Silver near municipal wastewater discharges into western Lake Ontario,Canada

Because of the widespread use of silver nanoparticles in commercial products, discharges of municipal wastewater may be a point source of silver in the aquatic environment. We monitored two sites in western Lake Ontario impacted by discharges from wastewater treatment plants serving the City of Toronto. Concentrations of silver were elevated in bottom sediments and suspended sediments collected at the two sites. We also deployed two types of passive samplers in the water column at the two sites, the newly developed Carbon Nanotube Integrative Samplers for monitoring “CNIS-labile” silver and Diffusive Gradient in Thin Film samplers for monitoring “DGT-labile” silver. Results from these passive samplers indicated that the concentrations of silver at the two sites were either below detection limits or were in the ng/L range. In laboratory experiments where the sediments were re-suspended in Milli-Q water, a small proportion of the silver (i.e., <?25%) was labile and partitioned as colloidal or dissolved silver into the liquid phase after agitation. Nanoparticles tentatively identified as silver nanoparticles were detected by single-particle ICP-MS in suspension after agitation of both suspended and bottom sediments. Therefore, there is a need to assess whether silver species, including silver nanoparticles are transported from wastewater treatment plants into sediments in the aquatic environment. This study is unique in focusing on the in situ distribution of silver in natural waters and in sediments that are potentially impacted by urban sources of nanoparticles.     

Postnatal nutrition influences male attractiveness and promotes plasticity in male mating preferences

Poor early-life nutrition could reduce adult reproductive success by negatively affecting traits linked to sexual attractiveness such as song complexity. If so, this might favor strategic mate choice, allowing males with less complex songs to tailor their mating tactics to maximize the reproductive benefits. However, this possibility has been ignored in theoretical and empirical studies. By manipulating the micronutrient content of the diet (e.g., low or high) during the postnatal period of male zebra finches, we show for the first time (1) that males reared on a poor (low) micronutrient diet had less complex songs as adults; (2) that these males, in contrast to the high micronutrient diet group, were more selective in their mating strategies, discriminating against those females most likely to reduce their clutch size when paired with males having less complex songs; and (3) that by following different mating strategies, males reared on the contrasting diets obtained similar reproductive benefits. These results suggest that early-life dietary conditions can induce multiple and long-lasting effects on male and female reproductive traits. Moreover, the results seem to reflect a previously unreported case of adaptive plasticity in mate choice in response to a nutritionally mediated reduction in sexual attractiveness.     

Modelling Water Blending—Sensitivity of Optimal Policies

Water blending is modelled as a combination of a linear program and a stochastic dynamic program. Optimal policies are found for linear and integer-linear formulations using both an expected monetary value and conditional value-at-risk criterion. The sensitivity of these solutions to the discretisation over volume and over time is investigated.     

Evaluating repeated patient handling injuries following the implementation of a multi-factor ergonomic intervention program among health care workers

Objective

The objective of this study was to evaluate repeated patient handling injuries following a multi-factor ergonomic intervention program among health care workers.

Methods

This was a quasi-experimental study which had an intervention group and a non-randomized control group. Data were collected from six hospitals in Saskatchewan, Canada from September 1, 2001 to December 1, 2006.

Results

A total of 1,480 individuals who had a previous injury were eligible for the study. Medium and small size hospitals in the intervention group had significantly fewer repeated injuries than in the control group. Multivariate analysis showed that the intervention group had 38.1% lower odds of having repeated injury compared to the control group, after adjusting for hospital size.

Conclusions

The work-related repeated injury after a multi-factor intervention program was reduced. The synergistic relationships between components of multi-factor intervention and applicability of injury prevention programs to different settings need to be further explored.

Impact on Industry

Implementing a multi-factor program with the right equipment and training can lower the risk of injury among health care workers.     

