Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
2.
J Thromb Thrombolysis ; 57(1): 107-116, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37839023

RESUMO

Direct oral anticoagulants (DOAC) are the most widely prescribed oral anticoagulants in the United States. Despite advantages over warfarin, system-level improvements are needed to optimize outcomes. While Veterans Health Administration and others have described successful DOAC management dashboard implementation, the extent of use nationally is unknown. A survey of Anticoagulation Forum's members was conducted to assess access to digital tools available within a dashboard and to describe implementation models. An Expert Forum was subsequently convened to identify barriers to dashboard development and adoption. Responses were received from 340 targeted recipients (8.5% of invitees). Only a minority of inpatient (25/52, 48.1%) and outpatient (47/133, 35.3%) respondents outside of Veterans Health Administration were able to generate rosters of DOAC users on-demand, and fewer had the ability to digitally display key clinical data elements, identify drug-related problems, document interventions, or generate reports. The lack of regulatory requirements regarding Anticoagulation Stewardship was identified by the Expert Forum as the major barrier to widespread development of digital tools for improved anticoagulation management. While some health systems have demonstrated the feasibility of DOAC dashboards and described their impact on quality and efficiency, these tools do not appear to be widely available in the United States apart from Veterans Health Administration. The lack of regulatory requirements for Anticoagulation Stewardship may be the primary barrier to the development of digital resources to better manage anticoagulants. Efforts to secure regulatory requirements for Anticoagulation Stewardship are needed, and evidence of improvements in clinical and financial outcomes through DOAC dashboard use will likely bolster such efforts.


Assuntos
Anticoagulantes , Fibrilação Atrial , Humanos , Estados Unidos , Anticoagulantes/uso terapêutico , Varfarina/uso terapêutico , Coagulação Sanguínea , Administração Oral , Fibrilação Atrial/tratamento farmacológico
3.
JMIR Hum Factors ; 10: e49025, 2023 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-37874636

RESUMO

BACKGROUND: Direct oral anticoagulant (DOAC) medications are frequently associated with inappropriate prescribing and adverse events. To improve the safe use of DOACs, health systems are implementing population health tools within their electronic health record (EHR). While EHR informatics tools can help increase awareness of inappropriate prescribing of medications, a lack of empowerment (or insufficient empowerment) of nonphysicians to implement change is a key barrier. OBJECTIVE: This study examined how the individual authority of clinical pharmacists and anticoagulation nurses is impacted by and changes the implementation success of an EHR DOAC Dashboard for safe DOAC medication prescribing. METHODS: We conducted semistructured interviews with pharmacists and nurses following the implementation of the EHR DOAC Dashboard at 3 clinical sites. Interview transcripts were coded according to the key determinants of implementation success. The intersections between individual clinician authority and other determinants were examined to identify themes. RESULTS: A high level of individual clinician authority was associated with high levels of key facilitators for effective use of the DOAC Dashboard (communication, staffing and work schedule, job satisfaction, and EHR integration). Conversely, a lack of individual authority was often associated with key barriers to effective DOAC Dashboard use. Positive individual authority was sometimes present with a negative example of another determinant, but no evidence was found of individual authority co-occurring with a positive instance of another determinant. CONCLUSIONS: Increased individual clinician authority is a necessary antecedent to the effective implementation of an EHR DOAC Population Management Dashboard and positively affects other aspects of implementation. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1186/s13012-020-01044-5.


Assuntos
Comunicação , Registros Eletrônicos de Saúde , Humanos , Processos Grupais , Informática , Pesquisa Qualitativa
5.
Circ Cardiovasc Qual Outcomes ; 16(2): e009256, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36484253

