Water quality and plankton populations in an earthen polyculture pond

O presente estudo foi realizado durante um ano em viveiro de produção de peixes, com a finalidade de avaliar o efeito da qualidade da água na comunidade planctônica em função do manejo adotado. Maiores densidades de Euglenophyceae, Chlorophyceae e Cyanobacteria estiveram associadas aos elevados teores de nitrato (1 a 210 mg.L-1). Densidades de Cyanobacteria acima de 90 ind.m³ × 10³ (85,5%) ocorreram quando as concentrações de nitrato estiveram ao redor de 210 mg.L-1, fósforo total menor que 106 mg.L-1 e temperatura acima de 25 °C. Elevada densidade de Rotifera também esteve associada às altas densidades de Cyanobacteria (dezembro). Dentre os organismos zooplanctônicos, os Rotifera foram os mais abundantes e somente Trichocerca sp. foi constante em todos os pontos amostrados. Dentre os Cladocera, a espécie mais representativa foi Diaphanosoma birgei, variando de 4 a 342 ind.L-1 (0,7 e 2,4%) durante o período de estudo. Os resultados mostram que qualidade da água e o manejo empregado neste viveiro apresentaram influência direta na população planctônica, em função da baixa profundidade e constante carga de nutrientes que são incorporados no viveiro por meio de alimentos, fertilizantes e fezes de peixes, que contribuem para o aparecimento de organismos planctônicos não desejáveis.

Effects of glyphosate-resistant crops on water quality.

2009

SYSTEM DYNAMICS MODELING AS A QUANTITATIVE-QUALITATIVE FRAMEWORK FOR SUSTAINABLE WATER RESOURCES MANAGEMENT: INSIGHTS FOR WATER QUALITY POLICY IN THE GREAT LAKES REGION

Early water resources modeling efforts were aimed mostly at representing hydrologic processes, but the need for interdisciplinary studies has led to increasing complexity and integration of environmental, social, and economic functions. The gradual shift from merely employing engineering-based simulation models to applying more holistic frameworks is an indicator of promising changes in the traditional paradigm for the application of water resources models, supporting more sustainable management decisions. This dissertation contributes to application of a quantitative-qualitative framework for sustainable water resources management using system dynamics simulation, as well as environmental systems analysis techniques to provide insights for water quality management in the Great Lakes basin. The traditional linear thinking paradigm lacks the mental and organizational framework for sustainable development trajectories, and may lead to quick-fix solutions that fail to address key drivers of water resources problems. To facilitate holistic analysis of water resources systems, systems thinking seeks to understand interactions among the subsystems. System dynamics provides a suitable framework for operationalizing systems thinking and its application to water resources problems by offering useful qualitative tools such as causal loop diagrams (CLD), stock-and-flow diagrams (SFD), and system archetypes. The approach provides a high-level quantitative-qualitative modeling framework for "big-picture" understanding of water resources systems, stakeholder participation, policy analysis, and strategic decision making. While quantitative modeling using extensive computer simulations and optimization is still very important and needed for policy screening, qualitative system dynamics models can improve understanding of general trends and the root causes of problems, and thus promote sustainable water resources decision making. Within the system dynamics framework, a growth and underinvestment (G&U) system archetype governing Lake Allegan's eutrophication problem was hypothesized to explain the system's problematic behavior and identify policy leverage points for mitigation. A system dynamics simulation model was developed to characterize the lake's recovery from its hypereutrophic state and assess a number of proposed total maximum daily load (TMDL) reduction policies, including phosphorus load reductions from point sources (PS) and non-point sources (NPS). It was shown that, for a TMDL plan to be effective, it should be considered a component of a continuous sustainability process, which considers the functionality of dynamic feedback relationships between socio-economic growth, land use change, and environmental conditions. Furthermore, a high-level simulation-optimization framework was developed to guide watershed scale BMP implementation in the Kalamazoo watershed. Agricultural BMPs should be given priority in the watershed in order to facilitate cost-efficient attainment of the Lake Allegan's TP concentration target. However, without adequate support policies, agricultural BMP implementation may adversely affect the agricultural producers. Results from a case study of the Maumee River basin show that coordinated BMP implementation across upstream and downstream watersheds can significantly improve cost efficiency of TP load abatement.

