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1.
Sci Adv ; 5(1): eaau7126, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30662947

RESUMO

During the European Middle Ages, the opening of long-distance Asian trade routes introduced exotic goods, including ultramarine, a brilliant blue pigment produced from lapis lazuli stone mined only in Afghanistan. Rare and as expensive as gold, this pigment transformed the European color palette, but little is known about its early trade or use. Here, we report the discovery of lapis lazuli pigment preserved in the dental calculus of a religious woman in Germany radiocarbon-dated to the 11th or early 12th century. The early use of this pigment by a religious woman challenges widespread assumptions about its limited availability in medieval Europe and the gendered production of illuminated texts.


Assuntos
Silicatos de Alumínio/história , Cálculos Dentários/história , Literatura Medieval/história , Freiras/história , Datação Radiométrica , Restos Mortais , Cor , Feminino , Alemanha , História Medieval , Humanos , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Pinturas , Espectrometria por Raios X , Análise Espectral Raman
2.
HNO ; 66(4): 280-289, 2018 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-29222682

RESUMO

The human nose takes primary responsibility for preconditioning inhaled air. Numerous pathologies can affect the physiology of the nose. The beginnings of flow analyzes were carried out with three-dimensional casting models and differently colored liquids. Temperature and humidity could not be taken into account. Today, much more complex analyzes are possible using computational fluid dynamics (CFD), which are based on three-dimensional models generated from computed tomography (CT) or magnetic resonance imaging (MRI) datasets. Here, flow velocities, temperature, humidity, and pressure differences can be simulated and displayed in high-resolution videos as a function of multiple boundary conditions. The analysis of pathological changes or surgical interventions is thereby possible.


Assuntos
Hidrodinâmica , Nariz , Simulação por Computador , Humanos , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Modelos Anatômicos , Nariz/diagnóstico por imagem , Nariz/fisiologia , Tomografia Computadorizada por Raios X
3.
Chemosphere ; 160: 149-54, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27372264

RESUMO

Within the agriculturally-intensive Mississippi River Basin of the United States, significant conservation efforts have focused on management practices that reduce nutrient runoff into receiving aquatic ecosystems. Only a small fraction of those efforts have focused on phytoremediation techniques. Each of six different aquatic macrophytes were planted, in monoculture, in three replicate mesocosms (1.2 m × 0.15 m × 0.65 m). Three additional unvegetated mesocosms served as controls for a total number of 21 mesocosms. Over two years, mesocosms were amended once each summer with sodium nitrate, ammonium sulfate, and potassium phosphate dibasic to represent nitrogen and phosphorus in agricultural runoff. System retention was calculated using a simple aqueous mass balance approach. Ammonium retention in both years differed greatly, as Panicum hemitomon and Echinodorus cordifolius retentions were significantly greater than controls in the first year, while only Myriophyllum aquaticum and Typha latifolia were significantly greater than controls in the second year. Greater soluble reactive phosphorus retention was observed in T. latifolia compared to controls in both years. Several other significant differences were observed in either the first or second year, but not both years. In the first year's exposure, P. hemitomon was significantly more efficient than the control, Saururus cernuus, and T. latifolia for overall percent nitrate decrease. Results of this novel study highlight inherent variability within and among species for nutrient specific uptake and the temporal variations of species for nutrient retention. By examining this natural variability, scientists may design phytoremediation systems with greater impact on improving agricultural runoff water quality.


Assuntos
Compostos de Amônio/química , Nitratos/química , Fósforo/química , Plantas/metabolismo , Agricultura , Alismataceae/metabolismo , Biodegradação Ambiental , Ecossistema , Poluentes Ambientais , Mississippi , Nitrogênio/química , Panicum/metabolismo , Rios , Typhaceae/metabolismo , Microbiologia da Água , Qualidade da Água
4.
Bull Environ Contam Toxicol ; 97(2): 244-8, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27225509

RESUMO

Standard procedures do not exist for drying and storage of plant samples prior to chemical analyses. Since immediate analysis is not always possible, current research examined which plant drying and storage method yielded the highest cyfluthrin recovery rates compared to traditional mechanical freeze-drying methods. Fifteen mesocosms were planted with rice. Cyfluthrin (5 mg L(-1)) was amended into the water column of individual mesocosms. 48 h later, plant material in the water column was collected from each mesocosm. Control (mechanical freeze drying) recovery was significantly greater (p < 0.001) than all 14 combinations of drying and storage. Significant differences also existed between all 14 different combinations. Greatest cyfluthrin recoveries in non-control plants were from the freezer-greenhouse-freezer drying and storage method. Results offer evidence for the efficient plant drying and storage methods prior to cyfluthrin analysis. Future studies should perform comparable analyses on various pesticide classes to determine possible relationships.


