Trapping Phosphorus in Runoff with a Phosphorus Removal Structure

Reduction of phosphorus (P) inputs to surface waters may decrease eutrophication. Some researchers have proposed fi ltering dissolved P in runoff with P-sorptive byproducts in structures placed in hydrologically active areas with high soil P concentrations. Th e objectives of this study were to construct and monitor a P removal structure in a suburban watershed and test the ability of empirically developed fl ow-through equations to predict structure performance. Steel slag was used as the P sorption material in the P removal structure. Water samples were collected before and after the structure using automatic samples and analyzed for total dissolved P. During the fi rst 5 mo of structure operation, 25% of all dissolved P was removed from rainfall and irrigation events. Phosphorus was removed more effi ciently during low fl ow rate irrigation events with a high retention time than during high fl ow rate rainfall events with a low retention time. Th e six largest fl ow events occurred during storm fl ow and accounted for 75% of the P entering the structure and 54% of the P removed by the structure. Flow-through equations developed for predicting structure performance produced reasonable estimates of structure “lifetime” (16.8 mo). However, the equations overpredicted cumulative P removal. Th is was likely due to diff erences in pH, total Ca and Fe, and alkalinity between the slag used in the structure and the slag used for model development. Th is suggests the need for an overall model that can predict structure performance based on individual material properties

Trapping Phosphorus in Runoff with a Phosphorus Removal Structure

Reduction of phosphorus (P) inputs to surface waters may decrease eutrophication. Some researchers have proposed fi ltering dissolved P in runoff with P-sorptive byproducts in structures placed in hydrologically active areas with high soil P concentrations. Th e objectives of this study were to construct and monitor a P removal structure in a suburban watershed and test the ability of empirically developed fl ow-through equations to predict structure performance. Steel slag was used as the P sorption material in the P removal structure. Water samples were collected before and after the structure using automatic samples and analyzed for total dissolved P. During the fi rst 5 mo of structure operation, 25% of all dissolved P was removed from rainfall and irrigation events. Phosphorus was removed more effi ciently during low fl ow rate irrigation events with a high retention time than during high fl ow rate rainfall events with a low retention time. Th e six largest fl ow events occurred during storm fl ow and accounted for 75% of the P entering the structure and 54% of the P removed by the structure. Flow-through equations developed for predicting structure performance produced reasonable estimates of structure “lifetime” (16.8 mo). However, the equations overpredicted cumulative P removal. Th is was likely due to diff erences in pH, total Ca and Fe, and alkalinity between the slag used in the structure and the slag used for model development. Th is suggests the need for an overall model that can predict structure performance based on individual material properties

Non-O157 Shiga Toxin–producing Escherichia coli Associated with Venison

News reports of “E. coli outbreaks” usually refer to Shiga toxin–producing E. coli O157. But there are other types of Shiga toxin–producing E. coli, often called STEC,about which less is known. For these other types of STEC, what is the source? What are the risk factors? An outbreak among 29 high school students in Minnesota provided some answers. The source of this outbreak was a white-tailed deer that had been butchered and eaten at the school. The risk factors for infection were handling raw or eating undercooked venison. To prevent this type of STECinfection, people should handle and cook venison with the same caution recommended for other meats

Salmonella enterica Pulsed-Field Gel Electrophoresis Clusters, Minnesota, USA, 2001–2007

This procedure can help identify outbreaks of salmonellosis

Incidence of Cronobacter spp. Infections, United States, 2003–2009

During 2003–2009, we identified 544 cases of Cronobacter spp. infection from 6 US states. The highest percentage of invasive infections occurred among children <5 years of age; urine isolates predominated among adults. Rates of invasive infections among infants approximate earlier estimates. Overall incidence of 0.66 cases/100,000 population was higher than anticipated