RESUMO

BACKGROUND: Direct oral anticoagulants are first-line therapy for common thrombotic conditions, including atrial fibrillation and venous thromboembolism. Despite their strong efficacy and safety profile, evidence-based prescribing can be challenging given differences in dosing based on indication, renal function, and drug-drug interactions. The Veterans Health Affairs developed and implemented a population management dashboard to support pharmacist review of anticoagulant prescribing. The dashboard includes information about direct oral anticoagulants and dose prescribed, renal function, age, and weight, potential interacting medications, and the need for direct oral anticoagulant medication refills. It is a stand-alone system. METHODS: Using login data from the dashboard, nationwide implementation was evaluated using elements from the Reach, Effectiveness, Adoption, Implementation, and Maintenance framework. RESULTS: Between August 2016 and June 2020, 150/164 sites within the Veterans Health Affairs system used the dashboard, averaging 1875 patients per site. The dashboard was made available to sites on a staggered basis. Moderate or high adoption, defined as at least one login on at least 2 separate days per month, began slowly with 3/5 sites in the pilot phase but rapidly grew to 142/150 (94.7%) sites by June 2020. The average number of unique users per site increased from 2.4 to 7.5 over the study period. Moderate to high adoption of the dashboard's use was maintained for > 6 months in 126/150 (84.0%) sites by the end of the study period. CONCLUSIONS: There was rapid and sustained implementation and adoption of a population health dashboard for evidence-based anticoagulant prescribing across the national United States Veterans Health Administration health system. The impact of this tool on clinical outcomes and strategies to replicate this care model in other health systems will be important for broad dissemination and uptake.


Assuntos
Fibrilação Atrial , Tromboembolia Venosa , Veteranos , Humanos , Estados Unidos , Anticoagulantes , Fibrilação Atrial/tratamento farmacológico , Tromboembolia Venosa/tratamento farmacológico , Administração Oral , United States Department of Veterans Affairs
6.
J Am Heart Assoc ; 10(24): e022758, 2021 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-34796718

RESUMO

Over the past decade, direct oral anticoagulants (DOACs) have contributed to a major paradigm shift in thrombosis management, replacing vitamin K antagonists as the most commonly prescribed anticoagulants in many countries. While DOACs provide distinct advantages over warfarin (eg, convenience, simplicity, and safety), they are frequently associated with inappropriate prescribing and adverse events. These events have prompted regulatory agencies to mandate oversight, which individual institutions may find difficult to comply with given limited resources. Veterans Health Administration (VHA) has leveraged technology to develop the DOAC Population Management Tool (PMT) to address these challenges. This tool has empowered VHA to update a 60-year standard of care from one-to-one provider-to-patient anticoagulation monitoring to a population-based management approach. The DOAC PMT allows for the oversight of all patients prescribed DOACs and leads to intervention only when clinically indicated. Using the DOAC PMT, facilities across VHA have maximized DOAC oversight while minimizing resource usage. Herein, we discuss how the DOAC PMT was conceived, developed, and implemented, along with the challenges encountered throughout the process. Additionally, we share the impact of the DOAC PMT across VHA, and the potential of this approach beyond anticoagulation and VHA.


Assuntos
Anticoagulantes , Saúde da População , Administração Oral , Anticoagulantes/administração & dosagem , Humanos , Serviços de Saúde para Veteranos Militares
7.
J Environ Qual ; 50(1): 185-197, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33111360

RESUMO

Urea-nitrogen (N) is commonly applied to crop fields, yet it is not routinely monitored despite its association with reduced water quality and its ability to increase toxicity of certain phytoplankton species. The purpose of this work was to characterize temporal fluctuations in urea-N concentrations and associated environmental conditions to infer sources of urea-N in agricultural drainage ditches. Physicochemical properties and N forms in ditch waters were measured weekly during the growing seasons of 2015-2018. Fertilizer application was only associated with spring peaks of urea-N concentrations in ditches next to cornfields, whereas summer peaks in ditches adjacent to corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] fields were not associated with fertilizer applications. Environmental conditions of warmer temperatures, lower dissolved oxygen concentrations, and lower redox potentials were correlated with higher urea-N concentrations. In 2018, peaks of urea-N and ammonium-N during the summer co-occurred with peaks of dissolved organic N and total dissolved N, suggesting they might be associated with the breakdown of organic matter and with the turnover of the organic N pool. Although the highest urea-N concentrations occurred when ditch surface waters were hydrologically disconnected from nearby streams, heavy rainfalls can potentially flush accumulated urea-N into coastal waters, where it may affect algal bloom toxicity. Therefore, implementation of available drainage ditch management practices is recommended, but these strategies need to be optimized for targeting periods with high rainfall that coincide with fertilizer additions as well as for periods with low rainfall that promote stagnant water conditions.


