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1.
J Invertebr Pathol ; 186: 107397, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-32446865

RESUMO

Shrimp is not only one of the world's most valuable aquaculture species, but also a species that encounter high economic losses due to diseases. Diseases are sufficiently important to influence global supply and prices for longer periods. Profitability is the driving force behind shrimp farming and high profits associated with the absence of disease largely determines where shrimp production does take place; i.e. prevalence of disease leads to geographic relocation. In this paper, a basic economic model for the impact of the disease on a shrimp farm is provided and a Monte Carlo simulation is provided to illustrate the impact of disease on economic risk. Improved technologies, knowledge, and governance are important elements utilized in the mitigation of diseases in various shrimp producing countries. Economic aspects such as profitability in the absence and presence of diseases and cost of treatment determines the global production of shrimp along with shaping technologies and production systems.


Assuntos
Aquicultura/economia , Penaeidae/microbiologia , Penaeidae/parasitologia , Animais , Penaeidae/virologia
2.
Proc Natl Acad Sci U S A ; 115(44): 11221-11225, 2018 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30249663

RESUMO

Sustainability of global fisheries is a growing concern. The United Nations has identified three pillars of sustainability: economic development, social development, and environmental protection. The fisheries literature suggests that there are two key trade-offs among these pillars of sustainability. First, poor ecological health of a fishery reduces economic profits for fishers, and second, economic profitability of individual fishers undermines the social objectives of fishing communities. Although recent research has shown that management can reconcile ecological and economic objectives, there are lingering concerns about achieving positive social outcomes. We examined trade-offs among the three pillars of sustainability by analyzing the Fishery Performance Indicators, a unique dataset that scores 121 distinct fishery systems worldwide on 68 metrics categorized by social, economic, or ecological outcomes. For each of the 121 fishery systems, we averaged the outcome measures to create overall scores for economic, ecological, and social performance. We analyzed the scores and found that they were positively associated in the full sample. We divided the data into subsamples that correspond to fisheries management systems with three categories of access-open access, access rights, and harvest rights-and performed a similar analysis. Our results show that economic, social, and ecological objectives are at worst independent and are mutually reinforcing in both types of managed fisheries. The implication is that rights-based management systems should not be rejected on the basis of potentially negative social outcomes; instead, social considerations should be addressed in the design of these systems.


Assuntos
Pesqueiros/economia , Conservação dos Recursos Naturais/economia , Ecologia/economia , Ecossistema , Humanos , Alimentos Marinhos/economia , Fatores Socioeconômicos
3.
J Paediatr Child Health ; 50(11): 908-15, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24920104

RESUMO

AIM: To examine associations of prenatal maternal smoking and second-hand smoke (SHS) exposure with the development of adolescent obesity. METHODS: Longitudinal data (1991-2007) from National Institute of Child Health and Human Development Study of Early Child Care and Youth Development involving mothers that smoked and or exposed to SHS during the year before birth were analysed. Adolescent obesity in ages 12.0-15.9 years was defined as a BMI ≥ 95th percentile. Generalised estimating equations (GEE) were used for the analyses. RESULTS: Obesity was more prevalent among adolescents whose mothers smoked or had SHS exposure than those that did not smoke or exposed to SHS. After adjusting for maternal and child factors, GEE models showed that odds of adolescent obesity increased with prenatal maternal smoking (OR = 1.57, 95% CI = 1.03-2.39) and SHS exposure (OR = 1.53, 95% CI = 1.04-2.27). The odds for obesity increased more than two times among adolescents exposed to both maternal smoking and SHS (OR = 2.10, 95% CI = 1.24, 3.56) compared with those without exposure. Additionally, not breastfeeding, maternal obesity, and longer screen viewing hours per day were associated with increased odds of obesity. CONCLUSIONS: There is possibly a long-term joint effect of prenatal maternal smoke (smoking and SHS) exposure on obesity among adolescent offspring, and the effect is independent of birthweight. These findings suggest that adolescent obesity could possibly be curtailed with the development and promotion of smoking cessation programmes for families during the year before birth.


