Reusable Enzymatic Strip for Detection of Arsenic

HIGHLIGHTS Arsenic is considered as one of the highly hazardous elements in the environment and a serious carcinogen for the human health. An enzymatic method has been described by using arsenite oxidase for arsenic detection. Residual activity of the immobilized enzyme was 43% of the initial activity after being recycled 10 times.

Abstract Arsenic is considered as one of the highly hazardous elements in the environment and a serious carcinogen for the human health. More attention has taken towards the arsenic due to its presence in ground water in India, China, Bangladesh, Inner Mongolia and several other regions of the world. It's been a challenge to remove arsenic due to the lack of its efficient detection approach in the complicated environmental matrix. The proposed method describes an enzymatic method for arsenic determination using arsenite oxidase, which catalyzes the oxidation of arsenite to arsenate. Hence, a colorimetric PVC strip with immobilized arsenite oxidase has been developed to detect the arsenic concentration and also having potential for the field-testing. The influence of the optimal conditions i.e. pH, temperature, storage stability, and reusability of free and immobilized enzyme were evaluated and compared. The results have shown that the stabilities were significantly enhanced compared with free counterpart. Residual activity of the immobilized enzyme was 43% of the initial activity after being recycled 10 times. We approve that this novel low cost immobilized carrier presents a new approach in large scale applications and expected to act as a model for establishment of indigenous arsenic sensor in miniature form.

Heterocontrole da fluoretação da água de abastecimento público em cidades do estado de Goiás, Brasil / External control of fluoridation in public water supply systems in the state of Goiás, Brazil

Resumo A adição do flúor na água é um método empregado na redução de cárie dentária. O controle da fluoretação é importante para manter a sua eficiência e, ao mesmo tempo, evitar o risco de ocorrência de fluorose, fruto do consumo de água com flúor em excesso. O objetivo deste trabalho foi avaliar a adequação dos níveis do fluoreto na água distribuída à população do estado de Goiás, Brasil. Foram analisadas 5.039 amostras de água coletadas em 225 municípios de Goiás, entre 2011 e 2013. Os resultados foram analisados por sazonalidade, tipo de manancial e localização geográfica. Ocorreu uma variação entre ausência e 2,5 mg F/L, com 28,2% das amostras entre 0,6 e 0,8 mg F/L e 39,1% entre 0,55 e 0,84 mg F/L. No período de chuva ocorreu um maior número de resultados atípicos e maiores valores quando comparados ao período da seca. Verificou-se que os sistemas abastecidos por água proveniente de mananciais subterrâneos possuem um menor controle de fluoreto quando comparados a sistemas provenientes de mananciais superficiais. Observou-se menores concentrações nas amostras coletadas no Norte e Leste goianos, com menos de 7,5% entre 0,6 e 0,8 mg F/L, para aquelas coletadas de sistemas de abastecimento que utilizam água de manancial subterrâneo com adição de fluoreto, existindo dificuldades na manutenção dos seus teores.

Abstract The addition of fluoride to the public water supply is a method used for reducing tooth decay. In this sense, the control of fluoridation is important for maintaining its efficiency and, at the same time, for avoiding the risk of fluorosis as a result of the consumption of water with excess of fluoride. The objective of this study was to evaluate the adequacy of fluoride levels in the water distributed to populations of the state of Goiás, Brazil. Towards this aim, 5,039 water samples collected between 2011 and 2013 in 225 municipalities of the state of Goiás were analyzed for fluoride level. The results were assessed with regard to season, type of water source and geographic location. Fluoride levels were found to vary between complete absence and 2.5 mg F/L, with 28.2% of the samples being between 0.6 and 0.8 mg F/L, and 39.1% between 0.55 and 0.84 mg F/L. The rainy season produced a greater number of atypical results and higher values than the dry period. The systems supplied by groundwater sources were shown to have a limited control of fluoride concentration compared to systems supplied by surface water sources. Lower concentrations of fluoride were found in samples collected in the North and East Mesoregions of Goiás, with less than 7.5% being between 0.6 and 0.8 mg F/L, which systems are mainly supplied by groundwater sources with fluoride addition .

