Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Rivers”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2001

Establishing river basin organisations inVietnam: Red River, Dong Nai River and Lower Mekong Delta.

River basin management is receiving considerable attention at present. Part of the debate, now occurring worldwide, concerns the nature of the organisations that are required to manage river basins successfully, and whether special-purpose river basin organisations (RBOs) are always necessary and in what circumstance they are likely to (i) add to the management of the water resources and (ii) be successful. The development of river basin management requires a number of important elements to be developed to a point where the river basin can be managed successfully. These include the relevant laws, the public and non-government institutions, the technical capabilities of the people, the understanding and motivation of people, and the technical capacity and systems, including information. A river basin organisation (or RBO) is taken to mean a special-purpose organisation charged with some part of the management of the water resources of a particular river basin. Generally speaking, such organisations are responsible for various functions related to the supply, distribution, protection and allocation of water, and their boundaries follow the watershed of the river in question. However, the same functions can be carried out by various organisations, which are not configured on the geographical boundaries of a river basin. This paper outlines recent work on river basin organisation in Vietnam, and makes some comparisons with the situation in Australia.

Conservation of Natural Resources↗
PubMed2005

Management of regional German river catchments (REGFLUD) impact of nitrogen reduction measures on the nitrogen load in the River Ems and the River Rhine.

The REGFLUD-project, commissioned by Germany's Federal Research Ministry (BMBF), addresses the problem of reducing diffuse pollution from agricultural production. The objective of the project is the development and application of multi-criteria scientific methods, which are able to predict diffuse pollution in river basins subject to economic feasibility and social acceptability. The selected river basins (Ems and Rhine basins) cover a variety of landscape units with different hydrological, hydrogeological and socio-economic characteristics. This paper focuses on the analysis of the effects of certain policy measures to reduce diffuse pollution by nitrogen. For this purpose a model system consisting of an agricultural sector model, a water balance model and a residence time/denitrification model was developed and applied. First results indicate a wide range of annual nitrogen surpluses for the rural areas between less than 10 kg N/ha up to 200 kg N/ha or more depending on the type and intensity of farming. Compared to the level of nitrogen surpluses the level of nitrogen inputs into the surface waters is relatively moderate because of degradation processes during transport in soil and groundwater. Policy impact analysis for a nitrogen tax and a limitation of the livestock density stress the importance of regionally tailored measures.

Agriculture↗
PubMed2001

Emissions of nitrous oxide (N2O) from a tidal, freshwater river, the Hudson River, New York.

Rivers receive a significant fraction of the anthropogenic nitrogen applied to the world's watersheds. Environmental conditions in rivers should be conducive to the formation of N2O, and recent models suggest that rivers could constitute up to 25% of the anthropogenic contribution of N2O to the atmosphere. Few direct measurements exist, however, of N2O flux between rivers, especially large rivers, and the overlying atmosphere. We measured the concentration of N2O over a 2-year period in a large, tidal, freshwater river. We coupled these measurements with a physical model of gas exchange based on inert gas tracer additions to this river and computed the flux of N2O to the atmosphere. The tidal, freshwater Hudson River is persistently supersaturated in N2O with respect to the atmosphere, with average partial pressure of N2O (pN2O) of 0.58 muatm or about 185% of atmospheric equilibrium. At all times during a 2-year cycle and at all locations sampled along a 200 km stretch of the river, the river was a net source of N2O to the atmosphere. We estimate that the tidal, freshwater Hudson River contributes 0.056 g of N2O-N m(-2) to the atmosphere annually. Despite relatively high concentrations of NO3 in the Hudson River, the tidal, freshwater river is a minor source of N2O in comparison to other rivers for which estimates exist and to components of its own watershed. The river itself accounts for only 1.3% of the total N2O contribution to the atmosphere that occurs in the Hudson watershed.

Air Pollution↗
PubMed2003

Community-based river management in Southeast Sulawesi, Indonesia: a case study of the Bau-Bau River.