Assuntos
Agricultura , Nitrogênio , Fertilizantes , Estações do Ano , Ureia
8.
Heliyon ; 6(4): e03711, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32322713

RESUMO

Agricultural drainage ditches represent a major source of nutrient pollution. Shifts in nitrogen source and use of animal manures have changed the bacterial composition both in species of bacteria and their abundance in agricultural ditches. This change affects how nitrogen is being cycled and potentially the final forms of available nutrients. In particular, animal manures often have bacteria such as Escherichia coli present, increasing the abundance of a bacterial species in ditches. Research has shown that the effect of different nitrogen sources is to change bacterial community composition (class, family). How this influences the role of an individual bacterial species is poorly understood. Thus, our question was how individual species would respond to different sources of nitrogen. We used Aeromonas hydrophila, Bacillus thuringiensis, Escherichia coli and Pseudomonas aeruginosa that are common in agricultural ditches and exposed them to different concentrations of nitrogen in cultures of 1 × 100 and 1 × 10-1 dilutions from a stock solution of bacteria. Nitrogen sources were ammonium chloride, sodium nitrate and urea. The results showed A. hydrophila and E. coli have strong similarities particularly with nitrate-N and urea-N utilization and the response was often correlated with the amount of nutrient added. P. aeruginosa while similar did not show any strong correlation with amount of nutrient added. B. thuringiensis was different from the other three bacteria in utilization or production. Research has provided insight into the role of some bacteria in nitrogen cycling and may be valuable in the future to developing management strategies to reduce nutrients.

9.
J Environ Qual ; 46(2): 302-310, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28380555

RESUMO

Urea-N is linked to harmful algal blooms in lakes and estuaries, and urea-N-based fertilizers have been implicated as a source. However, the export of urea-N-based fertilizers appears unlikely, as high concentrations of urea-N are most commonly found in surface waters outside periods of fertilization. To evaluate possible autochthonous production of urea-N, we monitored urea-N released from drainage ditch sediments using mesocosms. Sediments from a cleaned (recently dredged) drainage ditch, uncleaned ditch, forested ditch, riparian wetland, and an autoclaved sand control were isolated in mesocosms and flooded for 72 h to quantify urea-N, NH-N, and NO-N in the floodwater. Sediments were flooded with different N-amended solutions (distilled HO, 1.5 mg L NH-N, 3.0 mg L NH-N, 2.6 mg L NO-N, or 5.1 mg L NO-N) and incubated at three water temperatures (16, 21, and 27°C). Urea-N concentrations in mesocosms representing uncleaned and cleaned drainage ditches were significantly greater than nonagricultural sediments and controls. While flooding sediments with N-enriched solution had no clear effect on urea-N, warmer (27°C) temperatures resulted in significantly higher urea-N. Data collected from field ditches that were flooded by a summer rainstorm showed increases in urea-N that mirrored the mesocosm experiment. We postulate that concentrations of urea-N in ditches that greatly exceed environmental thresholds are mediated by biological production in sediments and release to stagnant surface water. Storm-driven urea-N export from ditches could elevate the risk of harmful algal blooms downstream in receiving waters despite the dilution effect.


Assuntos
Agricultura , Ureia/análise , Poluentes Químicos da Água/análise , Áreas Alagadas , Meio Ambiente , Inundações , Sedimentos Geológicos
10.
Ann Pharmacother ; 51(5): 373-379, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28367699

