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1.
Brain Inj ; 34(1): 98-109, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31661629

RESUMO

Primary Objective: To investigate the nature and patterns of narrative discourse impairment in people with severe Traumatic Brain Injury (TBI) during early recovery.Methods and Procedures: A single image picture description task was administered to 42 participants with severe TBI at 3 and 6-months post-injury. The same task was administered to 37 control participants. Discourse samples were analyzed with measures of productivity, informativeness and story organization. The performance of people with TBI was compared with the control group at both 3 and 6 months, and the performance of the participants with TBI was also compared across the two time points. Individual patterns of performance were also examined.Results: Inferential analyses revealed significant differences between the control group and the group with TBI on informativeness at both time points and  number of complete episodes at 3 months, but no significant differences for productivity measures. There was no significant change for the group with TBI between 3 and 6 months. However, individual improvement over time was observed.Conclusions: People with TBI have discourse difficulties early post TBI that are also present at 6-months post-injury. In order to understand longer-term discourse recovery, it is necessary to examine participant patterns over further time points on this narrative task.


Assuntos
Lesões Encefálicas Traumáticas , Lesões Encefálicas , Lesões Encefálicas Traumáticas/complicações , Humanos , Narração
2.
Semin Speech Lang ; 41(1): 10-19, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31869845

RESUMO

AphasiaBank is a shared, multimedia database for the study of communication in aphasia. This article describes a variety of discourse measurement tools and teaching resources available at the AphasiaBank website. The discourse measurement tools include main concept analysis, core lexicon checklists, correct information unit computation techniques, and other automated analyses using the CLAN program. These tools can be used to measure a variety of aspects of language production for assessment as well as treatment evaluation and clinical research purposes. Importantly, they are intended to help make the discourse analysis process more efficient and reliable. Teaching resources include an online tutorial on aphasia, videos of typical behaviors seen in aphasia, group treatment videos, classroom activities, tutorial screencasts, and conference posters. These resources can be used for a variety of clinical and educational purposes. The AphasiaBank website is part of the larger TalkBank project which provides many other shared databases and resources that are relevant to professionals interested in communication and communication disorders.


Assuntos
Afasia/terapia , Comunicação , Bases de Dados Factuais , Humanos , Resultado do Tratamento
3.
Brain Inj ; 32(2): 167-181, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29281420

RESUMO

BACKGROUND: There is limited research on communicative recovery during the early stages after a severe traumatic brain injury (TBI) in adults. METHODS AND PROCEDURES: In the current study 43 people with severe TBI described a simple procedure at 3 and 6 months post injury and this was compared to the description provided by 37 healthy speakers. Linguistic productivity and the presence of macrostructural discourse elements were analysed. MAIN OUTCOMES AND RESULTS: No change occurred in productivity in the TBI group between the two time points. There was increased use of relevant information (macrostructure) over time for the TBI group, reflecting improvement. People with TBI differed from controls in speech rate and in two out of three macrostructural categories at both time points, indicating difficulties even after 12 weeks of recovery. CONCLUSIONS: Overall, the quality, rather than the quantity of discourse was disordered for participants with TBI. Findings indicate that procedural discourse is sensitive to discourse deficits of people with TBI and can be used to map recovery during the sub-acute phase.


Assuntos
Lesões Encefálicas Traumáticas/complicações , Transtornos da Linguagem/diagnóstico , Transtornos da Linguagem/etiologia , Adolescente , Adulto , Idoso , Estudos de Coortes , Feminino , Escala de Resultado de Glasgow , Humanos , Linguística , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Comportamento Verbal/fisiologia , Adulto Jovem
4.
Support Care Cancer ; 24(11): 4567-75, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27278271