Optimising the environmental benefits of emission reductions from UK coal- and oil-fired power stations: a critical loads approach

This paper describes a method for determining reductions of SO₂ emissions from coal- and oil-fired power stations, oil refineries and large industrial units in the UK taking into account their pollution potential. The method is based on the use of two gridded data sets: critical loads, which represent the sensitivity of the environment to acid deposition and modelled estimates of total (wet + dry) sulphur deposition for 646 point sources within the UK. An iterative method is used to identify and subsequently reduce emissions from point sources that contribute most to areas of critical loads exceedance. This paper demonstrates how the method may be used to determine an optimal allocation of emissions across the UK which yields the maximum amount of environmental protection per unit of emission.The paper then goes on to consider the changes that will have to take place within the UK power generation industry in order to meet the revised EC Large Combustion Plant Directive which comes into force on 1 January 2008. Particular emphasis is placed upon proposed emissions trading schemes and the environmental implications of allowing trading between stations with high and low pollution potentials. The paper concludes by suggesting that the emissions trading process should take into account the pollution potential of each source, irrespective of whether the proposed emission is within the plant's agreed emission limit. An approach based entirely on minimizing environmental damage rather than one which takes cost into account, as in current integrated assessment modelling, could provide an interesting approach across the rest of Europe.     

Geolocation of free-ranging fish on the European continental shelf as determined from environmental variables II. Reconstruction of plaice ground tracks

Between December 1993 and February 1997, 302 electronic data storage tags (DSTs), programmed to record depth at 10-min intervals and temperature daily, were attached to mature female plaice, Pleuronectes platessa, and released in the southern North Sea. Fifty tags were returned, 38 of which functioned fully and recorded 2,955 days of data. Twenty-seven tags recorded data over the full period at liberty, and 34 geographical ground tracks were reconstructed. Reconstruction was performed using a two-dimensional tidal stream simulation model that translated vertical movement of fish, recorded by DSTs, into horizontal movement assuming an initial down-tide swimming speed of 0.6 body lengths s^–1. Geographical accuracy of reconstructed tracks was assessed based on closeness of fit between (1) reconstruction endpoint and reported recapture position; (2) reconstructed locations and corresponding locations based on tidal data recorded by DSTs using the tidal location method (TLM; location of areas with similar tidal range and time of high water); and (3) DST temperature records and corresponding averaged sea surface temperature data records for corresponding locations. The results demonstrate that the assumptions of the tidal stream simulation model were sufficient to reconstruct geographically accurate representations of the migrations of individual plaice, which have in turn provided new information on the extent, duration, and directionality of movement. Our study demonstrates how DSTs can provide fishery-independent data with direct management applications in behaviourally driven, individual-based predictive models of fish migration.Communicated by J.P. Thorpe, Port Erin     

The environmental fate of the primary degradation products of alkylphenol ethoxylate surfactants in recycled paper sludge.

Alkylphenol ethoxylates (APEOs) are a group of non-ionic surfactants that are degraded microbially into more lipophilic degradation products with estrogenic potential, including nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), octylphenol (4-tOP) and nonylphenol (4-NP). Nonylphenol ethoxylates are used in paper recycling plants for de-inking paper and have the potential to be released into the environment through spreading of wastewater treatment sludge for soil amendment. Three samples of recycled paper sludge were collected from farmers' fields and analyzed for concentrations of NP1EO, NP2EO, 4-NP and 4-tOP. Each sample differed in the amount of time elapsed since the sludge was placed on farmers' fields. Primary degradation products of APEOs were present at low micrograms/g concentrations in the sludge samples. Differences in the concentrations of these analytes in sludge samples indicated that APEO concentrations declined by 84% over a period of 14 weeks on farmers' fields. Changes in the chromatographic patterns of acetylated 4-NP indicated that there is a group of recalcitrant nonylphenol isomers that degrades more slowly than other isomers. These data indicate that microbial degradation may reduce the risk of environmental contamination by these compounds, but more work is required to assess the toxic potential of APEOs in sludges used for soil amendment.