Effect of ferric and bromide ions on the formation and speciation of disinfection byproducts during chlorination

The effects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts （DBPs） during chlorination were studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, were used for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lower content of total organic carbon （TOC） and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions, four trihalomethanes （THMs）, nine haloacetic acids （HAAs）, total organic halogen （TOX） and its halogen species fractions, including total organic chlorine （TOC1） and total organic bromide （TOBr）, were determined. The results showed that co-existent ferric and bromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration of bromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species, which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromide ions in raw water samples produced higher percentages of unknown TOBr.

Seasonal variation effects on the formation of trihalomethane during chlorination of water from Yangtze River and associated cancer risk assessment

For the system of water samples collected from Yangtze River,the effects of seasonal variation and Fe（III） concentrations on the formation and distribution of trihalomethanes （THMs） during chlorination have been investigated.The corresponding lifetime cancer risk of the formed THMs to human beings was estimated using the parameters and procedure issued by the US EPA.The results indicated that the average concentration of THMs （100.81 μg/L） in spring was significantly higher than that in other seasons,which was related to the higher bromide ion concentration resulted from the intrusion of tidal saltwater.The total cancer risk in spring reached 8.23 × 10 ？5 and 8.86 × 10 ？5 for males and females,respectively,which were about two times of those in summer under the experimental conditions.Furthermore,it was found that the presence of Fe（III） resulted in the increased level of THMs and greater cancer risk from exposure to humans.Under weak basic conditions,about 10% of the increment of THMs from the water samples in spring was found in the presence of 0.5 mg/L Fe（III） compared with the situation without Fe（III）.More attention should be given to the effect of the coexistence of Fe（III） and bromide ions on the risk assessment of human intake of THMs from drinking water should be paid more attention,especially in the coastland and estuaries.

Differences in functional traits among distinct populations of the plant invader Bunias orientalis

Plants that expand their range and become invasive in other areas may shift several functional traits in response to specific environments.However,local conditions at the place of origin may have shaped the functional traits,which may to some extent remain visible in plants growing in new habitats.The present study aimed to explore the trait variation in different plant populations of native,invasive and naturalized status of Bunias orientalis grown in common conditions in relation to the climatic conditions at their place of origin.Seeds of B.orientalis were collected from 12 populations(4 per status)in 8 countries and grown under standardized conditions in a common field garden.The variation in several functional traits related to phenology,growth and reproduction was compared among status and among populations.Phenology did not differ according to status.However,several plants of the native populations,originating from areas with low annual temperatures,did not start flowering.Plants of the invasive populations produced more leaves than natives,potentially indicating their vigor in building up vegetative biomass.Number and mass of silicles and other growth traits did not differ among status groups but varied among populations.Some of the variation in functional traits may be explained by long-term adaptations to local conditions at the areas of origin and genetic diversity,while other environmental factors differing in the novel environment may contribute to a high trait variation.