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1.
BMC Fam Pract ; 22(1): 124, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34162331

RESUMO

BACKGROUND: Defining multimorbidity has proved elusive in spite of attempts to standardise definitions. For national studies, a broad definition is required to capture national diversity. For locally based studies, the definition may need to reflect demographic and morbidity patterns. We aimed to define multimorbidity for an inner city, multi-ethnic, deprived, young age community typical of many large cities. METHODS: We used a scoping literature review to identify the international literature, standards and guidelines on Long Term Condition (LTC) definitions for inclusion in our multimorbidity definition. Consensus was categorised into high, medium or low consensus, depending on the number of literature sources citing each LTC. Findings were presented to a workshop consisting of local health service stakeholders who were asked to select LTCs for inclusion in a second stage review. In the second stage, each LTC was tested against seven evaluation domains: prevalence, impact, preventability, treatment burden, progression to multiple LTCs, impact on younger people, data quality. These domains were used to create 12 target criteria. LTC rankings according to consensus group and target criteria scores were presented to a second workshop for a final decision about LTC inclusion. RESULTS: The literature review identified 18 literature sources citing 86 LTCs: 11 were excluded because they were LTC clusters. The remainder were allocated into consensus groupings: 13 LTCs were 'high consensus' (cited by ≥ 11 sources); 15 were 'medium consensus' (cited by 5-10 sources); 47 were 'low consensus' (cited by < 5 sources). The first workshop excluded 31 LTCs. The remaining 44 LTCs consisted of: 13 high consensus LTCs, all with high target score (score 6-12); 15 medium consensus LTCs, 11 with high target scores; 16 low consensus LTCs, 6 with high target scores. The final workshop selected the 12 high consensus conditions, 12 medium consensus LTCs (10 with high target scores) and 8 low consensus LTCs (3 with high target scores), producing a final selection of 32 LTCs. CONCLUSIONS: Redefining multimorbidity for an urban context ensures local relevance but may diminish national generalisability. We describe a detailed LTC selection process which should be generalisable to other contexts, both local and national.


Assuntos
Etnicidade , Multimorbidade , Consenso , Humanos , Prevalência
2.
Environ Entomol ; 48(6): 1331-1339, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31789364

RESUMO

Human activity is rapidly increasing the radiance and geographic extent of artificial light at night (ALAN) leading to alterations in the development, behavior, and physiological state of many organisms. A limited number of community-scale studies investigating the effects of ALAN have allowed for spatial aggregation through positive phototaxis, the commonly observed phenomenon of arthropod movement toward light. We performed an open field study (without restricted arthropod access) to determine the effects of ALAN on local arthropod community composition, plant traits, and local herbivory and predation rates. We found strong positive phototaxis in 10 orders of arthropods, with increased (159% higher) overall arthropod abundance under ALAN compared to unlit controls. The arthropod community under ALAN was more diverse and contained a higher proportion of predaceous arthropods (15% vs 8%). Predation of immobilized flies occurred 3.6 times faster under ALAN; this effect was not observed during the day. Contrary to expectations, we also observed a 6% increase in herbivory under ALAN. Our results highlight the importance of open experimental field studies in determining community-level effects of ALAN.


Assuntos
Artrópodes , Herbivoria , Animais , Humanos , Luz , Plantas , Comportamento Predatório
3.
Environ Sci Pollut Res Int ; 21(4): 3191-5, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24310904

RESUMO

Soil is a complex natural resource that is considered non-renewable in policy frameworks, and it plays a key role in maintaining a variety of ecosystem services (ES) and life-sustaining material cycles within the Earth's Critical Zone (CZ). However, currently, the ability of soil to deliver these services is being drastically reduced in many locations, and global loss of soil ecosystem services is estimated to increase each year as a result of many different threats, such as erosion and soil carbon loss. The European Union Thematic Strategy for Soil Protection alerts policy makers of the need to protect soil and proposes measures to mitigate soil degradation. In this context, the European Commission-funded research project on Soil Transformations in European Catchments (SoilTrEC) aims to quantify the processes that deliver soil ecosystem services in the Earth's Critical Zone and to quantify the impacts of environmental change on key soil functions. This is achieved by integrating the research results into decision-support tools and applying methods of economic valuation to soil ecosystem services. In this paper, we provide an overview of the SoilTrEC project, its organization, partnerships and implementation.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Solo , União Europeia , Modelos Teóricos , Pesquisa
4.
Environ Pollut ; 179: 285-93, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23707951

