Dry and wet sieving were compared on their suitability for the size fractionation of bottom sediment samples, collected from a brackish water, coastal lagoon, prior to flameless atomic absorption analysis of the sediment concentration of total mercury. The work aimed at identifying the most important point sources of mercury to the lagoon waters and at assessing the distribution, throughout the ecosystem, of the mercury discharged. The results reported in this paper refer to the lagoon sediments and fishes. Ongoing work is extending the survey to the other inland ecological niches and to the coastal waters and sediments. A chlor-alkali plant proved to be the most important source of mercury but its contribution has not yet been disentangled from those originating at a pyrite roasting facility and a PVC factory operating in the same industrial park. Sewage discharges from the bankside communities are the other significant point sources of Hg. Concentrations of Hg in the superficial sediments ranged from 850 mgkg−1, near the chlor-alkali sewer outlet, to 0.05 mgkg−1 in the intertidal sands of the coastal beaches. Sewage-affected sediments have concentrations of Hg in the range of 1 to 2 mgkg−1. The concentrations observed in the water samples and superficial sediments suggest that some of the Hg historically discharged into the lagoon may have been exported to the Atlantic Ocean coastal waters. Bioaccumulation of Hg in fish tissues shows the usual dependence on species, territoriality, feeding habits and size. Concentrations as high as 25 mgkg−1 fresh weight have been observed but the average values do not exceed the EEC quality objective of 0.3 mgkg−1 (EEC, 1982).

Difficulty in obtaining abundant sporulation in culture of many species of Cercospora may be the limiting factor for studies of biology, systematics, and inoculation of the genus. Therefore, it is necessary to understand the nutritional and environmental requirements that influence mycelial growth, sporulation and germination. As it is difficult to obtain conidia of Cercospora coffeicola in vitro, different temperatures (17, 22, 27, and 32 °C) and light intensities (80, 160, 240, and 320 μmol m -2 s -1 ) were evaluated to optimize pathogen sporulation and assess favorable conditions for spore germination, aiming for a strategy of disease control. The dark treatment (0 μmol m -2 s -1 ) was added for sporulation. A significant interaction was found between temperature and light intensity for both variables. The highest sporulation rate of C. coffeicola occurred at a light intensity of 240 μmol m -2 s -1 and air temperature of 22 °C, reaching 5.9x10 6 con mL -1 . Germination was higher at temperature 17 °C and light intensity of 320 μmol m -2 s -1 , reaching 52%. Interaction between light intensity and temperature proved to influence the processes of sporulation and germination of C. coffeicola.Index terms: Environmental variables; Cercospora leaf spot; Coffea arabica. RESUMOObter abundante esporulação em meio de cultura, para muitas espécies de Cercospora, pode ser o fator limitante em estudos de biologia, sistemática e inoculação das espécies do gênero. Por isso, faz-se necessário o entendimento dos requerimentos nutricionais e ambientais, os quais influenciam o crescimento micelial, a esporulação e a germinação Em razão da dificuldade de obter conídios de Cercospora coffeicola in vitro, objetivou-se avaliar diferentes condições de temperatura (17, 22, 27 e 32 °C) e intensidade luminosa (80, 160, 240 e 320 µmol m -2 s -1 ), com o intuito de otimizar a esporulação do patógeno e avaliar as condições favoráveis à germinação dos conídios, visando a táticas de controle da doença. Para a esporulação, adicionou-se o tratamento escuro (0 µmol m -2 s -1 ). Observou-se interação significativa entre temperatura e intensidade luminosa para ambas as variáveis testadas. A maior esporulação de C. coffeicola foi observada na intensidade de 240 µmol m -2 s -1 e na temperatura de 22 °C, atingindo 5,9x10 6 con mL -1 . Com relação à germinação, esta foi maior na temperatura de 17 °C e na intensidade luminosa de 320 µmol m -2 s -1 , atingindo 52%. A interação entre intensidade luminosa e temperatura do ar, influenciou os processos de esporulação e germinação de C. coffeicola.

RESUMOCom o objetivo de determinar algumas características anatômicas e físico-químicas de duas cultivares de Brachiaria brizantha, cvs. Marandu e MG-5 Vitória, colhidas aos 45 e 65 dias após o plantio, sob doses crescentes de nitrogênio (N), foi conduzido um experimento em vasos, em casa de vegetação do Departamento de Ciência do Solo da Universidade Federal de Lavras-UFLA, Lavras, MG. Foi utilizado o delineamento experimental de blocos ao acaso com os tratamentos dispostos em esquema fatorial 2x2x5, sendo dois genótipos, duas idades de corte e cinco doses de N (0, 100, 200, 300 e 400 mg/dm³), com quatro repetições, totalizando 20 tratamentos e 80 unidades experimentais (vasos). As variáveis estudadas foram: densidade de perfilhos, diâmetros polar e equatorial dos estômatos nas superfícies adaxial e abaxial das folhas, teores de PB, FDN e FDA e coeficientes de DIVMS. Os resultados obtidos permitem verificar que o aumento das doses de N influencia positivamente a produção de MS nas duas idades de corte. A idade de corte influencia o número de perfilhos, a densidade e os diâmetros polar e equatorial dos estômatos e a cv. Vitória mostra-se mais plástica nas características estomáticas comparada à cv. Marandu. As doses mais altas de N proporcionam aumentos nos teores de PB e DIVMS. Os menores intervalos entre corte proporcionam os menores teores de FDN e FDA.Termos para indexação: Digestibilidade, estômatos, Marandu, MG -5 Vitória. ABSTRACTWith the objective of determining some anatomical and physicochemical characteristics of two cultivars of Brachiaria brizantha cvs. Marandu and MG-5 Vitória, harvested at 45 and 65 days after planting under growing doses of ,nitrogen (N), an assay was conducted in pots in greenhouse of the Science Department in the Federal University of Lavras -UFLA, Lavras, MG. An experimental randomized block design with the treatments arranged in a factorial scheme 2x2x5 was used, with, two genotypes, two cutting ages and five doses of N (0, 100, 200, 300 and 400 mg/dm³) with four replicates totalizing to 20 treatments and 80 experimental units (pots). The variables studied were: tiller density, polar and equatorial diameters of stomata on the adaxial and abaxial leaf surfaces, CP, NDF and ADF contents and IVDMD coefficients. The results allow to verify that increased doses of N influences positively DM yield at the two cutting ages. The cutting age influences the number o tillers, the density and polar and equatorial diameters of stomata and the cultivar Vitória presents more plastic in the stomata characteristics compared to the cultivar Marandu. Higher doses of N cause increase in the contents of CP and IVDMD. Lower inter-curtting intervals promoted the lowest contents of NDF and ADF.

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