl per mole CuCl₂ were observed between 200 and 300 °C; this suggests that nearly 100% CuCl₂ was utilized, assuming a conversion of two moles of CuCl₂ to CuCl per mole Cl added to DD/DF. In a short duration experiment (DF/Cu=0.3), nearly 100% DF adsorption and conversion to CDF was achieved. The degree of CDF chlorination was strongly dependent on gas velocity. At high gas velocity, corresponding to a gas–particle contact time of 0.3 s, mono-CDF (MCDF) yield was largest, with yields decreasing with increasing CDF chlorination. At low gas velocity, corresponding to a gas–particle contact time of 5 s, octa-CDF yield was largest. DF/DD chlorination was strongly favored at lateral sites, with the predominant CDF/CDD isomers within each homologue group those containing Cl substituents at only the 2,3,7,8 positions. At the higher temperatures and lower gas velocities studied, however, broader isomer distributions, particularly of the less CDD/CDF products, were observed, likely due to preferential destruction of the 2,3,7,8 congeners.     

Characteristics of Ion Components and Trace Elements of Fine Particles at Gosan, Korea in Spring time from 2001 to 2002

Size-segregated measurements of the composition of an aerosol are used to determine the transport of natural and anthropogenic aerosols to the Gosan site in springtime from 2001 to 2002. Although the transport of Asian dust is a well-known phenomenon in springtime, this study shows that not only is soil dust transported into Gosan each spring but so are anthropogenic aerosols, including sulfur, enriched trace metals such as Pb, Zn, Ni, K, S. This study also combines the size- and time-resolved aerosol composition measurements with isentropic, backward air-mass trajectories in order to identify some potential source regions of the anthropogenic aerosols. Finally, four types of transport episodes were identified: (1) anthropogenic pollutants, (2) dust storm mixed with the anthropogenic aerosols, (3) typical dust storms, (4) some sea salt with clean air mass. Overall, in addition to typical soil dust, a large amount of anthropogenic aerosols, whether mixed with the soil dust or not, are transported to Gosan each spring.