In this paper we explain the current condition of the Bau-Bau River, examine community participation for management of the river system, and consider options for improving the institutional capacity for a community-based approach. This assessment is based on a research project with the following objectives: (1) analyse the biophysical and socio-economic condition of the river as a basis for future planning; (2) identify current activities which contribute waste or pollution to the river; (3) assess the status and level of pollution in the river; (4) analyse community participation related to all stages of river management; and (5) identify future river management needs and opportunities. Due to the increasing population in Bau-Bau city, considerable new land is required for housing, roads, agriculture, social facilities, etc. Development in the city and elsewhere has increased run-off and erosion, as well as sedimentation in the river. In addition, household activities are generating more solid and domestic waste that causes organic pollution in the river. The research results show that the water quality in the upper river system is still good, whilst the quality of water in the vicinity of Bau-Bau city, from the mid-point of the watershed to the estuary, is not good, being contaminated with heavy metals (Cd and Pb) and organic pollutants. However, the levels of those pollutants are still below regulatory standards. The main reasons for pollution in the river are mainly lack of management for both liquid and solid wastes, as well as lack of community participation in river management. The government of Bau-Bau city and the community are developing a participatory approach for planning to restore and conserve the Bau-Bau River as well as the entire catchment. The activities of this project are: (1) forming institutional arrangements to support river conservation; (2) implementing extension initiatives to empower the community; (3) identifying a specific location to establish an urban forest; (4) implementing demonstration projects for liquid system management; (5) promoting coordination amongst the different organisations and agencies in the catchment; (6) improving domestic waste transportation; and (7) recycling waste to create compost material to become an income source for the community.

Agriculture↗
PubMed2000

River Styles, a Geomorphic Approach to Catchment Characterization: Implications for River Rehabilitation in Bega Catchment, New South Wales, Australia.

/ Geomorphologically derived river styles provide an integrative framework for examining the interactions of biophysical processes in rivers throughout a drainage basin. Nine styles of river character and behavior are identified in Bega catchment, on the south coast of New South Wales, Australia. Headwater streams above the escarpment drain into gorges in the escarpment zone. In different subcatchments at the base of the escarpment, there are three different river styles, namely cut-and-fill, vertically accreted floodplains, and fans. Downstream of these river styles, in the rounded foothills of the catchment, throughput and transfer river styles convey sediments to the lowland plain. In one mid-catchment setting, a floodout traps sediment. Finally, along the lowland plain of Bega River, there is a floodplain accumulation river style. Downstream patterns of river styles in differing subcatchments of the Bega River basin are differentiated into three types, reflecting river adjustments to valley width, slope, and responses to human disturbance. Analysis of the character and condition of each river style in Bega catchment, and their downstream patterns, are used to provide a biophysical basis to prioritorize river management strategies. These reach-scale strategies are prioritorized within an integrative catchment framework. Conserving near-intact sections of the catchment is the first priority. Second, those parts of the catchment that have natural recovery potential are targeted. Finally, rehabilitation priorities are considered for highly degraded reaches. At these sites, erosion and sedimentation problems may reflect irreversible changes to river structure.

Journal Article↗
PubMed2004

Heavy-metal pollution and its state in algae in Kakehashi river and Godani river at the foot of Ogoya mine, Ishikawa Prefecture.

Alga as Achnanthes minutissima among diatoms is a widely adaptable taxon on the state of an aquatic environment. In this study, it was found that diatom had a specific tolerance to heavy metals (Cu, Zn, Pb, and Cd etc.) in river water samples, because the diatom assemblage consisted of almost only Achnanthes minutissima in Kakehashi river and Godani river, which were polluted with waste water from Ogoya copper mine. The relationship between the concentrations of heavy metals (Cu, Zn, Pb and Cd) in river water and the attached substances (algae and silt etc.) and the relative abundances of diatom taxa were investigated in detail. The results indicated that the higher is the concentration of heavy metals in the river environment, the higher is only the relative abundances of Achnanthes minutissima. Thus, the taxon can be used as a bioindicator of heavy metal pollution. The relative rates of toxic chemical forms of copper in algae were 61 - 92% in the attached substances and 49-70% in the sediment on the river bed, respectively. Therefore, it was found that diatom as Achnanthes minutissima had a tolerance to heavy metals in river water, being able to live in such an environment. Since the water treated with calcium hydroxide from the deposition reservoir of Ogoya mine enters in Godani river, the river is polluted by heavy metals (Cu, Zn, Pb and Cd etc.). From the viewpoint of both biological and chemical analyses, Godani river is still polluted with heavy metals, because their concentrations in the river samples were very high. On the other hand, in Kakehashi river, the concentrations of heavy metals were very low and the distributions of some diatoms appeared in an unpolluted Nishimata river were observed. Therefore, Kakehashi river seems to be considerably recovered from heavy-metal pollution after closing the Ogoya mine.