Avaliação dos níveis de cromo total em águas para consumo humano / Evaluation of total chromium levels in drinking water

Níveis elevados de cromo associados às águas naturais não são comuns, mas concentrações elevadas desse elemento, de ocorrência natural, têm sido relatadas nas águas subterrâneas de vários sistemas aquíferos, incluindo o Aquífero Bauru, SP, Brasil. Este fato está associado à ocorrência de rochas máficas/ultramáficas e às condições alcalinas e oxidantes. Neste estudo foi desenvolvido e aplicado um método para monitorar a concentração de cromo total em amostras de água da cidade de São José do Rio Preto. Esta cidade está localizada no estado de São Paulo, na região onde concentrações superiores ao limite estabelecido pela legislação brasileira (0,05 mg/L) foram detectadas em águas subterrâneas de poços de abastecimento. O cromo total foi determinado usando-se Espectrometria de Massas com Plasma Indutivamente Acoplado (ICPMS) em 104 amostras de água coletadas, entre 2013 e 2017, em diferentes pontos de distribuição (zona rural, residencial, distrito industrial, comercial, reservatório de distribuição e estação de tratamento de água), considerando-se 52 locais. Em 99 % das amostras as concentrações de Cr estavam acima do limite de quantificação calculado para o método (0,001 mg/L). E 15% apresentaram concentrações acima do limite de regulação na água potável (Portaria 2914/2011), sendo, portanto, consideradas impróprias para o consumo humano.

Elevated chromium levels in the natural waters are not common, but the high concentrations of naturally occurring Cr have been reported in the groundwater of several aquifer systems. This finding is linked with the occurrence of mafic/ultramafic rocks and associated with the alkaline and oxidizing conditions. This study aimed at monitoring the total chromium concentration in drinking water samples from São José do Rio Preto city. Cr concentrations higher than the limit established by the Brazilian Legislation (0.05 mg/L) were detected in the groundwater from the deep supply wells. Total chromium was determined by using an Inductively Coupled Mass Spectrometer (ICP-MS) in 104 samples collected from the public drinking water distribution networks in 52 sites, from 2013 to 2017. Cr concentrations above the method limit of quantification (0.001 mg/L) were found in 99% of the analyzed samples. Approximately 15% of the collected samples presented Cr in concentrations above the established legislation limit for drinking water (Ordinance 2914/2011), that should be considered as improper for consumption.

Estudio epidemiológico de arsénico en agua subterránea para consumo humano en el territorio del Cluster Lechero Regional, Argentina / Epidemiological study of arsenic in groundwater for human consumption in the territory of the Cluster Lechero Regional, Argentina

En diversas regiones del mundo se han encontrado acuíferos, destinados para el consumo humano, con niveles de arsénico que sobrepasan los límites recomendados por las agencias ambientales o fijados por la legislación, lo que representa un grave problema de salud pública. En el noroeste de la provincia de Santa Fe y sur de Santiago del Estero, área en estudio, los antecedentes indican la existencia de acuíferos con concentraciones de minerales que superan ampliamente los valores recomendados para consumo humano. Estos niveles de salinidad aumentan con la profundidad, y se detecta además, la presencia de tóxicos como el arsénico, siendo un factor condicionante para el aprovechamiento del agua subterránea. En el territorio del Cluster Lechero Regional, se estudió la composición salina del agua subterránea y, en particular, la concentración de arsénico, con el objetivo de establecer niveles de toxicidad y el potencial desarrollo de enfermedades crónicas. Los resultados muestran elevada salinidad y una concentración media de arsénico en la zona de 0,203 mg/L. Estimamos que, para una población de riesgo de 57.436 habitantes que no tienen acceso a sistemas de agua de red, expuestos teóricamente a la concentración de arsénico hallada en este estudio, se manifiesten 500 casos de cáncer atribuibles a este nivel de exposición en los próximos años. La población infantil comprendida entre 0 y 2 años de edad (3.690 niños de la región) podría desarrollar lesiones dérmicas y efectos neurológicos de distinta magnitud.

