Synthesis of intracellular cobalt ferrite nanocrystals by extreme acidophilic archaea Ferroplasma thermophilum

Ferroplasma thermophilum,a sort of extreme acidophilic archaea,which can synthesize intracellular cobalt ferrite nanocrystals,is investigated in this study.The nanocrystals were analyzed with ultrathin sections and transmission electron microscope,with the size of 20−60 nm,the number of more than 30 in each cell at average,which indicated that F.thermophilum can synthesize intracellular nanocrystals and also belongs to high-yield nanocrystals-producing strain.Intriguingly,the nanocrystals contain ferrite and cobalt characterized by EDS X-ray analysis,suggesting that both cobalt and ferrite are potentially contributed to the formation of nanocrystals.Moreover,under the different energy source culture conditions of FeSO4 and CuFeS2,the size and the morphology of the nanocrystals are different.It was also found that the higher initial Fe availability leads to an induced synthesis of larger nanocrystals and the lower oxidation-reduction potential(ORP)leads to an induced effect on the synthesis of nanocrystals with abnormal unhomogeneous size,which suggested that the higher initial Fe availability and the lower oxidation-reduction potential lead to a higher uptake efficiency of iron ions of F.thermophilum by iron and ORP gradient culture.

Effect of typhoon with extreme precipitation on mountain reservoir drinking water treatment: a case study in Ningbo, China

Due to frequent drinking water pollution accidents in the past decade, it is common that mountain reservoirs were used as the source of drinking water in China. However, some coastal areas frequently suffer from typhoon with extreme precipitation, which results in the water quality deterioration of the reservoirs. The influence of typhoons with extreme precipitation on Jiaokou reservoir and the emergency treatment process of Maojiaping water treatment plant in the past three typical typhoons with extreme precipitation from the year of 2012-2015 were studied. It was found that the degradation of water quality, such as the increase of turbidity and bacteria index, may not merely appear during the events, but last for several days. Changing the dosage of water purification agent, such as coagulant and disinfectant at right time and place may be an efficient emergency water treatment process. Based on the analysis of water quality variation rule during and after the events, it was also found that emergency treatment can be fully prepared before the arrival of a typhoon with extreme precipitation. And in order to better respond to the typhoon with extreme precipitation, several suggestions are also proposed in this paper as follows: establishing vegetated buffers at right place, such as macrophanerophytes,shrub or herbage, increasing investments in infrastructure management, merging or cancelling the small-scale water treatment plants, preparing adequate water purification agent before the typhoon comes, etc.