Cristiano Poleto

The identification of sediment sources in a small urban watershed in southern Brazil: An application of sediment fingerprinting

Soil particles eroded from the land surface and transported into rivers by runoff are considered one of the main components of non‐point source pollution in urban watersheds. These particles also serve as a vector for a wide variety of both organic and inorganic constituents. As a result, the identification of sediment sources in an urban watershed is necessary not only to understand erosion dynamics, but also to help implement more effective measures to control and/or remediate non‐point source pollution. The present study employs sediment ‘fingerprinting’ to determine the main sediment sources in a small residential urban watershed (0.83 km2) on the outskirts of Porto Alegre in southern Brazil. Based on an evaluation spanning 12 rainfall events, the results show that paved and unpaved roads and the stream channel itself contribute, on average, 46%, 23%, and 31%, respectively, to the suspended sediment flux in the watershed. Furthermore, the source contributions varied both between events and over the course of a single event. This appears to imply that source contributions, at least to some extent, depend on local precipitation patterns. The results from this study indicate that the level of uncertainty in source ascription tends to decline with increasing numbers of tracers; hence, successful sediment fingerprinting and source ascription in complex hydrologic environments, such as urban watersheds, may require the use of a large number of chemical and/or physical tracers.

Overview of the work in Latin America on erosion and sediment dynamics

Recently, hydrosedimentological investigations have gained increasing attention from society due to a broader understanding and appreciation of the socioeconomic and environmental impacts of erosion and sedimentation processes. In Latin America, where much of the produced electricity comes from hydroelectric power plants and where land use changes at a considerable rate, a deeper understanding of sediment-related processes is important. Other driving forces that have boosted hydrosedimentological research in the Latin American continent are the increasing international demand for food, which has led to the expansion of agricultural frontiers; mining activities; the unplanned occupation of erosion-prone urban sites by vulnerable families in large cities; the attempts to further exploit new waterways; the management of sediment in harbors; as well as environmental issues associated with aquatic systems. A clear evidence of the societal—including the governmental sectors—perception of sediment-associated issues and questions can be demonstrated by the new regulation published in 2010 by two Brazilian agencies: National Water Agency (ANA) and National Energy Agency (ANEEL). According to the new regulation, the companies that own hydroelectric power plants are obliged to monitor not only water but also sediment fluxes in reservoirs. This initiative generated a large demand for experts in the area and induced investments in research regarding sediment dynamics in fluvial systems, focusing on the socioeconomic sustainability of anthropogenic interventions. Furthermore, the recent construction of hydroelectric power plants in the Amazon region, which receives a considerable input from the Andes, also demands expert knowledge regarding sediment fluxes and integrated water–sediment management. In regions where water conflicts are already a reality, the number of multipurpose surface reservoirs expands at a high rate, generating complex networks, which strongly intervene in sediment and water flows. Considering that the siltation of strategic water reservoirs lessens water availability, a more thorough understanding of sediment sources and dynamics is of paramount interest for water-scarce regions in the continent. The advance of agricultural frontiers and the construction of dams in the Upper Paraguay River basin are, for instance, generating severe changes in the natural sediment fluxes, which lead to discussions on the long-term impact on the Pantanal Biome. The 150,000-km biome is one of the largest wetland systems on earth. Another Latin American region that raises international concern related to sediment fluxes is the area that drains its waters into the Panama Canal. Due to its economic significance, the constant engineering works for the expansion of the canal and its dredging have been a relevant driving force for advances in terms of erosion and sedimentation studies. The great extent of Latin America—with a broad spectrum of climate, relief, soil, and land use—generates a favorable environment for diversified research initiatives in sedimentology. This is an overview related to sediment erosion, transport, and sedimentation in present Latin America. It clearly encompasses great possibilities for scientific and technological advances in the near future. C. Poleto (*) Hydraulic Research Institute, Federal University of Rio Grande do Sul, Porto Alegre, RS CEP 91501970, Brazil e-mail: cristiano_poleto@hotmail.com

