Water quality assessment of Toledo River and determination of metal concentrations by using SR-TXRF technique

The region of Toledo River, Parana, Brazil is characterized by intense anthropogenic activities. Hence, metal concentrations and physical-chemical parameters of Toledo River water were determined in order to complete an environmental evaluation catalog. Samples were collected monthly during one year period at seven different sites from the source down the river mouth, physical-chemical variables were analyzed, and major metallic ions were measured. Metal analysis was performed by using the synchrotron radiation total reflection X-ray fluorescence technique. A statistical analysis was applied to evaluate the reliability of experimental data. The analysis of obtained results have shown that a strong correlation between physical-chemical parameters existed among sites 1 and 7, suggesting that organic pollutants were mainly responsible for decreasing the Toledo River water quality.

Public land use planning using bioregions and other attributes : determining the study area of the VEAC river red gum forests investigation

In order to plan for the best use of public land at a regional scale the determination of an appropriate regional boundary is important for ecological, resource use and recreational reasons. The study area for the Victorian Environmental Assessment Council's (VEAC) River Red Gum Forests Investigation incorporated bioregional boundaries, modelled pre- I750 vegetation distribution, recent public land use investigations, and the distribution of public land. This paper outlines how ecological attributes and past land use studies were used to inform the boundary for this major study of public land along the Murray River in northern Victoria.

Flooding requirements for biodiversity values along the Victorian floodplain of the Murray Valley

Overbank flooding of rivers is a key process in the maintenance of vegetation types and the species that rely on the floodplain forests and woodlands of northern Victoria. Yet the flooding requirements of species and vegetation types are poorly known. Here we present initial estimates of the water requirements for flood dependent Ecological Vegetation Classes (EVCs) and rare and threatened flora and fauna species associated with the floodplain of the Murray River and its tributaries. Some 110 EVCs were found to be at least partly flood-dependent on the Murray River floodplains. The total current extent of these EVCs in the study area is 224 247 ha, of which 162 266 ha are on public land. One hundred and twenty-four rare or threatened plant taxa and 62 threatened vertebrate fauna taxa (excluding fish) were classified as at least partly flood-dependent. These initial estimates provide important information for land and water managers and researchers alike.

Assessment of the ichthyofauna in stretches under the influence of Salto Grande Reservoir (Middle Paranapanema River, SP/PR, Brazil).

Aim: To analyze the composition, species richness and spatial distribution of the fish fauna in the area under influence of the Salto Grande Reservoir; Methods: Fish were caught every two months from November/05 to October/06, using gill nets, seining nets and sieve; Results: It was registered 67 fish species, 1,964 individuals and 146.2 kg, representing CPUEn of 1,964 and CPUEb of 278 kg. The most representative orders were Characiformes, with 29 species, Siluriformes (21 species) and Perciformes (11 species) Nine non-native species were registered. The most abundant species in the reservoir were Astyanax altiparanae, Steindachnerina insculpta and Acestrorhynchus lacustris, indicating the predominance of medium and small fishes in this reservoir. The dendrogram of similarity separated the Dam and Pedra Branca stretches from Pardo River Mouth, indicating differences in the assemblages. The species turnover among the stretches was demonstrated by the beta diversity, which may be related to the diversity of habitat; Conclusions: Although being a small reservoir, it displays great habitat diversity, reflecting in the composition and structure of fish assemblages.

