Assessing the quality of water quality assessments: An analytical quality control protocol for benthic diatoms

In this paper, the background to the development of an analytical quality control procedure for the Trophic Diatom Index (TDI) is explained, highlighting some of the statistical and taxonomic problems encountered, and going on to demonstrate how the system works in practice. Most diatom-based pollution indices, including the TDI, use changes in the relative proportions of different taxa to indicate changing environmental conditions. The techniques involved are therefore much simpler than those involved in many studies of phytoplankton, for example, where absolute numbers are required.

High-resolution automatic water quality monitoring systems applied to catchment and reservoir monitoring

Automatic recording instruments provide the ideal means of recording the responses of rivers, lakes and reservoirs to short-term changes in the weather. As part of the project ‘Using Automatic Monitoring and Dynamic Modelling for the Active Management of Lakes and Reservoirs', a family of three automatic monitoring stations were designed by engineers at the Centre for Ecology and Hydrology in Windermere to monitor such responses. In this article, the authors describe this instrument network in some detail and present case studies that illustrate the value of high resolution automatic monitoring in both catchment and reservoir applications.

Generation of a high-quality partially coherent dark hollow beam with a multimode fiber

We report the experimental generation of a high-quality partially coherent dark hollow beam (DHB) by coupling a partially coherent beam into a multimode fiber (MMF) with a suitable incidence angle. The interference experiment of the generated partially coherent DHB passing through double slits is demonstrated. It is found that the coupling efficiency of the MMF, the quality, and the coherence of the generated partially coherent DHB are closely controlled by the coherence of the input beam. (c) 2008 Optical Society of America.

Temporal and spatial variations in the quality of water in El Gergal Reservior, Seville, Spain

It is often difficult to define ‘water quality’ with any degree of precision. One approach is that suggested by Battarbee (1997) and is based on the extent to which individual lakes have changed compared with their natural ‘baseline’ status. Defining the base-line status of artificial lakes and reservoirs however, is, very difficult. In ecological terms, the definition of quality must include some consideration of their functional characteristics and the extent to which these characteristics are self-sustaining. The challenge of managing lakes in a sustainable way is particularly acute in semi-arid, Mediterranean countries. Here the quality of the water is strongly influenced by the unpredictability of the rainfall as well as year-to-year variations in the seasonal averages. Wise management requires profound knowledge of how these systems function. Thus a holistic approach must be adopted and the factors influencing the seasonal dynamics of the lakes quantified over a range of spatial and temporal scales. In this article, the authors describe some of the ways in which both long-term and short-term changes in the weather have influenced the seasonal and spatial dynamics of phytoplankton in El Gergal, a water supply reservoir situated in the south of Spain. The quality of the water stored in this reservoir is typically very good but surface blooms of algae commonly appear during warm, calm periods when the water level is low. El Gergal reservoir is managed by the Empresa Municipal de Abastecimiento y Saneamiento (EMASESA) and supplies water for domestic, commercial and industrial use to an area which includes the city of Seville and twelve of its surrounding towns (ca. 1.3 million inhabitants). El Gergal is the last of two reservoirs in a chain of four situated in the Rivera de Huelva basin, a tributary of the Guadalquivir river. It was commissioned by EMASESA in 1979 and since then the company has monitored its main limnological parameters on, at least, a monthly basis and used this information to improve the management of the reservoir. As a consequence of these intensive studies the physical, chemical and biological information acquired during this period makes the El Gergal database one of the most complete in Spain. In this article the authors focus on three ‘weather-related’ effects that have had a significant impact on the composition and distribution of phytoplankton in El Gergal: (i) the changes associated with severe droughts; (ii) the spatial variations produced by short-term changes in the weather; (iii) the impact of water transfers on the seasonal dynamics of the dinoflagellate Ceratium.

Worsening water quality conditions at Inner Puno Bay, Lake Titicaca, Peru, and their effect on Lemna spp. biomass

Although there have been a number of studies on aquatic conditions and the flora and fauna of Lake Titicaca over many decades, most of this work has been centred on the offshore regions of the main lake. Water quality there has been degrading and abundant growth of Lemna spp. has been developing. Lemna spp., commonly called floating duck-weed or ‘lenteja de agua’ in Puno, occurs perennially in most parts of the inner Puno Bay shore-line. In this article, the authors compare water quality changes over recent decades in shore-line regions of Inner Puno Bay and their possible effects on the distribution, abundance and biomass of Lemna spp..

Questionário sobre o consumo de álcool e drogas entre profissionais de saúde: um estudo exploratório

