Application of statistical modeling to optimize a coastal water quality monitoring program

The long-term water quality monitoring program implemented by the Massachusetts Water Resources Authority in 1992 is extensive and has provide substantial understanding of the seasonality of the waters in both Boston Harbor and Massachusetts Bay and the response to improvements in effluent quality and offshore transfer of the effluent in September 2000. The monitoring program was designed with limited knowledge of spatial and temporal variability and long-term trends within the system. This led to an extensive spatial and temporal sampling program. The data through 2003 showed high correlation within physical parameters measured (e.g., salinity, dissolved oxygen) and in biological measures such as chlorophyll fluorescence. To address the potential sampling redundancies in the measurement program, an assessment of the impact of reduced levels of monitoring on the ability to make water quality decisions was completed. The optimization was conducted by applying statistical models that took into account whether there was evidence of a seasonal pattern in the data. The optimization used model survey average readings to identify temporal fixed effects, model survey-average-corrected individual station readings to identify spatial fixed effects, corrected the individual station readings for temporal and spatial fixed effects and derived a correlation model for the corrected data, and applied the correlation model to characterize the correlation of annual average readings from reduced monitoring programs with true parameter levels. Reductions in the number of sampling stations were found less detrimental to the quality of the data for annual decision-making than reductions in the number of surveys per year, although there is less of a difference in this regard for dissolved oxygen than there is for chlorophyll. The analysis led to recommendations for a substantially lower monitoring effort with minimal loss of information. The recommendation supported an annual budget savings of approximately $183,000. Most of the savings was from fewer surveys as approximately $21,000 came from the reduction in the number of stations monitored from 21 to 7 and associated laboratory analytical costs.     

Biological invasions: recommendations for U.S. policy and management.

The Ecological Society of America has evaluated current U.S. national policies and practices on biological invasions in light of current scientific knowledge. Invasions by harmful nonnative species are increasing in number and area affected; the damages to ecosystems, economic activity, and human welfare are accumulating. Without improved strategies based on recent scientific advances and increased investments to counter invasions, harm from invasive species is likely to accelerate. Federal leadership, with the cooperation of state and local governments, is required to increase the effectiveness of prevention of invasions, detect and respond quickly to new potentially harmful invasions, control and slow the spread of existing invasions, and provide a national center to ensure that these efforts are coordinated and cost effective. Specifically, the Ecological Society of America recommends that the federal government take the following six actions: (1) Use new information and practices to better manage commercial and other pathways to reduce the transport and release of potentially harmful species; (2) Adopt more quantitative procedures for risk analysis and apply them to every species proposed for importation into the country; (3) Use new cost-effective diagnostic technologies to increase active surveillance and sharing of information about invasive species so that responses to new invasions can be more rapid and effective; (4) Create new legal authority and provide emergency funding to support rapid responses to emerging invasions; (5) Provide funding and incentives for cost-effective programs to slow the spread of existing invasive species in order to protect still uninvaded ecosystems, social and industrial infrastructure, and human welfare; and (6) Establish a National Center for Invasive Species Management (under the existing National Invasive Species Council) to coordinate and lead improvements in federal, state, and international policies on invasive species. Recent scientific and technical advances provide a sound basis for more cost-effective national responses to invasive species. Greater investments in improved technology and management practices would be more than repaid by reduced damages from current and future invasive species. The Ecological Society of America is committed to assist all levels of government and provide scientific advice to improve all aspects of invasive-species management.     

Variation of leaf gland volatile oil within a population of sweet gale (Myrica gale) (Myricaceae)

Summary The leaf gland volatile oils of ten sweet gale plants from a Scottish population were extracted in early summer. The results differed notably from reports of other populations in respect of the sesquiterpenes, -elemenone and germacrone, which were major components of the volatile oil. Three dihydrochalcones were also detected in the volatile oil. Variation within the population existed, particularly with respect to the relative importance of germacrone. Five plants were resampled in late summer and exhibited a marked reduction in -elemenone, a lesser reduction in germacrone and changes in the proportions of some monoterpenes.     

Effects of surrounding land use and water depth on seagrass dynamics relative to a catastrophic algal bloom

Seagrasses are the foundation of many coastal ecosystems and are in global decline because of anthropogenic impacts. For the Indian River Lagoon (Florida, U.S.A.), we developed competing multistate statistical models to quantify how environmental factors (surrounding land use, water depth, and time [year]) influenced the variability of seagrass state dynamics from 2003 to 2014 while accounting for time‐specific detection probabilities that quantified our ability to determine seagrass state at particular locations and times. We classified seagrass states (presence or absence) at 764 points with geographic information system maps for years when seagrass maps were available and with aerial photographs when seagrass maps were not available. We used 4 categories (all conservation, mostly conservation, mostly urban, urban) to describe surrounding land use within sections of lagoonal waters, usually demarcated by land features that constricted these waters. The best models predicted that surrounding land use, depth, and year would affect transition and detection probabilities. Sections of the lagoon bordered by urban areas had the least stable seagrass beds and lowest detection probabilities, especially after a catastrophic seagrass die‐off linked to an algal bloom. Sections of the lagoon bordered by conservation lands had the most stable seagrass beds, which supports watershed conservation efforts. Our results show that a multistate approach can empirically estimate state‐transition probabilities as functions of environmental factors while accounting for state‐dependent differences in seagrass detection probabilities as part of the overall statistical inference procedure.     

Alabama Electric Cooperative Flue Gas Desulfurization Operating and Maintenance Experience

Alabama Electric Cooperative, Leroy, AL, has recently started up two 255 MW units, including a flue gas desulfurization system, at their Tomblgbee Station. The flue gas desulfurization system was designed by Peabody Process Systems, Inc., Stamford, CT. After 20 months operation, performance, in terms of start-up operations and maintenance, has been exceptionally good. This paper discusses those design factors which contributed to this successful performance.     