In various regions of the world, it has been found aquifers, destined for human consumption, with arsenic levels that exceed the limits recommended by the environmental agencies or required by law, so that represents a serious public health problem. In the northwest of the province of Santa Fe and the south of Santiago del Estero, defined study area, the background information indicates the existence of aquifers with concentrations of minerals that far exceeded the recommended values for human consumption. These levels of salinity increases with depth and, in addition, it was detected the presence of toxic substances such as arsenic, being a conditioning factor for the groundwater use. In the territory of the Cluster Lechero Regional, the composition of the saline groundwater was analized and, in particular, the concentration of arsenic was assessed, with the aim of setting levels of toxicity and the potential development of chronic diseases. Results showed high salinity and an average concentration of arsenic in the area of 0.203 mg/L. We believe that for a high risk population of 57,436 inhabitants, with no access to a water system network, and theoretically exposed to the concentration of arsenic found in this study, it would be expected 500 cases of cancer attributable to this level of exposure, in the next years. Children between 0 and 2 years old (3,690 children from the region) could develop skin lesions and neurological effects of different magnitude.

Residuos de plaguicidas organofosforados y carbamatos en aguas subterráneas de bebida en las zonas rurales de Plottier y Senillosa, Patagonia Norte, Argentina / Organophosphate and carbamate pesticide residues in drinking groundwater in the rural areas of Plottier and Senillosa, North Patagonia, Argentina

Plottier y Senillosa son dos localidades contiguas que forman parte del área de producción agrícola del Alto Valle de Río Negro y Neuquén, Patagonia Norte. Entre los plaguicidas más utilizados predominan las familias de neonicotinoides, carbamatos y organofosforados. El conocimiento de los niveles de estos compuestos en aguas superficiales y subterráneas se ha convertido en un tema de interés social debido a su posible impacto en el ambiente y la salud. El objetivo del presente trabajo fue determinar niveles de residuos de plaguicidas en agua subterránea utilizada para bebida en zonas rurales de Plottier y Senillosa. Se analizaron carbamatos: propoxur, carbofuran, pirimicarb, carbaril y organofosforados: clorpirifos, dimetoato, metidation, fenaminfos, triazofos, fosmet y metil azinfos, por cromatografía gaseosa (GC), en seis sitios de muestreo, durante la época de aplicación y no aplicación de insecticidas. No se detectaron residuos de los plaguicidas estudiados por el método analítico utilizado. El límite de detección fue 0,010 µg/L para organofosforados y 0,030 µg/L para carbamatos. Estos resultados indican que las buenas prácticas agrícolas aplicadas en la zona así como las características fsicoquímicas del suelo, su espesor y el contenido de materia orgánica y las propiedades fsicoquímicas de los plaguicidas estudiados son factores que contribuyen favorablemente a la calidad del agua de bebida de la población rural.

Plottier and Senillosa are two adjoining towns that belong to the agricultural production area of Upper Valley, Río Negro and Neuquén, North Patagonia. Among the most widely used pesticides, neonicotinoids, carbamates and organophosphates are predominant. The levels of these compounds in surface and groundwater have become a topic of public concern, since the possible impact on health and environment. The aim of this study was the determination of pesticide residue levels in drinking ground-water in the rural areas of Plottier and Senillosa. Carbamates: propoxur, carbofuran, pirimicarb, carbaryl and organophosphate: chlorpyrifos, dimethoate, methidathion, fenaminfos, triazophos, phosmet, azinphos methyl, were analyzed by GC in six sampling sites during insecticide application and non-application season. No pesticide residues were detected by the analytical method used. The detection limit for organophosphates was 0.010 µg/L and 0.030 µg/L for carbamates. These results indicate that good agricultural practices, the physicochemical characteristics of the soil, its thickness, the content of organic matter and the physicochemical properties of pesticides studied are factors that positively contribute to the drinking water quality in the rural population.

Qualidade da água subterrânea obtida de poços em áreas urbanas na cidade de JI-Paraná ­ RO / Groundwater of quality obtained from wells in urban areas in the city of JI-Parana - RO

Foram realizadas análises microbiológicas de 45 amostras da água subterrânea em poços de áreas urbanas na cidade de Ji-Paraná - RO. As amostras foram analisadas para Coliformes totais e Escherichia coli, ambos com resultados expressos em número mais provável (NMP/100mL), com a finalidade de avaliar as condições de potabilidade dessas águas de poços. Os resultados das 45 amostras de águas coletadas foram comparados aos valores máximos permissíveis para consumo humano nas legislações federais vigentes no Brasil. Foram encontrados Coliformes totais em 42,22% das amostras e E. coli em 89,47% das amostras com presença de Coliformes totais, ou seja, os resultados não apresentaram conformidade comparando-se aos padrões preconizado na Portaria 2914/MS, representando um risco à saúde dos consumidores das águas destes poços. Em todo o Brasil, 22% das crianças morrem antes de completarem 6 anos de idade devido a males provocados por regiões sem água tratada. Além de que, 65% das internações de crianças com até 10 anos de idade são devido à ingestão de água não tratada.

