Comparison of Three Algaecides for Controlling the Density of Prymnesium parvum1

Rodgers, John H., Jr., Brenda M. Johnson, and West M. Bishop, 2010. Comparison of Three Algaecides for Controlling the Density of Prymnesium parvum. Journal of the American Water Resources Association (JAWRA) 46(1):153-160. DOI: 10.1111/j.1752-1688.2009.00399.x Abstract: Prymnesium parvum has become more prevalent in water resources of the southern United States. As the potential impacts of P. parvum are relatively well known, especially its capability to severely affect fish, managers have sought efficacious, environmentally sound, and socially acceptable strategies for mitigating this noxious species. Laboratory testing was used to identify an effective algaecide for control of P. parvum from Texas, Arizona, Florida, North Carolina, and South Carolina. Cutrine^®-Plus at 0.2 mg Cu/l significantly decreased the density of P. parvum in samples from all of these locations. Both copper sulfate and Phycomycin^® were less effective for controlling the population growth of P. parvum. The predicted response from the laboratory study was confirmed in the field at the Arizona site. Strategic use of Cutrine^®-Plus in larger water resources could provide toxin-free refugia to allow some fish to survive and repopulate the water resource when the golden alga infestation abates.     

Aerobic biodegradation of dichloroethylenes in surface and subsurface soils

Laboratory studies were conducted to examine the aerobic biodegradation of dichloroethylenes (cis-1,2-DCE, trans-1,2-DCE and 1,1-DCE) in soil and groundwater. Authentic surface and subsurface materials with no reported DCE exposure history were used. All DCE isomers were observed to biodegrade to varying degrees in the soils examined. Use of radiolabeled [14C] test chemicals allowed correlation of DCE disappearance with mineralization to 14CO2. Study results indicate that naturally occurring microorganisms in soil and groundwater are capable of degrading cis-1,2-, trans-1,2- and 1,1-DCE without laboratory supplementation of exogenous organic nutrients, or previous exposure history. The data further suggest that degradative potential may vary with soil type, DCE isomer structure, and concentration.     

Nonfatal injuries following Hurricane Katrina--New Orleans, Louisiana, 2005

The Journal of Safety Research has partnered with the National Center for Injury Prevention and Control at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, USA, to briefly report on some of the latest findings in the research community. This report is the fourth edition in a series of CDC articles. BACKGROUND: An active injury and illness surveillance system was established by the Centers for Disease Control and Prevention (CDC) along with the Louisiana Department of Health and Hospitals (LDHH) in the aftermath of Hurricane Katrina in functioning hospitals and medical clinics. RESULTS: The surveillance system recorded 7,543 nonfatal injuries among residents and relief workers between September 8-October 14, 2005. The leading mechanisms of injury identified in both groups were fall and cut/stab/pierce, with a greater proportion of residents compared to relief workers injured during the repopulation period. Clean-up was the most common activity at the time of injury for both groups. CONCLUSION: Injuries documented through this system underscore the need for surveillance of exposed populations to determine the injury burden and initiate injury prevention activities and health communication campaigns.     

The Identification and Determination of Airborne Particulates By Means of the Ring Oven Technique

The ring oven technique was first introduced as a means for conducting separations and concentrations on filter paper for final spot test analysis. By means of the technique, a complete qualitative scheme of separation and analysis can be made on a single drop of unknown. Recently, the effectiveness of the ring oven as a tool for quantitative analysis has been recognized. The method is particularly attractive for studies of airborne particulates. Samples of airborne particulates can be collected by high volume samplers, tape samplers, electrostatic precipitators, or by other appropriate means. The samples may be put into solution and an aliquot added to filter paper on a ring oven and washed to the ring zone for final identification and estimation. Any necessary separations can normally be carried out during the ring oven operations. A convenient approach for most studies is to collect the samples on tapes and carry out the necessary dissolution, separation, identification, and estimation steps directly on the tape itself. The ring oven methods are usually selective or even specific. The method applies to the microgram to nanogram range and the accuracies are comparable with those obtained by emission spectroscopy, polarography, fluorimetry, and spectrophotometry.     