RESUMO

PURPOSE: For breast cancer (BrCa) survivors, premature menopause can result from conventional cancer treatment. Due to limited treatment options, survivors often turn to complementary therapies (CTs), but struggle to make informed decisions. In this study, we identified BrCa survivors' CT and general information and decision-making needs related to menopausal symptoms. METHODS: The needs assessment was informed by interpretive descriptive methodology. Focus groups with survivors (n = 22) and interviews with conventional (n = 12) and CT (n = 5) healthcare professionals (HCPs) were conducted at two Canadian urban cancer centers. Thematic, inductive analysis was conducted on the data. RESULTS: Menopausal symptoms have significant negative impact on BrCa survivors. Close to 70 % of the sample were currently using CTs, including mind-body therapies (45.5 %), natural health products (NHPs) and dietary therapies (31.8 %), and lifestyle interventions (36.4 %). However, BrCa survivors reported inadequate access to information on the safety and efficacy of CT options. Survivors also struggled in their efforts to discuss CT with HCPs, who had limited time and information to support women in their CT decisions. Concise and credible information about CTs was required by BrCa survivors to support them in making informed and safe decisions about using CTs for menopausal symptom management. CONCLUSIONS: High quality research is needed on the efficacy and safety of CTs in managing menopausal symptoms following BrCa treatment. Decision support strategies, such as patient decision aids (DAs), may help synthesize and translate evidence on CTs and promote shared decision-making between BrCa survivors and HCPs about the role of CTs in coping with menopause following cancer treatment.


Assuntos
Neoplasias da Mama/complicações , Terapias Complementares/métodos , Menopausa/fisiologia , Adulto , Neoplasias da Mama/terapia , Tomada de Decisões , Estudos de Avaliação como Assunto , Feminino , Grupos Focais , Humanos , Pessoa de Meia-Idade
5.
Semin Oncol Nurs ; 40(3): 151625, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38556365

RESUMO

OBJECTIVES: Internationally, there is limited evidence about the role and impact of nurse practitioners (NPs) in complex malignant hematology (CMH). In one Canadian CMH program, NPs have existed for 20 years but not been evaluated. This study aimed to understand stakeholder perceptions of CMH NP role structures, processes, and outcomes and the extent to which the role meets patient and health service needs. METHODS: A qualitative descriptive study was conducted, guided by the PEPPA-Plus framework. Purposive sampling was used to recruit stakeholders who participated in focus groups and interviews. Content analysis was used to analyze the data. RESULTS: Participants included patients (n = 8) and healthcare professionals (n = 27). Themes about structures related to evolution of the CMH Program, model of care, and need for strategic vision. Process themes related to provision of accessible, comprehensive, and holistic care and NP workload. Positive and negative outcomes and lack of outcome measurement were identified. CONCLUSION: Structures related to patient and NP characteristics, organizational change, staffing, and how NP work is organized impacts on NP role implementation and outcomes. Organizational structures can be strengthened to improve the model of care and NP role implementation and workload. Value-added NP contributions related to providing comprehensive care with attention to safety and social determinants of health. Research is needed to evaluate NP role outcomes in CMH. IMPLICATIONS FOR NURSING PRACTICE: The results can inform role design and organization policies and strategies to promote the recruitment, retention, and optimization of NP roles in CMH settings. Priorities for future research are also identified.


Assuntos
Profissionais de Enfermagem , Papel do Profissional de Enfermagem , Pesquisa Qualitativa , Humanos , Feminino , Masculino , Pessoa de Meia-Idade , Adulto , Canadá , Enfermagem Oncológica , Neoplasias Hematológicas/enfermagem , Grupos Focais , Idoso
6.
Semin Speech Lang ; 33(3): 217-22, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22851343

RESUMO

AphasiaBank is a shared, multimedia database containing videos and transcriptions of ~180 aphasic individuals and 140 nonaphasic controls performing a uniform set of discourse tasks. The language in the videos is transcribed in Codes for the Human Analysis of Transcripts (CHAT) format and coded for analysis with Computerized Language ANalysis (CLAN) programs, which can perform a wide variety of language analyses. The database and the CLAN programs are freely available to aphasia researchers and clinicians for educational, clinical, and scholarly uses. This article describes the database, suggests some ways in which clinicians and clinician researchers might find these materials useful, and introduces a new language analysis program, EVAL, designed to streamline the transcription and coding processes, while still producing an extensive and useful language profile.


