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1.
Environ Monit Assess ; 195(2): 298, 2023 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-36637512

RESUMEN

Polychlorinated dibenzo-p-dioxins and dibenzofurans in the sediments of aquatic systems are a persistent global problem that poses serious health risks. Identifying the sources of dioxins in natural water systems and the extent of their contributions to observed sediment concentrations is important from a health advisory and mitigation perspective. This paper proposes novel distribution-based qualitative and quantitative methods as source apportionment techniques and alternatives to conventional source attribution methods. Using sampled data, air, runoff, industrial effluent, and industrial paper and pulp wastes were identified as four distinct dioxin contributors to concentrations found in the sediments of the test bed region: the Houston Ship Channel-San Jacinto River-Galveston Bay (HSC-SJR-GB) estuarine system that also includes 2 Superfund sites with dioxin contamination. Two qualitative methods, the Kullback-Leibler divergence (K-L divergence) and the Bhattacharya measure (BM), and a quantitative method, the L2 norm, were used to investigate the spatial and temporal sourcing patterns of dioxins in the system sediments. The results indicated a global contribution from air and runoff sources across the estuarine system and over time with more localized impacts of the Superfund sites and the industrial sources. The results using the developed methodologies were compared with the output from the more conventional positive matrix factorization (PMF) method. Statistically significant correlations were observed among source contributions from the proposed methods and the PMF method, with Spearman's ρ ranging between - 0.596 to - 0.963 and 0.652 to 0.719, demonstrating the utility of the sourcing approaches used in the study. Additionally, the proposed methods were found to be rigorous in terms of elucidating spatial and temporal changes in the sourcing of dioxin to the estuary, indicating their suitability for use for other contaminants and other estuarine systems.


Asunto(s)
Dioxinas , Bifenilos Policlorados , Dibenzodioxinas Policloradas , Contaminantes Químicos del Agua , Dibenzodioxinas Policloradas/análisis , Dioxinas/análisis , Dibenzofuranos , Estuarios , Monitoreo del Ambiente , Sedimentos Geológicos , Contaminantes Químicos del Agua/análisis , Dibenzofuranos Policlorados
2.
Environ Monit Assess ; 192(5): 307, 2020 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-32328814

RESUMEN

Conventional water quality measurements are nearly impossible during and immediately after extreme storms due to dangerous conditions. In this study, remotely sensed reflectance is used to develop a regression equation that quantifies total suspended solids (TSS) in near real-time after Hurricane Harvey. The application focused specifically on sediment loading and deposition and its potential impacts on the Houston Ship Channel and Galveston Bay riverine-estuarine system. The European Space Agency's Sentinel-2 satellite captured images at critical points in the storm's progression, necessitating the development of a new algorithm for this relatively new satellite mission. Several linear regressions were analyzed with the goal of developing a simple one- or two-band equation, and the final model uses the red and near infrared bands (R2 = 0.74). Results show that record flows during Harvey delivered unprecedented suspended sediment loads to the Gulf of Mexico at concentrations above 125 mg/L with a mean concentration of 43 mg/L across the bay. The study findings demonstrated that it took up to 11 days after the storm for sediment transport to abate.


Asunto(s)
Tormentas Ciclónicas , Monitoreo del Ambiente , Clima Extremo , Modelos Teóricos , Calidad del Agua , Agua , Monitoreo del Ambiente/instrumentación , Sedimentos Geológicos/química , Golfo de México , Tecnología de Sensores Remotos , Comunicaciones por Satélite , Análisis Espectral , Texas , Agua/química
3.
Environ Sci Technol ; 53(9): 4832-4840, 2019 05 07.
Artículo en Inglés | MEDLINE | ID: mdl-30955326

