Garland J.L.,CSS-Dynamac |
Mackowiak C.L.,University of North Florida
Applied Soil Ecology | Year: 2010
Organic fertilizers provide long-term benefits to agronomic soils, but sometimes cause short-term reductions in crop yield due to microbially mediated nitrogen (N) immobilization. A simple, rapid method to assess the integrated use of both, carbon (C) and N by soil microbial communities will be a useful monitoring tool in production agriculture. The present study evaluated a new platform for performing community-level physiological profiles (CLPP) using fluorescent-based detection of O2 consumption by soil slurries within microtiter plates. Response of a spodic Florida soil to 3 organic fertilizer amendment treatments; (1) control with no organic amendment, (2) pelletized class A-A municipal biosolids amendment, and (3) fresh dairy waste solids amendment was measured in soils taken from a corn-rye crop rotation. The CLPP assay was used to assess endogenous and substrate induced (∼75 μg C as acetate, casein, coumaric acid, mannose, or asparagine g-1 soil) respiration, with and without assay N additions (8 μg N-NH4 g-1 soil). Endogenous and substrate-induced respiration were generally greater in the dairy waste-amended soils, as quantified by a reduced lag period and greater response peak. Stimulatory effects from biosolid-amended soils were less extensive and consistent. The degree of N limitation on microbial activity was determined by comparing the response peak with and without N amendment. This difference in response (Ndiff) was greatest for all treatments during the rye exponential growth phase (prior to heading), when extractable soil NH4-N and NO3-N concentrations were lowest (i.e., < 10 mg kg-1). The dairy waste treated soils had greater Ndiff values during the rye crop as compared to the other treatments, particularly for endogenous respiration and mannose-induced respiration. Ndiff was low in all treatments during the corn crop, where extractable soil NH4-N + NO3-N remained at or above 20 mg N kg-1. Plant yield data coincided with our estimates of N-limited microbial activity, with less mid-season rye biomass under dairy waste and no yield response with corn. Overall, these data indicate that this new method allows for a rapid, ecologically relevant evaluation of organic amendment impacts on microbial soil respiration and thereby plant yield response. Further characterization and interpretation of the variation in microbial respiration among specific C substrates and the relative impact of N amendments (i.e., Ndiff), will provide insight to C and N cycling in soils receiving organic N inputs. © 2010 Elsevier B.V.
Landing W.M.,Florida State University |
Caffrey J.M.,University of West Florida |
Nolek S.D.,CSS-Dynamac |
Gosnell K.J.,University of Connecticut |
Parker W.C.,Florida State University
Atmospheric Chemistry and Physics | Year: 2010
In an effort to understand and quantify the impact of local, regional, and far-distant atmospheric mercury sources to rainfall mercury deposition in the Pensacola, Florida watershed, a program of event-based rainfall sampling was started in late 2004. Modified Aerochem-Metrics wet/dry rainfall samplers were deployed at three sites in the region around the Crist coal-fired power plant and event-based samples were collected continuously for three years. Samples were analyzed for total Hg and a suite of trace elements including Al, As, Ba, Bi, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, La, Li, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Se, Si, Sn, Sr, Th, U, V, and Zn. Nutrients (ammonia and nitrate) and major anions (chloride and sulfate) were also measured on each sample. Multivariate statistical methods were used to sort these tracers into factors that represent potential source categories contributing to the rainfall chemistry. As, Hg, Sb, Se, Sn, and non sea-salt sulfate were all significantly correlated (R > 0.6) with one factor which we interpret as an anthropogenic source term reflecting input from coal combustion throughout the southeastern US. Using ratios of total Hg to volatile elements, we estimate that 22-33% of the rainfall Hg results from coal combustion in the southeastern US with the majority coming from the global background. © Author(s) 2010.