Assuntos
Afasia/terapia , Bases de Dados como Assunto , Terapia da Linguagem/métodos , Patologia da Fala e Linguagem/métodos , Humanos , Idioma , Multimídia , Gravação em Vídeo
7.
Water Sci Technol ; 62(8): 1865-71, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20962402

RESUMO

Removal of CBOD(5) and nitrogen from septic tank effluent was evaluated in four horizontal subsurface flow (HSSF) wetlands. An intermittently loaded cell was compared to a continuously loaded control cell, with both treatments receiving the same weekly volume. The intermittent cell was rapidly drained and "rested" for 24-hr, then refilled in steps, twice weekly. Two media with different particle sizes but similar porosities were also compared. The two media, light weight expanded shale and gravel, were both continuously loaded. As hypothesized, the wetland cell that was intermittently loaded had higher dissolved oxygen, greater ammonia removal, and greater nitrate production than the continuously loaded cells. Areal NH(3)-N removal for the intermittently loaded cell was 0.90 g m(-2) d(-1) compared to 0.47 g m(-2) d(-1) for the control. Ammonia removal was also higher in continuously loaded gravel cells than in cells with expanded shale. Ammonia-N removal was an order of magnitude lower in a similar SSF wetland that had been in operation for 3 years. However, CBOD(5), total suspended solids, and total nitrogen did not vary substantially among the treatments.


Assuntos
Nitrogênio/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Áreas Alagadas , Análise da Demanda Biológica de Oxigênio , Materiais de Construção , Filtração/métodos , Hidrodinâmica , Nitrogênio/análise , Tamanho da Partícula , Porosidade , Texas , Poluentes Químicos da Água/análise
8.
Am J Speech Lang Pathol ; 28(3): 1010-1018, 2019 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-31120767

RESUMO

Purpose This clinical focus article describes the development and use of the Famous People Protocol (FPP), a clinical tool for observing the strategies people with severe aphasia (PWSA) can use to communicate when speech is limited. Its goal is to provide a systematic approach to identifying individually appropriate communication strategies for PWSA. Method Though not a test, the FPP's development and pilot testing were consonant with qualitative approaches to test development. Eighty-one people with aphasia and 37 nonaphasic participants were given the current version of FPP and the Western Aphasia Battery-Revised (WAB-R; Kertesz, 2006). This clinical focus article reports on the 36 PWA who scored near or below the mean WAB score of the larger group. Results The FPP has a maximum score of 100 based on (a) identification of famous people in different categories, entertainers, athletes, U.S. presidents, sports figures, and internationally famous people, and (b) responses to additional questions about the famous people. Identification is scored quantitatively on a 3-point scale, and question responses are scored correct (1) or incorrect (0). Mean scores for the PWSA and control groups were 54.6 and 95.2, respectively. FPP and WAB-R scores were moderately correlated (r = .67). Qualitative results describe the variety of strategies that PWSA used on the FPP. Conclusions The FPP is a way for clinicians to engage PWSA in an activity that can reveal personally relevant strategies to help PWSA communicate more effectively. The strategies can then become the basis for subsequent training on using them conversationally. Appendixes provide examples of clinical approaches.