RESUMEN

Hurricane Harvey brought more than 50 in. of rainfall to some areas of the Greater Houston Metro area (GHMA) starting on August 25, 2017; the Hurricane was also associated with damage to environmental infrastructure such as wastewater facilities, superfund sites, and leaks and spills from industrial and municipal facilities. This study collected post-Harvey water quality data in multiple streams for several weeks after the Hurricane. In addition to measuring impact, the study compared the observed concentrations of several physical, chemical, and microbial constituents and water properties to their historical counterparts in an effort to understand the water quality impacts of Harvey on the natural water systems within the GHMA. Unusual water quality findings such as low pH were observed that likely had acute and chronic effects on ecosystems including the loss of oyster populations in Galveston Bay. In-stream microbial concentrations, using E. coli as the indicator, were within historical norms typically reported for the GHMA. The observed levels of measured dissolved metals post Harvey, while relatively low, when multiplied by the significant volume of water discharged from bayous to Galveston Bay, meant the delivery of a substantial load of trace metals to the estuary. Specifically, the load in the particulate phase would be expected to accumulate and gradually repartition to the dissolved phase for a long period of time. Total metal concentrations, when elevated relative to their historical counterparts, could be associated with the presence of industrial activities. Overall, anthropogenic activities including the presence of hydraulic flood control structures, local runoff from industrialized areas, and active superfund sites were recognized as key factors affecting short-term acute water quality impacts. Watersheds with very little human alterations experienced minimal water quality changes and had relatively rapid recoveries post-Harvey.


Asunto(s)
Tormentas Ciclónicas , Contaminantes Químicos del Agua , Ecosistema , Monitoreo del Ambiente , Escherichia coli , Estuarios , Humanos , Calidad del Agua
4.
Am J Public Health ; 105(5): 1036-43, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25790397

RESUMEN

OBJECTIVES: We developed the policy indicator checklist (PIC) to identify and measure policies for calorie-dense foods and sugar-sweetened beverages to determine how policies are clustered across multiple settings. METHODS: In 2012 and 2013 we used existing literature, policy documents, government recommendations, and instruments to identify key policies. We then developed the PIC to examine the policy environments across 3 settings (communities, schools, and early care and education centers) in 8 communities participating in the Childhood Obesity Research Demonstration Project. RESULTS: Principal components analysis revealed 5 components related to calorie-dense food policies and 4 components related to sugar-sweetened beverage policies. Communities with higher youth and racial/ethnic minority populations tended to have fewer and weaker policy environments concerning calorie-dense foods and healthy foods and beverages. CONCLUSIONS: The PIC was a helpful tool to identify policies that promote healthy food environments across multiple settings and to measure and compare the overall policy environments across communities. There is need for improved coordination across settings, particularly in areas with greater concentration of youths and racial/ethnic minority populations. Policies to support healthy eating are not equally distributed across communities, and disparities continue to exist in nutrition policies.


Asunto(s)
Ingestión de Energía , Preferencias Alimentarias , Política de Salud , Promoción de la Salud/organización & administración , Obesidad Infantil/prevención & control , Bebidas , Humanos , Características de la Residencia , Instituciones Académicas/normas , Factores Socioeconómicos , Edulcorantes
5.
Environ Sci Technol ; 49(13): 8254-62, 2015 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-26079990

RESUMEN

The exploration of unconventional shale energy reserves and the extensive use of hydraulic fracturing during well stimulation have raised concerns about the potential effects of unconventional oil and gas extraction (UOG) on the environment. Most accounts of groundwater contamination have focused primarily on the compositional analysis of dissolved gases to address whether UOG activities have had deleterious effects on overlying aquifers. Here, we present an analysis of 550 groundwater samples collected from private and public supply water wells drawing from aquifers overlying the Barnett shale formation of Texas. We detected multiple volatile organic carbon compounds throughout the region, including various alcohols, the BTEX family of compounds, and several chlorinated compounds. These data do not necessarily identify UOG activities as the source of contamination; however, they do provide a strong impetus for further monitoring and analysis of groundwater quality in this region as many of the compounds we detected are known to be associated with UOG techniques.


Asunto(s)
Sedimentos Geológicos/química , Agua Subterránea/química , Calidad del Agua , Aniones/análisis , Bromuros/análisis , Cloruros/análisis , Cromatografía de Gases , Metales/análisis , Cloruro de Metileno/análisis , Yacimiento de Petróleo y Gas/química , Texas , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua
6.
Environ Sci Technol ; 48(17): 10372-9, 2014 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-25110809

