Explore the vast range of titles available.

In 2005, the U.S. Environmental Protection Agency (USEPA) National Menu of Best Management Practices (BMPs) listed compost filter socks (FS) as an approved BMP for controlling sediment in storm runoff on construction sites. The objectives of this study were to determine if FS with or without the addition of a flocculation agent to the FS system can significantly remove (i) suspended clay and silt particulates, (ii) ammonium nitrogen (NH4-N) and nitrate-nitrite nitrogen (NO3-N), (iii) fecal bacteria, (iv) heavy metals, and (v) petroleum hydrocarbons from storm water runoff. Five separate (I-V) 30-min simulated rainfall-runoff events were applied to soil chambers packed with Hartboro silt loam (fine-loamy, mixed, active, nonacid, mesic fluvaquentic Endoaquepts) or a 6-mm concrete veneer on a 10% slope, and all runoff was collected and analyzed for hydraulic flow rate, volume, pollutant concentrations, pollutant loads, and removal efficiencies. In corresponding experiments, runoff was analyzed for (i) size of sediment particles, (ii) NH4-N and NO3-N, (iii) total coliforms (TC) and Escherichia coli, (iv) Cd, Cr, Cu, Ni, Pb and Zn, and (v) gasoline, diesel, and motor oil, respectively. Results showed that: (i) FS removed 65% and 66% of clay (<0.002 mm) and silt (0.002-0.05 mm), respectively; (ii) FS removed 17%, and 11% of NH4-N and NO3-N, respectively and when NitroLoxx was added to the FS, removal of NH4-N load increased to 27%; (iii) total coliform and E. coli removal efficiencies were 74 and 75%, respectively, however, when BactoLoxx was added, removal efficiency increased to 87 and 99% for TC and 89 and 99% for E. coli, respectively; (iv) FS removal efficiency for Cd, Cr, Cu, Ni, Pb, and Zn ranged from 37 to 72%, and, when MetalLoxx was added, removal efficiency ranged from 47 to 74%; and (v) FS removal efficiency for the three petroleum hydrocarbons ranged from 43 to 99% and the addition of PetroLoxx increased motor oil and gasoline removal efficiency in the FS system.

In 2005, the US Environmental Protection Agency National Menu of Stormwater Best Management Practices, National Pollutant Discharge Elimination System Phase II for Construction Sites, listed compost filter socks as an approved best management practice for controlling storm runoff and sediment on construction sites. Like most new technologies used to control sediment on construction sites, little has been done to evaluate their performance relative to conventional sediment control barriers, such as silt fences. The objectives of this study were (1) to determine and compare the sediment removal efficiency of silt fence and compost filter socks, (2) to determine if the addition of polymers to compost filter socks could reduce sediment and phosphorus loads, (3) to determine relationships between compost filter media particle size distribution and pollutant removal efficiency and hydraulic flow rate. Simulated rainfall was applied to soil chambers packed with Hatboro silt loam on a 10% slope. All runoff was collected and analyzed for hydraulic flow rate, volume, total suspended solids (TSS) concentration and load, turbidity, and total and soluble P concentration and load. Based on 7.45 cm h -1 (2.9 in hr -1 ) of simulated rainfall-runoff for 30 minutes duration, bare soil (control) runoff TSS concentrations were between 48,820 and 70,400 mg L -1 (6.5 oz gal -1 and 9.4 oz gal -1 ), and turbidity was between 19343 and 36688 Nephelometric Turbidity Units. Compost filter sock and silt fence removal efficiencies for TSS concentration (62% to 87% and 71% to 87%), TSS load (68% to 90% and 72% to 89%), and turbidity (53% to 78% and 54% to 76%) were nearly identical; however with the addition of polymers to the compost filter socks sediment removal efficiencies ranged from 91% to 99%. Single event support practice factors (P factor) for silt fence were between 0.11 and 0.29, for compost filter socks between 0.10 and 0.32, and for compost filter socks + polymer between 0.02 and 0.06. Total and soluble P concentration and load removal efficiencies were similar for compost filter socks (59% to 65% and 14% to 27%) and silt fence (63% and 23%). Although when polymers were added to the filter socks and installed on phosphorus fertilized soils, removal efficiencies increased to 92% to 99%. Compost filter socks restricted hydraulic flow rate between 2% and 22%, while the silt fence restricted between 5% and 29%. Significant correlations ( p < 0.05) were found between middle range particle sizes of compost filter media used in the filter socks and reduction of turbidity in runoff; however, hydraulic flow rate was a better indicator (stronger correlation) of total pollutant removal efficiency performance for compost filter socks and should be considered as a new parameter for federal and state standard specifications for this pollution prevention technology.