Assuntos
Afasia/terapia , Comunicação , Patologia da Fala e Linguagem/métodos , Adolescente , Adulto , Idoso , Afasia/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
9.
Am J Speech Lang Pathol ; 27(1S): 406-422, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29497752

RESUMO

Purpose: The purpose of this study was to examine the relationship between picture naming performance and the ability to communicate the gist, or essential elements, of a story. We also sought to determine if this relationship varied according to Western Aphasia Battery-Revised (WAB-R; Kertesz, 2007) aphasia subtype. Method: Demographic information, test scores, and transcripts of 258 individuals with aphasia completing 3 narrative tasks were retrieved from the AphasiaBank database. Narratives were subjected to a main concept analysis to determine gist production. A correlation analysis was used to investigate the relationship between naming scores and main concept production for the whole group of persons with aphasia and for WAB-R subtypes separately. Results: We found strong correlations between naming test scores and narrative gist production for the large sample of persons with aphasia. However, the strength of the correlations varied by WAB-R subtype. Conclusions: Picture naming may accurately predict gist production for individuals with Broca's and Wernicke's aphasia, but not for other WAB-R subtypes. Given the current reprioritization of outcome measurement, picture naming may not be an appropriate surrogate measure for functional communication for all persons with aphasia. Supplemental Materials: https://doi.org/10.23641/asha.5851848.


Assuntos
Anomia/psicologia , Afasia de Broca/psicologia , Afasia de Condução/psicologia , Afasia de Wernicke/psicologia , Compreensão , Idioma , Idoso , Idoso de 80 Anos ou mais , Anomia/diagnóstico , Afasia de Broca/diagnóstico , Afasia de Condução/diagnóstico , Afasia de Wernicke/diagnóstico , Bases de Dados Factuais , Feminino , Humanos , Testes de Linguagem , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa , Índice de Gravidade de Doença
10.
Aphasiology ; 31(2): 152-165, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28713191

RESUMO

BACKGROUND: This work focuses on the twenty-six individuals who provided data to AphasiaBank on at least two occasions, with initial testing between 6 months and 5.8 years post-onset of aphasia. The data are archival in nature and were collected from the extensive database of aphasic discourse in AphasiaBank. AIMS: The aim is to furnish data on the nature of long-term changes in both the impairment of aphasia as measured by the Western Aphasia Battery-Revised (WAB-R) and its expression in spoken discourse. METHODS AND PROCEDURES: AphasiaBank's demographic database was searched to discover all individuals who were tested twice at an interval of at least a year with either: 1) the AphasiaBank protocol; or 2) the AphasiaBank protocol at first testing, and the Famous People Protocol (FPP) at second testing. The Famous People Protocol is a measure developed to assess the communication strategies of individuals whose spoken language limitations preclude full participation in the AphasiaBank protocol. The 26 people with aphasia (PWA) who were identified had completed formal speech therapy before being seen for AphasiaBank. However, all were participants in aphasia centers where at least three hours of planned activities were available, in most cases, twice weekly. WAB-R Aphasia Quotient scores (AQ) were examined, and in those cases where AQ scores improved, changes were assessed on a number of measures from the AphasiaBank discourse protocol. OUTCOMES AND RESULTS: Sixteen individuals demonstrated improved WAB-R AQ scores, defined as positive AQ change scores greater than the WAB-R AQ standard error of the mean (WAB-SEM); seven maintained their original WAB quotients, defined as AQ change scores that were not greater than the WAB-SEM; and the final three showed negative WAB-R change scores, defined as a negative WAB-R AQ change score greater than the WAB-SEM. Concurrent changes on several AphasiaBank tasks were also found, suggesting that the WAB-R improvements were noted in more natural discourse as well. CONCLUSIONS: These data are surprising, since conventional wisdom suggests that spontaneous improvement in language is unlikely to occur beyond one year. Long-term improvement or maintenance of early test scores, such as that shown here, has seldom been demonstrated in the absence of formal treatment. Speculations about why these PWA improved, maintained or declined in their scores are considered.