RESUMEN

Interest in incorporating nanomaterials into water treatment technologies is steadily growing, driving the necessity to understand the interaction of these new materials with specific water contaminants. In the present study, five different carbonaceous materials: activated carbon (AC), charcoal (BC), carbon nanotubes (CNT), graphene (GE), and graphene oxide (GO) were investigated as sorbent materials for 11 polychlorinated biphenyl (PCB) congeners in aqueous concentrations in the pg-µg/L range. Sorbent-water distribution coefficients (Ks) calculated in aqueous concentrations of ng/L show that AC is superior to GE, GO, CNT, and BC for the 11 PCB congeners investigated by an average of 1.1, 1.1, 1.3, and 2.5 orders of magnitude, respectively. Additionally, maximum capacity and sorption affinity parameters from the Langmuir, Freundlich, and Polanyi-Dubinin-Manes (PDM) models show a similar result. Interestingly, however, the effect of molecular planarity has greater impact on PCB sorption to the nanomaterials, such that the planar congeners form stronger bonds with CNT, GE, and GO compared to AC and BC. This work demonstrated superior PCB sorption by AC as compared with the nanomaterials examined such that substantial post production modifications would be necessary for the nanomaterials to out-perform AC.


Asunto(s)
Carbono/química , Bifenilos Policlorados/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Carbón Orgánico/química , Grafito/química , Nanotubos de Carbono/química , Soluciones , Temperatura , Agua/química
7.
Environ Sci Pollut Res Int ; 29(5): 7514-7531, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34476713

RESUMEN

Understanding the transport of sediments in urban estuaries and their effects on water quality and microorganisms is a convergent challenge that has yet to be addressed especially as a result of natural hazards that affect the hydrodynamics of estuarine systems. This study provides a holistic view of the longitudinal nature and character of sediment in an urban estuary, the Galveston Bay Estuary System (GBES), under daily and extreme flow regimes and presents the results of water and sediment sampling after Hurricane Harvey. The sediment sampling quantified total suspended sediment (TSS) concentrations, metal concentrations, and the diversity of microbial communities. The results revealed the impact of the substantial sediment loads that were transported into the GBES in terms of sediment grain type, the spatial distribution of trace metals, and the diversity of microbial communities. A measurable shift in the percentage of silt relative to historical norms was noted in the GBES after Hurricane Harvey. Not only did sediment metal data confirms this shift and its ensuing impact on metal concentrations; microbial data provided ample evidence of the effect of leaks and spills from wastewater treatment plants, superfund sites, and industrial runoff on microbial diversity. The research demonstrates the importance of understanding longitudinal sediment transport and deposition in estuarine systems under daily flow regimes but more critically, following natural hazard events to ensure sustainability and resilience of systems such as the GBES that encounter numerous acute and chronic stresses.


Asunto(s)
Tormentas Ciclónicas , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Estuarios , Sedimentos Geológicos , Estudios Retrospectivos , Contaminantes Químicos del Agua/análisis
8.
Ann Med ; 54(1): 1277-1286, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35521823

RESUMEN

Background: The objectives of the present study are to understand the longitudinal variability in COVID-19 reported cases at the county level and to associate the observed rates of infection with the adoption and lifting of stay-home orders.Materials and Methods: The study uses the trajectory of the pandemic in a county and controls for social and economic risk factors, physical environment, and health behaviors to elucidate the social determinants contributing to the observed rates of infection.Results and conclusion: Results indicated that counties with higher percentages of young individuals, racial and ethnic minorities and, higher population densities experienced greater difficulty suppressing transmission.Except for Education and the Gini Index, all factors were influential on the rate of COVID-19 spread before and after stay-home orders. However, after lifting the orders, six of the factors were not influential on the rate of spread; these included: African-Americans, Population Density, Single Parent Households, Average Daily PM2.5, HIV Prevalence Rate, and Home Ownership. It was concluded that different factors from the ones controlling the initial spread of COVID-19 are at play after stay-home orders are lifted.KEY MESSAGESObserved rates of COVID-19 infection at the County level in the U.S. are not directly associated with adoption and lifting of stay-home orders.Disadvantages in sociodemographic determinants negatively influence the rate of COVID-19 spread.Counties with more young individuals, racial and ethnic minorities, and higher population densities have greater difficulty suppressing transmission.


