Hydrogeochemistry of freshwaters crossed by the Transamazon highway, Northern Brazil

In the context of the comprehensive study of the hydrogeochemistry and classification of Amazon freshwaters, 80 rivers crossing the E-W transect of the Transamazon highway, between Altamira and Humaitá (Brazil) were analysed (pH, specific conductance, suspended solids, color, alkalinity, Cl, SO4, Na, K, Mg, Ca, Ba, Sr, Al, Fe, Mn, Cu, Si, C org, NH4, and PO4). The chemical data were evaluated and discussed under the following headings: - average content of major and trace elements compared to the world average. - relative dominance of major ions compared to the percentages of sum components of major cations and anions, respectively, - use of MAUCHA diagrams to depict the major ionic environment, - frequency distribution of major and trace elements and their relation to Amazonian and world scales, - variability of major and trace element content along the transect in relation to the geological conditions in the respective watersheds, - comparison of chemical characteristics of groups of waters from geologically different watersheds with their signifìcant differences. The results are fully described and presented in 16 figures and 7 tables

Production, energy, and nutrient turnover of the cockroach Epilampra irmleri Rocha e Silva & Aguiar in a Central-Amazonian inundation forest

The cockroach Epilampra irmleri Rocha e Silva & Aguiar occuring in an Amazonian inundation forest was studied according to production, energy, and nutrient turnover. Production measurements of larvae were made for the field population from September till December 1976, whereas the adult population was investigated in cultures. P/B quotient amounts to 4,55. Epilampra irmleri was found on the forest ground directly after the inundation. Imaginal ecdysis occurs in December - January. Females carry the single ootheca with 40 - 45 eggs till young larvae are developed in the ootheca. Feeding tests were executed with two leaf species and natural leaf litter. Natural leaf litter is mostly fed. Soft leaves are prefered to hard leaves. The energy budget can only be compensated if natural leaf litter is fed. The following ecological efficiencies could be found for the larval population according to both feeding and respiration tests: A/C = 23, P/C = 9, R/C = 13, P/A = 41, and R/A = 56. Qxygen consumption of the larvae ranges from 500-700 ?l 0² * h-1 * g-1 at 25°C. The chemical analysis of food and faeces shows an increase of mineral concentrations in the faeces. The mineral budget is negativ if only leaves are fed. It is supposed that the mineral demand of the cockroach is compensated by substrat feeding and saprophagy on carcass. According to a leaf fall of 300 g * m² * yr-1 and a leaf consumption of 16,8 g * m-2 * yr-1 by the cockroach 5,6% of the yearly leaf fall is fed by the Epilampra population

Nutrient dynamics of submersed decomposing Amazonian herbaceous plant species Paspalum fasciculatum and Echinochloa polystachya

Dans la plaine inondée de l'Amazone, la décomposition des plantes herbacée est très rapide durant la période d'inondation. Des experiences menées sur les plantes herbacées aquatiques et terrestres #Echinochloa polystachya et #Paspalum fasciculatum dans des bassins remplis d'eau de source, suggèrent que de grandes quantités de bio-éléments (Na, K, Ca, Mg, N, et P) sont perdues durant les 2 à 4 premières semaines d'exposition du matériel végétal. De 76 à 100 % des quantités totales d'éléments perdues par le matériel végétal se retrouvent sous forme soluble dans l'eau, à l'exception de l'azote pour lequel les valeurs obtenues sont de 57 % pour #Echinochloa polystachya$et 47$. Un bilan des diverses sources de bio-éléments durant la période d'inondation, dans un hypothétique lac de la plaine inondée, montre que l'eau du fleuve est la plus importante source de Na (99,5 %), Ca (93 %) et Mg (86,5 %) sous forme dissoute. Cependant, les plantes herbacées terrestres et la litière de la forêt de la plaine inondée restent les plus importantes sources de N (77,2 %), P (83,2 %) et K (60,7 %). Ces résultats montrent l'importance de la végétation terrestre comme pompe à éléments des sédiments vers l'eau et sa grande contribution à la dynamique des éléments nutritifs et à la production des systèmes de plaine inondée. (Résumé d'auteur

Selected bioelements in bark and wood of native tree species from Central-Amazonian inundation forests

The chemical differences between tree foliage from várzea- and igapó forests are confirmed by respective analyses of bark and wood. While generally bark presents higher concentrations than wood, bark and wood of trees from the várzea have higher concentrations than those from the igapó forest. Species composition as well as river water chemistry and soil quality account for the differences between várzea and igapó

Nutrient dynamics of decomposing leaves from Amazonian floodplain forest species in water