11.
Am J Speech Lang Pathol ; 26(3): 762-768, 2017 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-28505222

RESUMO

PURPOSE: This study examined discourse characteristics of individuals with aphasia who scored at or above the 93.8 cutoff on the Aphasia Quotient subtests of the Western Aphasia Battery-Revised (WAB-R; Kertesz, 2007). They were compared with participants without aphasia and those with anomic aphasia. METHOD: Participants were from the AphasiaBank database and included 28 participants who were not aphasic by WAB-R score (NABW), 92 participants with anomic aphasia, and 177 controls. Cinderella narratives were analyzed using the Computerized Language Analysis programs (MacWhinney, 2000). Outcome measures were words per minute, percent word errors, lexical diversity using the moving average type-token ratio (Covington, 2007b), main concept production, number of utterances, mean length of utterance, and proposition density. RESULTS: Results showed that the NABW group was significantly different from the controls on all measures except MLU and proposition density. These individuals were compared to participants without aphasia and those with anomic aphasia. CONCLUSION: Individuals with aphasia who score above the WAB-R Aphasia Quotient cutoff demonstrate discourse impairments that warrant both treatment and special attention in the research literature.


Assuntos
Anomia/diagnóstico , Afasia/diagnóstico , Testes de Linguagem , Medida da Produção da Fala/métodos , Patologia da Fala e Linguagem/métodos , Fala , Qualidade da Voz , Anomia/fisiopatologia , Anomia/psicologia , Anomia/reabilitação , Afasia/fisiopatologia , Afasia/psicologia , Afasia/reabilitação , Estudos de Casos e Controles , Bases de Dados Factuais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fonética , Valor Preditivo dos Testes , Semântica
12.
J Speech Lang Hear Res ; 59(5): 1123-1132, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27657850

RESUMO

Purpose: This study evaluates how proposition density can differentiate between persons with aphasia (PWA) and individuals in a control group, as well as among subtypes of aphasia, on the basis of procedural discourse and personal narratives collected from large samples of participants. Method: Participants were 195 PWA and 168 individuals in a control group from the AphasiaBank database. PWA represented 6 aphasia types on the basis of the Western Aphasia Battery-Revised (Kertesz, 2006). Narrative samples were stroke stories for PWA and illness or injury stories for individuals in the control group. Procedural samples were from the peanut-butter-and-jelly-sandwich task. Language samples were transcribed using Codes for the Human Analysis of Transcripts (MacWhinney, 2000) and analyzed using Computerized Language Analysis (MacWhinney, 2000), which automatically computes proposition density (PD) using rules developed for automatic PD measurement by the Computerized Propositional Idea Density Rater program (Brown, Snodgrass, & Covington, 2007; Covington, 2007). Results: Participants in the control group scored significantly higher than PWA on both tasks. PD scores were significantly different among the aphasia types for both tasks. Pairwise comparisons for both discourse tasks revealed that PD scores for the Broca's group were significantly lower than those for all groups except Transcortical Motor. No significant quadratic or linear association between PD and severity was found. Conclusion: Proposition density is differentially sensitive to aphasia type and most clearly differentiates individuals with Broca's aphasia from the other groups.


Assuntos
Afasia/diagnóstico , Diagnóstico por Computador , Narração , Reconhecimento Automatizado de Padrão , Fala , Idoso , Feminino , Humanos , Testes de Linguagem , Masculino , Pessoa de Meia-Idade , Análise Multivariada
15.
Handb Clin Neurol ; 110: 325-34, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23312652

RESUMO

Aphasia is one of the most striking cognitive sequels of strokes and other cerebral lesions, and attempts to rehabilitate aphasic patients have been undertaken for many years. Following a brief overview of the epidemiology and the clinical characteristics of aphasia, the chapter presents the major traditional approaches to rehabilitation. They include the stimulation approach (also called classic), the behavior modification approach, Luria's approach (functional reorganization), the pragmatic approach, as well as the neurolinguistic approach. The next section illustrates some of the current approaches to aphasia rehabilitation, specifically the syndromic approach (also called neoassociationist), the cognitive neuropsychological approach, and the social approach. The chapter then provides examples of specific methods. While all intervention strategies may be classified, more or less correctly, into one or another of the above categories, it is not possible to mention the hundreds of specific interventions to be found in the literature, some of which have been described only briefly and in reference to a single case. The chapter concludes with a review of efficacy studies on aphasia therapy. Despite some opinions to the contrary, the current consensus is that sufficient experimental evidence of efficacy exists to recommend treatment of aphasia.