Asunto(s)
COVID-19 , Negro o Afroamericano , COVID-19/epidemiología , Humanos , Pandemias , Prevalencia , SARS-CoV-2 , Estados Unidos/epidemiología
9.
Mar Pollut Bull ; 175: 113359, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-35124375

RESUMEN

Estuaries experience variable physicochemical conditions, especially after hurricanes and due to anthropogenic sources of pollution. Their microbial communities are not as well understood in terms of community structure and diversity, particularly in response to stresses from pollution and severe events. This study presents a 16S rRNA-based description of sediment microbial communities in the Houston Ship Channel-Galveston Bay estuary after Hurricane Harvey in 2017. A total of 11 sites were sampled, and microbial genomic DNA was isolated from sediment. The presence and abundance of specific bacterial and archaeal taxa in the sediment indicated pollutant inputs from identified legacy sources. The abundance of certain microbial groups was explained by the mobilization of contaminated sediment and sediment transport due to Harvey. Several microorganisms involved in the biodegradation of xenobiotics were observed. The spatial occurrence of Dehalococcoidia, a degrader of persistent polychlorinated compounds, was explained in relation to sediment properties and contaminant concentrations.


Asunto(s)
Tormentas Ciclónicas , Estuarios , Bacterias/genética , Sedimentos Geológicos/microbiología , ARN Ribosómico 16S/genética
11.
Nat Commun ; 12(1): 1947, 2021 04 13.
Artículo en Inglés | MEDLINE | ID: mdl-33850131

RESUMEN

Superfund sites could affect life expectancy (LE) via increasing the likelihood of exposure to toxic chemicals. Here, we assess to what extent such presence could alter the LE independently and in the context of sociodemographic determinants. A nationwide geocoded statistical modeling at the census tract level was undertaken to estimate the magnitude of impact. Results showed a significant difference in LE among census tracts with at least one Superfund site and their neighboring tracts with no sites. The presence of a Superfund site could cause a decrease of -0.186 ± 0.027 years in LE. This adverse effect could be as high as -1.22 years in tracts with Superfund sites and high sociodemographic disadvantage. Specific characteristics of Superfund sites such as being prone to flooding and the absence of a cleanup strategy could amplify the adverse effect. Furthermore, the presence of Superfund sites amplifies the negative influence of sociodemographic factors at lower LEs.


Asunto(s)
Sustancias Peligrosas/análisis , Esperanza de Vida , Algoritmos , Exposición a Riesgos Ambientales , Humanos , Aprendizaje Automático , Estados Unidos
12.
Transl Behav Med ; 11(2): 393-407, 2021 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-32667038

RESUMEN

Although reliable strategies exist to promote healthy habits that reduce childhood obesity, the sustainability of these strategies remains an ongoing public health challenge. This study aimed to identify factors experienced in a large, multisite project aimed at reducing childhood obesity that might contribute to project sustainability. Hypothesized constructs underpinning sustainability included replicability, continuation of benefits, institutionalization, and community capacity. Key informants (n = 27) completed 60 min, in-depth interviews, which were audio recorded and transcribed. Transcripts were first coded using a combined deductive and inductive approach. Four major themes emerged (with numerous subthemes): developing partnerships, challenges to the sustainability of implemented programming, the importance of intervening in multiple settings, and ongoing implementation and evaluation strategies. Replicability of complex childhood obesity interventions is possible when there are strong partnerships. Benefits can continue to be conferred from programming, particularly when evidence-based strategies are used that employ best practices. Implementation is facilitated by institutionalization and policies that buffer challenges, such as staffing or leadership changes. Community capacity both enhances the sustainability of interventions and develops as a result of strengthening partnerships and policies that support childhood obesity programming.


Asunto(s)
Prestación Integrada de Atención de Salud , Obesidad Infantil , Niño , Humanos , Obesidad Infantil/prevención & control , Salud Pública
13.
Water Environ Res ; 82(4): 302-18, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20432648

RESUMEN

Bacterial pollution in the Houston metropolitan area (Texas) watersheds was studied using statistical methods to determine the Escherichia coli levels and causes of their spatial and temporal variability. Houston bayous generally exhibit elevated E. coli concentrations. The more urban watersheds had higher concentration ranges and geometric means and had more spatial variation with higher overall ranges at downstream monitoring stations. They also were less sensitive to temperature variations and more strongly influenced by rainfall events. The median flow in the more urban bayous is predominantly wastewater. Frequent rainfall in the region, combined with relatively long travel times in the bayous, results in elevated bacterial levels in the bayous. Multiple regression models using water quality parameters were more representative on the segment level and not at the watershed level and may not be useful for predictions that rely on conventional water quality measures, particularly in urban watersheds, such as those studied here. Cluster analysis for the segments resulted in two distinct clusters differentiated by their developed land-use, population density, domestic animal density, and grassy land-use.