RESUMO

BACKGROUND: Improved anticoagulation control with warfarin reduces adverse events and represents a target for quality improvement. No previous study has described an effort to improve anticoagulation control across a health system. OBJECTIVE: To describe the results of an effort to improve anticoagulation control in the New England region of the Veterans Health Administration (VA). METHODS: Our intervention encompassed 8 VA sites managing warfarin for more than 5000 patients in New England (Veterans Integrated Service Network 1 [VISN 1]). We provided sites with a system to measure processes of care, along with targeted audit and feedback. We focused on processes of care associated with site-level anticoagulation control, including prompt follow-up after out-of-range international normalized ratio (INR) values, minimizing loss to follow-up, and use of guideline-concordant INR target ranges. We used a difference-in-differences (DID) model to examine changes in anticoagulation control, measured as percentage time in therapeutic range (TTR), as well as process measures and compared VISN 1 sites with 116 VA sites located outside VISN 1. RESULTS: VISN 1 sites improved on TTR, our main indicator of quality, from 66.4% to 69.2%, whereas sites outside VISN 1 improved from 65.9% to 66.4% (DID 2.3%, P < 0.001). Improvement in TTR correlated strongly with the extent of improvement on process-of-care measures, which varied widely across VISN 1 sites. CONCLUSIONS: A regional quality improvement initiative, using performance measurement with audit and feedback, improved TTR by 2.3% more than control sites, which is a clinically important difference. Improving relevant processes of care can improve outcomes for patients receiving warfarin.


Assuntos
Anticoagulantes/uso terapêutico , Coagulação Sanguínea/efeitos dos fármacos , Atenção à Saúde/normas , Coeficiente Internacional Normatizado , Melhoria de Qualidade , Varfarina/uso terapêutico , Anticoagulantes/administração & dosagem , Anticoagulantes/efeitos adversos , Atenção à Saúde/tendências , Humanos , New England , Estados Unidos , United States Department of Veterans Affairs , Varfarina/administração & dosagem , Varfarina/efeitos adversos
11.
J Environ Qual ; 45(3): 1062-70, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27136175

RESUMO

Studies of harmful algal blooms and associated urea concentrations in the Chesapeake Bay and in coastal areas around the globe strongly suggest that elevated urea concentrations are associated with harmful algal blooms. The observed increased frequency and toxicity of these blooms in recent decades has been correlated with increased agricultural use of N inputs and increased use of urea as a preferred form of commercial N. This rainfall simulation study sought to assess the potential for different N fertilizers and manures to contribute to urea in runoff from a Coastal Plain soil on the Eastern Shore of Maryland. Under worst-case conditions, ~1% of urea-N applied as commercial fertilizer and surface-applied poultry litter was lost in runoff in a simulated rainfall event, roughly equivalent to a 1-yr return period rain storm in the study area, 12 h after application. Cumulative urea-N losses, including four subsequent weekly rainfall events, approached 1.7% from urea-N fertilizer containing a urease inhibitor. Urea-N loss from incorporated poultry litter was negligible, and losses from dairy manure were intermediate. These losses are likely confined to hydrological contributing areas that extend several meters from a drainage ditch or stream for storms with frequent recurrence intervals. Cumulative dissolved N losses in runoff (urea-N + ammonium-N + nitrate-N) as a proportion of total applied plant-available N were <5%, suggesting that most of the applied N was lost by other pathways or was immobilized in soil. Results also highlight the potential for simple management options, such as shallow incorporation or timing, to greatly reduce urea runoff losses.


Assuntos
Fertilizantes , Nitrogênio , Ureia , Animais , Esterco , Fósforo , Chuva , Movimentos da Água
12.
Circ Cardiovasc Qual Outcomes ; 9(1): 64-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26715651

RESUMO

Because of the recent publication of several important studies, there has been a major change in how we think about perioperative management of anticoagulation. Because of these changes, existing consensus guidelines are suddenly out of date and can no longer be used as is, particularly the 2012 American College of Chest Physicians Antithrombotic Guidelines, version 9. We estimate that well over 90% of patients receiving warfarin therapy should not receive bridging anticoagulation during periprocedural interruptions of therapy, except under unusual circumstances and with appropriate justification. Accumulating evidence also suggests that bridging is not indicated among patients receiving direct-acting oral anticoagulant therapy. The large number of patients potentially affected represents an important safety concern and requires an immediate change in practice.


