[Further study on possibility of diffusion of Oncomelania hupensis with water in river channels of the east route of South-to-North Water Diversion Project].

OBJECTIVE: To study the drifting law of floats and potential risks of Oncomelania hupensis diffusion in the water diversion rivers of the east route of South-to-North Water Diversion Project. METHODS: The O. hupensis snails in the river channels were monitored by the salvage method and snail luring method with rice straw curtains, and the diffusion possibility of snails along with water was assessed through the drift test of floats with GPS. RESULTS: In the flood seasons from 2006 to 2013, totally 8 338.0 kg of floats were salvaged, and 2 100 rice straw curtains were put into water in the Li Canal and Jinbao shipping channel, but no Oncomelania snails were found. The drift test of floats with GPS before water diversion showed that the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.56 - 0.60 m/s, and the average drift distances each time were 999.70 - 1 995.50 m in the Gaoshui River section, while there were no obvious drift in Jinbao shipping channel section. During the water diversion period, the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.35 - 0.41m/s, and the average drift distances each time were 1 248.06 -1 289.44 m in the Gaoshui River, while in Jinbao shipping channel section, the flow velocity on water surface was 0.28 m/s, the average drift velocity of the floats was 0.25 - 0.27 m/s, and the average drift distances each time were 477.76 - 496.38 m. The drift test showed that the floats gradually closed to the river bank as affected by water flow, wind direction and ship waves, when blocked by the reeds, water plants or other obstacles, and they would stopped and could not continue to drift without outside help. CONCLUSIONS: There are no Oncomelania snails found in the river channels of the east route of South-to-North Water Diversion Project. The drifting distance of the floating debris along with the water is restricted by the flow rate and shore environment.

[Natural attenuation of BTEX in the underground environment].

It was found that the naturally attenuation of BTEX occurred. In this process, volatilization and biodegradation are the important mechanisms. Taking benzene for example, at the concentration of 11.40 mg/L, the relative proportions of volatilization and biodegradation accounting for natural degradation were 16.36% and 4.91%. Comparatively, at the concentration of 3.30 mg/L for toluene, the relative proportions of volatilization and biodegradation accounting for natural degradation were 11.04% and 41.50%. It demonstrated that different components of BTEX had different attenuation trends. Furthermore, the higher the concentration of BTEX was, the faster the BTEX volatilized, and more important volatilization was. The effect of biodegradation on toluene was more efficiency, whose proportion accounting for natural degradation was 41.50%, and xylene only occupied 8.49%, while, benzene and ethylbenzene were hardly degraded.

[Redox zones and its functional bacteria in a contaminated landfill site].

A column filled with sandy soil was constructed to investigate biogeochemical process of leachate polluted zones. Experimental results demonstrated that four sequent redox zones appeared in pollution plume. The zones can be named sulfate reduction zone, iron reduction zone, nitrate reduction zone and oxygen reduction zone, ranges of them were 0-27 cm, 27-62 cm, 47-74 cm, 74-91 cm. In the redox zones bacterial community structure changed, and the preponderant bacteria were sulfate reduction bacteria (SRB), iron reduction bacteria (IRB), nitrate reduction bacteria (NRB) correspondingly, however there were other bacteria in the redox zones. Distribution of redox zones and functional bacteria means that there is not a significant boundary between redox zones, moreover one redox zone overlaps others. Evolvement of functional bacterial community brings the redox zones substitute.

Glucose biosensor based on multi-wall carbon nanotubes and screen printed carbon electrodes.

This paper describes a disposable electrochemical biosensor for glucose monitoring. The sensor was based on multi-wall carbon nanotubes (MWCNTs) immobilized with glucose oxidase and upon screen printed carbon electrode. The effect of MWCNTs on the response of amperometric glucose oxidase electrode for glucose was examined. Results obtained, of interest for basic and applied biochemistry, represent a first step in construction of a MWCNT-enzyme electrode biosensor with potentialities for a successful application in the biosensor area.