Asunto(s)
Microbiología del Agua , Movimientos del Agua , Ciudades , Análisis por Conglomerados , Ecosistema , Escherichia coli , Océanos y Mares , Lluvia , Estaciones del Año , Temperatura , Texas , Factores de Tiempo , Contaminación del Agua
14.
PLoS One ; 15(10): e0241166, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33119721

RESUMEN

BACKGROUND: The spread of coronavirus in the United States with nearly five and half million confirmed cases and over 170,000 deaths has strained public health and health care systems. While many have focused on clinical outcomes, less attention has been paid to vulnerability and risk of infection. In this study, we developed a planning tool that examines factors that affect vulnerability to COVID-19. METHODS: Across 46 variables, we defined five broad categories: 1) access to medical services, 2) underlying health conditions, 3) environmental exposures, 4) vulnerability to natural disasters, and 5) sociodemographic, behavioral, and lifestyle factors. The developed tool was validated by comparing the estimated overall vulnerability with the real-time reported normalized confirmed cases of COVID-19. ANALYSIS: A principal component analysis was undertaken to reduce the dimensions. In order to identify vulnerable census tracts, we conducted rank-based exceedance and K-means cluster analyses. RESULTS: All of the 5 vulnerability categories, as well as the overall vulnerability, showed significant (P-values <<0.05) and relatively strong correlations (0.203<ρ<0.57) with the normalized confirmed cases of COVID-19 at the census tract level. Our study showed a total of 722,357 (~17% of the County population) people, including 171,403 between the ages of 45-65 (~4% of County's population), and 76,719 seniors (~2% of County population), are at a higher risk based on the aforementioned categories. The exceedance and K-means cluster analysis demonstrated that census tracts in the northeastern, eastern, southeastern and northwestern regions of the County are at highest risk. CONCLUSION: Policymakers can use this planning tool to identify neighborhoods at high risk for becoming hot spots; efficiently match community resources with needs, and ensure that the most vulnerable have access to equipment, personnel, and medical interventions.


Asunto(s)
Infecciones por Coronavirus/epidemiología , Neumonía Viral/epidemiología , Medición de Riesgo , Poblaciones Vulnerables , Adulto , Anciano , Betacoronavirus , COVID-19 , Análisis por Conglomerados , Humanos , Persona de Mediana Edad , Pandemias , Prevalencia , Salud Pública/métodos , Características de la Residencia , SARS-CoV-2 , Análisis Espacial , Texas/epidemiología
15.
Arch Public Health ; 78: 13, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32082567

RESUMEN

BACKGROUND: In the context of health-related interventions, sustainability is the capacity to maintain the changes resulting from the intervention. These can be improved policies, practices or trends intended to improve population health. The Childhood Obesity Research Demonstration (CORD) project was a multi-site, multi-intervention collaboration testing the Obesity Chronic Care Model with interventions for childhood obesity prevention and management. We present the model, definitions and methodology used for the cross-site sustainability evaluation of CORD. METHODS: We applied the Ecologic Model of Obesity to childhood obesity interventions to operationalize four sustainability constructs: replicability, continuation of benefits, institutionalization, and community capacity. We used a triangulation approach and employed mixed methods to assess sustainability constructs at each level of the Ecologic Model of Obesity: Micro, Meso, Exo and Macro. We constructed checklists to count and code intervention activities, use of evidence-based practices among providers, and environmental factors and policies hypothesized to influence intervention sustainability. We developed in-depth interviews for principal investigators and project leads. We applied the Wilder Collaboration Factors Inventory with key stakeholders. RESULTS: Lessons learned suggested that sustainability constructs should be clearly identified and operationalized a priori. Constructs must be flexible to account for differences between intervention plans and implementation to obtain robust and informative data. CONCLUSION: Strong links are needed among researchers, program implementers and communities to accomplish consistent, robust and valuable data collection efforts to assure sustainable and healthy communities.

