Controlling the fate of roxarsone and inorganic arsenic in poultry litter

A growing body of literature reports 3-nitro-4-hydroxyphenylarsonic acid (roxarsone) degradation in poultry litter (PL) to the more toxic inorganic arsenic (As). Aluminum-based drinking-water treatment residuals (WTR) present a low-cost amendment technology to reduce As availability in PL, similar to the use of alum to reduce phosphorus availability. Batch experiments investigated the effectiveness of WTR in removing roxarsone and inorganic As species from PL aqueous suspensions. Incubation experiments with WTR-amended PL evaluated the effects of WTR application rates (2.5-15% by weight) and incubation time (up to 32 d) at two incubation temperatures (23 and 35 degrees C) on As availability in PL. Batch PL aqueous experiments showed the high affinity of As(V), As(III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and roxarsone for the WTR. The 10% WTR amendment rate decreased As availability in PL by half of that of the unamended (no WTR) PL-incubated samples. The reduction in dissolved As concentrations during incubation of WTR-amended PL samples was kinetically limited, being complete within 13 d. Parallel reductions in roxarsone, As(V), and DMA concentrations were observed with liquid chromatography-inductively coupled plasma mass spectrometry, whereas As(III) and MMA concentrations were always <5% of dissolved As. Incubation temperature did not significantly (p > 0.05) influence dissolved As concentrations in the WTR-amended PL. Potential formation of a copper-containing roxarsone metabolite was considered in PL aqueous suspensions with the aid of electrospray mass spectrometry. Further experiments in the field are necessary to ensure that sorbed As is stable in WTR-amended PL.     

A two-agent dynamic model with an invasive weed diffusion externality: an application to Yellow Starthistle (Centaurea solstitialis L.) in New Mexico

This paper presents a bioeconomic model for two agents, a cattle rancher and a non-rancher, with interdependencies between their individual effort of invasive weed management and profitability. Dynamic simulations allow us to find numerically the optimal effort of weed control over a 5-year time horizon under a variety of beginning infestation levels. In a base-case scenario without governmental cost-share of control costs, we find that efforts to control the weed are not profitable. The base-case scenarios also indicate that grazing contributes to giving the invasive weed a competitive edge. A second series of simulations include incentive payments for weed control which are set at the minimum level required to have a net positive impact on the rancher's profitability. From these simulations, we find that the level of infestation impacts the size of the incentive necessary to get the agent to control the weeds and that the incentive payments impact the level of effort of the rancher. In addition, results reveal that the higher incentive payments for lower levels of weed infestations reduce the total cumulative incentive payments over time. Efficient policies directed towards management of invasive weeds may need to be adjusted for each individual case.     

Economic Linkages to Changing Landscapes

Many economic processes are intertwined with landscape change. A large number of individual economic decisions shape the landscape, and in turn the changes in the landscape shape economic decisions. This article describes key research questions about the economics of landscape change and reviews the state of research knowledge. The rich and varied economic–landscape interactions are an active area of research by economists, geographers, and others. Because the interactions are numerous and complex, disentangling the causal relationships in any given landscape system is a formidable research challenge. Limited data with mismatched temporal and spatial scales present further obstacles. Nevertheless, the growing body of economic research on these topics is advancing and shares fundamental challenges, as well as data and methods, with work in other disciplines.     

Perceptions of Wildfire and Landscape Change in the Kenai Peninsula, Alaska

Despite a broad literature addressing the human dimensions of wildfire, current approaches often compartmentalize results according to disciplinary boundaries. Further, relatively few studies have focused on the public’s evolving perceptions of wildfire as communities change over time. This paper responds to these gaps by exploring perceptions of landscape dynamics and wildfire between 2003 and 2007 using a typological framework of intersecting ecological, social, and cultural processes. Designed as a restudy, and using key informant interviews, this research allowed us to observe risk perception as they are related to community challenges and opportunities in the Kenai Peninsula, Alaska. Risk perceptions were examined as an integral part of community and landscape change. Wildfire was a concern among informants in 2003 and remained a concern in 2007, although informants were less likely to discuss it as a major threat compared to the original study. Informants in the western part of the peninsula tended to express more concern about wildfire than their eastern counterparts largely due to their experiences with recent fires. Other important factors residents considered included changing forest fuels, the expanding wildland urban interface, and contrasting values of new residents. Underscoring the localized nature of risk perceptions, informants had difficulty describing the probability of a wildfire event in a geographical context broader than the community scale. This paper demonstrates how a holistic approach can help wildfire and natural resource professionals, community members, and other stakeholders understand the social and physical complexities influencing collective actions or inactions to address the threat of wildfire.     

Trends in bicycle-related injuries,hospital admissions,and deaths in the USA 1997–2013

Objective: Cycling is associated with numerous health benefits but also the risk of traumatic injury. Recent data demonstrate an increase in overall cycling injuries as well as hospital admissions from 1997 to 2013 in the United States. We seek to better understand the causes of the increase in cycling injuries and hospital admissions.

Methods: Data regarding cycling-related injuries and hospital admissions were obtained from the National Electronic Injury Surveillance System (NEISS). Participation data were derived from the National Sporting Goods Association Sports Participation Survey, and fatality data were collected from the Fatality Analysis Reporting System (FARS). Population estimates were obtained using a complex survey design. Linear regression was used to evaluate univariate relationships between cycling injuries, hospital admissions, deaths, and participation. To evaluate factors associated with hospital admission, we developed a multivariable logistic regression model that included year, age, gender, body part injured, and injury type (i.e., contusion, fracture, or laceration).