Vegetated filter strips (VFS) have become an important component of water quality improvement by reducing sediment and nutrients transport to surface water. This management practice is also beneficial for controlling manure-borne pathogen transport to surface water. The objective of this work was to assess the VFS efficiency and evaluate the uncertainty in predicting the microbial pollutant removal from overland flow in VFS. We used the kinematic wave overland flow model as implemented in KINEROS2 coupled with the convective-dispersive overland transport model which accounts for the reversible attachment-detachment and surface straining of infiltrating bacteria. The model was successfully calibrated with experimental data obtained from a series of simulated rainfall experiments at vegetated and bare sandy loam and clay loam plots, where fecal coliforms were released from manure slurry applied on the top of the plots. The calibrated model was then used to assess the sensitivity of the VFS efficiency to the model parameters, rainfall duration, and intensity for a case study with a 6-m VFS placed at the edge of 200-m long field. The Monte Carlo simulations were also performed to evaluate the uncertainty associated with the VFS efficiency given the uncertainty in the model parameters and key inputs. The VFS efficiency was found to be <95% in 25%, <75% in 23%, and <25% in 20% of cases. Relatively long high-intensity rainfalls, low hydraulic conductivities, low net capillary drives of soil, and high soil moisture contents before rainfalls caused the partial failure of VFS to retain coliforms from the infiltration excess runoff.

Perchlorate is a goitrogenic anion that competitively inhibits the sodium iodide transporter and has been detected in forages and in commercial milk throughout the U.S. The fate of perchlorate and its effect on animal health were studied in lactating cows, ruminally infused with perchlorate for 5 weeks. Milk perchlorate levels were highly correlated with perchlorate intake, but milk iodine was unaffected, and there were no demonstrable health effects. We provide evidence that up to 80% of dietary perchlorate was metabolized, most likely in the rumen, which would provide cattle with a degree of refractoriness to perchlorate. Data presented are important for assessing the environmental impact on perchlorate concentrations in milk and potential for relevance to human health.

The efficiency of silt fence and compost filter socks for sediment removal is determined and compared. The effects of adding polymers to compost filter socks in reducing phosphorous loads and sediments are also studied.The relationships between compost filter media particle size distribution and pollutant removal efficiency and hydraulic flow rate, are also determined.

Accurate characterization of lateral transport components is an important step toward a more quantitative assessment of the fate and transport of nutrients and the functionality of riparian/wetland systems. Our specific objectives were: (i) to design an in situ chamber for studying lateral flow under shallow watertable and riparian zone conditions; (ii) to monitor predominantly horizontal transport of non-conservative (NO3) and conservative (Br) tracers in shallow saturated zone of the soil monolith; and (iii) to obtain reaction and transport parameters, and additional insights about the flow and transport inside the soil monolith. HYDRUS-2D model was used to simulate flow and transport of Br and NO3, and to evaluate the applicability of this model to the observed flow and transport. Advective-dispersive equation (ADE) and mobile-immobile zone model (MIM) options were tested using the Br data. The breakthrough curves (BTCs) of NO3 and Br were similar while the concentrations rose, then became distinctly different with NO3 concentrations decreasing much faster. The calibrated denitrification rate of 0.713 +/- 0.211 d(-1) was about an order and a half of magnitude larger in the loam layer (25-35 cm) than in the overlaying sandy loam layer (0-25 cm) and in the sandy clay loam layer (35-65 cm) below. Up to 60% of the introduced NO3 was lost to denitrification. The methodology presented here allowed the in situ estimation reaction and transport needed for modeling; and it showed a potential to provide detailed information critical for the interpretation of the modeling outcomes performed at field and watershed levels.

A field study was conducted in 1987 to 1991 to determine the effect of tillage and rainfall on distribution of atrazine in soil. Soil samples (10-cm increments to 50 cm) and crop residue samples were taken at regular intervals after application each year and analyzed for atrazine. Crop residue and living vegetation on no-till plots intercepted 60 to 70% of the applied atrazine; 3 to 16% of the atrazine remained in crop residue 1 to 2 wk later. The amount of atrazine recovered in soil, 1 to 2 wk posttreatment, ranged from 22 to 59 and 47 to 73% of the amount applied for no-till and conventional till, respectively. An average of 2.6 times more atrazine was recovered in the surface 10 cm of soil under conventional till than under no-till for all samplings and years. Total amounts of atrazine in the sampled profile (0- to 50-cm depth) were also generally lower under no-till than conventional till. More leaching below 10 cm occurred under no-till than conventional till, particularly in 1988 and 1990 when rain fell soon after application. Variation in soil atrazine levels among years was related to timing and amount of the first and subsequent rainfall after application.