Using Relative Risk to Compare the Effects of Aquatic Stressors at a Regional Scale

The regional-scale importance of an aquatic stressor depends both on its regional extent (i.e., how widespread it is) and on the severity of its effects in ecosystems where it is found. Sample surveys, such as those developed by the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), are designed to estimate and compare the extents, throughout a large region, of elevated conditions for various aquatic stressors. In this article, we propose relative risk as a complementary measure of the severity of each stressor’s effect on a response variable that characterizes aquatic ecological condition. Specifically, relative risk measures the strength of association between stressor and response variables that can be classified as either “good” (i.e., reference) or “poor” (i.e., different from reference). We present formulae for estimating relative risk and its confidence interval, adapted for the unequal sample inclusion probabilities employed in EMAP surveys. For a recent EMAP survey of streams in five Mid-Atlantic states, we estimated the relative extents of eight stressors as well as their relative risks to aquatic macroinvertebrate assemblages, with assemblage condition measured by an index of biotic integrity (IBI). For example, a measure of excess sedimentation had a relative risk of 1.60 for macroinvertebrate IBI, with the meaning that poor IBI conditions were 1.6 times more likely to be found in streams having poor conditions of sedimentation than in streams having good sedimentation conditions. We show how stressor extent and relative risk estimates, viewed together, offer a compact and comprehensive assessment of the relative importances of multiple stressors.     

Toward Reversal of Eutrophic Conditions in a Subtropical Estuary: Water Quality and Seagrass Response to Nitrogen Loading Reductions in Tampa Bay, Florida, USA

Coastal waters have been significantly influenced by increased inputs of nutrients that have accompanied population growth in adjacent drainage basins. In Tampa Bay, Florida, USA, the population has quadrupled since 1950. By the late 1970s, eutrophic conditions including phytoplankton and macroalgal blooms and seagrass losses were evident. The focus of improving Tampa Bay is centered on obtaining sufficient water quality necessary for restoring seagrass habitat, estimated to have been 16,400 ha in 1950 but reduced to 8800 ha by 1982. To address these problems, targets for nutrient load reductions along with seagrass restoration goals were developed and actions were implemented to reach adopted targets. Empirical regression models were developed to determine relationships between chlorophyll a concentrations and light attenuation adequate for sustainable seagrass growth. Additional empirical relationships between nitrogen loading and chlorophyll a concentrations were developed to determine how Tampa Bay responds to changes in loads. Data show that when nitrogen load reduction and chlorophyll a targets are met, seagrass cover increases. After nitrogen load reductions and maintenance of chlorophyll a at target levels, seagrass acreage has increased 25% since 1982, although more than 5000 ha of seagrass still require recovery. The cooperation of scientists, managers, and decision makers participating in the Tampa Bay Estuary Program’s Nitrogen Management Strategy allows the Tampa Bay estuary to continue to show progress towards reversing many of the problems that once plagued its waters. These results also highlight the importance of a multi-entity watershed management process in maintaining progress towards science-based natural resource goals.     

用Autospec-Ultima NT气相色谱-高分辨质谱分析二噁英及相关的持久性有机污染物

"二噁英"是指一类化学结构和生物特征均有某些相似之处的化合物.这些有毒化合物有几百种,可分为相关的三大类:氯代二苯并-对-二噁英(CDDs),氯代二苯并呋喃(CDFs)和某些多氯代联苯(PCBs).CDDs和CDFs并非与生具有,而是由于人类活动不注意而生成的.天然过程也会产生CDDs和CDFs.     

Changes in motorcycle-related injuries and deaths after mandatory motorcycle helmet law in a district of Vietnam

Objective: Our study measured the change in head injuries and deaths among motorcycle users in Cu Chi district, a suburban district of Ho Chi Minh City.

Methods: Hospital records for road traffic injuries (RTIs) were collected from the Cu Chi Trauma Centre and motorcycle-related death records were obtained from mortality registries in commune health offices. Head injury severity was categorized using the Abbreviated Injury Score (AIS). Rate ratios (RRs) were used to compare rates pre- and post-law (2005/2006–2009/2010). Cu Chi's population, stratified by year, age, and sex, was used as the denominator.

Results: Of records identifying the transportation mode at the time of injury, motorcyclists accounted for most injuries (3,035, 87%) and deaths (238, 90%). Head injuries accounted for 70% of motorcycle-related hospitalizations. Helmet use was not recorded in any death records and not in 97% of medical records. Males accounted for most injuries (73%) and deaths (88%). The median age was 28 years and 32 years for injuries and deaths, respectively. Compared to the pre-law period, rates of motorcycle injuries (RR = 0.53; 95% confidence interval [CI], 0.49–0.58), head injuries (RR = 0.35; 95% CI, 0.31–0.39), severe head injuries (RR = 0.47; 95% CI, 0.34–0.63), and deaths (RR = 0.69; 95% CI, 0.53–0.89) significantly decreased in the post-law period.

Conclusions: Rates of head injuries and deaths among motorcycle riders decreased significantly after implementation of the mandatory helmet law in Vietnam. To further examine the impact of the motorcycle helmet law, including compliance and helmet quality, further emphasis should be placed on gathering helmet use data from injured motorcyclists.     