Assuntos
Afasia/reabilitação , Fonoterapia/métodos , Afasia/epidemiologia , Afasia/etiologia , Lesões Encefálicas/complicações , Lesões Encefálicas/patologia , Córtex Cerebral/fisiopatologia , Terapia Cognitivo-Comportamental/história , Terapia Cognitivo-Comportamental/métodos , História do Século XX , Humanos , Fonoterapia/história
16.
Aphasiology ; 25(11): 1286-1307, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22923879

RESUMO

BACKGROUND: AphasiaBank is a computerized database of interviews between persons with aphasia (PWAs) and clinicians. By February 2011, the database had grown to include 145 PWAs and 126 controls from 12 sites across the United States. The data and related analysis programs are available free over the web. AIMS: The overall goal of AphasiaBank is the construction of a system for accumulating and sharing data on language usage by PWAs. To achieve this goal, we have developed a standard elicitation protocol and systematic automatic and manual methods for transcription, coding, and analysis. METHODS #ENTITYSTARTX00026; PROCEDURES: We present sample analyses of transcripts from the retelling of the Cinderella story. These analyses illustrate the application of our methods for the study of phonological, lexical, semantic, morphological, syntactic, temporal, prosodic, gestural, and discourse features. MAIN CONTRIBUTION: AphasiaBank will allow researchers access to a large, shared database that can facilitate hypothesis testing and increase methodological replicability, precision, and transparency. CONCLUSIONS: AphasiaBank will provide researchers with an important new tool in the study of aphasia.

17.
Aphasiology ; 25(11): 1431-1447, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22347765

RESUMO

PURPOSE: This study examined responses of persons with aphasia (PWAs) to a general question about their speech. The goal was to describe their evaluative responses as positive, negative, or neutral/mixed and determine if responses differed, based on time post-onset, aphasia severity, and aphasia type. METHODS: 71 participants from the AphasiaBank project were included. As part of a larger protocol, investigators asked, "How do you think your speech is these days?" Responses were videotaped and transcribed using CLAN. Two authors coded the evaluative responses and categorized themes in the elaborative content provided by the participants. RESULTS: Positive responses accounted for 59% of all responses, followed by neutral/mixed (18%), and negative (17%). Participants also mentioned specific speech problems (35%), improvement (31%), and therapy (8%) in their responses. Time post-onset and aphasia type were not significantly associated with nature of response. Aphasia severity was significantly associated with nature of response, with higher AQ scores in the positive group and vice versa. CONCLUSIONS: The responses are discussed in the context of self-image and self-expression in PWA and social models in aphasia therapy. Results are also compared with those of others with chronic disabilities and research on resilience, positive affect, and optimism.

18.
Aphasiology ; 24(6-8): 856-868, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25067870

RESUMO

BACKGROUND: AphasiaBank is a collaborative project whose goal is to develop an archival database of the discourse of individuals with aphasia. Along with databases on first language acquisition, classroom discourse, second language acquisition, and other topics, it forms a component of the general TalkBank database. It uses tools from the wider system that are further adapted to the particular goal of studying language use in aphasia. AIMS: The goal of this paper is to illustrate how TalkBank analytic tools can be applied to AphasiaBank data. METHODS & PROCEDURES: Both aphasic (n = 24) and non-aphasic (n = 25) participants completed a 1-hour standardised videotaped data elicitation protocol. These sessions were transcribed and tagged automatically for part of speech. One component of the larger protocol was the telling of the Cinderella story. For these narratives we compared lexical diversity across the groups and computed the top 10 nouns and verbs across both groups. We then examined the profiles for two participants in greater detail. CONCLUSIONS: Using these tools we showed that, in a story-retelling task, aphasic speakers had a marked reduction in lexical diversity and a greater use of light verbs. For example, aphasic speakers often substituted "girl" for "stepsister" and "go" for "disappear". These findings illustrate how it is possible to use TalkBank tools to analyse AphasiaBank data.