RESUMO

The addition of calcium carbonate to catchments or watercourses--liming--has been used widely to mitigate freshwater acidification but the abatement of acidifying emissions has led to questions about its effectiveness and necessity. We conducted a systematic review and meta-analysis of the impact of liming streams and rivers on two key groups of river organisms: fish and invertebrates. On average, liming increased the abundance and richness of acid-sensitive invertebrates and increased overall fish abundance, but benefits were variable and not guaranteed in all rivers. Where B-A-C-I designs (before-after-control-impact) were used to reduce bias, there was evidence that liming decreased overall invertebrate abundance. This systematic review indicates that liming has the potential to mitigate the symptoms of acidification in some instances, but effects are mixed. Future studies should use robust designs to isolate recovery due to liming from decreasing acid deposition, and assess factors affecting liming outcomes.


Assuntos
Compostos de Cálcio/química , Recuperação e Remediação Ambiental/métodos , Óxidos/química , Rios/química , Poluentes da Água/química , Animais , Peixes/fisiologia , Água Doce , Concentração de Íons de Hidrogênio , Invertebrados/fisiologia , Poluentes da Água/análise
5.
Clin Transl Sci ; 5(5): 400-7, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23067352

RESUMO

Despite the increased emphasis on formal training in clinical and translational research and the growth in the number and scope of training programs over the past decade, the impact of training on research productivity and career success has yet to be fully evaluated at the institutional level. In this article, the Education Evaluation Working Group of the Clinical and Translational Science Award Consortium introduces selected metrics and methods associated with the assessment of key factors that affect research career success. The goals in providing this information are to encourage more consistent data collection across training sites, to foster more rigorous and systematic exploration of factors associated with career success, and to help address previously identified difficulties in program evaluation.


Assuntos
Escolha da Profissão , Estudos de Avaliação como Assunto , Pesquisadores/estatística & dados numéricos , Pesquisa Translacional Biomédica/estatística & dados numéricos , Coleta de Dados , Apoio Social , Pesquisa Translacional Biomédica/educação
6.
J Environ Monit ; 14(6): 1531-41, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22522663

RESUMO

Sulfate adsorption capacity of B-horizons of base-poor, predominantly stagnopodzol, soils from the Plynlimon catchments, mid-Wales was determined by combination of laboratory adsorption and desorption isotherms. Results show that sulfate adsorption capacity of a range of stagnopodzol (Histic-stagno-podzol (Leptic), WRB), brown podzolic soil (Histic-umbrisol (Leptic), WRB) and stagnohumic gley (Histic-stagno-gleysol, WRB) B-horizons was positively related to the amounts of extractable (pyrophosphate and oxalate) Fe + Al, with the stagnopodzol and brown podzolic soil Bs horizon having the largest adsorption capacity and stagnohumic gley Bg horizon the smallest adsorption capacity. Results show that dissolved organic carbon (DOC) has a negative but limited effect on sulfate adsorption in these soils. Results obtained from a set of historical soil samples revealed that the grassland brown podzolic soil Bs horizon and afforested stagnopodzol Bs horizon were highly saturated with sulfate in the 1980s, at 63% and 89% respectively, whereas data from some recently sampled soil from two sites revisited in 2010-11 indicates that percentage sulfate adsorption saturation has since fallen substantially, to 41% and 50% respectively. Between 1984 and 2009 the annual rainfall-weighted mean excess SO(4)-S concentration in bulk precipitation declined linearly from 0.37 mg S l(-1) to 0.17 mg S l(-1). Over the same period, flow weighted annual mean stream water SO(4)-S concentrations decreased approximately linearly from 1.47 mg S l(-1) to 0.97 mg S l(-1) in the plantation afforested Hafren catchment compared to a drop from 1.25 to 0.69 mg S l(-1) in the adjacent moorland catchment of the Afon Gwy. In flux terms, the mean decrease in annual stream water SO(4)-S flux has been approximately 0.4 kg S ha(-1) yr(-1), whilst the recovery in stream water quality in the Afon Cyff grassland catchment has been partly offset by loss of SO(4)-S by desorption from the soil sulfur pool of approximately 0.2 kg S ha(-1) yr(-1).


