Quantifying the phenolic content of freshwaters using simple assays with different underlying reaction mechanisms

Five different assays, Gibbs, Prussian Blue, Folin-Ciocalteau, fluorescence quenching of added phenol and precipitation of phenolics with bovine serum albumin (BSA) were investigated for their suitability in measuring the phenolic content of freshwaters. Phenol and a hydrolysable tannic acid were used as standards for monophenolics and polyphenolics, respectively. The individual and simultaneous application of both standards in doubly distilled water and filtered freshwater samples showed no matrix interference for the Gibbs, the Prussian Blue and the Folin-Ciocalteau assays. The quenching of phenol fluorescence and incomplete precipitation of added tannic acid in the freshwater samples were thought to originate from complexation. The Gibbs assay was specific for monophenolics, monohydroxybenzenes, with a Criterion of Detection (CoD) of 0.027 mg l(-1). Evaluating the assay using twenty-two monophenolics of lignin origin showed, apart from phenol itself, the phenolic acids vanillic, isovanillic, ferulic and syringic to have a linear response between 0 and 10 microM. The other monophenolics were not responsive in the Gibbs assay. The oxidation-based assays Prussian Blue and Folin-Ciocalteau had a CoD of 0.169 and 0.025 mg l(-1), respectively. The ratio of response of both assays for each sample was taken as an indication of the degree of polymerisation of the phenolic content. The Folin-Ciocalteau assay was used directly on the samples, on samples spiked with tannic acid at 2 and 4 mg l(-1), and after precipitation of phenolics with BSA. The difference in tannic acid equivalents before and after treatment, assayed the amount of protein precipitated phenolics. The results of all assays allowed differentiation between monophenolics (Gibbs), polyphenolics (Prussian Blue), total phenolics (Folin-Ciocalteau), complexation of added phenol and protein-precipitated phenolics. The reaction mechanisms underlying the assays were matched onto those occurring during humification. The assays were applied to six filtered freshwater samples and two humic and two fulvic acids. The results showed a different pattern for each site and illustrated varying reactivity of the 'phenolic content' of freshwater.     

Prosulfocarb at center stage!

Environmental Science and Pollution Research - Prosulfocarb is a thiocarbamate herbicide that is rapidly growing in use due to the progressive bioresistance of weeds to certain pesticides and the...     

Evaluating impaired drivers confidence and intention to "(Please) drink responsibly"

Introduction

Currently, alcohol industry-sponsored advertisements subsume traditional designated driver and don't drink and drive messages within responsible drinking campaigns. Yet, to date, there remains a dearth of literature specifically examining the attitudinal beliefs impaired drivers attach to the responsible drinking message.

Objective

This investigation sought to examine the responsible drinking attitudes and beliefs of impaired drivers, specifically examining their confidence and intention to drink responsibly the next time they consumed alcohol.

Methods

A random sample of 729 students attending a large, public Texas university completed a web-based administration of the Characteristic of Responsible Drinking Survey (CHORDS).

Results

Participants in this sample who had driven while impaired by alcohol exhibited significantly less confidence in refraining from drinking and driving and reported significantly lower intentions to designate a driver, take a taxi, or use a safe-ride program the next time they consumed alcohol. Additionally, they also reported less confidence, and lower intentions, to ensure their blood alcohol concentrations remained below the legal limit (0.08%) the next time they consumed alcohol.

Conclusions

Drivers who had driven while impaired significantly differed in their confidence and intention to drink responsibly the next time they consumed alcohol. Logistic regression results indicate that by increasing one's confidence in responsible drinking, and increasing their intention to drink responsibly, the likelihood of impaired driving can be decreased.

Impact on industry

Results from this investigation demonstrate one’s responsible drinking attitudinal beliefs accounts for a significant amount of the variance associated with one’s alcohol-related behaviors. Thus, further research should examine and establish how individuals conceptualize and practice responsible drinking.     

Where artisanal mines and forest meet: Socio‐economic and environmental impacts in the Congo Basin

While mineral exploitation can provide significant income and employment, it may negatively impact the environment, being ultimately detrimental to livelihoods in the long term. The consequences of mining are of concern in high value forest ecosystems such as the Sangha Tri‐National (TNS) landscape covering Cameroon, the Central African Republic and Republic of the Congo. This paper captures the socio‐economic and environmental impacts of small‐scale mining in the TNS. Using structured questionnaires, consultations and observation, diamonds and gold were found to contribute directly to the livelihoods of at least 5% of the landscape's population. Although up to eight income‐generating strategies are used, mining contributes on average to 65% of total income and is used mainly to meet basic needs. A gold miner's average income is US$ 3.10 a day, and a diamond miner earns US$ 3.08, making them slightly wealthier than an average Cameroonian and three times wealthier than an average non‐miner in the TNS. Environmental impacts were temporary, low impact and of limited scale. However, with mining likely to increase in the near future, an increasing population and miners' low environmental awareness, measures are needed to ensure and reinforce the positive impact of artisanal mining on livelihoods and maintain its low environmental footprint in the TNS landscape.