Assuntos
Inseticidas/análise , Nitrilas/análise , Plantas/química , Piretrinas/análise , Dessecação , Monitoramento Ambiental , Liofilização , Inseticidas/química , Nitrilas/química , Piretrinas/química
5.
Laryngorhinootologie ; 93(11): 746-50, 2014 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-25369158

RESUMO

INTRODUCTION: The nose is responsible for humidification, heating and cleaning of the inhaled air. The sneeze reflex leads to a shock-like cleaning of the nose in strong particle exposure. The aim of this study was the simulation of intranasal air flow of sneezing in a realistic computer model. MATERIALS AND METHODS: Based on the CT scan of a 40 year old man a three-dimensional computer model of the nasal cavity and the ethmoid sinuses was created. Flow simulations were performed for different inspiratory and expiratory velocities (± 2 m/s to ± 45 m/s) in order to simulate sneezing. RESULTS were visualized and analyzed by video simulation. RESULTS: During inspiration the main airflow takes place along the middle turbinate. During expiration, the flow is located more cranially. This effect is caused by the shape of the nasopharynx and the posterior portions of the nasal turbinates. During very high speeds (sneezing) also adjacent ethmoid sinuses and the olfactory region are covered by the shock-like expiratory flow. A large vortex formation in the nasopharynx is responsible for a uniform distribution of the airflow also on lower nasal areas. CONCLUSION: Sneezing is a protective reflex that provides for cleaning of the nose. From a flow rate of 10 m/s, the cranial nasal areas as well as adjacent ethmoid sinuses are covered by the -airflow. Compared to the inspiratory airflow the exhalation is not just vice versa. Particles that deposed in the cranial nasal areas during quiet breathing are removed.


Assuntos
Simulação por Computador , Seio Etmoidal/fisiologia , Imageamento Tridimensional , Cavidade Nasal/fisiologia , Ventilação Pulmonar/fisiologia , Espirro/fisiologia , Tomografia Computadorizada por Raios X , Gravação em Vídeo , Adulto , Expiração/fisiologia , Humanos , Inalação/fisiologia , Masculino , Mucosa Nasal/fisiologia , Nasofaringe/fisiologia , Conchas Nasais/fisiologia
6.
Bull Environ Contam Toxicol ; 93(5): 574-9, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25145638

RESUMO

Vegetated buffers of different designs are often used as edge-of-field treatment practices to remove pesticides that may be entrained in agricultural runoff. However, buffer system efficacy in pesticide runoff mitigation varies widely due to a multitude of factors including, but not limited to, pesticide chemistry, vegetation composition, and hydrology. Two experimental systems, a control (no vegetation) and a grass-wetland buffer system, were evaluated for their ability to retain diazinon and permethrin associated with a simulated storm runoff. The two systems were equally inefficient at retaining diazinon (mean 9.6 % retention for control and buffer). Grass-wetland buffers retained 83 % and 85 % of cis- and trans-permethrin masses, respectively, while the control only retained 39 % and 44 % of cis- and trans-permethrin masses, respectively. Half-distances (the distance required to decrease pesticide concentration by one-half) for both permethrin isomers were 26 %-30 % shorter in grass buffers (22-23 m) than in the control (32 m). The current study demonstrates treatment efficacy was a function of pesticide properties with the more strongly sorbing permethrin retained to a greater degree. The study also demonstrates challenges in remediating multiple pesticides with a single management practice. By using suites of management practices, especially those employing vegetation, better mitigation of pesticide impacts may be accomplished.