19.
Environ Sci Technol ; 39(12): 4621-7, 2005 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-16047801

RESUMO

Most subsurface flow treatment wetlands, also known as reed bed or root zone systems, use sand or gravel substrates to reduce organics, solids, and nutrients in septic tank effluents. Phosphorus (P) retention in these systems is highly variable and few studies have identified the fate of retained P. In this study, two substrates, expanded shale and masonry sand, were used as filter media in five subsurface flow pilot-scale wetlands (2.7 m3). After 1 year of operation, we estimated the annual rate of P sorption by taking the difference between total P (TP) of substrate in the pilot cells and TP of substrate not exposed to wastewater (control). Means and standard deviations of TP retained by expanded shale were 349 +/- 171 mg kg(-1), respectively. For a substrate depth of 0.9 m, aerial P retention by shale was 201 +/- 98.6 g of P m(-2) year(-1), respectively. Masonry sand retained an insignificant quantity of wastewater P (11.9 +/- 21.8 mg kg(-1)) and on occasion exported P. Substrate samples were also sequentially fractionated into labile P, microbial P, (Fe + Al) P, humic P, (Ca + Mg) P, and residual P. In expanded shale samples, the greatest increase in P was in the relatively permanent form of (Fe + Al) P (108 mg kg(-1)), followed by labile P (46.7 mg kg(-1)) and humic P (39.8 mg kg(-1)). In masonry sand, there was an increase in labile P (9.71 mg kg(-1)). Results suggest that sand is a poor candidate for long-term P storage, but its efficiency is similar to that reported for many sand, gravel, and rock systems. By contrast, expanded shale and similar products with high hydraulic conductivity and P sorption capacity could greatly improve performance of P retention in constructed wetlands.


Assuntos
Sedimentos Geológicos/química , Fósforo/química , Fósforo/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Movimentos da Água , Purificação da Água/métodos , Adsorção , Fracionamento Químico , Dióxido de Silício/química
20.
Environ Sci Technol ; 38(3): 892-8, 2004 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-14968879

RESUMO

Using surface flow constructed wetlands for long-term phosphorus (P) retention presents a challenge due to the fact that P is stored primarily in the sediments. Subsurface flow wetlands have the potential to greatly increase P retention; however, the substrate needs to have both high hydraulic conductivity and high P sorption capacity. The objective of our study was to assess the P retention capacity of two substrates, masonry sand and lightweight expanded shale. We used sorption/desorption isotherms, flow-through column experiments, and pilot-scale wetlands to quantify P retained from treated municipal wastewater. Langmuir sorption isotherms predicted that the expanded shale has a maximum sorption capacity of 971 mg/kg and the masonry sand 58.8 mg/kg. In column desorption and column flow-through experiments, the masonry sand desorbed P when exposed to dilute P solutions. The expanded shale, however, had very little desorption and phosphorus did not break through the columns during our experiment. In pilot cells, masonry sand retained (mean +/- standard deviation) 45 +/- 62 g P/m2/yr and expanded shale retained 164 +/- 110 g P/m2/yr. We conclude that only the expanded shale would be a suitable substrate for retaining P in a subsurface flow wetland.


Assuntos
Materiais de Construção , Ecossistema , Fósforo/análise , Purificação da Água/métodos , Biodegradação Ambiental , Monitoramento Ambiental , Sedimentos Geológicos/química , Fósforo/química , Fósforo/isolamento & purificação , Dióxido de Silício , Solubilidade
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