Assuntos
Poluição do Ar/estatística & dados numéricos , Poluentes do Solo/análise , Sulfatos/análise , Enxofre/análise , Adsorção , Atmosfera , Meio Ambiente , Monitoramento Ambiental , Rios/química , Solo/química , País de Gales , Poluentes Químicos da Água/análise
7.
Sci Total Environ ; 434: 3-12, 2012 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-22245159

RESUMO

Eighteen months of 7-hourly analyses of rainfall and stream water chemistry are presented, spanning a wide range of chemical determinands and building on over 20 years of weekly records for the moorland headwaters of the river Severn. The high-frequency time series data show that hydrochemical responses to major hydrological and biological drivers of short-term variability in rainfall and rivers are not captured by conventional low-frequency monitoring programmes. A wealth of flow related, flow independent, diurnal, seasonal and annual fluctuations indicate a cacophony of interactions within the catchment and stream. The complexity of the chemical dynamics is visually obvious, although there appears to be no clear way of translating this complexity into a simple algorithm. The work provides a proof of concept for the complex structure of catchment functioning revealed by extensive high-frequency measurements coupled with high analytical sensitivity and reproducibility. It provides new insights into hydrogeochemical functioning and a novel resource for catchment modelling.


Assuntos
Chuva , Movimentos da Água , Qualidade da Água , Monitoramento Ambiental , Controle de Qualidade
8.
Sci Total Environ ; 434: 186-200, 2012 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-22119034

RESUMO

This paper examines two hydrochemical time-series derived from stream samples taken in the Upper Hafren catchment, Plynlimon, Wales. One time-series comprises data collected at 7-hour intervals over 22 months (Neal et al., 2012-this issue), while the other is based on weekly sampling over 20 years. A subset of determinands: aluminium, calcium, chloride, conductivity, dissolved organic carbon, iron, nitrate, pH, silicon and sulphate are examined within a framework of non-stationary time-series analysis to identify determinand trends, seasonality and short-term dynamics. The results demonstrate that both long-term and high-frequency monitoring provide valuable and unique insights into the hydrochemistry of a catchment. The long-term data allowed analysis of long-term trends, demonstrating continued increases in DOC concentrations accompanied by declining SO(4) concentrations within the stream, and provided new insights into the changing amplitude and phase of the seasonality of the determinands such as DOC and Al. Additionally, these data proved invaluable for placing the short-term variability demonstrated within the high-frequency data within context. The 7-hour data highlighted complex diurnal cycles for NO(3), Ca and Fe with cycles displaying changes in phase and amplitude on a seasonal basis. The high-frequency data also demonstrated the need to consider the impact that the time of sample collection can have on the summary statistics of the data and also that sampling during the hours of darkness provides additional hydrochemical information for determinands which exhibit pronounced diurnal variability. Moving forward, this research demonstrates the need for both long-term and high-frequency monitoring to facilitate a full and accurate understanding of catchment hydrochemical dynamics.


Assuntos
Estações do Ano , Qualidade da Água , País de Gales
9.
Sci Total Environ ; 408(21): 5035-51, 2010 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-20708776

RESUMO

This paper presents new information on the hydrology and water quality of the eroding peatland headwaters of the River Severn in mid-Wales and links it to the impact of plantation conifer forestry further down the catchment. The Upper Hafren is dominated by low-growing peatland vegetation, with an average annual precipitation of around 2650 mm with around 250 mm evaporation. With low catchment permeability, stream response to rainfall is "flashy" with the rising limb to peak stormflow typically under an hour. The water quality is characteristically "dilute"; stormflow is acidic and enriched in aluminium and iron from the acid organic soil inputs. Baseflow is circum-neutral and calcium and bicarbonate bearing due to the inputs of groundwater enriched from weathering of the underlying rocks. Annual cycling is observed for the nutrients reflecting uptake and decomposition processes linked to the vegetation and for arsenic implying seasonal water-logging within the peat soils and underlying glacial drift. Over the decadal scale, sulphate and nitrate concentrations have declined while Gran alkalinity, dissolved organic carbon and iron have increased, indicating a reduction in stream acidification. Within the forested areas the water quality is slightly more concentrated and acidic, transgressing the boundary for acid neutralisation capacity as a threshold for biological damage. Annual sulphate and aluminium concentrations are double those observed in the Upper Hafren, reflecting the influence of forestry and the greater ability of trees to scavenge pollutant inputs from gaseous and mist/cloud-water sources compared to short vegetation. Acidification is decreasing more rapidly in the forest compared to the eroding peatland possibly due to the progressive harvesting of the mature forest reducing the scavenging of acidifying inputs. For the Lower Hafren, long-term average annual precipitation is slightly lower, with lower average altitude, at around 2520mm and evaporation is around double that of the Upper Hafren.