Assuntos
Anticoagulantes/administração & dosagem , Assistência Perioperatória , Anticoagulantes/efeitos adversos , Hemorragia/etiologia , Heparina de Baixo Peso Molecular/administração & dosagem , Heparina de Baixo Peso Molecular/efeitos adversos , Humanos , Tromboembolia/prevenção & controle , Varfarina/administração & dosagem
13.
J Environ Qual ; 44(2): 524-34, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26023971

RESUMO

Leaching of phosphorus (P) mobilizes edaphic and applied sources of P and is a primary pathway of concern in agricultural soils of the Delmarva Peninsula, which defines the eastern boundary of the eutrophic Chesapeake Bay. We evaluated P leaching before and after poultry litter application from intact soil columns (30 cm diameter × 50 cm depth) obtained from low- and high-P members of four dominant Delmarva Peninsula soils. Surface soil textures ranged from fine sand to silt loam, and Mehlich-3 soil P ranged from 64 to 628 mg kg. Irrigation of soil columns before litter application pointed to surface soil P controls on dissolved P in leachate (with soil P sorption saturation providing a stronger relationship than Mehlich-3 P); however, strong relationships between P in the subsoil (45-50 cm) and leachate P concentrations were also observed ( = 0.61-0.73). After poultry litter application (4.5 Mg ha), leachate P concentrations and loads increased significantly for the finest-textured soils, consistent with observations that well-structured soils have the greatest propensity to transmit applied P. Phosphorus derived from poultry litter appeared to contribute 41 and 76% of total P loss in leachate from the two soils with the finest textures. Results point to soil P, including P sorption saturation, as a sound metric of P loss potential in leachate when manure is not an acute source of P but highlight the need to factor in macropore transport potential to predict leaching losses from applied P sources.

14.
J Environ Qual ; 44(2): 560-71, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26023975

RESUMO

Leaching of nutrients through agricultural soils is a priority water quality concern on the Atlantic Coastal Plain. This study evaluated the effect of tillage and urea application on leaching of phosphorus (P) and nitrogen (N) from soils of the Delmarva Peninsula that had previously been under no-till management. Intact soil columns (30 cm wide × 50 cm deep) were irrigated for 6 wk to establish a baseline of leaching response. After 2 wk of drying, a subset of soil columns was subjected to simulated tillage (0-20 cm) in an attempt to curtail leaching of surface nutrients, especially P. Urea (145 kg N ha) was then broadcast on all soils (tilled and untilled), and the columns were irrigated for another 8 wk. Comparison of leachate recoveries representing rapid and slow flows confirmed the potential to manipulate flow fractions with tillage, albeit with mixed results across soils. Leachate trends in the finer-textured soil suggest that tillage impeded macropore flow and forced greater matrix flow. Despite significant vertical stratification of soil P that suggested tillage could prevent leaching of P via macropores from the surface to the subsoil, tillage had no significant impact on P leaching losses. Relatively high levels of soil P below 20 cm may have served as the source of P enrichment in leachate waters. However, tillage did lower losses of applied urea in leachate from two of the three soils, partially confirming the study's premise that tillage would destroy macropore pathways transmitting surface constituents to the subsoil.

15.
J Vis Exp ; (86)2014 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-24748061

RESUMO

Rainfall is a driving force for the transport of environmental contaminants from agricultural soils to surficial water bodies via surface runoff. The objective of this study was to characterize the effects of antecedent soil moisture content on the fate and transport of surface applied commercial urea, a common form of nitrogen (N) fertilizer, following a rainfall event that occurs within 24 hr after fertilizer application. Although urea is assumed to be readily hydrolyzed to ammonium and therefore not often available for transport, recent studies suggest that urea can be transported from agricultural soils to coastal waters where it is implicated in harmful algal blooms. A rainfall simulator was used to apply a consistent rate of uniform rainfall across packed soil boxes that had been prewetted to different soil moisture contents. By controlling rainfall and soil physical characteristics, the effects of antecedent soil moisture on urea loss were isolated. Wetter soils exhibited shorter time from rainfall initiation to runoff initiation, greater total volume of runoff, higher urea concentrations in runoff, and greater mass loadings of urea in runoff. These results also demonstrate the importance of controlling for antecedent soil moisture content in studies designed to isolate other variables, such as soil physical or chemical characteristics, slope, soil cover, management, or rainfall characteristics. Because rainfall simulators are designed to deliver raindrops of similar size and velocity as natural rainfall, studies conducted under a standardized protocol can yield valuable data that, in turn, can be used to develop models for predicting the fate and transport of pollutants in runoff.


