Evaluating the use of in-situ turbidity measurements to quantify fluvial sediment and phosphorus concentrations and fluxes in agricultural streams.

Accurate quantification of suspended sediments (SS) and particulate phosphorus (PP) concentrations and loads is complex due to episodic delivery associated with storms and management activities often missed by infrequent sampling. Surrogate measurements such as turbidity can improve understanding of pollutant behaviour, providing calibrations can be made cost-effectively and with quantified uncertainties. Here, we compared fortnightly and storm intensive water quality sampling with semi-continuous turbidity monitoring calibrated against spot samples as three potential methods for determining SS and PP concentrations and loads in an agricultural catchment over two-years. In the second year of sampling we evaluated the transferability of turbidity calibration relationships to an adjacent catchment with similar soils and land cover. When data from nine storm events were pooled, both SS and PP concentrations (all in log space) were better related to turbidity than they were to discharge. Developing separate calibration relationship for the rising and falling limbs of the hydrograph provided further improvement. However, the ability to transfer calibrations between adjacent catchments was not evident as the relationships of both SS and PP with turbidity differed both in gradient and intercept on the rising limb of the hydrograph between the two catchments. We conclude that the reduced uncertainty in load estimation derived from the use of turbidity as a proxy for specific water quality parameters in long-term regulatory monitoring programmes, must be considered alongside the increased capital and maintenance costs of turbidity equipment, potentially noisy turbidity data and the need for site-specific prolonged storm calibration periods.

Identification of selected organic contaminants in streams associated with agricultural activities and comparison between autosampling and silicone rubber passive sampling.

This study evaluates the potential of silicone rubber passive sampling devices (SR-PSDs) as a suitable alternative to automatic water samplers (autosamplers) for the preliminary identification of a wide range of organic contaminants in freshwater systems. The field performance of SR-PSDs deployed at three sites on two streams of an agricultural catchment area in North East (NE) Scotland, United Kingdom (UK) was assessed concurrently with composite water samples collected from two of the sites using autosamplers. The analytical suite consisted of selected plant protection products (PPPs; commonly referred to collectively as 'pesticides'), including 47 pesticides and a separate sub-category of 22 acid/urea herbicides. Of these, a total of 54 substances, comprising 46 pesticides and 8 urea herbicides were detected in at least one of the SR samplers. All but 6 of these SR-PSD detected substances were quantifiable. By comparison, a total of 25 substances comprising 3 pesticides and 22 acid/urea herbicides were detected in the composite water samples, of which only 8 acid/urea herbicides were quantifiable. The larger number and chemical classes of compounds detected and quantified via passive sampling reflect the lower limits of detection achieved by this device when compared to autosamplers. The determination of dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) added to the information on contaminant pressures at each site, allowing assessment of the reliability of SR-PSDs in freshwater systems and the identification of possible contaminant sources. The study demonstrated the utility of SR-PSDs for detecting and semi-quantifying low concentrations of analytes, including those which hitherto have not been measured in the catchment area and also some pesticides that are no longer approved for agricultural use in the UK and EU. The SR-PSD approach can thus provide a better understanding and clearer picture of the use and presence of organic contaminants within catchments.

Validation for a scoring system of the ALS cardiac arrest simulation test (CASTest).

AIM: The cardiac arrest simulation test (CASTest) assesses resuscitation knowledge and skills during a simulated cardiac arrest. The aim of this study is to validate an alternative scoring system for measuring individual candidate performance during research involving the CASTest. METHODS: The performance of 537 participants was measured using the new scoring system. Evidence of internal structure was sought by comparing the score with global rating of performance and pass/fail decision; identification of participants with instructor potential, skill tests and MCQ scores. Relationships between CASTest score, profession and seniority were also examined. RESULTS: Global assessment of performance identified 413 passes (76.9%) and 124 fails (23.1%). CASTest score was significantly higher in those that passed than in those that failed (median 77 vs 62.5, P<0.0001). There were no differences between professions. Senior staff performed slightly better than junior staff (median 74 and 72 respectively, P=0.01). Excellent participants (identified as having instructor potential) scored significantly higher than the other participants (median 94 and 72 respectively, P<0.0001). A strong correlation was demonstrated between domains in the CASTest (rho 0.72-0.82, P<0.01). Other assessment outcomes for the ALS course correlated poorly with CASTest scores (rho 0.27-0.37, P<0.01). CONCLUSION: This new simple scoring system can be used to better characterise performance on the ALS course CASTest than the current binary pass-fail outcome.

Mobile phones and driving.

Prior to the introduction of legislation in the United Kingdom, observational road-side studies showed that approximately 2 per cent of drivers use a mobile phone while driving. We studied the change in the usage rate of hand-held mobile phones from 10 weeks before to 10 weeks after the legislation came into force in December 2003. Across three different sites during the evening rush-hour, the usage rate changed from 1.85 to 0.97 per cent, a reduction of almost half. This change is attributed to the legislation. The effect of the legislation on accident and injury rates is unknown.