16.
Environ Toxicol Chem ; 28(11): 2307-17, 2009 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19606914

RESUMEN

Elevated but variable levels of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/Fs) were observed in hardhead sea catfish (HH) and blue crabs (BCs), as well as in water and sediment, of the Houston Ship Channel system, Texas, USA. It is hypothesized that the variation was caused by the spatial variability of PCDD/F contamination, together with the natural mobility of organisms in satisfying prey, temperature, salinity, and reproductive requirements. Structural equation modeling was applied to explore the congener-specific relationships between PCDD/F levels in HH and BC tissues and independent predictors such as PCDD/F contamination levels, environmental factors such as salinity and temperature, temporal-spatial factors such as site depth and season, and biological factors such as length, weight, and lipid content. Contamination levels in both sediment and water were statistically significant predictors of the levels of less chlorinated congeners in both HH and BCs, with the standardized regression weight for sediment concentration roughly twice that for the water concentration. This implies that sediments are the dominant route for PCDDIF exposure and remediation efforts should focus on legacy sediment ontamination. Tissue lipid content was a significant predictor of tissue concentrations in HH but only to a lesser extent in BCs, perhaps due to their low lipid content. Site depth and seasonal factors also were significant predictors of tissue concentrations. For the highly chlorinated congeners, only a small fraction of the variance in tissue concentrations was explained by the independent predictors, possibly indicating that uptake and elimination kinetics, biotransformation processes, or both may be more important factors controlling the bioaccumulation of those congeners.


Asunto(s)
Benzofuranos/análisis , Braquiuros/metabolismo , Bagres/metabolismo , Dibenzodioxinas Policloradas/análogos & derivados , Contaminantes Químicos del Agua/análisis , Animales , Benzofuranos/toxicidad , Dibenzofuranos Policlorados , Sedimentos Geológicos/química , Análisis Multivariante , Dibenzodioxinas Policloradas/análisis , Dibenzodioxinas Policloradas/toxicidad , Salinidad , Texas , Contaminantes Químicos del Agua/toxicidad
17.
Sci Total Environ ; 677: 230-240, 2019 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-31055102

RESUMEN

One of the most significant causes of poor water quality is the presence of pathogens. To reduce the cost of human exposure to microbial contamination, monitoring of Fecal Indicator Bacteria (FIB), as a surrogate for the presence of pathogens in natural waters, has become the norm. A total maximum daily load (TMDL) framework is used to establish limits for microbial concentrations in impaired waterbodies. In order to meet microbial loads determined by the TMDLs, reductions in microbial sources varying from 50% to almost complete elimination are required. Such targets are fairly difficult, if not impossible, to achieve. A natural attenuation (NA) framework is proposed that takes into account the connectivity between freshwater streams and their receiving coastal estuaries. The framework accounts for destructive and non-destructive mechanisms and defines three regimes: NA 1 - reaction-dilution mixing at the freshwater-tidal interface, NA 2 - advection-reactions within the tidally influenced coastal stream, and NA 3 - dilution-discharge at the interface with the estuary. The framework was illustrated using the Houston Metropolitan area freshwater streams, their discharge into the Houston Ship Channel (HSC) and into Galveston Bay. FIB concentrations in Galveston Bay were much lower when compared to FIB concentrations in Houston streams. Lower enterococci concentrations in tributary tidal waters were found compared to their counterparts in fresh waters (NA1 regime). Additionally, 70% reduction in FIB loads within the HSC was demonstrated as well as a decreasing trend in enterococci geometric means, from upstream to downstream, on the order of 0.092 day-1 (NA2 regime). Lower enterococci concentrations in Galveston Bay at the confluence with the HSC were also demonstrated (NA3 regime). Statistical testing showed that dilution, tide-associated processes, and salinity are the most important NA mechanisms and indicated the significant effect of ambient temperature and rainfall patterns on FIB concentrations and the NA mechanisms.


Asunto(s)
Bacterias/aislamiento & purificación , Monitoreo del Ambiente/métodos , Microbiota , Estuarios , Heces/microbiología , Ríos/microbiología , Texas , Calidad del Agua
18.
Chemosphere ; 70(4): 593-606, 2008 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17850847