River avulsions on the Taquari megafan, Pantanal wetland, Brazil

The Pantanal wetland is located in a tectonically active interior sedimentary basin in west-central Brazil. The south-flowing Paraguay River is the trunk-river of an alluvial constructional landform comprising several large alluvial fans, the largest one of which is the Taquari megafan. The Taquari River flows in two distinct geomorphologic zones within the megafan. Entrenched on sediments of Pleistocene fan lobes, the Taquari River flows in a 3 to 5 km wide meander belt in the upper fan, where avulsion is hindered by entrenchment. Downstream of the intersection point, stream discharge progressively decreases and the Taquari River becomes narrow and shallow toward the Paraguay River plain. Within the distributary fan lobe, the channel-levee sandy complex is topographically higher than the adjacent floodplains and avulsion is a natural consequence of crevasses in the natural levees. Many channel avulsions have occurred during the last decades and documented cases show that significant channel changes may take place in a few years. Beginning with crevassing in 1988 and ending with the abandonment of the former channel in 1998, the river completely changed course in the lower fan. Presently, a major avulsion is occurring in the upper portion of the growing fan lobe, where many crevasses have appeared in the natural levees with associated splays onto the floodbasin. New anastomosed channels have formed north of the Taquari River, but downstream of them the flow is unconfined and the water spreads into natural floodbasins. This avulsion is still in process and allows observation of channel evolution, the geomorphic features produced, the sedimentary processes involved, and resulting effects. If the new channels do not rejoin the main channel, the river mouth may abandon its present master channel and shift to a position a hundred kilometers north from its present position. A large volume of sediment has been transferred to the floodbasin, with progradation of crevasse splay deposits over fine overbank sediments. Many geomorphic features, recognizable in satellite and radar images, clearly show that avulsion has occurred many limes before in the Taquari River. Avulsion belt deposits and former diverted channels testify to ancient avulsion events within the fan lobe and show that progradation of splays onto the floodbasin is the most important infilling process within the Taquari distributary fan lobe. The avulsion process in the lower Taquari River has accelerated in the last 30 years, along with the magnitude of flooding. Pasture and intensive agriculture in the catchment area has increased the sediment supply to the wetland, but larger floods are also a consequence of higher rainfall since 1973. Avulsion and floods have been a cause of great concern among the local population and landowners. Before human intervention in attempting to control floods, however, a better understanding of the avulsive river system is needed, especially because a major navigation project including the channelization of the Paraguay River was recently proposed. (c) 2005 Elsevier B.V. All rights reserved.

Longitudinal distribution of Copepoda populations in the transition zone of Paranapanema River and Jurumirim Reservoir (São Paulo, Brazil) and interchange with two lateral lakes.

Longitudinal changes in composition, abundance, and distribution of copepods were studied at the transition zone of Paranapanema River-Jurumirim Reservoir (SP, Brazil). The interchange of biotic material between marginal lakes and the river system was also examined. Water samples were obtained from 6 stations along a stretch of 13 km of the Paranapanema River, from an upstream reach with high water velocity up to the river mouth into Jurumirim Reservoir. Two other sites in lateral lakes were also sampled. Nine copepod taxa were identified: 3 calanoids (Argyrodiaptomus furcatus Sars, Notodiaptomus iheringi Wright, and N. conifer Sars) and 6 cyclopoids (Eucyclops Claus, Microcyclops Claus, Mesocyclops longisetus Thiébaud, Thermocyclops decipiens Fischer, T. minutus Lowndes, and Paracyclops Claus). Harpacticoids were also collected. Calanoid and cyclopoid nauplii and copepodids, and harpacticoids were the most abundant organisms. In general, there was a longitudinal decrease in copepod abundance, whereas an increase was detected near the lakes. The abundance of most copepods was inversely correlated with current velocity and suspended solids. Higher abundance was observed in the river main course during the rainy season, during which there is a higher connectivity between the lakes and the main river. This promotes exportation of biologic material from marginal lakes to the river system, a biotic exchange reflecting the importance of marginal lakes to the river community structure.

Seasonal Distribution and Movements of Shortnose Sturgeon and Atlantic Sturgeon in the Penobscot River Estuary, Maine

Relatively little is known about the distribution and seasonal movement patterns of shortnose sturgeon Acipenser brevirostrum and Atlantic sturgeon Acipenser oxyrinchus oxyrinchus occupying rivers in the northern part of their range. During 2006 and 2007, 40 shortnose sturgeon (66-113.4 cm fork length [FL]) and 8 Atlantic sturgeon (76.2-166.2 cm FL) were captured in the Penobscot River, Maine, implanted with acoustic transmitters, and monitored using an array of acoustic receivers in the Penobscot River estuary and Penobscot Bay. Shortnose sturgeon were present year round in the estuary and overwintered from fall (mid-October) to spring (mid-April) in the upper estuary. In early spring, all individuals moved downstream to the middle estuary. Over the course of the summer, many individuals moved upstream to approximately 2 km of the downstream-most dam (46 river kilometers [rkm] from the Penobscot River mouth [rkm 0]) by August. Most aggregated into an overwintering site (rkm 36.5) in mid-to late fall. As many as 50% of the tagged shortnose sturgeon moved into and out of the Penobscot River system during 2007, and 83% were subsequently detected by an acoustic array in the Kennebec River, located 150 km from the Penobscot River estuary. Atlantic sturgeon moved into the estuary from the ocean in the summer and concentrated into a 1.5-km reach. All Atlantic sturgeon moved to the ocean by fall, and two of these were detected in the Kennebec River. Although these behaviors are common for Atlantic sturgeon, regular coastal migrations of shortnose sturgeon have not been documented previously in this region. These results have important implications for future dam removals as well as for rangewide and river-specific shortnose sturgeon management.

