Irineu Bianchini Junior

Humic substance mineralization in a tropical oxbow lake (São Paulo, Brazil)

We evaluated the mineralization rates of humic substances in Infernão oxbow lake (State of São Paulo, Brazil). Experiments were conducted under aerobic and anaerobic conditions using fulvic acid and humic acid from four sources: Scirpus cubensis and Cabomba piauhyensis leachate submitted to a 120-day degradation process, sediment, and dissolved organic matter from the lake water. A fixed amount of substrate was added to 450 ml of water from Infernão lake, filtered over glass wool. After adding substrate, the flasks were incubated at 21.0°C under aerobic and anaerobic conditions. The dissolved organic carbon was monitored during 95 days. The results were fitted to first-order kinetics model, which pointed to one labile and one refractory fraction. The refractory fractions predominated, ranging from 71.4 to 84.3% for fulvic acid and from 73.4 to 85.0% for humic acid. Mineralization rates of the labile fractions of dissolved organic carbon were higher under aerobic than anaerobic conditions, while the converse was true for the refractory fractions.We evaluated the mineralization rates of humic substances in Infernão oxbow lake (State of São Paulo, Brazil). Experiments were conducted under aerobic and anaerobic conditions using fulvic acid and humic acid from four sources: Scirpus cubensis and Cabomba piauhyensis leachate submitted to a 120-day degradation process, sediment, and dissolved organic matter from the lake water. A fixed amount of substrate was added to 450 ml of water from Infernão lake, filtered over glass wool. After adding substrate, the flasks were incubated at 21.0°C under aerobic and anaerobic conditions. The dissolved organic carbon was monitored during 95 days. The results were fitted to first-order kinetics model, which pointed to one labile and one refractory fraction. The refractory fractions predominated, ranging from 71.4 to 84.3% for fulvic acid and from 73.4 to 85.0% for humic acid. Mineralization rates of the labile fractions of dissolved organic carbon were higher under aerobic than anaerobic conditions, while the converse was true for the refractory fractions.

Oxygen consumption during mineralization of organic compounds in water samples from a small sub-tropical reservoir (Brazil)

ABSTRACT Assays were carried out to evaluate the oxygen consumption resulting from mineralization of different organiccompounds: glucose, sucrose, starch, tannic acid, lysine and glycine. The compounds were added to 1 l of watersample from Monjolinho Reservoir. D issolved oxygen and dissolved organic carbon were monitored during 20 daysand the results were fitted to first order kinetics model. During the 20 days of experiments, the oxygen consumptionvaried from 4.5 mg.l -1 (tannic acid) to 71.5 mg.l -1 (glucose). The highest deoxygenation rate ( k D ) was observed formineralization of tannic acid (0.321 day -1 ) followed by glycine, starch, lysine, sucrose and glucose (0.1004, 0.0504,0.0486, 0.0251 and 0.0158 day -1 , respectively). From theoretical calculations and oxygen and carbonconcentrations we obtained the stoichiometry of the mineralization processes. S toichiometric values varied from 0.17(tannic acid) to 2.55 (sucrose).Key words: Oxygen consumption; aerobic mineralization; Reservoir of Monjolinho ( UFSCar - Sao Carlos, SP)

Water and sediment quality assessment - Ribeirão do Laranjal watershed

The sediment and water of a river can be impacted by the development of modern society. The sediment is responsible for the transport, release and accumulation of toxic compounds and nutrients and can alter the quality of the water. Thus, the objective of this study was to analyze the water and sediment quality of Laranjal stream, located in Laranjal Paulista (Sao Paulo, Brazil). Water and sediment samples were collected in the rainy and dry seasons of the year 2012. The analysis indicated that the sediment presented high content of Cd, Ni, Pb, Cu and Cr. The toxicity test indicated that the river mouth was distinct from the spring and the middle course and the electrical conductivity of the water was high at the sampling point within the urban mesh of Laranjal Paulista. Considering the use and occupation of the Laranjal stream watershed, the rural mes h (dominated by pasture and plantation) influences predominantly the quality of water and sediments.