Microbiological analyzes were performed of 45 samples of groundwater in urban areas wells in the city of Ji-Paraná-RO. The samples were analyzed for Total coliforms and Escherichia coli, both with results expressed in most probable number (MPN / 100ml) for the purpose of evaluating the potability of these conditions well water. The results of the 45 samples collected water were compared to the maximum permissible values for human consumption under federal laws in force in Brazil. Coliform bacteria were found in samples of 42.22% and 89.47% E. coli in the samples with the presence of Total Coliforms, or non-compliance results presented up to the recommended comparing the Ruling 2914 standards / MS, representing a risk to consumer health from the waters of these wells. In Brazil, 22% of children die before reaching the age of 6 due to ailments caused by regions without clean water. Apart from that, 65% of hospitalizations of children under 10 years of age are due to ingestion of water untreated.

Atmospheric forcing of cool subsurface water events in Bahía Culebra, Gulf of Papagayo, Costa Rica / Forzamiento atmosférico de eventos de agua fría subterránea en Bahía Culebra, Golfo de Papagayo, Costa Rica

Bahía Culebra, at Gulf of Papagayo on the north Pacific coast of Costa Rica, is an area of seasonal upwelling where more intense cooling events may occur during some boreal winter weeks mainly. To study these extreme cool events, records of nine sea subsurface temperature stations from 1998 to 2010 were analyzed. Five events associated with extremely cool temperatures in this region were identified from these records and taken as study cases. Sea temperatures decreased about 8-9ºC during these events and occurred while cold fronts were present in the Caribbean, with strong trade wind conditions over Central America. These strong wind conditions may have favored the offshore displacement of the sea surface water. The axis of Bahía Culebra runs northeastsouthwest, a condition that favors and triggers cool water events, mainly because the displaced water is replaced by water from deeper levels.

Bahía Culebra, localizada en el Golfo de Papagayo, al norte de la costa del Pacífico de Costa Rica, es un área de afloramiento estacional, en donde pueden ocurrir eventos de enfriamiento más intensos, principalmente durante algunas semanas del invierno boreal. Para estudiar estos eventos de enfriamiento extremo, se analizaron datos de nueve estaciones con registros de la temperatura subsuperficial del mar, desde 1998 hasta el 2010. A partir de estos registros, se identificaron cinco casos de estudio asociados a enfriamientos del mar en la región. Los descensos de la temperatura de estos eventos fueron de aproximadamente 8-9ºC y se asociaron al paso de empujes fríos en la región del Caribe y una fuerte magnitud del viento alisio sobre América Central. Este reforzamiento del flujo alisio favorece el desplazamiento del agua superficial hacia afuera de Bahía Culebra, cuyo eje principal se ubica en la dirección noreste-suroeste. Lo anterior favorece y provoca un enfriamiento de la temperatura del mar en la bahía, ya que el agua desplazada es reemplazada por aguas más frías provenientes de profundidades mayores.

Selection of groundwater sites in Egypt, using geographic information systems, for desalination by solar energy in order to reduce greenhouse gases

Although Egypt has already reached the water poverty limit, it possesses a high potential brackish groundwater available from different aquifers. All Arab countries lie in the best sun-belt region in the world and Egypt has the highest number of sun hours all year round. Solar energy for groundwater; desalination is an independent infinite energy resource; it has low running costs and reduces the contribution of greenhouse gases [GHG] to global warming. Perfect meteorological conditions and land space are available in remote areas, where solar desalination could supply freshwater for drinking, industry, and for greenhouse agriculture. The present study uses Geographic Information System[s] [GIS] as a spatial decision support tool to select appropriate sites in Egypt for groundwater solar desalination. Solar radiation, aquifer depth, aquifer salinity, distance from the Delta and the Nile Valley, incidence of flash floods, sand dunes, rock faults, and sea-water intrusion in the North Delta, are the criteria that have been taken into consideration in the process of analysis. A specific weight is given to each criterion according to its relative influence on the process of decision making. The results from the application of the presented methodology determine the relative suitability of sites for groundwater solar desalination. These sites are ranked in descending order to help decision-makers in Egypt. The results show that groundwater solar desalination is suitable in remote regions on the North Western Coast, on the North Sinai Coast, and at the Southern Oasis, for reducing greenhouse gases and that it is particularly useful for poor communities suffering from polluted water