Zabaloy M.C.,National University of the South |
Garland J.L.,CSS-Dynamac |
Gomez M.A.,National University of the South
Applied Soil Ecology | Year: 2010
The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) may influence soil microbial communities by altering the balance between resident populations. Our objective was to assess the effect of environmentally relevant levels (ERLs) of 2,4-D on microbial community function and on the population dynamics of 2,4-D degrading bacteria using a microcosm approach. The most probable number approach was used to enumerate 2,4-D-degrading soil bacteria. Carbon substrates utilization was tested with a microtiter-based oxygen sensor system to evaluate short-term functional shifts caused by herbicide treatment. Shifts in the community in response to potential toxicity of 2,4-D were assessed in the agricultural soil and a reference forest soil using the pollution-induced community-tolerance (PICT) approach. Results indicated that the agricultural soil had a stable 2,4-D degrading population able to use the herbicide as C and energy source, which increases immediately after an ERL dose of 2,4-D and remains high for about 1 month after exposure has ceased. An enhanced, dose-dependent response to 2,4-D as substrate was observed in the microtiter assay, while heterotrophic bacterial activity appeared mostly unchanged. The PICT assay showed higher tolerance to 2,4-D in the agricultural soil than in the unexposed forest soil. Our results suggest that agricultural use of 2,4-D at recommended level leads to selection for (1) a copiotrophic degrader population and (2) a persistently herbicide-tolerant, but functionally similar, microbial community. © 2010 Elsevier B.V.
Renee Brooks J.,U.S. Environmental Protection Agency |
Barnard H.R.,Oregon State University |
Coulombe R.,CSS-Dynamac |
McDonnell J.J.,Oregon State University |
McDonnell J.J.,University of Aberdeen
Nature Geoscience | Year: 2010
Water movement in upland humid watersheds from the soil surface to the stream is often described using the concept of translatory flow1,2, which assumes that water entering the soil as precipitation displaces the water that was present previously, pushing it deeper into the soil and eventually into the stream. Within this framework, water at any soil depth is well mixed and plants extract the same water that eventually enters the stream2. Here we present water-isotope data from various pools throughout a small watershed in the Cascade Mountains, Oregon, USA. Our data imply that a pool of tightly bound water that is retained in the soil and used by trees does not participate in translatory flow, mix with mobile water or enter the stream. Instead, water from initial rainfall events after rainless summers is locked into small pores with low matric potential until transpiration empties these pores during following dry summers. Winter rainfall does not displace this tightly bound water. As transpiration and stormflow are out of phase in the Mediterranean climate of our study site, two separate sets of water bodies with different isotopic characteristics exist in trees and streams. We conclude that complete mixing of water within the soil cannot be assumed for similar hydroclimatic regimes as has been done in the past3,4. © 2010 Macmillan Publishers Limited. All rights reserved.
Lane C.R.,U.S. Environmental Protection Agency |
Journal of the American Water Resources Association | Year: 2016
Geographically isolated wetlands (GIWs) are wetlands completely surrounded by uplands. While common throughout the United States (U.S.), there have heretofore been no nationally available, spatially explicit estimates of GIW extent, complicating efforts to understand the myriad biogeochemical, hydrological, and habitat functions of GIWs and hampering conservation and management efforts at local, state, and national scales. We used a 10-m geospatial buffer as a proxy for hydrological or ecological connectivity of National Wetlands Inventory palustrine and lacustrine wetland systems to nationally mapped and available stream, river, and lake data. We identified over 8.3 million putative GIWs across the conterminous U.S., encompassing nearly 6.5 million hectares of wetland resources (average size 0.79 ± 4.81 ha, median size 0.19 ha). Putative GIWs thus represent approximately 16% of the freshwater wetlands of the conterminous U.S. The water regime for the majority of the putative GIWs was temporarily or seasonally flooded, suggesting a vulnerability to ditching or hydrologic abstraction, sedimentation, or alterations in precipitation patterns. Additional analytical applications of this readily available geospatially explicit mapping product (e.g., hydrological modeling, amphibian metapopulation, or landscape ecological analyses) will improve our understanding of the abundance and extent, effect, connectivity, and relative importance of GIWs to other aquatic systems of the conterminous U.S. © 2016 American Water Resources Association.