Assuntos
Exposição Materna/efeitos adversos , Obesidade/etiologia , Efeitos Tardios da Exposição Pré-Natal/etiologia , Fumar/efeitos adversos , Adolescente , Distribuição por Idade , Peso ao Nascer , Distribuição de Qui-Quadrado , Estudos de Coortes , Feminino , Idade Gestacional , Humanos , Incidência , Estudos Longitudinais , Masculino , Análise Multivariada , Obesidade/epidemiologia , Obesidade Infantil/epidemiologia , Obesidade Infantil/etiologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/epidemiologia , Prognóstico , Medição de Risco , Distribuição por Sexo
4.
Bull Volcanol ; 86(5): 45, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38617076

RESUMO

Volcanic islands are often subject to flank instability, resulting from a combination of magmatic intrusions along rift zones and gravitational spreading causing extensional faulting at the surface. Here, we study the Koa'e fault system (KFS), located south of the summit caldera of Kilauea volcano in Hawai'i, one of the most active volcanoes on Earth, prone to active faulting, episodic dike intrusions, and flank instability. Two rift zones and the KFS are major structures controlling volcanic flank instability and magma propagation. Although several magmatic intrusions occurred over the KFS, the link between these faults, two nearby rift zones and the flank instability, is still poorly studied. To better characterize the KFS and its structural linkage with the surrounding fault and rift zones, we performed a detailed structural analysis of the extensional fault system, coupled with a helicopter photogrammetric survey, covering part of the south flank of Kilauea. We generated a high-resolution DEM (~ 8 cm) and orthomosaic (~ 4 cm) to map the fracture field in detail. We also collected ~ 1000 ground structural measurements of extensional fractures during our three field missions (2019, 2022, and 2023). We observed many small, interconnected grabens, monoclines, rollover structures, and en-echelon fractures that were in part previously undocumented. We estimate the cumulative displacement rate across the KFS during the last 600 ~ 700 years and found a decrease toward the west of the horizontal component from 2 to 6 cm per year, consistent with GNSS data. Integrating morphology observations, fault mapping, and kinematic measurements, we propose a new kinematic model of the upper part of the Kilauea's south flank, suggesting a clockwise rotation and a translation of a triangular wedge. This wedge is bordered by the extensional structures (ERZ, SWRZ, and the KFS), largely influenced by gravitational spreading. These findings illustrate a structural linkage between the two rift zones and the KFS, the latter being episodically affected by dike intrusions. Supplementary Information: The online version contains supplementary material available at 10.1007/s00445-024-01735-7.

5.
Nat Commun ; 15(1): 5274, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38902254

RESUMO

Aquaculture is a rapidly growing food production technology, but there are significant concerns related to its environmental impact and adverse social effects. We examine aquaculture outcomes in a three pillars of sustainability framework by analyzing data collected using the Aquaculture Performance Indicators. Using this approach, comparable data has been collected for 57 aquaculture systems worldwide on 88 metrics that measure social, economic, or environmental outcomes. We first examine the relationships among the three pillars of sustainability and then analyze performance in the three pillars by technology and species. The results show that economic, social, and environmental outcomes are, on average, mutually reinforced in global aquaculture systems. However, the analysis also shows significant variation in the degree of sustainability in different aquaculture systems, and weak performance of some production systems in some dimensions provides opportunity for innovative policy measures and investment to further align sustainability objectives.


Assuntos
Aquicultura , Conservação dos Recursos Naturais , Aquicultura/economia , Aquicultura/métodos , Conservação dos Recursos Naturais/métodos , Conservação dos Recursos Naturais/economia , Humanos , Meio Ambiente , Animais , Desenvolvimento Sustentável/economia , Pesqueiros/economia
6.
Matern Child Health J ; 17(5): 940-8, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22833333

RESUMO

To examine the association between maternal depressive symptoms during early childhood of their offspring and later overweight in the children. Only children (n = 1,090) whose weights and heights were measured at least once for three time points (grades one, three and six) from the National Institute of Child Health and Human Development Study were included. Maternal depressive symptoms, defined as a Center for Epidemiologic Studies Depression Scale (CES-D) score of 16 or greater, were assessed using CES-D when the child was 1, 24, and 36 months. Childhood overweight was based on standardized height and weight measures taken during the interviews, and was defined according to appropriate CDC age- and sex-specific BMI percentiles. Generalized estimating equation was used to examine the impact of maternal depressive symptoms on the childhood overweight after adjusting for covariates. Compared to children of mothers without depression at any of the three time points, when children were one, 24 and 36 months of age, children of mothers with depression at all three time points were 1.695 times more likely to be overweight after adjusting for other child characteristics (95 % CI = 1.001-2.869). When further adjusted for maternal characteristics, children of mothers with depression at all three time points were 2.13 times more likely to be overweight (95 % CI = 1.05-4.31). Persistent maternal depressive symptoms may be associated with an increased risk of childhood overweight in their offspring. Children of mothers with depression may benefit from special attention in terms of obesity prevention.