RESUMEN

Polychlorinated biphenyls (PCBs) were quantified in water, sediment, and catfish and crab tissue collected from the Houston Ship Channel (HSC) in Texas. The total concentrations of the 209 PCB congeners ranged from 0.49 to 12.49 ng l(-1), 4.18 to 4601 ng g(-1) dry wt, 4.13 to 1596 ng g(-1) wet wt, and 3.44 to 169 ng g(-1) wet wt, in water, sediment, catfish and crab tissue, respectively. All media showed maximum concentrations greater than studies in other regions with the highest concentrations occurring in the most industrialized segments of the channel. Inter-media correlations suggested that sediment is a source to water. Galveston Bay sediment concentrations compared to a previous study showed a declining trend though the rate of the decline may be slowing. Detailed homolog profiles revealed that the industrialized part of the channel may be receiving PCB-laden sediment from its tributaries. An unusually high fraction of the deca-chlorinated congener (PCB-209) was found in all media. Seen in only a few other studies and in previous air concentrations in the channel, this may point to unusual Aroclor mixtures used in the history of the HSC or to contemporary sources from local industry. A comparison of PCB concentrations obtained using Aroclor, representative congener, and all congener methods, indicated that Aroclors are not an appropriate surrogate for total PCBs and that the NOAA NST method is more representative than the NOAA EPA method.


Asunto(s)
Sedimentos Geológicos/análisis , Bifenilos Policlorados/análisis , Contaminantes Químicos del Agua/análisis , Animales , Braquiuros/metabolismo , Bagres/metabolismo , Monitoreo del Ambiente , Geografía , Sedimentos Geológicos/química , Texas
19.
Sci Total Environ ; 644: 398-405, 2018 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-29981989

RESUMEN

Polychlorinated biphenyls (PCBs) are persistent hydrophobic compounds that are present widely in the environment. Due to poorly maintained hazardous waste sites, electrical equipment leakage, and illegal disposal, PCBs were deposited in sediments present in bays and estuaries. PCBs continuously partition into the overlying water posing a long-term exposure risk to the environment and human health. This study demonstrates the efficacy of carbon-based materials in reducing the partitioning of PCBs from sediment to the water column. Both existing carbon-based materials [activated carbon (AC), black carbon (BC)] and emerging nanomaterials [graphene (GE), graphene oxide (GO), carbon nanotube (CNT)] were tested to determine their efficacy to bind PCBs in sediment. The comparison between the sorbents was accomplished by examining their distribution coefficient (Ks). The magnitude of Ks provides an idea about the bioavailable fraction of PCBs in the system; the higher the Ks, the greater the strength of sorption by the sorbent and therefore, the lower the PCB bioavailability. Results from the sorption experiment indicated that CNT performed the best overall followed by AC, BC, GO and GE. Results indicated that the Ks value for CNT was 1.16, 1.15, 1.13 and 1.04 log units greater than GE, GO, BC, and AC.

20.
Environ Sci Pollut Res Int ; 25(34): 34380-34391, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30302734

RESUMEN

Competing demand for high-quality fresh water for agricultural, industrial, and municipal uses has placed tremendous stress on water resources; irrigating crops with fresh water is expensive and unsustainable. Using unconventional water sources such as oilfield produced water (PW) and treating PW with physical treatment methods such as electromagnetic treatment may overcome water-limitation challenges. A germination experiment was conducted using treated and untreated PW to examine the effect on the germination of iron and clay cowpeas (ICCs) since germination is the stage at which plants are most sensitive to external factors and stresses. The results from the study showed that ICCs germinated when irrigated with higher salinity water that was treated using the electromagnetic technology. A plant growth study was also conducted to assess the effect of electromagnetic treatment of high-salinity PW on the growing ability and crop health of ICCs. A reduction in leaf area expansion rate, the first indicator of salt stress on plants, was observed. After 14 days, plants showed early signs of salt stress such as wilting, lightening in color, and reduction in leaf area. After 28 days, plants watered with higher salinity PW (21,475-42,950 mg/L total dissolved solids) died and plants watered with lower salinity PW (< 21,475 mg/L total dissolved solids) survived but grew smaller than plants irrigated using fresh water. Results from both experiments suggested a potential total dissolved solids limit of ICCs or electromagnetic technology (or both) between 4000 and 10,000 mg/L. The results further suggested that while the electromagnetic technology did not have a strong effect on plant growth, high-salinity water might be treated for reuse in agriculture.


Asunto(s)
Riego Agrícola/métodos , Yacimiento de Petróleo y Gas , Vigna/crecimiento & desarrollo , Purificación del Agua/métodos , Productos Agrícolas/crecimiento & desarrollo , Radiación Electromagnética , Germinación , Hojas de la Planta/crecimiento & desarrollo , Salinidad , Calidad del Agua
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