Qualidade das águas e hemerobia da bacia do córrego do Mineirinho, São Carlos, SP

O monitoramento limnologico auxilia no diagnostico da qualidade dos recursos hidricos e pode ser utilizado como uma ferramenta de gestao ambiental, fornecendo subsidios para a tomada de decisao e no planejamento ambiental de bacias hidrograficas. A qualidade da agua das nascentes e da foz do corrego do Mineirinho, localizado na area urbana do municipio de Sao Carlos, SP, foi avaliada por 11 variaveis limnologicas e pelo indice de qualidade da agua, no periodo de cheia e de seca, sendo enquadrada como regular a ruim. Dentre os indicadores ambientais da agua que apresentaram maior influencia sobre sua qualidade, os coliformes fecais e a DBO5 foram os que mais contribuiram para a diminuicao da qualidade da agua nesse ambiente lotico. Tanto as variaveis limnologicas quanto o indice de qualidade da agua se relacionaram com os elevados graus de hemerobia no entorno do corrego do Mineirinho, que caracteriza a area estudada com baixa capacidade de autorregulacao e alta dependencia do manejo humano para a manutencao de suas funcoes ecossistemicas.

Qualidade dos sedimentos do rio Monjolinho: índice de geoacumulação

A adocao de valores de referencia ( guidelines ) para as concentracoes de metais auxilia no diagnostico de ambientes antropizados, bem como na elaboracao de diretrizes para o manejo. Este estudo buscou avaliar a qualidade do sedimento do rio Monjolinho (Sao Carlos, SP) utilizando o indice de geoacumulacao aplicado aos metais analisados (Cd, Cu, Pb, Cr, Fe, Ni, Mn e Zn) em tres trechos: nascente, curso medio e foz durante a estacao seca e de cheia. Os resultados indicaram que o Cd foi o unico elemento que se enquadrou na categoria que indica contaminacao moderada a forte. Verificou-se que Zn, Pb, Ni e Cu apresentaram concentracoes significativamente diferentes entre o curso alto e baixo. A poluicao difusa das areas agricolas e urbana sao as principais causas do enriquecimento de Cd nos sedimentos do rio Monjolinho.

Eutrofização: aspectos conceituais, usos da água e diretrizes para a gestão ambiental

Nessa revisao foram abordados aspectos conceituais relacionando o crescimento populacional humano aos usos multiplos da agua e a eutrofizacao. Foram apontados os problemas associados ao descarte de nutrientes na agua e as consequencias da eutrofizacao. As bases conceituais envolvendo os aspectos ecologicos e de modelagem matematica tambem foram considerados. Por ultimo, as varias diretrizes para a gestao ambiental envolvendo a eutrofizacao foram discutidas tanto no âmbito federal quanto no âmbito estadual, assim como as ferramentas de gestao envolvidas na esfera local e especifica quanto na delimitacao da bacia hidrografica. Com base nos conceitos e discussoes sobre a eutrofizacao apresentados nessa revisao, e notorio que o enriquecimento de nitrogenio e fosforo e um dos principais problemas nao somente no Brasil, mas tambem no mundo. Apesar da existencia de diversas formas de tecnologias para tratar esse problema, a prevencao ainda e uma das melhores alternativas para evitar a eutrofizacao.

Effects of detritus chemical composition on the anaerobic mineralization of Salvinia auriculata and Utricularia breviscapa

Aim: This study was conducted to evaluate the effect of the detritus composition on the anaerobic mineralization of two species of aquatic macrophytes with different life forms (submerged and free floating). The hypothesis that guided this study was that the carbon concentration derived from detritus hydrosoluble fraction can act as a facilitating factor on its degradation.Material and MethodsIncubations containing detritus and water sample from the Oleo Lagoon (21° 33’ to 21° 37’ S and 47° to 47° 45’ to 51’ W) for each specie (Salvinia auriculata and Utricularia breviscapa) were set-up with: (i) integral detritus (sample of dried plant), (ii) lignocellulosic matrix (particulate organic matter (POM) remaining from leachate extraction) and (iii) leachate. The incubations were kept in the dark under anaerobic conditions. Daily rates of gas formation were evaluated and after 138 days, the incubations were fractioned in dissolved and particulate fractions and the mass balances were performed. A mass loss experiment (180 days) was performed for assessment of the dissolved organic carbon, particulate organic carbon and mineralized carbon variations.ResultsRegardless of the type of detritus (S. auriculata and U. breviscapa), C-mineralization was faster and higher in the DOC incubations (ca. 85%). For U. breviscapa the POM mineralization was slower than the corresponding integral detritus and S. auriculata mineralization was slower than U. breviscapa.ConclusionsThe composition of the detritus (i.e. macrophyte type, presence and proportion of leachate) interfered synergistically in anaerobic degradation of these plants. The leachate tends to act as a facilitator, supporting the growth of microorganisms and intensifying mineralization.