A influência da poluição difusa e do regime hidrológico peculiar do semiárido na qualidade da água de um reservatório tropical

In semiarid region of northeast Brazil, the majority of reservoirs used for public supply has suffered degradation of water quality affected by diffuse pollution from agricultural and livestock areas of the watershed and by hydrologic regime peculiar to the region, characterized by a rainy season with higher volumes stored in reservoirs and a dry season with a reduction in water level due to high evaporation and increase of eutrophication. The Dourado reservoir, located in Currais Novos city, semiarid region of Rio Grande do Norte state, is one example of a water supply reservoir that can have degradation of water quality and impracticability of their use, due to the high external input of nutrients from non-point sources of watershed during the rainy season and increasing of eutrophication due to decrease the stored volume during the dry period. This study aimed to investigate and quantify diffuse pollution and the hydrologic regime of semiarid region in order to establish standards regarding the water quality of Dourado reservoir. The study period was between the months of May 2011 to March 2012. The diffuse pollution was quantified in terms of watershed from the mass balance of phosphorus in the reservoir, as in relation to areas under different types of land use within the riparian zone of the reservoir from the assessment of soil chemical properties and losses of phosphorus in each area. The influence of hydrological regime on water quality of the reservoir was evaluated from the monthly monitoring of the morphometric, meteorological and limnological features throughout the study period. The results showed that the reservoir has received a high load of phosphorus coming from the drainage basin and presents itself as a system able to retain some of that load tributary, giving an upward trend of the eutrophication process. Diffuse pollution by nutrients from areas under different types of land use within the riparian zone of the reservoir was higher in areas under the influence of livestock, being this area considered a potential diffuse source of nutrients to the reservoir. Regarding the water regime during the rainy season the reservoir was characterized by high concentrations of nutrients and small algal biomass, while in the dry season the reduction of volume and increase of the water retention time of the reservoir, contributing to the excessive growth algal biomass, favoring an increase in eutrophication and deterioration of water quality. In synthesis the water quality of Dourado reservoir is directed by diffuse pollution coming from the drainage basin and the hydrological regime of the peculiar semiarid region, where the rainy season is characterized by high input of allochthonous compounds from the tributaries and erosion of the soil in the reservoir riparian zone, and the dry season characterized by reducing the storage volume due to high evaporation, high residence time of water and consequent degradation of water quality due to the increase of eutrophication process

Avaliação da disponibilidade hídrica e da demanda hídrica no trecho do Rio Piranhas-Açu entre os açudes Coremas-mãe D´água e Armando Ribeiro Gonçalves

Piranhas-Açu basin is a Federal watershed with a drainage area of 43.681,5 km2, sited at Brazilian northeast semi arid, with 60% of your area in Paraiba State and 40% in Rio Grande do Norte State. The main river, Piranhas-Açu, has strategic importance for development of these states, because it s an essential source for many socio-economics activities developed along watercourse. The river s reach between Coremas-Mãe D`água Dam and Armando Ribeiro Gonçalves Dam has many irrigation projects, and supply many riverside cities. All this activities practiced in this river s reach consumes high water volumes. Due the importance of this stream and the necessity of an adequate management, this work aims for an impartial and detailed evaluation of real water supply conditions in this river s reach, by the application of hydrological modeling, including the arrangement of main dams in tributaries, and storage reservoir water balance. The rainfall-discharge model s applied in each sub-basins it was selected the model MODHISA- Hydrological Model of Semi Arid, that is a concentrated model with easy application. The simulation produced 50 years of inflows into the reservoirs, for which, were constructed the guaranties curves; and produced 50 years of synthetic discharge data in relevant points on the river and on its affluents; so it was constructed the permanence curves. Confronting the available discharge with the current and futures volumes of raw water captured in this river s reach, it was verified that de demands have high guaranties. This work concluded that the MODHISA Model is suitable to reproduce the hydrologic characteristics of Piranhas-Açu sub-basins, and showing good results

Desenvolvimento de uma metodologia para caracterização de amostras de sedimento: Rio Jundiaí RN