A droga na atualidade é considerada uma ameaça para a humanidade. Nos países em desenvolvimento, o álcool é o principal fator de risco, dentre as demais substâncias psicoativas. Existem poucos estudos sobre a prevalência do uso de drogas nos locais de trabalho no Brasil, e sobre os meios de enfrentamento das instituições empregadoras frente ao consumo de drogas por seus trabalhadores e as condições que levam a tal uso. O estudo foi estruturado em duas etapas: 1) revisão bibliográfica de instrumentos auto-aplicáveis sobre drogas entre trabalhadores e 2) elaboração e aplicação de um questionário auto-aplicável sobre o consumo de drogas entre trabalhadores. Foi traçado os seguintes objetivos: 1 etapa - Levantar os estudos publicados, que apresentam como objeto o uso de álcool e drogas por trabalhadores, entre os anos de 1998 e 2008; Identificar e analisar os instrumentos auto-aplicáveis, que mensuram a prevalência e o padrão de consumo de drogas em trabalhadores, utilizados pelos estudos; e Subsidiar o desenvolvimento de um questionário auto-aplicável sobre o padrão de consumo de álcool e drogas entre trabalhadores; 2 etapa - Desenvolver um questionário auto-aplicável que permite identificar a prevalência e padrão de consumo de álcool e drogas entre profissionais de saúde, assim como, as formas de enfrentamento por parte do trabalhador e das instituições empregadoras; Realizar análise descritiva do questionário desenvolvido e de seus principais resultados; e Avaliar a compreensão das perguntas do questionário desenvolvido, a partir das sugestões e respostas marcadas pelos sujeitos do estudo. Trata-se de uma pesquisa quantitativa, descritiva e exploratória realizada com 111 alunos de pós-graduação latu sensu de uma Faculdade Pública de Enfermagem situada na Cidade do Rio de Janeiro. Através da revisão bibliográfica verificamos que existem poucos instrumentos auto-aplicáveis sobre o padrão de consumo de álcool e drogas entre trabalhadores. Foi construído um questionário visando identificar informações sócio-demográficas, a história profissional, informações sobre o consumo de álcool e outras drogas, informações sobre o estresse laboral, e informações sobre as formas de enfrentamento por parte do trabalhador e das instituições empregadoras sobre o consumo de drogas. Pela análise do questionário aplicado, observou-se que algumas questões foram de difícil compreensão e precisam ser reformuladas, a fim de melhorar a compreensão dos respondentes, já que um questionário auto-aplicável deve ser auto-explicativo. As escalas AUDIT e Job Stress Scale se mostraram importantes para identificar problemas relacionados ao álcool e o estresse laboral. O álcool foi a droga mais utilizada pelos profissionais de saúde, seguido pelas substâncias psicoativas. Portanto, deve-se dar um enfoque sobressalente para a questão do fenômeno das drogas no ambiente de trabalho, promovendo programas de prevenção e de qualidade de vida ao trabalhador. Ressalta-se, também, a importância de abordar as questões sobre drogas nas graduações da área da saúde, promovendo o conhecimento do futuro profissional quanto aos riscos e danos decorrentes do uso e abuso de drogas.

Novel method to construct a quality map for phase unwrapping based on modulation and the phase gradient

A novel method to construct a quality map, called modulation-phase-gradient variance (MPGV), is proposed, based on modulation and the phase gradient. The MPGV map is successfully applied to two phase-unwrapping algorithms - the improved weighted least square and the quality-guided unwrapping algorithm. Both simulated and experimental data testify to the validity of our proposed quality map. Moreover, the unwrapped-phase results show that the new quality map can have higher reliability than the conventional phase-derivative variance quality map in helping to unwrap noisy, low-modulation, and/or discontinuous phase maps. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

A reliable phase unwrapping algorithm based on the local fitting plane and quality map

A fast and reliable phase unwrapping (PhU) algorithm, based on the local quality-guided fitting plane, is presented. Its framework depends on the basic plane-approximated assumption for phase values of local pixels and on the phase derivative variance (PDV) quality map. Compared with other existing popular unwrapping algorithms, the proposed algorithm demonstrated improved robustness and immunity to strong noise and high phase variations, given that the plane assumption for local phase is reasonably satisfied. Its effectiveness is demonstrated by computer-simulated and experimental results.

Novel method to construct a quality map for phase unwrapping based on modulation and the phase gradient

A novel method to construct a quality map, called modulation-phase-gradient variance (MPGV), is proposed, based on modulation and the phase gradient. The MPGV map is successfully applied to two phase-unwrapping algorithms - the improved weighted least square and the quality-guided unwrapping algorithm. Both simulated and experimental data testify to the validity of our proposed quality map. Moreover, the unwrapped-phase results show that the new quality map can have higher reliability than the conventional phase-derivative variance quality map in helping to unwrap noisy, low-modulation, and/or discontinuous phase maps. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Impact of watercress cultivation on river water quality: progress report for the period, January - December 1987

The objective of this short project progress report is to investigate the possible water quality implications of modern watercress growing practices. Chalk receiving watercourses are usually of high supply, amenity, game fishing and fish farming value. Any headwater pollution load, therefore, needs characterising and quantifying. Two sites of watercress farming were studied in 1986-87 and nutrient levels examined. Different approaches of watercress farmers in Dorset and Hampshire are summarised.

Pollution and water quality control of the River Tejo. Report on a visit to Portugal, Sep 27th - October 10th, 1987

Fundamental changes in the management of water resources in Portugal are now evolving. Five regional organisations termed Administracaos de Regiao Hidrographic (ARH), will be created to manage water resources within their respective geographical areas. These areas will be catchment based. As a fore-runner to the implementation of the five ARH's a foundation project has been established within the Direcao-Geral do Recursos Naturais to examine the practical implications of the new system. This project has been divided into a number of sub-projects and complementary projects to include the Tejo complementary project. The Tejo complementary project is the focus of this report. The report is to advise on the role of biology in the proposed ARH, to establish priorities for biological studies within the present Projecto de Gestao Integrada dos Recursos Hidricos da Bacia Hidrografica do Rio Tejo (PGIRH/T) and to assist with the planning of laboratory facilities for biology at the new PGIRH/T laboratory at Alges, Lisboa.