Preferential flow path development and its influence on long-term PRB performance: column study

The operating life of an Fe(0)-based permeable reactive barrier (PRB) is limited due to chemical reactions of Fe(0) in groundwater. The relative contributions from mineral precipitation, gas production, and microbial activity to the degradation of PRB performance have been uncertain. In this controlled field study, nitrate-rich, site groundwater was treated by Fe(0) in large-volume, flow-through columns to monitor the changes in chemical and hydraulic parameters over time. Tracer tests showed a close relationship between hydraulic residence time and pH measurements. The ionic profiles suggest that mineral precipitation and accumulation is the primary mechanism for pore clogging around the inlet of the column. Accumulated N(2) gas generated by biotic processes also affected the hydraulics although the effects were secondary to that of mineral precipitation. Quantitative estimates indicate a porosity reduction of up to 45.3% near the column inlet over 72 days of operation under accelerated flow conditions. According to this study, preferential flow through a PRB at a site with similar groundwater chemistry should be detected over approximately 1 year of operation. During the early operation of a PRB, pH is a key indicator for monitoring the change in hydraulic residence time resulting from heterogeneity development. If the surrounding native material is more conductive than the clogged Fe-media, groundwater bypass may render the PRB ineffective for treating contaminated groundwater.     

Refined tunable methodology for characterization of contaminant-particle relationships in surface water

To understand contaminant transport in aquatic systems, it is essential to define the physical characteristics of the primary particulate carriers. The distribution of organic pollutants with particle-size class and particle morphology in a freshwater embayment (Hamilton Harbor, western Lake Ontario) was studied using a sequence of novel sample preparation and characterization techniques. Water samples (24 L) were fractionated according to particle-size distribution using differential cascade sedimentation and centrifugation methods. These size fractions were subsequently subjected to a physicochemical characterization using scanning transmission electron microscopy and energy-dispersive spectroscopy to identify flocs and individual colloidal particles in the size range of 1 nm to 1 mm in diameter. Analytical chemical analyses were performed to identify organic contaminants in extracts prepared from particle-size classes, including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The contaminant distribution trends were very similar for all compound classes studied; contaminants were primarily associated with fractions containing particles less than 2 mum in diameter. Morphological characterization of these fractions showed the majority of the particulates to be humic fractals. The results of this study show that contaminants in aquatic systems can be preferentially associated with specific types of particle carriers, the characteristics of which can be clearly defined in terms of size and morphology.     

Modeling inorganic aerosols and their response to changes in precursor concentration in Mexico City

Based on data from the 1997 Investigación sobre Materia Particulada y Deterioro Atmosférico-Aerosol and Visibility Evaluation Research (IMADA-EVER) campaign and the inorganic aerosol model ISORROPIA, the response of inorganic aerosols to changes in precursor concentrations was calculated. The aerosol behavior is dominated by the abundance of ammonia and thus, changes in ammonia concentration are expected to have a small effect on particle concentrations. Changes in sulfate and nitrate are expected to lead to proportional reductions in inorganic fine particulate matter (PM2.5). Comparing the predictions of ISORROPIA with the observations, the lowest bias and error are achieved when the aerosols are assumed to be in the efflorescence branch. Including crustal species reduces the bias and error for nitrate but does not improve overall model performance. The estimated response of inorganic PM2.5 to changes in precursor concentrations is affected by the inclusion of crustal species in some cases, although average responses are comparable with and without crustal species. Observed concentrations of particle chloride suggest that gas phase concentrations of hydrogen chloride may not be negligible, and future measurement campaigns should include observations to test this hypothesis. Our ability to model aerosol behavior in Mexico City and, thus, design control strategies, is constrained primarily by a lack of observations of gas phase precursors. Future campaigns should focus in particular on better understanding the temporal and spatial distribution of ammonia concentrations. In addition, gas phase observations of nitric acid are needed, and a measure of particle water content will allow stable versus metastable aerosol behavior to be distinguished.