The study of sediment in water bodies presents great environmental importance, because of its ability to adsorb the pollutants, they may facilitate the understanding of the history of the current quality of the water system. Depending on how it is done the collection, analysis can show both a recent contamination as old. The detailed characterization of the sediment may reveal details that can understand how each type of pollutant interacts with the material given its composition. In this work it has developed a systematic methodology to characterize samples of sediment, with the aim to understand how a series of metal is distributed in different size fractions of the sediment. This study was conducted in five samples of sediment (P1, P2, P3a, P3B and P3c) collected in Jundiaí river, one of the most important tributaries of the river Potengi in the region of Macaíba, RN. The characterization was made with the samples previously sieved into meshes with different granulometries (+8#, -8+16#, -16+65# - 65+100#,-100+200#,-200+250# and -250#), using the following techniques: Analysis of specific surface area by BET method, determining the levels of organic matter (OM%) and humidity through the gravimetry and Analysis Thermogravimetric (TG), Infrared Spectroscopy in a Fourier transform (FTIR ), Analysis of X ray diffraction (XRD), analysis of heavy metals by optical emission spectrometry with the Argon Plasma (ICP-OES). The analyzed elements were Al, Cd, Cr, Cu, Fe, Mn, Ni, Zn and P. In addition to the techniques of characterization above, was also made the rebuilding of the samples P1, P2 and P3B in relation to the levels of organic matter and concentration of heavy metals. Then, the results of the recomposed samples were compared with those obtained in crude samples, showing great consistency. The gravimetry, used in determining the levels of organic matter, was not considered an appropriate method because the clay minerals present in the sediment samples analyzed fall apart in the same range of temperature (550-600 0C) used in roasting (600 0C). The results also showed the trend of organic matter and heavy metals to focus on the thin fractions, although the largest concentrations of metals are in intermediate fractions

Monitoramento geoambiental do estuário do Rio Paraíba do Norte - PB por meio da cartografia temática digital e de produtos de sensoriamento remoto

The North Paraíba River Estuary, located in the eastern portion of the Paraíba State, Northeast Brazil, on coordinates 34º50 00 -34º57 30 S and 6º55 00 -7º7 30 W, constitutes a fluvio-marine plain formed by the North Paraíba River and its tributaries Sanhauá, Paroeira, Mandacaru, Tiriri, Tambiá, Ribeira and Guia. This estuary comprises an area of about 260 km2. Increasing human demands on the estuary area and inadequate environment managing have generated conflicts. The present work main purpose is to evaluate the geodynamic evolution of the North Paraíba River Estuary in the period from 1969 to 2001, using digital image processing techniques, thematic digital cartography and multitemporal data integration, combined to geological-geophysical field surveys. The SUDENE cartographic database, converted to digital format were, used to obtain occupation and topographic maps from 1969 and to generate a Digital Elevation Model (DEM). Digital Landsat 7 ETM+ and Spot HRVIR-PAN satellite images interpretation allowed the environmental characterization of the estuary. The most important digital processing results were achieved color composites RGB 5-4-3, 5-3-1, 5-2-NDWI and band ratio 7/4-5/3-4/2, 5/7-3/1-5/4). In addition the fusion image technique RGBI was used by the inclusion of the Spot HRVRI and Landsat 7 ETM+ panchromatic band on I layer with RGB triplets 5-4-3, 5-3-1 and 5/7-3/1-5/4. The DEM and digital images integration allowed the identification of seven geomorphological units: coastal tableland, flowing tray, tide plain, fluvial terrace, submerged dune, beach plain and beach). Both Side Scan Sonar and Echosound were used to analyse underwater surface and bedforms of the estuarine channel, sand predominance (fine to very fine) and 2D dune features 5 m wide and 0.5 m height. This investigation characterized the estuary as an environment dominated by regimen of average flow. The channel depth varies between 1 m and 11 m, being this last quota reached in the area of Porto de Cabedelo. The chanel estuary is relatively shallow, with erosion evidences mainly on its superior portion, attested by sand banks exposed during the low tide. Multitemporal digital maps from 1969 and 2001 integration were obtained through geoprocessing techniques, resulting the geodynamic evolution of the estuary based on landuse, DEM geomorphology and bathymetric maps

Efeito da seca na dinâmica dos grupos funcionais fitoplanctônicos em reservatórios eutróficos do semiárido

Reservoirs are the main sources of surface water in Brazil´s semiarid region. The majority of these water supplies, however, are compromised by eutrophication. A severe drought in 2012 contributed to significant losses in water volume, influencing the availability of resources (nutrients and light) for phytoplankton. The aim of this study is to understand the dynamics of the functional groups of phytoplankton and the factors that affect them during a severe drought in the semiarid reservoirs of the northeast. We therefore studied the Dourado, Gargalheiras and Passagem das Traíras reservoirs in Rio Grande do Norte from January 2012 to January 2013. The effect of drought favoured homogeneity within the reservoir, in relation to biotic and abiotic variables, notably the absence of water supply given the lack of flow from its tributaries (intermittent river). The phytoplankton functional groups of bloomforming cyanobacteria (SN, S1 and M) dominated throughout the year 2012, in both the shallow and deep areas of the three reservoirs studied. The groups were related to high concentrations of volatile solids, total phosphorus and ammonia, and high turbidity. Cylindrospermopsis raciborskii (SN group) was the species with the greatest biomass in the three reservoirs. M group (Sphaerocavum brasiliense) performed better in shallow waters with more available phosphorus. Our data showed that high concentrations of nutrients and low availability of light, besides the stability of the water column due to lack of flow and the system´s high residence time, favoured the dominance of bloom-forming cyanobacteria groups, especially those tolerant to shadow