Assuntos
Diazinon/isolamento & purificação , Diazinon/metabolismo , Permetrina/isolamento & purificação , Permetrina/metabolismo , Poaceae/metabolismo , Áreas Alagadas , Agricultura , Biodegradação Ambiental , Meia-Vida , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/metabolismo
7.
Bull Environ Contam Toxicol ; 92(5): 503-8, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24526283

RESUMO

The smallmouth buffalo Ictiobus bubalus is a native benthivore to floodplain lakes in the Yazoo River Basin, USA. Based on evidence from other benthivorous fish studies we hypothesized high biomasses of I. bubalus contribute to poor water quality conditions. We tested this hypothesis in shallow (<1.5 m) 0.05 ha earthen ponds at three stocking biomasses over a 10-week period during the summer of 2012. The most notable results from the permutational multivariate analysis of variance suggest I. bubalus at high and moderate biomasses significantly (p < 0.05) enhanced turbidity and suspended solid levels while decreasing Secchi depth. Our results suggest that effects of I. bubalus on water clarity may have considerable ecological implications in natural habitats such as shallow floodplain lakes.


Assuntos
Cipriniformes/fisiologia , Poluentes Químicos da Água/análise , Animais , Biomassa , Cipriniformes/crescimento & desenvolvimento , Eutrofização , Nitrogênio/análise , Oxigênio/análise , Fósforo/análise , Crescimento Demográfico , Qualidade da Água
8.
J Environ Qual ; 42(5): 1480-5, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24216425

RESUMO

Low-grade weirs are controlled surface drainage management structures that are being advocated for improving water quality of downstream ecosystems within agricultural landscapes. Low-grade weirs are small controlled drainage structures that are placed in series in an agricultural drainage ditch to create biogeochemical conditions for enhanced nutrient retention but also to slow runoff velocities and encourage sedimentation. This study evaluated eight low-grade weirs for sediment and P accumulation in agricultural drainage ditches 1 yr after installation. On average, sediment (weir: 54 ± 25cm; reference: 13 ± 7 cm; ≤ 0.001) and water (weir: 9 ± 7cm; reference: 1.16 ± 2 cm; ≤ 0.05) depth was greater upstream of weirs when compared within ditch references sites. There were no significant differences in total P concentrations of sediments or between any P fractions between 1-yr-old weirs and their respective references. Bioavailability ratios of P (i.e., the ratio of potentially bioavailable to nonbioavailable P fractions) were also found to be similar between weir and reference sites. Based on these results, weirs increase the hydrological capacity of drainage ditches and significantly retain more sediment and P within the drainage ditch within 1 yr of construction. Future research will examine temporal changes in weir sediments and associated P concentrations to aid our understanding of how maintenance of weirs should occur to maximize physical and chemical characteristics for greatest sediment and P retention.


Assuntos
Fósforo , Poluentes Químicos da Água , Agricultura , Drenagem , Meio Ambiente , Sedimentos Geológicos/química , Fósforo/química , Movimentos da Água
9.
Environ Sci Process Impacts ; 15(9): 1685-91, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23842895

RESUMO

Reduction-oxidation or redox potential is typically collected by measuring redox at a single time interval and returning to the electrode to collect subsequent intervals to generate a temporal gradient of changes in redox. Typically, intervals between sampling are on the scale of hours, days, and weeks, rather than one, five, or 20 minutes due to logistical constraints of collection. These constraints are labor (i.e., constant measurements 24/7) and technology driven (i.e., construction of a unit that is capable of accurately and precisely measuring redox at fine temporal scales). This study describes a continuous, short interval redox data logger that is capable of measuring ±10 mV at minute time intervals. To ensure quality assured and quality controlled data, the redox unit was subjected to tiered verification procedures that documented hardware and probe sensitivity to changes in voltage. Furthermore, the setup was laboratory tested against known mV redox solutions (Zobel, 225 mV), flooded in soil medium over 48 h, and subjected to drying over 48 h. Results highlight and verify the accuracy and precision of the redox probes and hardware for measuring stability and changes in redox. Future research will investigate field operations of redox probes and create spatially and temporally detailed investigations to changes in redox as a result of vegetation, flooding, and management.