Wynne T.T.,National Oceanic and Atmospheric Administration |
Stumpf R.P.,National Oceanic and Atmospheric Administration |
International Journal of Remote Sensing | Year: 2013
A spectral shape algorithm applied to Medium Resolution Imaging Spectrometer (MERIS) imagery has detected cyanobacterial blooms, with extensive examples in Lake Erie. The detection algorithm uses an approximation of the second derivative as a measure of spectral shape around the 681 nm band S 2d(681). With the end of the MERIS mission on 8 April 2012, an analogue was developed for the Moderate Resolution Imaging Spectroradiometer (MODIS) to continue monitoring for these blooms. The MODIS analogue uses the standard ρs (Rayleigh-corrected reflectance) to determine S 2d(678), which is computationally equivalent to the negative of the MODIS fluorescent line height (FLH). A comparison was made of the two products from image pairs during a period of relatively severe blooms of cyanobacteria (2008-2011). When the MODIS bands do not saturate due to surface scums from high cyanobacteria biomass or conditions of glint or dense aerosols, the algorithms produce comparable results with a linear transform of the MODIS S 2d(678). The results indicate that MODIS can be used to monitor these blooms. Dense cyanobacteria blooms will produce negative FLH showing a limitation of FLH for bloom detection. The S 2d(678) offers a tool to support monitoring for dense algal blooms. © 2013 Copyright International copyright, 2013, US Department of Commerce, US Government.
Cline S.P.,U.S. Environmental Protection Agency |
River Research and Applications | Year: 2012
Historic unconstrained, unregulated streamflow along the upper Willamette River, Oregon produced a floodplain of coalescent bars supporting a mosaic of vegetation patches. We sampled 42 bars and adjacent floodplain that formed recently to >64years ago in four >1-km-long reaches to assess differences in vegetation and bar characteristics. Bar disturbance and environmental factors (streamflow, precipitation and regional climate indices) were estimated within six aerial photo intervals between 1936 and 2006. Black cottonwood (Populus balsamifera ssp. trichocarpa) and Salix species rapidly colonized new and disturbed bars, and independent estimates of bar and vegetation age were positively correlated across photo intervals (R 2=0.95). Overstory communities varied with age: Populus-Salix spp. on gravel bars (trees aged 9-16years [interquartile range]), Populus on islands (24-45years), Populus/Acer-Fraxinus on islands coalesced to floodplain (49-72years) and Acer-Populus on adjacent floodplain forested since 1936 (64-102years). Meanwhile, bar height, silt/clay fraction, overstory basal area and community wetland prevalence index (WPI) increased. We identified a common but distinct Pacific willow (Salix lucida ssp. lasiandra) community (30-43years) associated with back channels and island tails. Six understory communities varied by age and by WPI within age strata; in these communities 55-75% of total cover was introduced species, predominantly Phalaris arundinacea and Rubus armeniacus. Vegetation resets occurred in all photo intervals and affected 31% of sampled bars. Mean bar disturbance rate, Q 1.5 frequency, precipitation and the Pacific Decadal Oscillation index followed cyclic trends across photo intervals whereas Q max decreased linearly and relatively fewer, younger bars were disturbed. Results suggest that Populus patch initiation is ongoing but channel stability may be hindering the long-term self-sustainability of plant communities associated with the upper Willamette's historic shifting habitat mosaic. © 2011.