Assuntos
Agroquímicos/química , Modelos Teóricos , Chuva , Solo/química , Ureia/química , Movimentos da Água , Poluentes Químicos da Água/química , Monitoramento Ambiental/métodos
16.
J Environ Qual ; 41(3): 664-71, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22565248

RESUMO

High levels of accumulated phosphorus (P) in soils of the Delmarva Peninsula are a major source of dissolved P entering drainage ditches that empty into the Chesapeake Bay. The objective of this study was to design, construct, and monitor a within-ditch filter to remove dissolved P, thereby protecting receiving waters against P losses from upstream areas. In April 2007, 110 Mg of flue gas desulfurization (FGD) gypsum, a low-cost coal combustion product, was used as the reactive ingredient in a ditch filter. The ditch filter was monitored from 2007 to 2010, during which time 29 storm-induced flow events were characterized. For storm-induced flow, the event mean concentration efficiency for total dissolved P (TDP) removal for water passing through the gypsum bed was 73 ± 27% confidence interval (α = 0.05). The removal efficiency for storm-induced flow by the summation of load method was 65 ± 27% confidence interval (α = 0.05). Although chemically effective, the maximum observed hydraulic conductivity of FGD gypsum was 4 L s(-1), but it decreased over time to <1 L s(-1). When bypass flow and base flow were taken into consideration, the ditch filter removed approximately 22% of the TDP load over the 3.6-yr monitoring period. Due to maintenance and clean-out requirements, we conclude that ditch filtration using FGD gypsum is not practical at a farm scale. However, we propose an alternate design consisting of FGD gypsum-filled trenches parallel to the ditch to intercept and treat groundwater before it enters the ditch.


Assuntos
Sulfato de Cálcio/química , Filtração/instrumentação , Fósforo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Agricultura , Substâncias Perigosas/análise , Metais Pesados/química
17.
J Environ Qual ; 40(2): 412-20, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21520748

RESUMO

The application of poultry litter to soils is a water quality concern on the Delmarva Peninsula, as runoff contributes P to the eutrophic Chesapeake Bay. This study compared a new subsurface applicator for poultry litter with conventional surface application and tillage incorporation of litter on a Coastal Plain soil under no-till management. Monolith lysimeters (61 cm by 61 cm by 61 cm) were collected immediately after litter application and subjected to rainfall simulation (61 mm h(-1) 1 h) 15 and 42 d later. In the first rainfall event, subsurface application of litter significantly lowered total P losses in runoff (1.90 kg ha(-1)) compared with surface application (4.78 kg ha(-1)). Losses of P with subsurface application were not significantly different from disked litter or an unamended control. By the second event, total P losses did not differ significantly between surface and subsurface litter treatments but were at least twofold greater than losses from the disked and control treatments. A rising water table in the second event likely mobilized dissolved forms of P in subsurface-applied litter to the soil surface, enriching runoff water with P. Across both events, subsurface application of litter did not significantly decrease cumulative losses of P relative to surface-applied litter, whereas disking the litter into the soil did. Results confirm the short-term reduction of runoff P losses with subsurface litter application observed elsewhere but highlight the modifying effect of soil hydrology on this technology's ability to minimize P loss in runoff.