Assuntos
Técnicas Eletroquímicas/instrumentação , Solo/química , Monitoramento Ambiental/instrumentação , Desenho de Equipamento , Oxirredução
10.
Sci Total Environ ; 442: 263-74, 2013 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-23178830

RESUMO

This review provides a critical overview of conservation practices that are aimed at improving water quality by retaining phosphorus (P) downstream of runoff genesis. The review is structured around specific downstream practices that are prevalent in various parts of the United States. Specific practices that we discuss include the use of controlled drainage, chemical treatment of waters and soils, receiving ditch management, and wetlands. The review also focuses on the specific hydrology and biogeochemistry associated with each of those practices. The practices are structured sequentially along flowpaths as you move through the landscape, from the edge-of-field, to adjacent aquatic systems, and ultimately to downstream P retention. Often practices are region specific based on geology, cropping practices, and specific P related problems and thus require a right practice, and right place mentality to management. Each practice has fundamental P transport and retention processes by systems that can be optimized by management with the goal of reducing downstream P loading after P has left agricultural fields. The management of P requires a system-wide assessment of the stability of P in different biogeochemical forms (particulate vs. dissolved, organic vs. inorganic), in different storage pools (soil, sediment, streams etc.), and under varying biogeochemical and hydrological conditions that act to convert P from one form to another and promote its retention in or transport out of different landscape components. There is significant potential of hierarchically placing practices in the agricultural landscape and enhancing the associated P mitigation. But an understanding is needed of short- and long-term P retention mechanisms within a certain practice and incorporating maintenance schedules if necessary to improve P retention times and minimize exceeding retention capacity.


Assuntos
Agricultura , Conservação dos Recursos Naturais/métodos , Água Doce/química , Fósforo/análise , Solo/análise , Drenagem Sanitária , Solo/química , Solo/normas , Estados Unidos , Movimentos da Água , Poluentes Químicos da Água/análise
11.
Rhinology ; 50(2): 157-64, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22616076

RESUMO

BACKGROUND: The temperature of inhaled air is highly relevant for the humidification process. Narrow anatomical conditions limit possibilities for in vivo measurements. Numerical simulations offer a great potential to examine the function of the human nose. OBJECTIVE: In the present study, the nasal humidification of inhaled air was simulated simultaneously with temperature distribution during a respiratory cycle. METHODS: A realistic nose model based on a multislice CT scan was created. The simulation was performed by the Software Fluent(r). Boundary conditions were based on previous in vivo measurements. Inhaled air had a temperature of 20(deg)C and relative humidity of 30%. The wall temperature was assumed to be variable from 34(deg)C to 30(deg)C with constant humidity saturation of 100% during the respiratory cycle. RESULTS: A substantial increase in temperature and humidity can be observed after passing the nasal valve area. Areas with high speed air flow, e.g. the space around the turbinates, show an intensive humidification and heating potential. Inspired air reaches 95% humidity and 28(deg)C within the nasopharynx. CONCLUSION: The human nose features an enormous humidification and heating capability. Warming and humidification are dependent on each other and show a similar spacial pattern. Concerning the climatisation function, the middle turbinate is of high importance. In contrast to in vivo measurements, numerical simulations can explore the impact of airflow distribution on nasal air conditioning. They are an effective method to investigate nasal pathologies and impacts of surgical procedures.


Assuntos
Temperatura Corporal , Inalação/fisiologia , Nariz/fisiologia , Adulto , Feminino , Humanos , Umidade , Masculino , Modelos Anatômicos , Conchas Nasais/fisiologia
12.
Arch Environ Contam Toxicol ; 59(4): 574-81, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20387062

RESUMO

Rice (Oryza sativa L.) is one of the most important food crops worldwide. However, it is also a valuable tool in assessing toxicity of organic and inorganic compounds. For more than 20 years, it has been an approved species for standardized phytotoxicity experiments. The objective of this study is to determine germination and radicle (root) and coleoptile (shoot) growth of rice seeds exposed to three insecticides and two herbicides, commonly used in the agricultural production landscape. Although no germination effects of pesticide exposure were observed, significant growth effects were noted between pesticide treatments. Coleoptile growth was significantly (p ≤ 0.05) lowered in metolachlor/atrazine mixture, diazinon, and lambda-cyhalothrin exposures when compared with controls. Radicles of fipronil-exposed seeds were significantly larger (p ≤ 0.05) when compared with controls. This research contributes to the phytotoxicity assessment database, in addition to laying the foundation for the use of rice as a phytoremediation tool for agricultural pesticide runoff.