Assuntos
Ácidos/análise , Monitoramento Ambiental , Rios/química , Poluentes Químicos da Água/análise , Alumínio/análise , Concentração de Íons de Hidrogênio , Árvores , Poluição da Água/prevenção & controle , Poluição da Água/estatística & dados numéricos
10.
Environ Pollut ; 156(3): 636-43, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18653264

RESUMO

Nitrate (NO3-) is often observed in surface waters draining terrestrial ecosystems that remain strongly nitrogen (N) limited. It has been suggested that this occurs due to hydrological bypassing of soil or vegetation N retention, particularly during high flows. To test this hypothesis, artificial rain events were applied to 12 replicate soil blocks on a Welsh podzolic acid grassland hillslope, labelled with 15N-enriched NO3- and a conservative bromide (Br-) tracer. On average, 31% of tracer-labelled water was recovered within 4 h, mostly as mineral horizon lateral flow, indicating rapid vertical water transfer through the organic horizon via preferential flowpaths. However, on average only 6% of 15N-labelled NO3- was recovered. Around 80% of added NO3- was thus rapidly immobilised, probably by microbial communities present on the surfaces of preferential flowpaths. Transitory exceedance of microbial N-uptake capacity during periods of high water and N flux may therefore provide a mechanism for NO3- leaching.


Assuntos
Chuva Ácida , Nitratos/análise , Poluentes do Solo/análise , Solo/análise , Adsorção , Brometos/análise , Ecologia/instrumentação , Ecologia/métodos , Nitrogênio/análise , Isótopos de Nitrogênio/análise , Estações do Ano , Compostos de Sódio/análise , Microbiologia do Solo , Árvores , Movimentos da Água , Poluentes Químicos da Água/análise
11.
Sci Total Environ ; 404(2-3): 316-25, 2008 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-18096207

RESUMO

In the United Kingdom, as in other regions of Europe and North America, recent decreases in surface water sulphate concentrations, due to reduced sulphur emissions, have coincided with marked increases in dissolved organic carbon (DOC) concentrations. Since many of the compounds comprising DOC are acidic, the resulting increases in organic acidity may have the potential to offset the benefits of a decrease in mineral (sulphate) acidity. To test this, we used a triprotic model of organic acid dissociation to estimate the proportional organic acid buffering of reduced mineral acidity as measured in the 22 lakes and streams monitored by the UK Acid Waters Monitoring Network. For an average non-marine sulphate decrease of 30 mueq l(-1) over 15 years from 1988-2003, we estimate that around 28% was counterbalanced by rising strong organic acids, 20% by rising alkalinity (partly attributable to an increase in weak organic acids), 11% by falling inorganic aluminium and 41% by falling non-marine base cations. The situation is complicated by a concurrent decrease in marine ion concentrations, and the impact this may have had on both DOC and acidity, but results clearly demonstrate that organic acid increases have substantially limited the amount of recovery from acidification (in terms of rising alkalinity and falling aluminium) that have resulted from reducing sulphur emissions. The consistency and magnitude of sulphate and organic acid changes are consistent with a causal link between the two, possibly due to the effects of changing acidity, ionic strength and aluminium concentrations on organic matter solubility. If this is the case, then organic acids can be considered effective but partial buffers to acidity change in organic soils, and this mechanism needs to be considered in assessing and modelling recovery from acidification, and in defining realistic reference conditions. However, large spatial variations in the relative magnitude of organic acid and sulphate changes, notably for low-deposition sites in northwestern areas where organic acid increases apparently exceed non-marine sulphate decreases, suggest that additional factors, such as changes in sea-salt deposition and climatic factors, may be required to explain the full magnitude of DOC increases in UK surface waters.