Zabaloy M.C.,CONICET |
Gomez E.,National University of Rosario |
Garland J.L.,CSS-Dynamac |
Garland J.L.,U.S. Environmental Protection Agency |
Applied Soil Ecology | Year: 2012
The large scale use of glyphosate to control weeds in transgenic crops and in no-till management systems emphasizes the need to understand its effects on soil microbial communities. The herbicide may change the soil environment due to toxicity to soil microorganisms and through the influx of carbon (C), phosphorus (P) and nitrogen (N) from the cometabolic decay of glyphosate. This study evaluated both the potential effects of glyphosate treatments on microbial community structure and function in laboratory incubation of soils. Soil from two sites in the Pampa region of Argentina (Vertic Argiudoll from Zavalla, ZAV; Petrocalcic Paleustoll from Coronel Dorrego, DOR), with long exposure to glyphosate were used in soil microcosms amended with different doses of herbicide (0, 15 and 150mgkg -1) and incubated for 7 days. Soil from a natural grassland at the ZAV site was used as a reference soil. Community respiration in response to different C and nutrient (N and P) sources, including glyphosate, were assessed using an O 2 consumption-based assay in microtiter plates. Microbial community structure was analyzed using quantitative PCR (qPCR) to estimate the bacterial abundance and terminal restriction fragment length polymorphism (T-RFLP) to investigate the structure of the bacterial community. Glyphosate addition to the microcosms had minimal effects on both structural and functional measures of the microbial community. The addition of a high dose of glyphosate to soil microcosms from one agricultural site significantly reduced N limitation, suggesting that glyphosate breakdown provided N for microbial activity. However, the immediate respiratory response of the reference and chronically exposed soils to glyphosate was distinctive. Glyphosate increased respiration in the reference grassland soil, potentially due to a stress response of glyphosate sensitive species, while it depressed respiration in the chronically exposed soil, probably as a result of selection for organisms acclimated for rapid assimilation of substrates from the cometabolic decay of the molecule. These results suggest that longer term studies involving repeated addition of glyphosate to previously unexposed soils are needed to understand important shifts in community metabolism caused by the typical agricultural use of this herbicide. © 2011 Elsevier B.V.
Entrekin S.,University of Central Arkansas |
Evans-White M.,University of Arkansas |
Johnson B.,U.S. Environmental Protection Agency |
Frontiers in Ecology and the Environment | Year: 2011
Extraction of natural gas from hard-to-reach reservoirs has expanded around the world and poses multiple environmental threats to surface waters. Improved drilling and extraction technology used to access low permeability natural gas requires millions of liters of water and a suite of chemicals that may be toxic to aquatic biota. There is growing concern among the scientific community and the general public that rapid and extensive natural gas development in the US could lead to degradation of natural resources. Gas wells are often close to surface waters that could be impacted by elevated sediment runoff from pipelines and roads, alteration of streamflow as a result of water extraction, and contamination from introduced chemicals or the resulting wastewater. However, the data required to fully understand these potential threats are currently lacking. Scientists therefore need to study the changes in ecosystem structure and function caused by natural gas extraction and to use such data to inform sound environmental policy. © The Ecological Society of America.
News Article | November 21, 2016
CSS Inc., a leading employer service provider, announced today it has been ranked #4 on HRO Today Magazine’s 2016 Baker’s Dozen Customer Satisfaction List for Background Screening. Out of thousands of background screening companies located throughout the country, CSS has achieved this prestigious ranking. HRO Today is a leading national publication for human resources decision makers and each year acknowledges the nation’s top 13 screening companies. The Baker’s Dozen ratings are determined by customer satisfaction feedback collected from current customers based on breadth of service, deal sizes, and quality of service. “We are extremely honored to be included in the Baker’s Dozen list, and for being acknowledged as a leader in our industry by our amazing customers,” said Mike Chalenski, CEO of CSS Inc. "While winning this award provides fantastic recognition for the hard work and dedication of the team here at CSS, our customers come first, and we work hard to provide them with the ultimate customer experience." “As an industry leader, being recognized by the HRO Today Baker’s Dozen is a benchmark of the quality and impact of our services and capabilities,” added Chalenski. “With our large footprint, we are able to partner with companies from around the world to provide reliable data, valuable insight, fast turn-around times and efficient solutions. As a market leader, we’re constantly looking for ways to enhance our service offerings and stay ahead of the trends.” About CSS Inc. CSS, a leading employer service provider, delivers comprehensive employee screening solutions to companies domestically and internationally. We partner with companies to provide reliable data, valuable insight, fast turn-around times and efficient solutions. Our services include background screenings, laboratory testing, occupational health screenings and workforce monitoring solutions. At every step of the way, we’ll provide you with unmatched customer excellence. CSS offers customized solutions with flexible speed to hire that helps companies achieve their goals. CSS is Ranked #4 on the HRO Today Magazine’s 2016 Baker’s Dozen Customer Satisfaction List and is accredited by NAPBS.