Limnology of Macrobrachium amazonicum grow-out ponds subject to high inflow of nutrient-rich water and different stocking and harvest management

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow-out ponds supplied with a high inflow of nutrient-rich water. Prawns were subject to different stocking and harvesting strategies: upper-graded juveniles, lower-graded juveniles, non-graded juveniles + selective harvesting and traditional farming (non-grading juveniles and total harvest only). Dissolved oxygen, afternoon N-ammonia and N-nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1-8.0) waters indicated a non-readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day(-1) and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow-out in ponds subjected to a high inflow of nutrient-rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non-readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient-rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.

Sistema com aeração, decantação e filtragem para a melhoria da qualidade de água em irrigação localizada

A qualidade da água é muito importante para irrigação por gotejamento, pois ela escoa por pequenos bocais dos emissores, podendo ocorrer obstrução devido à deposição dos sólidos em suspensão. Portanto, antes da instalação do projeto, devem-se avaliar parâmetros de qualidade da água, para adotar medidas preventivas, evitando o risco de entupimento do sistema. Este trabalho teve como objetivo avaliar um sistema composto por aeradores com aspersores, sobre leito de pedra, para a precipitação dos íons Fe+2e Mn+2 em tanque de decantação, e um conjunto de filtragem composto por três filtros de areia e um de disco, em sistema de irrigação localizada. O trabalho foi realizado na Fazenda Alvorada, no município de Nova Granada - SP, no período de março a outubro de 2008. Foram realizadas determinações de variáveis físicas e químicas da água, ao longo do sistema de aeração, decantação e filtragem, o qual foi eficiente para a melhoria da qualidade de água, reduzindo os níveis de risco de entupimento de severo para médio e de médio para baixo. Oxigênio dissolvido, condutividade elétrica, pH, Fe+2e Fe+3 não diferenciaram a qualidade de água entre os pontos do sistema de tratamento, porém a turbidez, sólidos dissolvidos, sólidos em suspensão, ferro total e manganês total reduziram-se significativamente pelo uso do sistema proposto, melhorando a qualidade da água.

Phytoplankton structure in two contrasting cascade reservoirs (Paranapanema River, Southeast Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rotifer abundance, biomass, and secondary production after the recovery of hydrologic connectivity between a river and two marginal lakes (São Paulo, Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mercury Redox Chemistry in the Negro River Basin, Amazon: The Role of Organic Matter and Solar Light

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultrasound efficiency in relation to sodium hypochlorite and filtration adsorption in microbial elimination in a water treatment plant

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preference ratios for mercury and other chemical elements in the Madeira River, Brazil

Samples of water, suspended solids, and bottom sediments from the Madeira River, Rondonia state, Brazil, were physically and chemically analyzed to investigate the actual Hg mobilization in the aquatic environment and compare it with that of other heavy metals and elements in the area. Two dimensionless Hg preference ratios were defined, expressing (1) the ratio of Hg and other elements in the liquid phase divided by the ratio of Hg and other elements in bottom sediments (P(l.phase)) and (2) the ratio of Hg and other elements in the particulate matter divided by the ratio of Hg and other elements in bottom sediments (P(s.solids)). These preference ratios are useful for comparing Hg transport in three different phases (liquid, particulate matter, and bottom sediments). They also were applicable to any analyzed elementin the area studied, because they generated an almost constant value when the maximum calculated was divided by the minimum (P(l.phase) = 2931; P(s.solids) = 84) and because of their sensitivity to the dominance of sorption processes by Fe oxides and hydroxides. Mercury could be transported preferentially to other analyzed elements in the particulate phase only if its concentration reached values at least 10(4)-fold higher than those expected or quantified in the area. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Avaliação da qualidade da água e autodepuração do ribeirão do meio, Leme (SP)

This investigation utilized hydrochemical relations to evaluate possible anthropogenic inputs at Meio Stream, São Paulo State. Realized three sampling of water during the months of February, April and July/2005, in five sampling points analyzing: discharge, temperature, turbidity, pH, electrical conductivity (EC), dissolved oxygen ( DO), TDS (total dissolved solids), TSS (total suspended solids), Ca(2+), Mg(2+), Na(+), K(+), HCO(3)(-), Cl(-), SO(4)(2-), PO(4)(3-) and NO(3)(-). The characteristics of water close to spring until Leme city allow concluding that there is a small interference in its quality, however the absence of treatment of domestic wastewater at Leme city reduced its quality. It was applied the QUAL 2K modeling to evaluate the Meio Stream auto-purification identified the auto-purification zones and indicated the necessity of secondary wastewater treatment, with 76% of efficiency.