Assuntos
Monitoramento Ambiental , Compostos Orgânicos/análise , Poluentes Químicos da Água/análise , Soluções Tampão , Carbono/análise , Carbono/química , Clima , Concentração de Íons de Hidrogênio , Compostos Orgânicos/química , Solubilidade , Fatores de Tempo , Reino Unido , Movimentos da Água , Poluentes Químicos da Água/química , Tempo (Meteorologia)
12.
Environ Pollut ; 151(1): 110-20, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17478019

RESUMO

Much uncertainty still exists regarding the relative importance of organic acids in relation to acid deposition in controlling the acidity of soil and surface waters. This paper contributes to this debate by presenting analysis of seasonal variations in atmospheric deposition, soil solution and stream water chemistry for two UK headwater catchments with contrasting soils. Acid neutralising capacity (ANC), dissolved organic carbon (DOC) concentrations and the Na:Cl ratio of soil and stream waters displayed strong seasonal patterns with little seasonal variation observed in soil water pH. These patterns, plus the strong relationships between ANC, Cl and DOC, suggest that cation exchange and seasonal changes in the production of DOC and seasalt deposition are driving a shift in the proportion of acidity attributable to strong acid anions, from atmospheric deposition, during winter to predominantly organic acids in summer.


Assuntos
Ácidos/análise , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Compostos Orgânicos/análise , Estações do Ano , Chuva Ácida , Ânions , Cátions , Inglaterra , Água Doce , Concentração de Íons de Hidrogênio , Rios , Solo , Poluentes do Solo/análise , Solubilidade , Movimentos da Água , Poluentes Químicos da Água/análise
13.
Environ Sci Technol ; 41(9): 3146-52, 2007 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-17539518

RESUMO

Peatlands export more dissolved organic carbon (DOC) than any other biome, contributing 20% of all terrestrial DOC exported to the oceans. Both warming and elevated atmospheric CO2 (eCO2) can increase DOC exports, but their interaction is poorly understood. Peat monoliths were, therefore, exposed to eCO2, warming and eCO2 + warming (combined). The combined treatment produced a synergistic (i.e., significant interaction) rise in DOC concentrations available for export (119% higher than the control, interaction P < 0.05) and enriched this pool with phenolic compounds (284%). We attribute this to increased plant inputs, coupled with impaired microbial degradation induced by competition with the vegetation for nutrients and inhibitory phenolics. Root biomass showed a synergistic increase (407% relative to the control, P < 0.1 only), while exudate inputs increased additively. Phenol oxidase was suppressed synergistically (58%, interaction P < 0.1 only) and beta-glucosidase (27%) additively, while microbial nutritional stress increased (51%) additively. Such results suggest intensified carbon exports from peatlands, with potentially widespread ramifications for aquatic processes in the receiving waters.


Assuntos
Dióxido de Carbono , Carbono/análise , Solo , Briófitas/crescimento & desenvolvimento , Magnoliopsida/crescimento & desenvolvimento , Monofenol Mono-Oxigenase/metabolismo , Nitrogênio/análise , Fenóis/análise , Monoéster Fosfórico Hidrolases/metabolismo , Temperatura , beta-Glucosidase/metabolismo
14.
Acad Emerg Med ; 11(8): 881-4, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15289197

RESUMO

OBJECTIVES: The authors sought to modify and validate a composite assessment evaluation process that assesses resident acquisition of the Accreditation Council for Graduate Medical Education (ACGME) general competencies (GCs). METHODS: This study critically analyzed the evaluation process used in a multicenter study (150 emergency medicine resident evaluations) to determine whether the procedure was psychometrically valid. For each GC, principal component analysis (PCA) was used to determine whether certain evaluation items could be eliminated, as well as to determine the magnitude of variability explained by up to three linear combinations or "principal components." The factor proportions (factor loadings) of various eigenvectors were measured to determine the degree of variability (determined by the square of the factor proportion) within a data or item set. The factor proportions essentially measure the length of the eigenvector as determined from a correlation matrix. RESULTS: The first three principal components are reported as factor proportion sum (% of total variability) as follows: patient care 0.91 (83%), medical knowledge 0.87 (76%), practice-based learning and improvement 0.90 (81%), interpersonal and communication skills 0.84 (71%), professionalism 0.74 (55%), and systems-based practice 0.80 (64%). PCA showed that evaluating certain traditional categories such as medical knowledge seemed to capture a single element, whereas professionalism appeared to measure a more complex, multidimensional phenomenon. CONCLUSIONS: By using a structured development process, the authors were able to create valid evaluation items for determining resident acquisition of the ACGME GCs.