Eukaryota↗
PubMed2005

[Distribution and sources of polycyclic aromatic hydrocarbons in sediments from rivers of Pearl River Delta and its nearby South China Sea].

Polycyclic aromatic hydrocarbons (PAHs) are measured in surface sediments from rivers and estuary of Pearl River Delta and its nearby South China Sea. Total PAH concentration varied from 255.9 - 16 670.3 ng/g and a moderate to low level compare to relevant areas worldwide. The order of PAHs concentration in sediments was: rivers of Pearl River Delta > estuary > South China Sea, and the most significant PAH contamination was at Guangzhou channel of Zhujiang river. A decrease trend for PAHs concentration with distance from estuary to open sea can be sees in South China Sea. Coal and biomass combustion is the major source of PAHs in nearshore of South China Sea, and petroleum combustion is the main source of pyrolytic PAHs in rivers and estuary of Pearl River Delta according to PAHs diagnostic ratios. Petroleum PAHs are revealed have a high contribution to PAHs in Xijiang River, estuary and some stations in Zhujiang River. A comparison of data from study in 1997 with data from present study indicates that there is no clear change in the PAH concentration over time but the source of PAHs in Pearl River Delta have been change from a main coal combustion to petroleum combustion and being reflect in the sediments in rivers and estuary of Pearl River Delta where there have high sedimentation rate.

China↗
PubMed2004

Tumor prevalence and biomarkers of exposure in brown bullhead (Ameiurus nebulosus) from Back River, Furnace Creek, and Tuckahoe River, Maryland.

Brown bullheads (Ameiurus nebulosus) were collected from 2 locations near Baltimore, Maryland, Back River and Furnace Creek, and 1 (reference) location, Tuckahoe River, to compare the prevalence of tumors (liver and skin) and visible skin lesions (fin erosion and abnormal barbels). Cytochrome P450 activity measured as ethoxyresorufin-O-deethylase, biliary PAH-like fluorescent metabolites, and fillet contaminant concentrations were determined as indicators of exposure in a randomly selected subset of the fish. There were no significant differences in liver tumor prevalence: Back River = 8% (4/50), Furnace Creek = 0% (0/50), and Tuckahoe River = 2.6% (1/39; p = 0.20, extension of Fisher's exact test). Skin tumor prevalence was as follows: Furnace Creek = 12% (6/50), Back River = 8% (4/50), and Tuckahoe River = 0% (0/39; p = 0.063). In the Back River fish, there was a 40% (20/50) prevalence of fin erosion and a 28% (14/50) prevalence of abnormal (shortened, clubbed, or missing) barbels. Fin erosion was not observed in the other collections, and only 10% (5/50) of the Furnace Creek fish had abnormal barbels (p < 0.001 for both lesions). There were statistically significant differences in mean EROD activity, with levels in Furnace Creek and Back River fish approximately twice that found in Tuckahoe River fish. There were also significant differences in mean benzo(a)pyrene-like bile metabolite concentrations: the lowest mean was in the Tuckahoe River fish, 8 times higher in Furnace Creek fish, and 13 times higher in Back River fish. Of the 3 groups, the Back River bullheads appear to be most adversely affected by contaminant exposure because they had the highest prevalence of liver tumors, fin erosion, and abnormal barbels.

Animals↗
PubMed2005

Establishing a context for river rehabilitation, North Fork Gunnison River, Colorado.