Assuntos
Germinação/efeitos dos fármacos , Herbicidas/toxicidade , Inseticidas/toxicidade , Oryza/efeitos dos fármacos , Poluentes do Solo/toxicidade , Acetamidas/toxicidade , Atrazina/toxicidade , Diazinon/toxicidade , Crescimento e Desenvolvimento/efeitos dos fármacos , Nitrilas/toxicidade , Oryza/crescimento & desenvolvimento , Oryza/fisiologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Pirazóis/toxicidade , Piretrinas/toxicidade , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/fisiologia
13.
Environ Pollut ; 158(1): 175-84, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19656598

RESUMO

Eutrophication and hypoxia within aquatic systems are a serious international concern. Various management practices have been proposed to help alleviate nutrient loads transported to the Gulf of Mexico and other high-profile aquatic systems. The current study examined the nutrient mitigation capacity of a vegetated (V) and non-vegetated (NV) agricultural drainage ditch of similar size and landform in the Mississippi Delta. While no statistically significant differences in ammonium, nitrate, or dissolved inorganic phosphorus mitigation between the two ditches existed, there were significant differences in total inorganic phosphorus percent load reductions (V: 36% +/- 4; NV: 71% +/- 4). However, both agricultural drainage ditches were able to mitigate nutrients, thus reducing the load reaching downstream aquatic receiving systems. Further studies examining ecosystem dynamics within drainage ditches such as sediment and plant nutrient partitioning, as well as microbial processes involved, are needed to provide a better understanding of natural nutrient variability, seasonality and flux.


Assuntos
Nitrogênio/análise , Fósforo/análise , Movimentos da Água , Biodegradação Ambiental , Monitoramento Ambiental
14.
Arch Environ Contam Toxicol ; 57(2): 282-8, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19458989

RESUMO

Increased focus is being placed on the ability of native vegetation to mitigate potential harmful effects of agricultural runoff, especially pyrethroid insecticides. Replicate 379 L Rubbermaid tubs (1.25 m [l] x 0.6 m [w] x 0.8 m [h]) were planted with individual species of cutgrass (Leersia oryzoides), cattails (Typha latifolia), bur-reed (Sparganium americanum), and powdery alligator-flag (Thalia dealbata), all common wetland macrophytes found in the Mississippi Delta, USA, agricultural region. Permethrin-enriched water (target concentration, 5 microg L(-1)) was pumped in at a 4-h hydraulic retention time at one end of the tub and discharged at the far end. Water samples were collected from discharge at 1-h intervals for 12 h and analyzed for permethrin concentrations. Permethrin removal rates were compared for the four different plant treatments and nonvegetated sediment-water controls. Results indicated that no particular single plant species was more effective at removing permethrin in water relative to unplanted controls. Overall mass reductions (from inflow to outflow) for cis-permethrin ranged from 67% +/- 6% in T. latifolia to 71% +/- 2% in L. oryzoides. The trans-permethrin overall mass reductions ranged from 76% +/- 4% in S. americanum to 82% +/- 2% in the unplanted control. Sediment and plant samples collected at the study conclusion indicated that 77%-95% of measured permethrin mass was associated with sediment for mesocosms planted with L. oryzoides, T. latifolia, and T. dealbata. Conversely, mesocosms planted with S. americanum had 83% of measured mass associated with the plant material. Specific plant-pesticide retention studies can lead to improved planning for best management practices and remediation techniques such as constructed wetlands and vegetated agricultural drainage ditches.