Assuntos
Depressão/diagnóstico , Depressão/psicologia , Mães/psicologia , Sobrepeso/etiologia , Complicações na Gravidez/diagnóstico , Complicações na Gravidez/psicologia , Índice de Massa Corporal , Criança , Pré-Escolar , Depressão/complicações , Depressão/epidemiologia , Feminino , Humanos , Lactente , Sobrepeso/epidemiologia , Gravidez , Complicações na Gravidez/epidemiologia , Efeitos Tardios da Exposição Pré-Natal , Prevalência , Escalas de Graduação Psiquiátrica , Fatores de Risco , Fatores Socioeconômicos , Inquéritos e Questionários , Tennessee/epidemiologia
7.
Nat Food ; 4(12): 1058-1069, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38093119

RESUMO

Food loss and waste (FLW) is a major challenge to food system sustainability, including aquatic foods. We investigated aquatic FLW in the food supply of the United States, the largest importer of aquatic food globally, using primary and secondary data and life cycle methodology. We show that there are significant differences in FLW among species, production technology, origin and stage of supply chain. We estimate total aquatic FLW was 22.7%, which is 43-55% lower than earlier estimates reported in the literature, illustrating the importance of applying a disaggregated approach. Production losses associated with imported food contribute over a quarter of total FLW, and addressing these losses requires multinational efforts to implement interventions along the supply chain. These findings inform prioritization of solutions-including areas of need for innovations, government incentives, policy change, infrastructure and equity.


Assuntos
Perda e Desperdício de Alimentos , Abastecimento de Alimentos , Estados Unidos , Humanos , Alimentos , Caquexia
9.
Nat Commun ; 10(1): 1641, 2019 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-30967539

RESUMO

We characterize the ecological, economic, and community performance of 21 major tuna fisheries, accounting for at least 77% of global tuna production, using the Fishery Performance Indicators. Our analysis reveals that the biggest variations in performance among tuna fisheries are driven by the final markets that they target: international sashimi market tuna fisheries considerably outperform a comparison set of 62 non-tuna fisheries in the Fishery Performance Indicator database, international canned tuna market fisheries perform similarly to the comparison set, and tuna fisheries supplying local markets in coastal states considerably underperform the comparison set. Differences among regional fishery management organizations primarily reflect regional species composition and market access, despite stark variation in governance, management, and other enabling conditions. With a legacy of open access, tuna's harvest sector performance is similar across all fisheries, reflecting only a normal return on the capital and skill invested: industrial vessels slightly outperform semi-industrial and artisanal vessels. Differences emerge in the post-harvest sector however, as value chains able to preserve quality and transport fish to high value markets outperform others.


Assuntos
Pesqueiros/organização & administração , Alimentos Marinhos/estatística & dados numéricos , Gestão da Qualidade Total/estatística & dados numéricos , Atum , Animais , Conservação dos Recursos Naturais/economia , Conservação dos Recursos Naturais/estatística & dados numéricos , Bases de Dados Factuais/estatística & dados numéricos , Pesqueiros/economia , Pesqueiros/estatística & dados numéricos , Alimentos Marinhos/economia , Gestão da Qualidade Total/economia
10.
Asia Pac J Public Health ; 27(2): NP2764-72, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23666844

RESUMO

Health literacy has become an important public health concern. Multistage cluster random sampling was used to select 12 450 individuals. Using the 2009 Chinese Health Literacy questionnaire, participants were divided into groups with poor or not poor health literacy status. The knowledge rates for 6 areas of health literacy were determined with the following results: science concept of health (60.0%), literacy for preventing acute infectious disease (66.8%), literacy for preventing noncommunicable chronic disease (51.9%), safety and first aid (66.8%), obtaining and making use of basic medical care (55.3%), and comprehensive health literacy (52.5%). Multiple logistic regression showed that living in a rural area, fewer individuals in a household, younger age, low education, agricultural or rural migrant occupation workers, and low family income were associated with a poor health literacy status. Our results support the use of health education and promotion interventions to improve health literacy in this high-risk population in China.