Initial river rehabilitation efforts along the North Fork Gunnison River in Colorado focused on the use of in-stream structures and channel stabilization to create a single-thread channel with pools along a braided river. These efforts were based on the assumption that the river's braided planform results primarily from land use during the past century. In order to establish a context for further rehabilitation, we evaluated the possibility that the river might be braided as a result of processes independent of land use. We estimated volume, grain-size distribution, and lithology of sediment sources along the river corridor and evaluated the planform stability of the river during the past century using historical sources, aerial photographs covering 1939-1997, and comparison of bankfull discharge and gradient in the study area to values published for braided and meandering rivers. Our results indicate that the North Fork Gunnison River has been primarily braided in its lower reaches during the past few hundred years, although the channel planform tends toward a single-thread channel during decades of lower precipitation and discharge. Although land use is not the primary cause of braiding along the North Fork Gunnison River, it has decreased channel stability, and rehabilitation efforts should be designed to reduce these effects. Our results illustrate the importance of planning river rehabilitation measures within a historical context that accounts for both catchment-scale and reach-scale controls on channel processes and planform.

Colorado↗
PubMed2002

Contributions of genotoxic precursors from tributary rivers and sewage effluents to the Yodo River in Japan.

The cause of water pollution in the Yodo River was examined regarding the mutagenic potentials formed by chlorination of river waters and sewage effluents along the river. Mutagenicity of the extracts from chlorinated waters was measured by Ames test using S. typhimurium TA100 strain without metabolic activation. Mutagenic formation potentials of sewage effluents were 4-5 times higher than those of the three tributary river waters, the Kizu, Uji and Katsura Rivers. The contribution rates of the pollution loads from the three river waters and total of four sewage effluents to the Yodo River were revealed to be 10.2%, 42.2%, 22.1% and 25.5%, respectively. The rate of the sewage effluents occupied one-fourth and exceeded the rates of the Kizu and Katsura Rivers. The contribution rate of the two sewage effluents to the Katsura River was 46.3%. It could be confirmed that the relationship between COD and MFP in river waters and sewage effluents was very high with a correlation coefficient. These results indicated that the waters inflowing to the Yodo River were contaminated with numerous organic compounds, and the sewage effluents especially contribute to the formation of genotoxicity by the interaction between chlorine and organic components as genotoxic precursors in the purification plants.

Chlorine Compounds↗
PubMed2002

A micro case study of the legal and administrative arrangements for river health in the Kangaroo River (NSW).

Kangaroo Valley is a drinking water supply catchment for Kangaroo Valley village, parts of the Southern Highlands and Sydney. It is also a popular recreation area both for swimming and canoeing. Land use has traditionally been dominated by dairy farming but there has been significant and continuing development of land for hobby farms and rural residential subdivision. Dairy industry restructuring has affected the viability of some farms in the Valley and created additional pressure for subdivision. River health is a function of flows, water quality, riparian vegetation, geomorphology and aquatic habitat and riverine biota. River flows in the Kangaroo River are affected by water extraction and storage for urban water supply and extraction by commercial irrigators and riparian land holders which have a significant impact at low flows. Current water quality often does not meet ANZECC Guidelines for primary contact and recreation and the river is a poor source of raw drinking water. Key sources of contaminants are wastewater runoff from agriculture, and poorly performing on-site sewage management systems. Riparian vegetation, which is critical to the maintenance of in-stream ecosystems suffers from uncontrolled stock access and weed infestation. The management of land use and resulting diffuse pollution sources is critical to the long term health of the river. The Healthy Rivers Commission of New South Wales Independent Inquiry into the Shoalhaven River System Final Report July, 1999 found that the longer term protection of the health of the Kangaroo River is contingent upon achievement of patterns of land use that have regard to land capability and also to the capability of the river to withstand the impacts of inappropriate or poorly managed land uses. This micro case study of Kangaroo Valley examines the complex legal and administrative arrangements with particular reference to the management of diffuse pollution for river health. In the past, diffuse pollution has fallen through the gaps in legislation and its administration. Although water pollution legislation is broad enough to embrace diffuse pollution, in practice the Environment Protection Authority has focused on regulating point sources. Water legislation has traditionally been concerned with issues of water quantity rather than water quality. Legislation which allows agency intervention in relation to land degradation has grown from soil conservation roots, neglecting the flow-on effects upon water quality. Under the land use planning system existing land uses are protected from new regulatory requirements. A number of recent developments in NSW law and its administration have set the scene for addressing this past neglect. Water planning provisions in the Water Management Act 2000 have the potential to enable community based Water Management Committees to move away from a narrow focus on water quantity to the broader issues of river health, including water quality. Improved management of on-site sewage management systems is expected as a result of the Local Government (Approvals) Amendment (Sewage Management Regulation) 1998. A draft Regional Environmental Plan prepared for the Sydney Catchment Authority aims to improve the assessment of new development in terms of its impact on drinking water quality. It also moves away from an exclusive concern with controlling new development towards grappling with existing uses. Proposed amendments to the Environmental Planning and Assessment Act, 1979 as detailed in the White Paper, Plan First (2001) include the integration of imperatives derived from catchment strategies and water management plans into local land use plans.