Minnesota Power’s Operating Experience with Integrated Particulate and SO2 Scrubbing

Minnesota Power currently has in commercial operation a 500 MW gas cleaning system consisting of a venturi particulate scrubber, integrated with a spray tower SO₂ absorber. The system was designed to achieve 99.7% particulate removal and 90% SO₂ removal based upon burning a 2.8 % sulfur coal.

Initially the concept of using a venturi for wet particulate collection was selected based upon a significant cost saving of $25 million compared to dry particulate collection devices. Subsequently, the Interaction of particulate collection with SO₂ removal provided additional operating cost benefits. Prior to start-up of the commercial system, a pilot plant was used to evaluate various modes of operation. Results showed that alkali contained in the fly ash removed with the venturi was sufficient to meet the alkali requirement for SO₂ removal.

Clay Boswell Station Unit No. 4 was started up during March 1980. Since initial start-up the system has exhibited almost 100% availability. EPA compliance testing has confirmed that the system Is meeting its emission standards. The unit is operating with fly ash as the only source of alkali. Since commercial operation started, no external alkali has been purchased.

This paper will discuss the design details of the system and performance of the commercial system.     

Design of a Cost-Effective Weighing Facility for PM2.5 Quality Assurance

Abstract

The U.S. Environmental Protection Agency (EPA) Quality Assurance (QA) Guidance Document 2.12: Monitoring PM_2.5 in Ambient Air Using Designated Reference or Class I Equivalent Methods¹ (Document 2.12) requires conditioning of PM_2.5 filters at 20-23 °C and 30-40% relative humidity (RH) for 24 hr prior to gravimetric analysis. Variability of temperature and humidity may not exceed ±2 °C and ±5% RH during the conditioning period. The quality assurance team at EPA Region 2’s regional laboratory designed a PM_2.5 weighing facility that operates well within these strict performance requirements.

The traditional approach to meeting the performance requirements of Document 2.12 for PM_2.5 filter analysis is to build a walk-in room, with costs typically exceeding $100,000. The initial one-time capital cost for the laboratory at EPA’s Edison, NJ, facility was approximately $24,000. Annual costs [e.g., National Institute of Standards and Technology (NIST) recertifications and nitrogen replacement cylinders used for humidity control] are approximately $500. The average 24-hr variabilities in temperature and RH in the Region 2 weighing chamber are small, ±0.2 °C and ±0.8% RH, respectively. The mass detection limit for the PM_2.5 weighing system of 47-mm stretched Teflon (lab blank) filters is 6.3 μg. This facility demonstrates an effective and economical example for states and other organizations planning PM_2.5 weighing facilities.     

Fish and ships: relating dispersal frequency to success in biological invasions

 Most studies characterizing successful biological invaders emphasize those traits that help a species establish a new population. Invasions are, however, multi-phase processes with at least two phases, dispersal and introduction, that occur before establishment. Characteristics that enhance survival at any of these three phases will contribute to invasion success. Here, we synthesize information on the dispersal, introduction, and establishment of fishes mediated by ship ballast-water transport. We synthesize 54 reports of at least 31 fish species collected from ballast tanks (Phase 1), including 28 new reports from our recent studies (1986 to 1996). Our literature survey revealed 40 reports of 32 fish species whose introductions have been attributed to ballast transport (Phase 2), of which at least 24 survived to establish persistent populations (Phase 3). We detected little overlap at the species level between these two data sets (Phase 1 vs Phases 2 and 3), but patterns emerged at the family level. The Gobiidae (6 species), Clupeidae (4 species), and Gasterosteidae (1 species) were the most commonly found fish families in ballast tanks (Phase 1). The Gobiidae (13 species), Blenniidae (6 species) and Pleuronectidae (2 species) dominated the list of ballast-mediated introductions (Phase 2); gobies and blennies were the families most frequently established (Phase 3). The invasive success of gobies and blennies may be explained in part by their crevicolous nature: both groups seek refuge and lay eggs in small holes, and may take advantage of the ballast-intake holes on ship hulls. This behavior, not typically associated with invasive ability, may contribute to successful introduction and establishment by facilitating the dispersal phase of invasion. The failure of the pleuronectids to invade may reflect poor salinity match between donor and recipient regions. To develop a predictive framework of invasion success, organisms must be sampled at all three phases of the invasion process. Our comparison of two ballast sampling methods suggests that fishes have been undersampled in ballast-water studies, including our own, and that the role of ballast transport in promoting fish invasions has been underestimated. Received: 13 January 1999 / Accepted: 24 February 2000     

The Impact of Occupational Load Carriage on Carrier Mobility: A Critical Review of the Literature

Military personnel and firefighters are required to carry occupational loads and complete tasks in hostile and unpredictable environments where a lack of mobility may risk lives. This review critically examines the literature investigating the impacts of load carriage on the mobility of these specialist personnel. Several literature databases, reference lists, and subject matter experts were employed to identify relevant studies. Studies meeting the inclusion criteria were critiqued using the Downs and Black protocol. Inter-rater agreement was determined by Cohen’s κ Twelve original research studies, which included male and female participants from military and firefighting occupations, were critiqued (κ = .81). A review of these papers found that as the carried load weight increased, carrier mobility during aerobic tasks (like road marching) and anaerobic tasks (like obstacle course negotiation) decreased. As such, it can be concluded that the load carried by some specialist personnel may increase their occupational risk by reducing their mobility.