Assuntos
Letramento em Saúde , Adulto , Fatores Etários , China/epidemiologia , Doença Crônica/prevenção & controle , Controle de Doenças Transmissíveis , Feminino , Primeiros Socorros , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Características de Residência , Fatores de Risco , Segurança , Fatores Socioeconômicos , Inquéritos e Questionários
11.
PLoS One ; 10(5): e0122809, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25946194

RESUMO

Pursuit of the triple bottom line of economic, community and ecological sustainability has increased the complexity of fishery management; fisheries assessments require new types of data and analysis to guide science-based policy in addition to traditional biological information and modeling. We introduce the Fishery Performance Indicators (FPIs), a broadly applicable and flexible tool for assessing performance in individual fisheries, and for establishing cross-sectional links between enabling conditions, management strategies and triple bottom line outcomes. Conceptually separating measures of performance, the FPIs use 68 individual outcome metrics--coded on a 1 to 5 scale based on expert assessment to facilitate application to data poor fisheries and sectors--that can be partitioned into sector-based or triple-bottom-line sustainability-based interpretative indicators. Variation among outcomes is explained with 54 similarly structured metrics of inputs, management approaches and enabling conditions. Using 61 initial fishery case studies drawn from industrial and developing countries around the world, we demonstrate the inferential importance of tracking economic and community outcomes, in addition to resource status.


Assuntos
Pesqueiros/normas , Gestão da Qualidade Total , Pesqueiros/economia
12.
J Agric Food Chem ; 50(1): 209-12, 2002 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-11754569

RESUMO

The chlorine loss of electrolyzed oxidizing (EO) water was examined during storage under different light, agitation, and packaging conditions. The chlorine loss of pH-adjusted EO water was also examined. Under open conditions, the chlorine loss through evaporation followed first-order kinetics. The rate of chlorine loss was increased about 5-fold with agitation, but it was not significantly affected by diffused light. Under closed conditions, the chlorine loss did not follow first-order kinetics, because the primary mechanism of chlorine loss may be self-decomposition of chlorine species rather than chlorine evaporation. The effect of diffused light was more significant compared to agitation after two months of storage under closed conditions. The chlorine loss of EO water and commercial chlorinated water decreased dramatically with the increase of pH from the acidic (pH 2.5) to the alkaline (pH 9.0) region.


Assuntos
Cloro/metabolismo , Conservação de Alimentos/métodos , Água/análise , Eletrólise , Embalagem de Alimentos , Concentração de Íons de Hidrogênio , Cinética , Luz , Oxirredução , Fatores de Tempo
13.
J Adolesc Health ; 54(2): 144-50, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24060576

RESUMO

PURPOSE: To estimate susceptibility to smoking among never-smoking youth globally and identify factors associated with such behavior. METHODS: Cross-sectional data for 168 countries were obtained from the Global Youth Tobacco Survey. Simple and multiple logistic regression analyses were conducted. Frequencies and proportions for descriptive statistics, and adjusted odds ratios with 95% confidence intervals for logistic regression models were reported. RESULTS: Approximately 12.5% of never-smoking youth worldwide were susceptible to smoking worldwide, of which 7.2% were males and 5.3% were females. Compared with youth in the Americas, those in other WHO regions were associated with decreased susceptibility to smoking. Regardless of gender, exposure to parental or peer smoking, secondhand smoke inside or outside home, and tobacco industry promotion was associated with increased smoking susceptibility. In contrast, support for smoke-free policies and school antismoking education was associated with decreased susceptibility to smoking among females. Moreover, exposure to antismoking media messages was associated with increased susceptibility to smoking among never-smoking youth. CONCLUSIONS: Approximately 1 in 8 never-smoking youth worldwide was found to be susceptible to smoking. A comprehensive approach involving parental and peer education, smoke-free policies, ban on tobacco advertising and promotions, and antismoking education in schools should be developed by policy makers and public health professionals to protect never-smoking youth from being susceptible to smoking and transforming into future regular smokers.