Pesticides in indoor dust and shallow groundwater in rural Egypt

This study was designed to examine the existence of pesticide residues in both indoor dust and consumable subsurface shallow ground water and its association with community health in an agro-ecosystem in the Nile Delta Region. Pesticide exposure via consumption of shallow groundwater and contact with indoor dust were assessed in 7 villages in the Nile Delta of Egypt. Hand-pumped water and households' dust samples were collected on a spatio-temporal monitoring basis. A total of 50 households were randomly selected and residents were interviewed using a structured questionnaire to determine pesticide usage, exposure pathways and behavioral/health risk factors. Analyses revealed that the examined shallow groundwater and indoor dust samples failed to realize the respective standards of safety in most cases. Pesticide residues detected in indoor dust were more abundant than those in groundwater. Pyrethroid compounds represented the highest residues detected in indoor dust samples, where their mean levels were 4.75, 2.69, and 15.21 ppm for permethrin, cypermethrin, and cyahalothrin respectively. DDT, HCH and endosulfan were also detected in many samples in mean concentrations of 10.42, 36.01 and 33.68 ppb; respectively. As for the link between environmental contamination and community health, through our field questionnaire, the villagers stated that water-related diseases particularly diarrhea and infectious hepatitis were predominant. Age, living in close proximity to agricultural fields, excessive use of pesticides indoors without adequate aeration, lack of awareness and poor water quality, represented the major risk factors. More exposure/risk assessment studies related to the Egyptian setting are necessary to enhance drinking water regulations and lower the health risks of pesticide exposure

Biodegradability of commercial and weathered diesel oils

This work aimed to evaluate the capability of different microorganisms to degrade commercial diesel oil in comparison to a weathered diesel oil collected from the groundwater at a petrol station. Two microbiological methods were used for the biodegradability assessment: the technique based on the redox indicator 2,6 - dichlorophenol indophenol (DCPIP) and soil respirometric experiments using biometer flasks. In the former we tested the bacterial cultures Staphylococcus hominis, Kocuria palustris, Pseudomonas aeruginosa LBI, Ochrobactrum anthropi and Bacillus cereus, a commercial inoculum, consortia obtained from soil and groundwater contaminated with hydrocarbons and a consortium from an uncontaminated area. In the respirometric experiments it was evaluated the capability of the native microorganisms present in the soil from a petrol station to biodegrade the diesel oils. The redox indicator experiments showed that only the consortia, even that from an uncontaminated area, were able to biodegrade the weathered diesel. In 48 days, the removal of the total petroleum hydrocarbons (TPH) in the respirometric experiments was approximately 2.5 times greater when the commercial diesel oil was used. This difference was caused by the consumption of labile hydrocarbons, present in greater quantities in the commercial diesel oil, as demonstrated by gas chromatographic analyses. Thus, results indicate that biodegradability studies that do not consider the weathering effect of the pollutants may over estimate biodegradation rates and when the bioaugmentation is necessary, the best strategy would be that one based on injection of consortia, because even cultures with recognised capability of biodegrading hydrocarbons may fail when applied isolated.