(Table 2) Geochemical composition of suspended matter samples from the northern Dvina River

The results of the analysis of samples of the Northern Dvina River's suspended particulate matter obtained by the sedimentation method from large water volumes in the periods of the spring high water and summer low water are presented. By the method of sequential leaching using different reagents, four fractions have been separated: the F1 is the sorbed complex and carbonates, the F2 is the amorphous hydroxides of Fe and Mn, the F3 is the form connected with the organic matter, and the F4 is the residual or silicate-detrital (inert) form. The data have shown that all ten elements determined were grouped with respect to the ratio of the distinguished forms: F4 is the predominant form for Al and Fe (73-88% of all the forms; however, the summer sample contains only 38% of this form of iron, and F2 is the predominant form for this period with 46.6%). As to Mn, the F1, F2, and F4 are nearly equally distributed in the spring high water samples, and only the F3 form is less important (5.4%). In the summer sample, the manganese sorbed complex is predominant (53.5%); for Cu, Ni, Cr, and Co, the inert F4 form is predominant (60-70%) in the sample of the spring suspended matter. The summer low water suspended matter has a lower F4 contribution (25-45%); for Zn, Pb, and Cd, the equal distribution of the forms in the spring samples is typical, while the summer suspended matter differs by the F2 form's predominance (53-61% for Zn and Pb). The main conclusion from the acquired data is that the geochemical mobility of all the studied elements, except for cadmium, in the summer low water suspended matter is higher than in the spring suspended matter. The more intensive biogeochemical processes in August, the high level of organic matter, and the higher contribution of phytoplankton lead to the intensification of the metals' geochemical activity in the Northern Dvina suspended matter in the end of the summer compared to the spring high water period when the physical processes are predominant over the biogeochemical ones due to the high speeds of the freshened waters flow.

Concentrations of organic compounds in suspended matter from surface waters and surface layer bottom sediments of the Obskay Guba (Ob River estuary) and the Kara Sea

Data are presented on concentrations of aliphatic and polycyclic aromatic hydrocarbons (AHC and PAH) in interstitial waters and bottom sediments of the Kara Sea compared to distribution of particulate matter and organic carbon. It was found that AHC concentrations within the water mass (aver. 16 µg/l) are mainly formed by natural processes. Distribution of AHC represents variability of hydrological and sedimentation processes in different regions of the sea. The widest ranges of the concentrations occurred in the Obskaya Guba - Kara Sea section: in water (10-310 µg/l for AHC and 0.4-7.2 ng/l for PAH) and in the surface layer of the bottom sediments (8-42 µg/l for AHC and 9-94 ng/g for PAH). Differentiation of hydrocarbons (HC) in different media follows regularities typical for marginal filters; therefore no oil and pyrogenic compounds are supplied to the open sea. In sediments contents of HC depend on variations in redox conditions in sediments and on their composition.

Hydrological and hydrochemical parameters in mouth areas of rivers entering the Kandalaksha Bay in June and September 2000

Distributions of dissolved oxygen concentration, pH, and concentrations of dissolved silica, phosphates, strontium, calcium, fluorine, and boron in mouth areas of small rivers (Niva, Kolvitsa, Knyazhaya, and Keret') entering Kandalaksha Bay of the White Sea were studied. Strontium, calcium, fluorine, and boron showed conservative, silica and phosphates showed non-conservative behavior caused by their biological consumption.

Methane in waters and bottom sediments of the North (Severnaya) Dvina mouth area in 2004-2006

The mouth area of the North (Severnaya) Dvina River is characterized by a high concentrations of methane in water (from 1.0 to 165.4 µl/l) and bottom sediments (from 14 to 65000 µl/kg), being quite comparable to productive mouth areas of rivers from the temperate zone. Maximum methane concentrations in water and sediments were registered in the delta in segments of channels and branches with low rates of tidal and runoff currents, where domestic and industrial wastewaters are supplied. In the riverine and marine water mixing zone with its upper boundary, locating far into the delta and moving depending on a phase of the tidal cycle, decrease of methane concentration with salinity increase was observed. The prevailing role in formation of the methane concentration level in water of the mouth area pertains to bottom sediments, which is indicated by close correlation between gas concentrations in these two media. Existence of periodicity in variations of methane concentration in river water downstream caused by tidal effects was found.