Assuntos
Agricultura/métodos , Esterco , Fósforo/metabolismo , Movimentos da Água , Poluentes da Água/metabolismo , Animais , Fertilizantes , Maryland , Aves Domésticas , Chuva , Abastecimento de Água
18.
J Environ Qual ; 39(6): 2080-8, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21284306

RESUMO

Little is known about the fate of arsenic (As) in land-applied litter from chickens that have been fed roxarsone, an organic feed additive containing As. This study seeks to elucidate the transfer of As in runoff from ditch-drained soils of the poultry-producing region of the Delmarva Peninsula by tracking As and phosphorus (P) export from seven drainage ditches over two water-years (1 July 2005 to 30 June 2007). Annual losses of As from ditches ranged from 0.004 to 0.071 kg ha(-1) while P losses ranged from 0.33 to 18.56 kg ha(-1), with the largest loads associated with a litter storage shed that served as a point source. Event-based As and P losses in ditch flow fluctuated by a factor of 162 and 1882, respectively. The two elements were correlated in flow from the ditch draining a litter storage shed (r = 0.99), and in sediment extracts in soils near the litter shed (r = 0.73), pointing to similar behavior under point source conditions. Indeed, As and P exhibited similar behavior within storms for all ditches, characterized by relatively high initial concentrations subject to rapid concentration declines before peak flow, consistent with dilution of a finite source. However, As and P concentrations varied significantly between ditches and showed considerable temporal variability within ditches, with no clear seasonal trends or associations with current management strategies. The results suggest that similar management strategies might be effective for As and P point sources, but that field management practices geared toward controlling nonpoint source P losses may not readily transfer to the control of As losses.


Assuntos
Agricultura , Arsênio/química , Abrigo para Animais , Fósforo/química , Solo/química , Poluentes Químicos da Água/química , Animais , Galinhas , Monitoramento Ambiental , Pisos e Cobertura de Pisos , Poluentes do Solo , Fatores de Tempo , Movimentos da Água
19.
J Environ Qual ; 38(6): 2449-57, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19875801

RESUMO

Drainage ditches are a key conduit of nitrogen (N) from agricultural fields to surface water. The effect of ditch dredging, a common practice to improve drainage, on the fate of N in ditch effluent is not well understood. This study evaluated the effect of dredging on N transport in drainage ditches of the Delmarva Peninsula. Sediments from two ditches draining a single field were collected (0-5 cm) to represent conditions before and after dredging. Sediments were packed in 10-m-long recirculating flumes and subjected to a three-phase experiment to assess the sediment's role as a sink or source of ammonium (NH4) and nitrate (NO3). Under conditions of low initial NH4-N and NO3-N concentrations in flume water, sediment from the undredged ditch released 113 times more NO3-N to water than did sediment from the dredged ditch. When flume water was spiked with NH4-N and NO3-N to simulate increases in N concentrations from drainage and runoff from adjacent fields, NO3-N in flume water increased during 48 h compared with the initial spiked concentration, while NH4-N decreased. These simultaneous changes were attributed to nitrification, with 23% more NO3-N observed in flume water with undredged ditch sediment compared with dredged ditch sediment. Replacing the N-spiked water with deionized water resulted in two times more NO3-N released from the undredged ditch sediment than the dredged ditch sediment. These results suggest that ditch sediments could represent significant stores of N and that dredging could greatly affect the ditch sediment's ability to temporarily assimilate N input from field drainage.


Assuntos
Drenagem Sanitária , Sedimentos Geológicos/análise , Nitrogênio/análise , Maryland
20.
J Environ Qual ; 38(5): 1981-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19704141

RESUMO

Studies have demonstrated some P loss reduction following implementation of remedial strategies at field scales. However, there has been little coordinated evaluation of best management practices (BMPs) on a watershed scale to show where, when, and which work most effectively. Thus, it is still difficult to answer with a degree of certainty, critical questions such as, how long before we see a response and where would we expect to observe the greatest or least response? In cases where field and watershed scales are monitored, it is not uncommon for trends in P loss to be disconnected. We review case studies demonstrating that potential causes of the disconnect varies, from competing sources of P at watershed scales that are not reflected in field monitoring to an abundance of sinks at watershed scales that buffer field sources. To be successful, P-based mitigation strategies need to occur iteratively, involve stakeholder driven programs, and address the inherent complexity of all P sources within watersheds.


Assuntos
Fósforo/análise , Poluentes da Água/análise , Poluição da Água/prevenção & controle , Abastecimento de Água , Agricultura , Conservação dos Recursos Naturais , Recuperação e Remediação Ambiental , Fósforo/química , Poluentes da Água/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...