Este trabalho objetivou avaliar a capacidade de diferentes microrganismos em degradar óleo diesel comercial em comparação com um óleo diesel intemperizado coletado da água subterrânea em um posto de combustíveis. Dois métodos microbiológicos foram usados para a avaliação da biodegradabilidade: a técnica baseada no indicador redox 2,6-diclorofenol indofenol (DCPIP) e os experimentos respirométricos usando os respirômetros de Bartha. No primeiro, testamos as culturas bacterianas Staphylococcus hominis, Kocuria palustris, Pseudomonas aeruginosa LBI, Ochrobactrum anthropi e Bacillus cereus, um inóculo comercial, consórcios obtidos do solo e da água subterrânea contaminados com hidrocarbonetos e um consórcio de uma área não contaminada. Nos experimentos respirométricos, foi avaliada a capacidade dos microrganismos nativos do solo de um posto de combustíveis em biodegradar os óleos diesel. Os experimentos com o indicador redox mostraram que apenas os consórcios, mesmo aquele de uma área não contaminada, foram capazes de biodegradar o diesel intemperizado. Em 48 dias, a remoção de hidrocarbonetos totais de petróleo (HTP) nos experimentos respirométricos foi aproximadamente 2,5 vezes maior quando o óleo diesel comercial foi usado. Esta diferença foi causada pelo consumo de hidrocarbonetos facilmente biodegradáveis, presentes em maior quantidade no óleo diesel comercial, como demonstrado pelas análises cromatográficas. Assim, resultados indicam que estudos de biodegradabilidade que não consideram o efeito de intemperização dos poluentes pode sobre estimar as taxas de biodegradação e quando o bioaumento é necessário, a melhor estratégia seria aquela baseada na injeção de consórcios, pois mesmo culturas com reconhecida capacidade de biodegradar hidrocarbonetos podem falhar quando aplicadas isoladamente.

Contaminação de poços tubulares em Juazeiro do Norte-CE / Contamination of a well field in Juazeiro do Norte - Ceará

A interação do riacho dos Macacos e de uma bateria de poços, na sua vizinhança, em Juazeiro do Norte-CE, foi avaliada segundo parâmetros físicos, químicos e bacteriológicos. Foram realizadas também análisés de oxigênio-18 a fim de avaliar a mistura de águas subterrâneas com águas superficiais. Verificou-se que o riacho dos Macacos, na maioria dos parâmetros analisados, não se enquadra em nenhuma das classes de águas doces da Resolução Nº 357 do CONAMA e da Portaria Nº 518 do Ministério da Saúde. Constatou-se que neste riacho e no lago da Timbaúba a concentração de coliformes totais e termotolerantes é extremamente elevada. Uma simulação computacional do transporte advectivo do contaminante de partículas do rio para o aqüífero com o modelo MODPATH/MOFLOW revela tempos mínimos de transito do manancial superficial poluído até os filtros dos poços entre 15 e 100 dias. Considerando a meia vida dos coliformes em águas subterrâneas de aproximadamente 8 dias e sua alta concentração na água superficial, contaminação dos poços de abastecimento é inevitável.

Säo Paulo 92: perfil ambiental e estratégias; a participaçäo da CETESB / Säo Paulo 92: environmental profile and strategies: the participation of CETESB

O conteúdo do relatório reflete, de maneira sucinta, o panorama ambiental do Estado de Säo Paulo desde os primórdios do processo de desenvolvimento brasileiro até o estágio atual do seus recursos naturais. Apresenta também - e principalmente - o nível de degradaçäo em que se encontra o meio ambiente natural e urbano destacando-se a influência do modelo econômico brasileiro dos últimos anos como uma das principais causas dessa degradaçäo. Em um outro momento foram apresentadas as estratégias da política ambiental do governo de Säo Paulo, onde se salientou a atuaçäo da CETESB - agente institucional do controle da poluiçäo ambiental -, bem como a existência de uma legislaçäo específica e outros instrumentos de planejamento e gestäo. Por último, o relatório traz uma série de indicadores para a evoluçäo da política do meio ambiente em nível nacional e sugere alguns subsídios para uma análise das conseqüências da política internacional de desenvolvimento sobre o meio ambiente brasileiro

Método espectrométrico de absorción atómica sin llama para determinación de mercurio en aguas naturales / Flameless atomic absorption spectrometric method for the determination of mercury in natural water

Se efectúa la evaluación de un método de espectrometría de absorción atómica empleando vapor frío con vistas a su posible utilización en el pesquisaje de la calidad del agua en los Centros de Higiene y Epidemiología del país que cuentan con el equipamiento necesario, atendiendo a la sencillez del procedimiento de digestión de la muestra. Se reportan los datos referentes a precisión, sensibilidad para el 1% de absorción, límite de detección y recuperación de mercurio orgánico e inorgánico. Se efectuó la comparación con un método normalizado internacionalmente