Animals↗
PubMed2004

A PCE groundwater plume discharging to a river: influence of the streambed and near-river zone on contaminant distributions.

An investigation of a tetrachloroethene (PCE) groundwater plume originating at a dry cleaning facility on a sand aquifer and discharging to a river showed that the near-river zone strongly modified the distribution, concentration, and composition of the plume prior to discharging into the surface water. The plume, streambed concentration, and hydrogeology were extensively characterized using the Waterloo profiler, mini-profiler, conventional and driveable multilevel samplers (MLS), Ground Penetrating Radar (GPR) surveys, streambed temperature mapping (to identify discharge zones), drivepoint piezometers, and soil coring and testing. The plume observed in the shallow streambed deposits was significantly different from what would have been predicted based on the characteristics of the upgradient plume. Spatial and temporal variations in the plume entering the near-river zone contributed to the complex contaminant distribution observed in the streambed where concentrations varied by factors of 100 to 5000 over lateral distances of less than 1 to 3.5 m. Low hydraulic conductivity semi-confining deposits and geological heterogeneities at depth below the streambed controlled the pattern of groundwater discharge through the streambed and influenced where the plume discharged into the river (even causing the plume to spread out over the full width of the streambed at some locations). The most important effect of the near-river zone on the plume was the extensive anaerobic biodegradation that occurred in the top 2.5 m of the streambed, even though essentially no biodegradation of the PCE plume was observed in the upgradient aquifer. Approximately 54% of the area of the plume in the streambed consisted solely of PCE transformation products, primarily cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC). High concentrations in the interstitial water of the streambed did not correspond to high groundwater-discharge zones, but instead occurred in low discharge zones and are likely sorbed or retarded remnants of past high-concentration plume discharges. The high-concentration areas (up to 5529 microg/l of total volatile organics) in the streambed are of ecological concern and represent potential adverse exposure locations for benthic and hyporheic zone aquatic life, but the effect of these exposures on the overall health of the river has yet to be determined. Even if the upgradient source of PCE is remediated and additional PCE is prevented from reaching the streambed, the high-concentration deposits in the streambed will likely take decades to hundreds of years to flush completely clean under natural conditions because these areas have low vertical groundwater flow velocities and high retardation factors. Despite high concentrations of contaminants in the streambed, PCE was detected in the surface water only rarely due to rapid dilution in the river and no cDCE or VC was detected. Neither the sampling of surface water nor the sampling of the groundwater from the aquifer immediately adjacent to the river gave an accurate indication of the high concentrations of PCE biodegradation products present in the streambed. Sampling of the interstitial water of the shallow streambed deposits is necessary to accurately characterize the nature of plumes discharging to rivers.

Biodegradation, Environmental↗
PubMed2005

Persistent organochlorine residues in sediments of Haihe River and Dagu Drainage River in Tianjin, China.