Results: The number of individuals who cycle did not change significantly over time, but there was a substantial increase in cycling-related injuries, leading to an increase in per participant injuries from 701/100,000 in 1997 to 1,164/100,000 in 2013. When the injuries were evaluated by age group, younger cyclists have an increased risk for injury, whereas the rise in injuries among older cyclists stemmed from an increase in ridership rather than a unique susceptibility to injury. Trends in hospital admissions and fatalities appeared to be driven by increases in the older age groups. In the multivariable model evaluating factors related to hospital admission, the odds of hospital admission increased for each decade after age 25, as well as male gender and body part injured.

Conclusion: On a per participant basis, the rate of cycling-related injuries and hospital admissions increased between 1997 and 2013. This trend likely reflects a combination of shifting demographics among cyclists with an increase in older cyclists who are at increased risk of severe injury.     

Consumer product-related eye injury in the United States, 1998-2002

PROBLEM: Eye injury is currently a leading cause of visual impairment and monocular blindness in the United States. Information regarding consumer products associated with eye injuries can have important implications for the prevention of these injuries. METHODS: The National Electronic Injury Surveillance System (NEISS) was used to describe the types of consumer products associated with emergency department treated eye injuries in the United States from 1998 through 2002. RESULTS: The leading product type associated with eye injuries was welding equipment followed by household cleaners, basketball equipment, workshop equipment, and adhesives. Eye injuries attributed to hardware, tools, construction, sports, toys, and lawn equipment were more common among males. In females, eye injuries attributable to chemicals, housewares, storage and organization, and bed and bath items were more common. Differences were also apparent across the age spectrum. CONCLUSION: This study identified specific products and categories of products frequently associated with eye injury and prevention initiatives should focus on these items. IMPACT ON INDUSTRY: This study has identified consumer products associated with eye injuries requiring medical treatment in the United States. Manufacturers of these products could be encouraged to add or strengthen safety messages regarding the potential for eye injury.     

Multi-species interactions impact the accumulation of weathered 2,2-bis (p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) from soil

The impact of interactions between the earthworms Eisenia foetida and Lumbricus terrestris and the plants Cucurbita pepo and Cucurbita maxima on the uptake of weathered p,p'-DDE from soil was determined. Although some combinations of earthworm and plant species caused significant changes in the p,p'-DDE burden in both organisms, the effects were species specific. Contaminant bioconcentration in C. pepo was increased slightly by E. foetida and by 3-fold when the plant was grown with L. terrestris. E. foetida had no effect on the contaminant BCF by C. maxima, but L. terrestris caused a 2-fold reduction in p,p'-DDE uptake by the plant. Contaminant levels in E. foetida and L. terrestris were unaffected by C. pepo. When grown with C. maxima, the concentration of p,p'-DDE decreased by approximately 4-fold and 7-fold in E. foetida and L. terrestris, respectively. The data suggest that the prediction of contaminant bioavailability should consider interactions among species.     

Geographical variation in the behaviour of a central place forager: Antarctic fur seals foraging in contrasting environments

Foragers show adaptive responses to changes within their environment, and such behavioural plasticity can be a significant driving force in speciation. We investigated how lactating Antarctic fur seals, Arctocephalus gazella, adapt their foraging within two contrasting ecosystems. Location and diving data were collected concurrently, between December 2003 and February 2004, from 43 seals at Bird Island, where krill, Euphausia superba, are the main prey, and 39 at Heard Island, where mostly fish are consumed. Seals at Heard Island were shorter and lighter than those at Bird Island and they spent longer at sea, dived more frequently and spent more time in the bottom phase of dives. Generalized additive mixed effects models showed that diving behaviours differed between the islands. Both populations exploited diel vertically migrating prey species but, on average, Heard Island seals dived deeper and exceeded their estimated aerobic dive limits. We propose that the recovery of the Heard Island population may be limited by the relative inaccessibility and scarcity of food, whereas at Bird Island, the presence of abundant krill resources helps sustain extremely high numbers of seals, even with increased intra- and inter-specific competition. Both populations of fur seals appear to be constrained by their physiological limits, in terms of their optimal diving behaviour. However, there does appear to be some flexibility in strategy at the level of trip with animals adjusting their time at sea and foraging effort, in order to maximize the rate of delivery of energy to their pups.     

Night-sky brightness monitoring in Hong Kong

Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light-sensing device called the Sky Quality Meter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong is severe—the urban night skies (sky brightness at 15.0 mag arcsec^− 2) are on average ~ 100 times brighter than at the darkest rural sites (20.1 mag arcsec^− 2), indicating that the high lighting densities in the densely populated residential and commercial areas lead to light pollution. In the worst polluted urban location studied, the night-sky at 13.2 mag arcsec^− 2 can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by human factors such as land utilization and population density of the observation sites, together with meteorological and/or environmental factors. Moreover, earlier night skies (at 9:30 p.m. local time) are generally brighter than later time (at 11:30 p.m.), which can be attributed to some public and commercial lightings being turned off later at night. On the other hand, no concrete relationship between the observed sky brightness and air pollutant concentrations could be established with the limited survey sampling. Results from this survey will serve as an important database for the public to assess whether new rules and regulations are necessary to control the use of outdoor lightings in Hong Kong.