Ten Year Study on Water Flushing Times and Water Quality in Southern Taylor Slough, Everglades National Park, FL

The purpose of this research was to investigate the effects of wetland restoration on the water balance, flushing time, and water chemistry of southern Taylor Slough, a major water way in Everglades National Park. Water balance and flushing time equations were calculated on a monthly time step from 2001 – 2011. Water chemistry of major ions and nutrients were analyzed and correlated with water flushing times. Results showed that evapotranspiration followed by water volume had the greatest influence on flushing time. The flushing times varied between 3 and 78 days, with longer times observed between October and December, and the shorter times between March and May. Ion concentrations at the coastal areas decreased with increased flushing times. Increased surface water inflow that resulted from restoration projects and water management changes were productive in the rainy season and should result in increased flushing times and decreased ion concentrations in Taylor Slough.

Trends in Water Quality within the Broward County Portion of the Biscayne Aquifer

Continuous and reliable monitoring of contaminants in drinking water, which adversely affect human health, is the main goal of the Broward County Well Field Protection Program. In this study the individual monitoring station locations were used in a yearly and quarterly spatiotemporal Ordinary Kriging interpolation to create a raster network of contaminant detections. In the final analysis, the raster spatiotemporal nitrate concentration trends were overlaid with a pollution vulnerability index to determine if the concentrations are influenced by a set of independent variables. The pollution vulnerability factors are depth to water, recharge, aquifer media, soil, impact to vadose zone, and conductivity. The creation of the nitrate raster dataset had an average RMS Standardized error close to 1 at 0.98. The greatest frequency of detections and the highest concentrations are found in the months of April, May, June, July, August, and September. An average of 76.4% of the nitrate intersected with cells of the pollution vulnerability index over 100.

Stream water‐quality monitoring conducted in support of the Iowa Nutrient Reduction Strategy (2016)

Monitoring of nitrogen and phosphorus in streams and rivers throughout Iowa is an essential element of the Iowa Nutrient Reduction Strategy (INRS). Sampling and analysis of surface water is necessary to develop periodic estimates of the amounts of nitrogen and phosphorus transported from Iowa. Surface and groundwater monitoring provides the scientific evidence needed to document the effectiveness of nutrient reduction practices and the impact they have on water quality. Lastly, monitoring data informs decisions about where and how best to implement nutrient reduction practices, by both point sources and nonpoint sources, to provide the greatest benefit at the least cost. The impetus for this report comes from the Water Resources Coordination Council (WRCC) which states in its 2014‐15 Annual Report “Efforts are underway to improve understanding of the multiple nutrient monitoring efforts that may be available and can be compared to the nutrient WQ monitoring framework to identify opportunities and potential data gaps to better coordinate and prioritize future nutrient monitoring efforts.” This report is the culmination of those efforts.

Iowa Nutrient Reduction Strategy stream water quality monitoring in Iowa : measuring progress (2016)

The Iowa Nutrient Reduction Strategy (NRS) is a research- and technology-based approach to assess and reduce nutrients—nitrogen and phosphorus—delivered to Iowa waterways and the Gulf of Mexico by 45 percent. To measure progress, researchers track many different factors, from inputs (e.g. funding) and the human domain (e.g. farmer perspectives) to land management (e.g. on-farm practices) and water quality. Monitoring Iowa streams provides valuable insight into measuring water quality progress and the reduction of surface water nutrient loss. The Iowa Nutrient Reduction Strategy (NRS) aims to reduce the load, or total amount (e.g. tons), of nutrients lost annually. Researchers calculate the load from water monitoring results, which measure concentration combined with stream flow.