Assuntos
Comportamento do Adolescente , Fumar , Adolescente , Comportamento do Adolescente/psicologia , Estudos Transversais , Feminino , Saúde Global , Educação em Saúde/estatística & dados numéricos , Humanos , Modelos Logísticos , Masculino , Fatores Sexuais
14.
J Mol Neurosci ; 50(2): 250-6, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23229837

RESUMO

Major depression disorder (MDD) is a complex and chronic disease that ranks fourth as cause of disability worldwide. About 14 million adults in the USA are believed to have MDD, and an estimated 75 % attempt suicide making MDD a major public health problem. Neuroticism has been recognized as an endophenotype of MDD; however, few genome-wide association (GWA) analyses of neuroticism as a quantitative trait have been reported to date. The aim of this study is to identify genome-wide genetic variants affecting neuroticism using a European sample. A linear regression model was used to analyze the association with neuroticism as a continuous trait in the Netherlands Study of Depression and Anxiety and Netherlands Twin Registry population-based sample of 2,748 individuals with Perlegen 600K single nucleotide polymorphisms (SNPs). In addition, the neuroticism-associated genes/loci of the top 20 SNPs (p < 10⁻4) were examined with anti-social personality disorder (ASPD) in an Australian twin family study. Through GWA analysis, 32 neuroticism-associated SNPs (p < 10⁻4) were identified. The most significant association was observed with SNP rs4806846 within the TMPRSS9 gene (p = 7.79 × 10⁻6) at 19p13.3. The next best signal was in GRIN2B gene (rs220549, p = 1.05 × 10⁻5) at 12p12. In addition, several SNPs within GRIN2B showed borderline associations with ASPD in the Australian sample. In conclusion, these results provide a possible genetic basis for the association with neuroticism. Our findings provide a basis for replication in other populations to elucidate the potential role of these genetic variants in neuroticism and MDD along with a possible relationship between ASPD and neuroticism.


Assuntos
Transtornos de Ansiedade/genética , Estudo de Associação Genômica Ampla , Receptores de N-Metil-D-Aspartato/genética , Serina Endopeptidases/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Transtorno da Personalidade Antissocial/genética , Austrália , Feminino , Genoma Humano , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos , Neuroticismo , Polimorfismo de Nucleotídeo Único , Característica Quantitativa Herdável , População Branca/genética
15.
Artigo em Inglês | MEDLINE | ID: mdl-28615549

RESUMO

BACKGROUND: Limited epidemiologic studies have investigated the effects of pesticide exposure during pregnancy on low birth weight in offspring in rural China. METHODS: A survey of a total of 503 women was conducted in Ling county of Shandong Province of China following delivery from 1 November 2009 to 8 February 2010. RESULTS: After adjustment for confounding and compared with no pesticide exposure, multiple logistic regression showed a non-significant increased likelihood of low birth weight for both children of mothers exposed to pesticides when not pregnant (OR = 1.80, 95% CI: 0.62, 5.22) and mothers exposed to pesticides during pregnancy (OR = 2.42, 95% CI: 0.73, 8.08); multiple linear regression showed a non-significant reduced birth weight for both children of mothers exposed to pesticides when not pregnant (ß=-0.59, p=0.28) and mothers exposed to pesticides during pregnancy (ß=-0.89, p=0.15). CONCLUSIONS: Exposure to pesticides during pregnancy was associated with a non-significant increase in low birth weight in this rural Chinese population. Future studies using larger sample sizes and longer follow-up periods are warranted.

16.
J Womens Health (Larchmt) ; 20(5): 711-8, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21426237

RESUMO

BACKGROUND: This longitudinal study examined maternal depression status from birth of a child to 36 months of age using data from the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and Youth Development. METHODS: Maternal depression was assessed using the Center of Epidemiological Studies Depression Scale (CES-D) and defined as a score of ≥16. For this study, early onset depression was defined as depression within the 6 months after birth, and late onset depression was depression onset when the child was ≥24 months old. Chronic depression was defined as depression that started within 6 months after birth and lasted until 24 months of age or longer. RESULTS: The prevalence of maternal depression was 32.2% for early onset, 7.4% for late onset, and 13.4% for chronic depression. The prevalence of maternal depression was highest at 1 month, decreased at 6 months, and then remained fairly stable until 36 months. Mothers 18-24 years of age, of black race, unemployed, with lower social support, single, or with poor general health had a higher prevalence of both early and chronic depression compared to other groups. CONCLUSIONS: Younger maternal age, poverty, lower education, and lack of social support were all significantly associated with increased maternal depression in multivariate regression models. Younger age, black race, unemployment, single status, lack of social support, and poor general health were all risk factors for increased prevalence of maternal depression.