Persistent organochlorine compounds were analyzed by means of GC-ECD in surface sediment samples from two selected rivers in Tianjin, Haihe River and Dagu Drainage River. A total of 16 surface sediment sites were selected along the both rivers. The frequency of detection of T-HCH and T-DDT in sediment samples both was up to 100%, which illustrated that the contamination of HCH and DDT was widespread in Haihe and Dagu Drainage Rivers. Results indicated that the concentrations of various pesticides in sediments from Haihe River were in the range of 3.30-75.96 ng/g dw for T-HCH and 1.57-211.57 ng/g dw for T-DDT. Compared with Haihe River, Dagu Drainage River was contaminated by HCHs and DDTs along the all locations and the values of T-HCH and T-DDT residues in sediments ranged from 2.30 to 124.61 ng/g dw and from 11.28 to 237.30 ng/g dw, respectively. The possible pollution sources were analyzed through monitoring results of organochlorine pesticides(OCPs) residues in sediments from the two rivers. The investigation also indicated that HCH was still used as pesticide in Tianjin partial area.

China↗
PubMed2000

Temporal variability of organic micropollutants in suspended particulate matter of the River Elbe at Hamburg and the River Mulde at Dessau, Germany.

The compound classes of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and a number of chlorinated hydrocarbons (CHs) in the River Elbe and its tributary Mulde were investigated on the basis of monthly mixed samples of suspended particulate matter (SPM). Covering the period from September 1994 to August 1995, samples from the River Elbe were taken at Hamburg, those from the River Mulde at Dessau. The samples were extracted by supercritical fluid extraction (SFE). Analysis of all substance groups were performed by highperformance liquid chromatography (HPLC), followed by gas chromatography with mass spectrometric detection (GC/MSD). As a statistical approach for the interpretation of data, hierarchical cluster analysis of the individual compound classes were performed to determine differences or similarities between the sampling sites Hamburg and Dessau to find spatial and seasonal concentration patterns. These analysis showed that, with a high significance, the concentration patterns of n-alkanes, PAHs, and CHs were sampling site-specific in both the Elbe and Mulde throughout the entire sampling period. In all cases, clustering of mostly consecutive months indicated continuous, slow changes of input, which moreover showed a constancy with respect to annual cycles. Correlation analysis of pollutant loads with different hydrographic parameters showed a number of linear dependencies of the contaminants with temperature, SPM content, and water discharge. Annual fluxes of particle-bound pollutants were calculated for each sampling site, taking into account the average monthly SPM levels and the water discharge. The particle-bound pollutant loads for the River Elbe at Hamburg were estimated to 13.4 t/a n-alkanes, 4.1 t/a PAHs, and 175. 8 kg/a CHs. The pollutant loads for the River Mulde at Dessau amounted 0.55 t/a n-alkanes, 0.14 t/a PAHs, and 15.5 kg/a CHs during the monitoring period. The input of n-alkanes originated from different sources. The n-alkane pattern of samples of the River Elbe showed a predominance of odd-numbered compounds in the range of C-20 and C-30 originating from terrestrial plants and, depending on the season, high concentrations of C-15 and C-17 due to aquatic organisms. Only a small proportion of n-alkane input originated from petroleum sources. Samples from the River Mulde showed high amounts of the n-alkanes C-12 to C-15, indicating the input of light oil throughout the entire sampling period, constituting approximately 25% of the total n-alkane concentration. PAHs, which are considered combustion products, were widely distributed in all samples. Although the major inputs of PAHs were probably combustion sources and urban runoff, unusually high concentrations were found for some PAHs, which can be explained by point sources. A comparison of the standardized PAH patterns in samples from both stations clearly showed that higher fused ring systems, which mainly originate from combustion processes (four- to six-ring systems), had considerably higher relative concentrations in SPM from the Elbe than from the Mulde, where higher relative concentrations of the two- and three-ring systems were measured. This confirms findings that petroleum input was higher in the Mulde than in the Elbe. Concentrations of chlorinated hydrocarbons in SPM samples from the river Mulde had comparatively high levels. The largest differences were found for p,p'-DDT and its metabolites p,p'-DDD and p,p'-DDE. On average, concentrations of p,p'-DDT, p,p'-DDD, and p,p'-DDE in the Mulde were about 10, 15, and 25 times higher, respectively, than in the Elbe. Concentrations of HCB, which in the samples from Hamburg had the highest concentrations of all CHs, were found to be higher by about a factor of 3 in the Mulde River. The PCB levels in samples from the Mulde and Elbe were about equal, although there were differences in the pattern of PCB congeners.