Risk assessment of herbicide mixtures in a large European lake

Lake Geneva is one of the largest European lakes with a surface area of 580 km2. Its catchment area covers 7400 km2, of which approximately 20% is arable land. Monitoring campaigns have been carried out in 2004 and 2005 to determine the contamination of the lake by pesticides. The results highlight the widespread presence of herbicides in water, the measured concentrations for most substances remaining constant in 2004 and 2005. However, for some individual herbicides the concentrations increased drastically (e.g., the herbicide foramsulfuron). We assessed the environmental risk of the herbicides detected in the lake using water quality criteria recently determined for the Swiss environmental protection agency. Furthermore, we assessed the risk of herbicide mixtures, grouped based upon their mode of action. Generally, the risk estimated for all single substances is low, except for some sulfonylurea compounds. For these substances, the measured concentrations are higher than the predicted no-effect concentration. Impact on the flora of the lake can therefore not be excluded. When mixtures of pesticides with similar mode of action are taken into account, the risk remains lower than the mixture water quality criteria for all groups, but can reach as high as one third of this quality criteria. A further step would therefore be to assess the risk of the total pesticide mixture, including similar and dissimilar modes of action

Risk Assessement of Herbicide Mixtures

Lake Geneva is one of the largest European lakes with a surface area of 580 km2. Its catchment area covers 7400 km2, of which approximately 20% is arable land. Monitoring campaigns have been carried out in 2004 and 2005 to determine the contamination of the lake by pesticides. The results highlight the widespread presence of herbicides in water, the measured concentrations for most substances remaining constant in 2004 and 2005. However, for some individual herbicides the concentrations increased drastically (e.g., the herbicide foramsulfuron). We assessed the environmental risk of the herbicides detected in the lake using water quality criteria recently determined for the Swiss environmental protection agency. Furthermore, we assessed the risk of herbicide mixtures, grouped based upon their mode of action. Generally, the risk estimated for all single substances is low, except for some sulfonylurea compounds. For these substances, the measured concentrations are higher than the predicted no-effect concentration. Impact on the flora of the lake can therefore not be excluded. When mixtures of pesticides with similar mode of action are taken into account, the risk remains lower than the mixture water quality criteria for all groups, but can reach as high as one third of this quality criteria. A further step would therefore be to assess the risk of the total pesticide mixture, including similar and dissimilar modes of action.

Avaliação da qualidade higiênico-sanitária da água de poços rasos localizados em uma área urbana: utilização de colifagos em comparação com indicadores bacterianos de poluição fecal

Foram submetidas às contagens de colifagos, coliformes totais, coliformes fecais e de estreptococos fecais, 104 amostras de água colhidas de 8 poços rasos localizados na área urbana do Município de Jaboticabal, SP, Brasil, com a finalidade de avaliar as condições higiênico-sanitárias e de verificar as correlações existentes entre o número de colifagos e o de bactérias indicadoras de poluição fecal. Os resultados obtidos evidenciaram a ocorrência de 96 (92,3%) amostras fora dos padrões bacteriológicos de potabilidade estabelecidos pelo Ministério da Saúde, monstrando ser precárias as condições higiênico-sanitárias das águas analisadas. Os achados evidenciaram a inexistência de correlação entre o número de colifagos e os números de bactérias indicadoras de poluição fecal.

Integrated Ecological Modeling and Decision Analysis Within the Everglades Landscape

Planning for complex ecosystem restoration projects involves integrating ecological modeling with analysis of performance trade-offs among restoration alternatives. The authors used the Everglades Landscape Model and Multi-Criteria Decision Analysis to explore the effect of simulated ecosystem performance, risk preferences, and criteria weights on the ranking of three alternatives to restoring overland sheet flow in the Everglades. The ecological model outputs included both hydrologic and water quality criteria. Results were scored in the decision analysis framework, highlighting the trade-offs between hydrologic restoration and water quality constraints. Given equal weighting of performance measures, the alternative with more homogenous sheet flow was preferred over other alternatives, despite evidence of some localized eutrophication risk.

Evaluation criteria guide for water pollution prevention, control, and abatement programs.

"23 April 1987."