Particle size characterization as a support for sediment contamination analysis

Purpose The purpose of this paper is to analyse the results of particle size profiles carried out in the dam Mae d’agua, located in the metropolitan region of Porto Alegre, Rio Grande do Sul, becoming a tool of support for geochemistry evaluation works of sediments in this basin. Design/methodology/approach The methodology comprised the particle size analysis of eight cores sampled using the extraction profile technique “Sampling Cores.” A total of 56 sub-samples were obtained at different depths, varying between 0 and 52 cm. The particle size analysis of the sub-samples was carried out with the protocol relating to Brazilian analysis standards NBR 7,181; for determination of the particle size distribution of thick sediments, the sieve method was used, and for fine sediments, the pipette method was used. Findings The results show that for the different depths, the sediment profiles show similarity in their sedimentary deposition layers. Cores T1, T6, T7 and T8 showed a classification with predominance of mud. Cores T2 and T5 showed variations throughout their sedimentary profile, varying of mud predominance to sand with gravel, and on cores T3 and T4, the predominant characteristic is sand with mud and sand with gravel, respectively. Originality/value It can be seen in this paper that energy of sedimentological flow reaches it in a different way, creating these three sectors (first, sand with gravel; second, sand with mud and third, mud) with different characteristics – morphodynamic and sedimentological. These characteristics are important for the study of the heavy metals on the soil and therefore for reducing the risk of contamination of water courses.

Comparison of the analytical performance of EDXRF and FAAS techniques in the determination of metal species concentrations using protocol 3050B (USEPA)

ABSTRACT Sediments are active environmental compartments capable of interchanging the chemical species with the water column, degrading their quality and influencing the toxicity of the matrix. The average concentrations of sediment-associated metallic species have been used to evaluate the extent of their contamination. The approaches used have progressed considerably over the last few decades and different instrumental techniques have been employed in quali-quantification of metal compounds associated with sediments. This study aimed to evaluate the accuracy of the technique of Energy Dispersive X-Ray Fluorescence Spectrometry (EDXRF) performed on the equipment Shimadzu (model Rany, Series EDX-720) in the validation process, adopting as reference the technique of Flame Atomic Absorption Spectroscopy (FAAS), appliance GBC (model Avanta) to quantify the species: Zn, Fe, Ni, Cu, Pb and Cr in solution, in chemically available fraction (3050B Protocol-United States Environmental Protection Agency), extracted from sediments of the River Barigüi, metropolitan region of Curitiba, southern Brazil. The samples were collected according to the clean techniques protocols. The analytical figures of precision, accuracy and determination limit of the method were evaluated using the two techniques separately and on the same samples. Statistically significant differences were observed between the two methods.

Use of legal reserve areas as geochemical background in hydrosedimentology studies

In hydrosedimentology studies the determination of the trace element concentrations at the study site is imperative, since this background can be used to assess the enrichment of sediments with these elements. This enrichment can be the result of the natural process of geological formation or of anthropogenic activities. In the latter case, guidelines are used to indicate the concentrations at which trace elements cause ecotoxicity effects on the environment. Thus, this study used legal reserve areas in the municipality of Toledo, PR, where natural forests are maintained, with no or minimal human interference to establish background levels. The results of atomic emission spectrometry with inductively coupled argon plasma showed that the legal reserves have lower levels of trace elements than other theoretical references, but equivalent concentrations to the safety levels recommended by international guidelines. It was concluded that determining values is fundamental to recommend this background as scientific database for research in the area of hydrosedimentology of this site and also as a way of environmental management of the watershed of this municipality.

Entropy for Determination of Suspended Sediment Concentration: Parameter Related to Granulometry

AbstractBecause of the relation between water quality and sediment quantity, the quantification of sediments in rivers and open channels is of utmost importance. This paper applies the theory of en...