Assuntos
Recuperação e Remediação Ambiental , Inseticidas/metabolismo , Permetrina/metabolismo , Plantas/metabolismo , Inseticidas/análise , Inseticidas/química , Cinética , Conformação Molecular , Permetrina/análise , Permetrina/química , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/metabolismo , Solo/análise , Estereoisomerismo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
15.
Langmuir ; 24(16): 9011-6, 2008 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-18646780

RESUMO

Catalytic properties of Pt nanoparticles can significantly depend on the crystallite shape, which renders shape control an important aim in the chemical synthesis. Starting from a colloidal synthesis of quasispherical Pt nanocrystals capped with dodecylamine ligands, systematic variations of different synthesis parameters were performed in the present work in order to obtain Pt nanowires. Mechanistic investigations revealed that nanowires can form by aggregation of quasispherical particles. The process of wire formation was found to be influenced by parameters such as the concentration of the stabilizing ligands on the particle surface. Furthermore, the thermal stability of the obtained nanoparticles was examined. The nanowires were found to be stable up to approximately 140-160 degrees C. In this temperature range a structural transition to a more spherical crystallite shape occurred, which can be understood by thermodynamic considerations.

16.
J Exp Biol ; 211(Pt 10): 1559-64, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18456882

RESUMO

Jawless fishes (Agnatha; lampreys and hagfishes) most closely resemble the earliest stage in vertebrate evolution and lamprey-like animals already existed in the Lower Cambrian [about 540 million years ago (MYA)]. Agnathans are thought to have separated from the main vertebrate lineage at least 500 MYA. Hagfishes have primitive eyes, but the eyes of adult lampreys are well-developed. The southern hemisphere lamprey, Geotria australis, possesses five types of opsin genes, three of which are clearly orthologous to the opsin genes of jawed vertebrates. This suggests that the last common ancestor of all vertebrate lineages possessed a complex colour vision system. In the eyes of many bony fishes and tetrapods, well-focused colour images are created by multifocal crystalline lenses that compensate for longitudinal chromatic aberration. To trace the evolutionary origins of multifocal lenses, we studied the optical properties of the lenses in four species of lamprey (Geotria australis, Mordacia praecox, Lampetra fluviatilis and Petromyzon marinus), with representatives from all three of the extant lamprey families. Multifocal lenses are present in all lampreys studied. This suggests that the ability to create well-focused colour images with multifocal optical systems also evolved very early.


Assuntos
Evolução Biológica , Lampreias/anatomia & histologia , Cristalino/anatomia & histologia , Visão Ocular/fisiologia , Animais , Lampreias/fisiologia , Microscopia Confocal , Retinoscopia , Especificidade da Espécie
17.
J Environ Qual ; 37(1): 107-13, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18178883

RESUMO

Phosphorus (P) loading from nonpoint sources, such as agricultural landscapes, contributes to downstream aquatic ecosystem degradation. Specifically, within the Mississippi watershed, enriched runoff contributions have far-reaching consequences for coastal water eutrophication and Gulf of Mexico hypoxia. Through storm events, the P mitigation capacity of agricultural drainage ditches under no-till cotton was determined for natural and variable rainfall conditions in north Mississippi. Over 2 yr, two experimental ditches were sampled monthly for total inorganic P concentrations in baseflow and on an event-driven basis for stormflows. Phosphorus concentrations, Manning's equations with a range of roughness coefficients for changes in vegetative densities within the ditches, and discharge volumes from Natural Resources Conservation Service dimensionless hydrographs combined to determine ranges in maximum and outflow storm P loads from the farms. Baseflow regressions and percentage reductions with P concentrations illustrated that the ditches alternated between being a sink and source for dissolved inorganic P and particulate P concentrations throughout the year. Storm event loads resulted in 5.5% of the annual applied fertilizer to be transported into the drainage ditches. The ditches annually reduced 43.92 +/- 3.12% of the maximum inorganic effluent P load before receiving waters. Agricultural drainage ditches exhibited a fair potential for P mitigation and thus warrant future work on controlled drainage to improve mitigation capacity.