Quality of water sources used as drinking water in a Brazilian peri-urban area

The objective of this paper was to assess bacteriological quality of drinking water in a peri-urban area located in the Metropolitan Region of São Paulo, Brazil. A total of 89 water samples were collected from community plastic tanks and 177 water samples from wells were collected bimonthly, from September 2007 to November 2008, for evaluating bacteriological parameters including: Escherichia coli, Enterococcus and heterotrophic plate count (HPC). Clostridium perfringens was investigated in a subsample (40 samples from community plastic tank and 40 from wells). E. coli was present in 5 (5.6%) samples from community plastic tanks (2.0 - 5.1x10(4) MPN/100mL) and in 70 (39.5%) well samples (2.0 - 8.6x10(4) MPN/100mL). Thus, these samples were not in accordance with the Brazilian Regulation. Enterococcus was detected in 20 (22.5%) samples of the community plastic tanks (1 to 79 NC/100mL) and in 142 (80.2%) well samples (1 to >200 NC/100mL). C. perfringens was detected in 5 (12.5%) community plastic tanks samples and in 35 (87.5%) wells samples (2.2 to >16 MPN/100mL). HPC were above 500 CFU/mL in 5 (5.6%) waters from community plastic tanks. In wells samples, the HPC ranged from <1 to 1.6x10(4) CFU/mL. The residual chlorine did not attend the standard established in the drinking water legislation (0.2 mg/L), except in 20 (22.5%) samples. These results confirm the vulnerability of the water supply systems in this peri-urban area what is clearly a public health concern.

Environmental impact on the bacteriological quality of domestic water supplies in Lagos, Nigeria

OBJECTIVE: To assess the impact of town planning, infrastructure, sanitation and rainfall on the bacteriological quality of domestic water supplies. METHODS: Water samples obtained from deep and shallow wells, boreholes and public taps were cultured to determine the most probable number of Escherichia coli and total coliform using the multiple tube technique. Presence of enteric pathogens was detected using selective and differential media. Samples were collected during both periods of heavy and low rainfall and from municipalities that are unique with respect to infrastructure planning, town planning and sanitation. RESULTS: Contamination of treated and pipe distributed water was related with distance of the collection point from a utility station. Faults in pipelines increased the rate of contamination (p<0.5) and this occurred mostly in densely populated areas with dilapidated infrastructure. Wastewater from drains was the main source of contamination of pipe-borne water. Shallow wells were more contaminated than deep wells and boreholes and contamination was higher during period of heavy rainfall (p<0.05). E. coli and enteric pathogens were isolated from contaminated supplies. CONCLUSIONS: Poor town planning, dilapidated infrastructure and indiscriminate siting of wells and boreholes contributed to the low bacteriological quality of domestic water supplies. Rainfall accentuated the impact.

Microbiological quality of drinking water of urban and rural communities, Brazil

OBJECTIVE: To evaluate the microbiological quality of treated and untreated water samples came from urban and rural communities and to examine the relationship between coliforms occurrence and average water temperature, and a comparison of the rainfall levels. METHODS: A sample of 3,073 untreated and treated (chlorinated) water from taps (1,594), reservoir used to store treated water (1,033), spring water (96) and private well (350) collected for routine testing between 1996 and 1999 was analyzed by the multiple dilution tube methods used to detect the most probable number of total and fecal coliforms. These samples were obtained in the region of Maringá, state of Paraná, Brazil. RESULTS: The highest numbers water samples contaminated by TC (83%) and FC (48%) were found in the untreated water. TC and FC in samples taken from reservoirs used to store treated water was higher than that from taps midway along distribution lines. Among the treated water samples examined, coliform bacteria were found in 171 of the 1,033 sampling reservoirs. CONCLUSIONS: Insufficient treatment or regrowth is suggested by the observation that more than 17% of these treated potable water contained coliform. TC and FC positive samples appear to be similar and seasonally influenced in treated water. Two different periods must be considered for the occurrence of both TC and FC positive samples: (i) a warm-weather period (September-March) with high percentage of contaminated samples; and (ii) cold-weather period (April-August) were they are lower. Both TC and TF positive samples declined with the decreased of water temperature.