Avaliação da rede de monitoramento de uma bacia hidrográfica do Rio Grande do Sul, Brasil

The Sinos River is one of the most polluted rivers in Brazil. This article presents a survey of information about the hydrological monitoring network of Sinos River Basin, state of Rio Grande do Sul. It aimed to identify the institutional actions in progress to evaluate the water quality of the river. A documentary research was conducted through which the entities responsible for the hydrological monitoring of the Sinos River and its tributaries were identified. It was found that there are several responsible organisms and that the sampling frequencies of water quality are varied. The main entity responsible for this monitoring is the State Foundation for Environmental Protection, which performs the analysis of physical, chemical and biological parameters in quarterly frequency. The owners of the sanitation services verify the hourly, daily and monthly frequency of the adduced water and the effluent standards dumped in the river. Other entities, state and federal, perform the monitoring in fluviometric and rainfall stations. It was verified, then, that the river is highly monitored, but there isn’t integration of the data. The quality results are available with a three-month time lapse and the daily results are not disclosed by the sanitation companies to the public.

Principle of maximum entropy in the estimation of suspended sediment concentration

A preocupacao com a qualidade das aguas vem promovendo o desenvolvimento de tecnicas cada dia melhores de monitoramento e controle. Como os sedimentos transportam a maior parte dos contaminantes da agua, seu estudo e fundamental. Diante do elevado numero de variaveis existentes para a estimativa da concentracao de sedimentos e elevados custos de campanhas de monitoramento, torna-se necessario o desenvolvimento de metodos mais acessiveis e que tragam resultados praticos satisfatorios. Para tanto, este trabalho trata da aplicacao do principio da entropia maxima, um metodo probabilistico, para determinar a concentracao de sedimentos em calhas com diversas concentracoes e granulometrias. Para isso, foi proposta uma relacao entre os parâmetros do principio da entropia maxima para determinar o indice entropico e facilitar o calculo. Os resultados mostraram-se satisfatorios para concentracoes acima de 10 g/L com R2 superiores a 0,88. Os erros quadraticos calculados neste trabalho foram inferiores aos encontrados quando utilizada a teoria da entropia por Tsallis e pela Equacao de Rouse, modelos classicos de estimativa do perfil de concentracao de sedimentos. A aplicabilidade do modelo proposto e a facilidade da utilizacao do metodo probabilistico, ja que reduz a quantidade de dados necessarios para realizar a estimativa, torna-o viavel em escala global.

Study of water resources management plans as a tool for integrated watershed management

ABSTRACT Water scarcity and floods caused by the effects of climate variability have been alarming and victimizing many people and alerting the authorities around the world, which has been promoting investments in the area. Nowadays, it is a global consensus that the best alternative for water resources management is the integrated approach, which combines several areas of knowledge and political organization levels for the maintenance of adequate quantity and quality of water. Therefore, the article presents an analysis of the main Brazilian watershed plans as a tool for integrated water resources management (IWRM), in comparison to selected plans from basins located in Portugal and the United States. A multicriteria analysis was performed to compare all the plans according to their completeness and quality of content. One of the greatest difficulties related to watershed plans and implementation of IWRM is the challenge of achieving the best planning strategies, elaboration and implementation. Brazil has elaborated strategies oriented to approach the challenges of water by regions, decentralization through user participation and organisms at a basin level such as the basin committees. The water concession and cost sharing based on the user-pay principle are also progressive approaches already used in Brazilian territory. In general, it was noted a superficial method of elaborating watershed plans in Brazil and the interference of political interests has been representing a problem to the quality and impartiality of the plans. On the other hand, the Portuguese and North American studied basin plans presented more descriptive characterizations. However, success of plans is more likely to be determined after applying and obtaining results regarding the qualitative and quantitative aspects of water, as well as other improvements set for the river basin.

Analysis of urban rivers' water quality using multivariate approach

This study performed a multivariate analysis about the water quality of rivers that go across the urban perimeter of Toledo - PR. For this study five rivers were chosen, where the physicochemical data of the water was collected as sediment samples to determine the amounts of copper and zinc with the use of spectrometry of optical emission with inductively coupled plasma (ICP-OES). The results showed that the physicochemical parameters were influenced by the contribution of anthropic pollution and explained the desorption of copper and zinc from the river bottom sediments. The control graphs demonstrated some results outside control limits, however the most part results inside the limits do not represent the best parameters of water quality. Therefore, it was concluded that the technique used is one relevant tool to interpret the behaviour of physicochemical parameters, allowing that the quality of water of rivers may be monitored.