Assuntos
Agricultura/métodos , Fósforo/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Mississippi , Chuva , Movimentos da Água , Poluição da Água/prevenção & controle
18.
J Environ Qual ; 36(6): 1646-52, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17940264

RESUMO

The application of inorganic nitrogen fertilizers on agricultural landscapes has the potential to generate concerns of environmental degradation at fine to coarse scales across the catchment and landscape. Inorganic nitrogen species (NO3*, NO2*, and NH3) are typically associated with subsurface flow processes; however, surface runoff from rainfall events in no-till agriculture with inorganic surface fertilizers might contribute to downstream eutrophication. Inorganic nitrogen reduction capacity of agricultural drainage ditches under no-till cotton was determined under natural, variable rainfall conditions in northern Mississippi. Monthly grab baseflow samples and storm-generated flow samples were variably sampled temporally within two experimental farm ditches over 2 yr. Inorganic nitrogen concentrations, in conjunction with Manning's equation and Natural Resources Conservation Service dimensionless hydrographs, provided individual water volumes per storm event and thus maximum effluent and outflow nitrogen loads. Base and stormflow regression results indicate drainage ditches reducing NO3* and NH3 over the length of the ditch for growing and dormant seasons. Overall, maximum storm loads of dissolved inorganic nitrogen (DIN) from the farm over the 2-yr sampling period accounted for 2.2% of the initial fertilizer application, of which 1.1% left the ditch (0.84 kg ha(-1) yr(-1)) (a 57% ditch reduction of DIN load over 2 yr). Long-term sampling incorporating data on application and loss of fertilizers and farm management will provide critical information for farmers and scientists on the potential of economic gains and downstream ecosystem eutrophication, respectively.


Assuntos
Agricultura , Compostos Inorgânicos/análise , Nitrogênio/análise , Rios/química , Monitoramento Ambiental , Mississippi , Chuva , Fatores de Tempo
19.
Environ Pollut ; 146(1): 114-9, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16905226

RESUMO

The beneficial uptake of nutrients by wetland plants is countered to some extent by nutrient release back into the aquatic environment due to vegetative die-back. This current study examined whether Leersia oryzoides, a common wetland plant, exhibits luxury uptake of nutrients from simulated farm runoff. The study also tested whether with subsequent decomposition, these nutrients are released back into the water column. When exposed to elevated (>2mg/L N and P) runoff, L. oryzoides assimilated significantly higher concentrations of nitrogen (p<0.001) and phosphorus (p<0.001) in above-ground biomass as compared to non-enriched treatments (<0.05 mg/L N and P). Subsequently, senescence of enriched above-ground biomass yielded significantly higher concentrations of phosphorus (2.19+/-0.84 mg P/L). Using L. oryzoides as our model, this study demonstrates nitrogen and phosphorus sequestration during the growing season and release of phosphorus in the winter.


Assuntos
Agricultura , Alimentos , Plantas/metabolismo , Estações do Ano , Poluentes Químicos da Água/metabolismo , Poluição da Água , Adsorção , Biodegradação Ambiental , Biomassa , Substâncias Húmicas , Nitratos/metabolismo , Fósforo/metabolismo , Desenvolvimento Vegetal , Áreas Alagadas
20.
Eur Radiol ; 16(12): 2842-8, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16924440

RESUMO

Breast cancers in BRCA1 gene mutation carriers often have specific histologic features: grade III tumors with pushing margins. Our purpose was to compare the mammographic and histologic features of breast cancers in carriers with those in age-matched sporadic controls. The features of breast cancers in 27 BRCA1 carriers found during annual surveillance were compared to those in 107 age-matched sporadic controls. The carriers had no (classic) spiculated mammographic lesions, a high percentage of well-defined masses and hardly any masses with microcalcifications, whereas the controls had significantly fewer well-defined ones and only in 27% spiculated lesions on the mammogram. The well-defined mammographic tumors correlated in 83% of the carriers and in 70% of the controls with histologic circumscribed tumor margins. Spiculated mammographic lesions in the controls were in 90% grade I or II tumors. DCIS with or without infiltration was seen in 22% of the carriers and in 45% of the controls. In conclusion, breast cancers diagnosed in BRCA1 carriers do not have classic malignant mammographic features. A minority of the young sporadic controls show the classic malignant lesion on the mammogram. Both carriers and controls generally show a good correlation between their mammographic- and histologic tumor pattern.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/genética , Genes BRCA1 , Mamografia , Adulto , Neoplasias da Mama/patologia , Estudos de Casos e Controles , Feminino , Humanos , Modelos Logísticos , Mutação , Vigilância da População
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