Assuntos
Transtorno Depressivo/epidemiologia , Mães/psicologia , Mães/estatística & dados numéricos , Adolescente , Adulto , Educação Infantil , Pré-Escolar , Transtorno Depressivo/diagnóstico , Feminino , Humanos , Lactente , Recém-Nascido , Modelos Logísticos , Estudos Longitudinais , Pessoa de Meia-Idade , Pobreza , Prevalência , Fatores de Risco , Apoio Social , Inquéritos e Questionários , Estados Unidos/epidemiologia , Adulto Jovem
18.
Environ Sci Technol ; 42(17): 6538-43, 2008 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-18800527

RESUMO

Uncertainty still exists regarding the role(s) of natural organic matter in the reduction of chemicals in anoxic environments. This work studied the effect of Suwannee river humic acid (SRHA) on the reduction of nitrobenzenes in goethite suspensions by Fe(II) species. The pseudo-first-order rate constant for the reduction of p-cyanonitrobenzene (k(CNNB)) was different for the first 3 half-lives in systems where Fe(II)aq and dissolved SRHA were equilibrated in reverse orders with goethite in suspensions. k(CNNB) and the reduction capacity of the system having SRHA added after Fe(II)aq was equilibrated with goethite was lower than that of the system for which the components were added in the reverse order. SRHA decreased the reduction capacity of the former system by oxidizing and/or complexing the surface-associated Fe(II), Fe(II)(surf), and/or hindering the access of CNNB to Fe(II)(surf). The log k(CNNB) increased linearlywith increasing concentrations of Fe(II)aq, which decreased as a result of increasing concentrations of SRHA in the system. Different k(CNNB)'s were observed for systems in which Fe(II)aq was equilibrated with goethite/SRHA suspensions for 24 and 48 h, suggesting sorbed SRHA oxidized and/or complexed Fe(II)aq. Findings suggest the concentration of Fe(II)aq and accessible Fe(ll)(surf) will influence the reduction rates of nitroaromatics in anoxic environments.


Assuntos
Compostos Ferrosos/química , Substâncias Húmicas , Compostos de Nitrogênio/química , Oxirredução
20.
Environ Sci Technol ; 40(16): 4976-82, 2006 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-16955895

RESUMO

The development of predictive models for the reductive transformation of nitroaromatics requires further clarification of the effect of environmentally relevant variables on reaction kinetics and the identification of readily available molecular descriptors for calculating reactivity. Toward these goals, studies were performed on the reduction of a series of monosubstituted nitrobenzenes in Fe(II)-treated goethite suspensions. The energy of the lowest unoccupied molecular orbital, ELUMO (B3LYP/6-31G*,water), of the nitrobenzenes was capable of explaining 99% of the variability in the rates. Results of experiments in which the surface area loading of ferric oxides was systematically varied indicate that (i) the reactivity of mineral-surface-associated Fe(II), Fe(II)surf, toward the reduction of p-cyanonitrobenzene (CNNB) decreased in the order hematite > goethite > lepidocrocite > ferrihydrite and (ii) the surface density of Fe(II)surf did not play a crucial role in determining the observed reactivity trend. CNNB was reduced in Fe(II)-only control experiments in a pH range of 7.28-7.97 with a pH dependency consistent with the transformation of Fe(II) to Fe(OH)3 or related oxides. The pH dependency of the reduction of CNNB in Fe(II)-treated ferric oxide suspensions (pH 6.1-7.97) could be accounted for by the oxidation of Fe(II)surf, forming an Fe(III) oxide.


Assuntos
Monitoramento Ambiental/métodos , Compostos Férricos/química , Compostos Ferrosos/química , Ferro/análise , Nitrobenzenos/análise , Compostos Nitrosos/química , Compostos Férricos/análise , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Nitrobenzenos/química , Oxirredução , Óxidos/química , Relação Quantitativa Estrutura-Atividade , Propriedades de Superfície , Fatores de Tempo
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