Socio-environmental consideration of phosphorus flows in the urban sanitation chain of contrasting cities

Understanding how cities can transform organic waste into a valuable resource is critical to urban sustainability. The capture and recycling of phosphorus (P), and other essential nutrients, from human excreta is particularly important as an alternative organic fertilizer source for agriculture. However, the complex set of socio-environmental factors influencing urban human excreta management is not yet sufficiently integrated into sustainable P research. Here, we synthesize information about the pathways P can take through urban sanitation systems along with barriers and facilitators to P recycling across cities. We examine five case study cities by using a sanitation chains approach: Accra, Ghana; Buenos Aires, Argentina; Beijing, China; Baltimore, USA; and London, England. Our cross-city comparison shows that London and Baltimore recycle a larger percentage of P from human excreta back to agricultural lands than other cities, and that there is a large diversity in socio-environmental factors that affect the patterns of recycling observed across cities. Our research highlights conditions that may be “necessary but not sufficient” for P recycling, including access to capital resources. Path dependencies of large sanitation infrastructure investments in the Global North contrast with rapidly urbanizing cities in the Global South, which present opportunities for alternative sanitation development pathways. Understanding such city-specific social and environmental barriers to P recycling options could help address multiple interacting societal objectives related to sanitation and provide options for satisfying global agricultural nutrient demand.

     

Key actions towards the sustainable management of European geese

Increasing abundance of geese in North America and Europe constitutes a major conservation success, but has caused increasing conflicts with economic, health and safety interests, as well as ecosystem impacts. Potential conflict resolution through a single, ‘one size fits all’ policy is hindered by differences in species’ ecology, behaviour, abundance and population status, and in contrasting political and socio-economic environments across the flyways. Effective goose management requires coordinated application of a suite of tools from the local level to strategic flyway management actions. The European Goose Management Platform, established under the Agreement on the Conservation of African-Eurasian Migratory Waterbirds, aims to harmonise and prioritise management, monitoring and conservation efforts, sharing best practice internationally by facilitating agreed policies, coordinating flyway efforts, and sharing and exchanging experiences and information. This depends crucially upon adequate government financing, the collection of necessary monitoring data (e.g., on distribution, abundance, hunting bags, demography, ecosystem and agricultural damage), the collation and effective use of such data and information, as well as the evaluation of outcomes of existing management measures.     

Pacific Islanders’ understanding of climate change: Where do they source information and to what extent do they trust it?

Regional Environmental Change - The experience of environmental stress and attitudes towards climate change was explored for 1226 students at the University of the South Pacific, the foremost...     

Critical review of the building downwash algorithms in AERMOD

The only documentation on the building downwash algorithm in AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model), referred to as PRIME (Plume Rise Model Enhancements), is found in the 2000 A&WMA journal article by Schulman, Strimaitis and Scire. Recent field and wind tunnel studies have shown that AERMOD can overpredict concentrations by factors of 2 to 8 for certain building configurations. While a wind tunnel equivalent building dimension study (EBD) can be conducted to approximately correct the overprediction bias, past field and wind tunnel studies indicate that there are notable flaws in the PRIME building downwash theory. A detailed review of the theory supported by CFD (Computational Fluid Dynamics) and wind tunnel simulations of flow over simple rectangular buildings revealed the following serious theoretical flaws: enhanced turbulence in the building wake starting at the wrong longitudinal location; constant enhanced turbulence extending up to the wake height; constant initial enhanced turbulence in the building wake (does not vary with roughness or stability); discontinuities in the streamline calculations; and no method to account for streamlined or porous structures.

Implications: This paper documents theoretical and other problems in PRIME along with CFD simulations and wind tunnel observations that support these findings. Although AERMOD/PRIME may provide accurate and unbiased estimates (within a factor of 2) for some building configurations, a major review and update is needed so that accurate estimates can be obtained for other building configurations where significant overpredictions or underpredictions are common due to downwash effects. This will ensure that regulatory evaluations subject to dispersion modeling requirements can be based on an accurate model. Thus, it is imperative that the downwash theory in PRIME is corrected to improve model performance and ensure that the model better represents reality.     

Black Carbon Aerosol at McMurdo Station,Antarctica

ABSTRACT

Aerosol light absorption as black carbon (BC) was measured from November 19, 1995, to February 6, 1996, at a location 0.65 km downwind of the center of McMurdo Station on the Antarctic coast. The results show a bimo-dal frequency distribution of BC concentrations. Approximately 65% of the measurements were found in a mode at a low range of concentrations centered at ~20 ng/m³. These concentrations are higher than those found at other remote Antarctic locations and probably represent contamination from the station. The remaining measurements were in a high-concentration mode (BC ~300 ng/m³), indicating direct impact of local emissions from combustion activities at the station. High values of BC were associated with winds from the direction of the station, and the BC flux showed a clear directionality. Maximum BC concentrations occurred between 7:00 and 11:00 a.m. The "polluted" mode accounted for more than 80% of the BC frequency-weighted impact at this location.     

Emerging technologies for removing nonpoint phosphorus from surface water and groundwater: introduction

Coastal and freshwater eutrophication continues to accelerate at sites around the world despite intense efforts to control agricultural P loss using traditional conservation and nutrient management strategies. To achieve required reductions in nonpoint P over the next decade, new tools will be needed to address P transfers from soils and applied P sources. Innovative remediation practices are being developed to remove nonpoint P sources from surface water and groundwater using P sorbing materials (PSMs) derived from natural, synthetic, and industrial sources. A wide array of technologies has been conceived, ranging from amendments that immobilize P in soils and manures to filters that remove P from agricultural drainage waters. This collection of papers summarizes theoretical modeling, laboratory, field, and economic assessments of P removal technologies. Modeling and laboratory studies demonstrate the importance of evaluating P removal technologies under controlled conditions before field deployment, and field studies highlight several challenges to P removal that may be unanticipated in the laboratory, including limited P retention by filters during storms, as well as clogging of filters due to sedimentation. Despite the potential of P removal technologies to improve water quality, gaps in our knowledge remain, and additional studies are needed to characterize the long-term performance of these technologies, as well as to more fully understand their costs and benefits in the context of whole-farm- and watershed-scale P management.