Decomposition experiments were performed in freshwater tanks using fresh leaves of four Amazonian tree species from blackwater and whitewater floodplain forests. Weight loss, loss of the major elements, Na, K, Mg, Ca, N and P from the leaves, and release of these elements into the water were studied during a four month period. Based on the nutrient contents of fresh multispecies leaf litter and data on the shedding of this litter, nutrient inputs from leaves into bodies of blackwater and whitewater in the forests during flood period were calculated. The input of dissolved inorganic N, P and K may be as great or even greater than input from river water, indicating the importance of the floodplain forest as nutrient pump from sediments into the water

Foliar nutrient levels of native tree species from Central Amazonia. I. Inundation forests

The study of the leaf size spectra and foliar concentrations of N, P, K, Ca, Mg and Na of 52 species sampled in three Central-Amazon inundation forests (2 várzea sites, 1 igapó site) yielded signifìcant differences between várzea and igapó forests. The várzea foliage consists of larger and less heavy leaves with elemental concentrations being high even by tropical standards. The igapó foliage consists of relatively small leaves which are heavier, but much lower in the studied elements. The igapó leaves are supposed to be sclerophyllous and evergreen

Seasonal variation in the major cation (Na, K, Mg, and Ca) content of the water of Lago Camaleão, an Amazonian floodplain- lake near Manaus, Brazil

Changes in the major cation content (Na, K, Mg and Ca) of the Lago Camaleão, one of the várzea lakes on an island in the Rio Solimões/Amazonas near Manaus were followed during one year. Comparative changes were also followed in the Rio Solimões. Changes in the electrolyte content of the lake water, presented as total maior cation content, are extremely great during the period of investigation. Nov. 1980 to Nov. 1981, and show a pronounced annual periodicity. During the low water period (Oct. 1981) the ion concentration reached its maximum and was more than 15 times higher than in the river at the same time. With rising water level, in flow of comparatively electrolyte poor water from the river and simultaneously increasing rain fall dilute the water in the lake. In the following months there is a relatively sudden reduction of the electrolyte content of the lake water. By the time of high water the levels have fallen almost to those of the river. With falling water level concentrations of major cations at first increase very slowly followed by an abrupt change within one month, from approx. 20 mg major cations/l to approx. 230 mg/l. Investigation of different lake sections showed that the electrolyte content is not uniform throughout the lake. Concentrations rise from the lake entrance to the inner part of the lake, so that the lake sections distant from the river are up to fifteen times as rich in electrolytes as the river itself. The changes in total ion content are accompanied by marked changes in the chemical composition of the lake water during the year, i. e. in the relative proportions of each of the four elements (Na, K, Mg and Ca). Greatest changes are shown by the element K. The deeper water of the lake during the high water period is richer in K probably due to the release of elements from the decomposition of K-rich terrestrial and aquatic macrophytes. The uptake of large quantities of nutrients from the system for the growth of macrophytic vegetation, the accumulation of nutrients in macrophytes and sediment, and the release of these nutrients during decomposition and resuspension are among the most important factors contributing to the electrolyte budget in the Lago Camaleão

Distribution, characterization and the commercialization of elite Rhizobia strains in Africa

Grain legumes play a significant role in smallholder farming systems in Africa because of their contribution to nutrition and income security and their role in fixing nitrogen. Biological Nitrogen Fixation (BNF) serves a critical role in improving soil fertility for legumes. Although much research has been conducted on rhizobia in nitrogen fixation and their contribution to soil fertility, much less is known about the distribution and diversity of the bacteria strains in different areas of the world and which of the strains achieve optimal benefits for the host plants under specific soil and environmental conditions. This paper reviews the distribution, characterization, and commercialization of elite rhizobia strains in Africa

Specialized 16SrX phytoplasmas induce diverse morphological and physiological changes in their respective fruit crops

The host-pathogen combinations-Malus domestica (apple)/`Candidatus Phytoplasma mali´, Prunus persica (peach)/`Ca. P. prunorum´ and Pyrus communis (pear)/`Ca. P. pyri´ show different courses of diseases although the phytoplasma strains belong to the same 16SrX group. While infected apple trees can survive for decades, peach and pear trees die within weeks to few years. To this date, neither morphological nor physiological differences caused by phytoplasmas have been studied in these host plants. In this study, phytoplasma-induced morphological changes of the vascular system as well as physiological changes of the phloem sap and leaf phytohormones were analysed and compared with non-infected plants. Unlike peach and pear, infected apple trees showed substantial reductions in leaf and vascular area, affecting phloem mass flow. In contrast, in infected pear mass flow and physicochemical characteristics of phloem sap increased. Additionally, an increased callose deposition was detected in pear and peach leaves but not in apple trees in response to phytoplasma infection. The phytohormone levels in pear were not affected by an infection, while in apple and peach trees concentrations of defence- and stress-related phytohormones were increased. Compared with peach and pear trees, data from apple suggest that the long-lasting morphological adaptations in the vascular system, which likely cause reduced sap flow, triggers the ability of apple trees to survive phytoplasma infection. Some phytohormone-mediated defences might support the tolerance