Assuntos
Competência Clínica , Educação de Pós-Graduação em Medicina/métodos , Avaliação Educacional/métodos , Medicina de Emergência/educação , Internato e Residência/métodos , Avaliação de Programas e Projetos de Saúde/normas , Estudos Transversais , Humanos , Análise de Componente Principal , Psicometria , Estados Unidos
15.
Acad Emerg Med ; 10(10): 1049-53, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14525736

RESUMO

OBJECTIVES: The Accreditation Council for Graduate Medical Education (ACGME) has promulgated six areas called General Competencies (GCs) that residency programs are required to evaluate. The authors sought to determine if these domains were an intrinsic part of emergency medicine (EM) residency training by using a global assessment evaluation device. METHODS: This was an observational, multicenter, cross-sectional study that compared GC acquisition between first-, second-, and third-year (EM1, EM2, and EM3) residents. Five postgraduate year (PGY) 1 to PGY 3 allopathic EM programs in Michigan participated. A global assessment form using a 1 through 9 ordinal scale with 86 scoring items was given to program directors for each resident in their programs. Analysis of variance (ANOVA) was used to compare the means between EM1, EM2, and EM3 scores. RESULTS: Five EM programs evaluated 150 residents. The GC scores were as follows: Patient Care: EM1 4.92, EM2 5.79, and EM3 6.40; Medical Knowledge: EM1 4.90, EM2 5.80, and EM3 6.46; Practice-based Learning and Improvement: EM1 4.60, EM2 5.48, and EM3 6.16; Interpersonal and Communication Skills: EM1 4.99, EM2 5.39, and EM3 6.01; Professionalism: EM1 5.43, EM2 5.68, and EM3 6.27; Systems-based Practice: EM1 4.80, EM2 5.48, and EM3 6.21. ANOVA showed statistically significant differences (p < 0.001) for all GCs. CONCLUSIONS: EM residents from several residency programs showed statistically significant progressive acquisition of the ACGME GCs using a global assessment device. This suggests that the GCs may be an intrinsic component in the training of EM residents.


Assuntos
Competência Clínica , Medicina de Emergência/educação , Internato e Residência , Estudos Transversais , Educação de Pós-Graduação em Medicina , Humanos , Michigan
16.
Sci Total Environ ; 314-316: 99-120, 2003 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-14499529

RESUMO

Soluble reactive phosphorus (SRP) data are presented for rainfall, cloud water, soil waters, stream waters and groundwaters at the Plynlimon catchments in mid Wales to examine the hydrochemical functioning of inorganic phosphorus for an acidic and acid sensitive area characteristic of much of the UK uplands. In general, stream water concentrations are low compared to lowland areas. Average concentrations of SRP in rainfall and cloud water (0.3 and 0.9 microM l(-1), respectively) are higher than in stream water with wider ranges in concentration (0-19.3 and 0-20.9 microM l(-1), respectively). Throughfall and stemflow is enriched in SRP compared to rain and cloud water by a factor of approximately twofold and sixfold, respectively: the average concentrations and ranges are 0.73 and 0-6.61 microM l(-1) for throughfall and 2.12 and 0-18.61 microM l(-1) for stemflow. Soil water SRP concentrations measured in the surface layers of representative areas of podzol and gley soils, are further enriched with respect to inputs. Average concentrations and ranges for the L/F and Oh horizons in the podzols are 3.1 microM l(-1) (range: 0.03-17.2 microM l(-1)) and 0.75 microM l(-1) (range: 0.03-2.64 microM l(-1)), respectively. Correspondingly, the average values and ranges for the L/F and Oh horizons in the gley are 2 microM l(-1) (range: 0.03-16.65 microM l(-1)) and 0.4 microM l(-1) (range: 0.03-8.61 microM l(-1)). SRP concentrations in stream and ground water are lower than in atmospheric inputs and surface soil waters and show marked spatial variability. This variability is linked to three catchment features. (1) For streams draining podzolic soils, most of the SRP is retained by the catchment. For this situation, stream and ground waters have average concentrations of approximately 0.05 microM l(-1) with a range of 0-1.47 microM l(-1). There is no clear stream or groundwater SRP response to felling despite a large release of SRP from felling debris (brash) and the forest floor (L/F horizon) with average post-felling concentrations of 11.02 microM l(-1) (0.40-155.0 microM l(-1)) and 23.60 microM l(-1) (0.26-172.23 microM l(-1)), respectively. (2) For forested catchments with gley soils, stream water SRP concentrations are more variable with, in one case, much higher concentrations than for the podzol counterparts (range in average 0.05-0.46 microM l(-1)). (3) For the streams draining gley soils, felling results in a mixed SRP response. At the local scale (ditch drainage), there is a marked enrichment in SRP concentration (average concentrations increase from 0.05 to 1.31 microM l(-1), with a peak concentration of 4.0 microM l(-1)). This response is consistent with the observed mobilisation of SRP from brash and forest floor material (post-felling mean concentrations of 9.39 and 11.94 microM l(-1), respectively). However, stream water concentrations are an order of magnitude lower than observed in the soil waters implying considerable immobilisation of SRP between the soils and the stream. At the larger catchment scale, no discernable enrichment in SRP is observed following felling. The results are related to input-output budgets and the findings interpreted in terms of the dominant hydrogeochemical processes operative and environmental management issues.