Itaipu reservoir limnology: eutrophication degree and the horizontal distribution of its limnological variables

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variação espacial e temporal da produtividade primária pelo fitoplâncton na represa de Jurumirim (Rio Paranapanema, SP)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência do tipo de coleta (comum ou seletiva) na reciclagem de filmes de poliolefinas pós-consumo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessment of aquatic plants in the reservoirs of AES-Tiete and development of an integrated control model for the most important species

The general objective of this work was to develop a monitoring and management model for aquatic plants that could be used in reservoir cascades in Brazil, using the reservoirs of AES-Tiete as a study case. The investigations were carried out at the reservoirs of Barra-Bonita, Bariri, Ibitinga, Promissao, and Nova-Avanhandava, located in the Tiete River Basin; Agua Vermelha, located in the Grande River Basin; Caconde, Limoeiro, and Euclides da Cunha, which are part of the Pardo River Basin; and the Mogi-Guacu reservoir, which belongs to the Mogi-Guacu River basin. The main products of this work were: development of techniques using satellite-generated images for monitoring and planning aquatic plant control; planning and construction of a boat to move floating plant masses and an airboat equipped with a DGPS navigation and application flow control system. Results allowed to conclude that the occurrence of all types of aquatic plants is directly associated with sedimentation process and, consequently, with nutrient and light availability. Reservoirs placed at the beginning of cascades are more subject to sedimentation and occurrence of marginal, floating and emerged plants, and are the priority when it comes to controlling these plants, since they provide a supply of weeds for the other reservoirs. Reservoirs placed downstream show smaller amounts of water-suspended solids, with greater transmission of light and occurrence of submerged plants.

A method for evaluating Ra-228 in environmental matrices and its use at Pocos de Caldas plateau, Brazil

This work describes a methodology developed for performing the extraction, detection and quantification of Ra-228 in waters, suspended solids and sediments. The technique proved to be useful for analyzing samples from the hydrological environment of Morro do Ferro, Pocos de Caldas plateau, Brazil. The 228Ra activity in underground waters of 5 boreholes drilled in the area varied from 0.02 up to 14.5 Bq/l, whereas for the surficial waters the variation was from 0.04 to 0.51 Bq/l; for the suspended solids, the values ranged from 1.5 up to 419 Bq/g, whereas it was possible to find a value of 2.04 Bq/g for the sediments. These results show the applicability of the method for characterizing different matrices of environmental interest. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Os efeitos da ação antrópica sobre a distribuição de macroinvertebrados no Rio Guareí, São Paulo

In this study, it was examined, during the period from March to December 2006, the effects of human disturbance on themacroinvertebrates that live near macrophytes in Guare River, São Paulo State - Brazil. It was questioned if the high conductivityrecorded in Guare River affected the distribution of the macroinvertebrates and what were the most important variables thataffect macroinvertebrates in a river with a strong nutrient concentration. The objective of this study was to investigate theeffects of environmental variables on densities and composition of the macroinvertebrates. Three stands of aquatic plantswere sampled with with 0.25 mm mesh net on a 0.07 m2 square metal frame. Air and water temperature, depth, pH, electricalconductivity, suspended solids, dissolved oxygen and macrophyte biomass were measured. A canonical correspondence analysis(CCA) was performed using the density of the macroinvertebrates and environmental variables. Chironomidae, Culicidae,Acanthagrion, Coryphaeschna, Erythrodiplax, Miathyria marcella, Micrathyria, Gastropoda, Ostracoda and Hemiptera werethe only taxa that showed significant correlation with the axes. From the results, we can conclude that the high conductivity recordedin Guare River due to the high amount of organic matter released during its course did not significantly affected thedistribution of the macroinvertebrates during the studied period. However, the ACC recorded that oxygen was the most significantenvironmental factor for the density variance of the macroinvertebrates, especially larval Odonata.

Temporal variation in C, N and P of the periphyton on the tropical aquatic macrophyte echinochloa polystachya (H.B.K.) hitch. In Jurumirim Reservoir (São Paulo, Brazil)

The temporal variations in C, N and P concentrations of the periphyton on the natural substratum (Echinochloa polystachya) and its relationships to the water's climatological (air temperature and precipitation), hydrodynamic (water discharge and water level), physical (temperature, transparency) and chemical variables (conductivity, total suspended solids, nitrate, nitrite, ammonia, silica, total phosphorus and orthophosphate) were evaluated in a lagoon at the Paranapanema River mouth into the Jurumirim Reservoir (São Paulo, Brazil) from August 1993 to July 1994. An amplitude variation of 2.0 m in water level was observed. Depending on to the hydrologic conditions, the lagoon presents intermediate conditions of lentic and lotic environments. The amplitude variations in C, N and P were 14.5-52.1% C DW-1, 0.5-3.2% N DW-1, and 0.03-0.4% P DW-1, respectively. The periphyton presented a decreased protein content. The environmental trophic degree appears to be decisive in chemical periphyton composition.