Assuntos
Fósforo/análise , Chuva , Solo , Água/química , Monitoramento Ambiental , Agricultura Florestal , Fenômenos Geológicos , Geologia , Fósforo/química , Folhas de Planta , Valores de Referência , Solubilidade , Árvores , País de Gales , Abastecimento de Água
17.
Sci Total Environ ; 314-316: 121-51, 2003 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-14499530

RESUMO

An extensive study of acidic and acid sensitive moorland and forested catchments in mid-Wales is used to show the water quality functioning with respect to nitrate and ammonium. For this, long-term records of rainfall, cloud water, throughfall, stemflow and stream water (up to 18 years of weekly data) are combined with shorter duration information on stream water associated with small tributary sources and drainage ditches, ground water from a network of exploratory boreholes and paired control and felled catchments. The ratio of nitrate to ammonium is about one in rainfall, cloud water, throughfall and stemflow but the concentrations are much lower in rainfall (approximately 25 microM l(-1)) than in cloud water (approximately 300 microM l(-1)) while throughfall and stemflow are intermediate (approximately 80 microM l(-1)). Within the streams draining moorland and forested areas, nitrate concentrations are close to the mean value in rainfall while ammonium concentrations are often over an order of magnitude lower in the stream than in rainfall and are typically only about a fifth that of nitrate. With felling, stream water nitrate concentrations increase for podzolic soils but show a variable response for gley soils. For the streams draining forested podzols, the concentrations of nitrate can be up to an order of magnitude higher for the first few years after felling compared to than pre-fell values but in later years, concentrations decline to pre-fell and even lower levels. Felling for the podzolic soils barely leads to any changes in ammonium concentration. For the gley soils, felling results in an order of magnitude increase in nitrate and ammonium for a small drainage ditch, but the pulse barely reaches the main stream channel. Rather, within-catchment and within-stream processes not only take up the nitrate and ammonium fluxes generated, but in the case of nitrate, concentrations with- and post-felling are lower than pre-felling concentrations. Groundwater concentrations of nitrate for the moorland and forested catchments are slightly lower than for the streams while for ammonium the reverse is the case: ammonium concentrations in groundwater are about a tenth those of nitrate. With felling, groundwater nitrate concentrations show sporadic increases. For two boreholes, these increases occur during wet periods when groundwater levels are at their shallowest; for one other borehole, there is a gradual and sustained increase over several years. The results are explained in relation to the dominant hydrogeochemical processes operative.


Assuntos
Nitrogênio/análise , Chuva , Solo , Abastecimento de Água , Monitoramento Ambiental , Agricultura Florestal , Fenômenos Geológicos , Geologia , Nitrogênio/química , Folhas de Planta , Compostos de Amônio Quaternário/análise , Árvores , País de Gales , Movimentos da Água
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