Alkanes↗
PubMed2001

A geomorphologist's criticism of the engineering approach to channelization of gravel-bed rivers: case study of the Raba River, Polish Carpathians.

River engineers use sediment transport formulas to design regulated channels in which the river's ability to transport bedload would remain in equilibrium with the delivery of materials from upstream. In gravel-bed rivers, a number of factors distort the simple relationship between particle size and hydraulic parameters at the threshold of sediment motion, inherent in the formulas. This may lead to significant errors in predicting the bedload transport rates in such streams and hence to instability of their regulated channels. The failure to recognize a nonstationary river regime may also result in unsuccessful channelization. Rapid channel incision has followed channelization of the main rivers of the Polish Carpathians in the 20th century. A case study of the Raba River shows that incision has resulted from the increase in stream power caused by channelization and the simultaneous reduction in sediment supply due to variations in basin management and a change in flood hydrographs. Calculations of bedload transport in the river by the Meyer-Peter and Müller formula are shown to have resulted in unrealistic estimates, perhaps because the different degree of bed armoring in particular cross-sections was neglected. It would have been possible to avoid improper channelization if the decreasing trend in sediment load of the Carpathian rivers had been recognized on the basis of geomorphological and sedimentological studies. Allowing the rivers to increase their sinuosity, wherever possible without an erosional threat to property and infrastructure, and preventing further instream gravel mining are postulated in order to arrest channel incision and reestablish the conditions for water and sediment storage on the floodplains.

Conservation of Natural Resources↗
PubMed2004

Seasonal water quality variations in a river affected by acid mine drainage: the Odiel River (South West Spain).

This paper intends to analyse seasonal variations of the quality of the water of the Odiel River. This river, together with the Tinto River, drains the Iberian Pyrite Belt (IPB), a region containing an abundance of massive sulphide deposits. Because of mining activity dating back to prehistoric times, these two rivers are heavily contaminated. The Odiel and Tinto Rivers drain into a shared estuary known as the Ría of Huelva. This work studies dissolved contaminant data in water of the Odiel River collected by various organisations, between October 1980 and October 2002, close to the rivers entry into the estuary. Flow data for this location were also obtained. The most abundant metals in the water, in order of abundance, are zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu). Arsenic (As), cadmium (Cd) and lead (Pb) are also present but in much lower quantities. The quality of the river water is linked to precipitation; the maximum sulphate, Fe, Zn, Mn, Cd and Pb concentrations occur during the autumn rains, which dissolve the Fe hydroxysulphates that were precipitated during the summer months. In winter, the intense rains cause an increase in the river flow, producing a dilution of the contaminants and a slight increase in the pH. During spring and summer, the sulphate and metal concentration (except Fe) recover and once again increase. The Fe concentration pattern displays a low value during summer due to increased precipitation of ferric oxyhydroxides. The arsenic concentration displays a different evolution, with maximum values in winter, and minimum in spring and summer as they are strongly adsorbed and/or coprecipitated by the ferric oxyhydroxides. Mn and sulphates are the most conservative species in the water. Relative to sulphate, Mn, Zn and Cd, copper displays greater values in winter and lower ones in summer, probably due to its coprecipitation with hydroxysulphates during the spring and summer months. Cd and Zn also appear to be affected by the same process, although to a lower degree than Cu, experiencing a slight reduction in summer with respect to Mn and sulphates.

Journal Article↗
PubMed2002

Comparisons of PBDE composition and concentration in fish collected from the Detroit River, MI and Des Plaines River, IL.

Polybrominated diphenyl ethers (PBDEs) were identified in fish collected from the Detroit River, MI and Des Plaines Rivers, IL. In the Detroit River fish, carp and large mouth bass, the congener patterns were dominated by the 2,2',4,4'-tetrabromo (BDE-47) congener, however, in Des Plaines River carp the dominant isomers were the heptabromo congeners BDE-181 and BDE-183 and lesser amounts of another heptabromo congener, BDE-190, and two hexabromo congeners, BDE-154 and BDE-153. Three possible sources exist for these less-commonly identified PBDE congeners: (a) waste discharge from manufacturing or discarded products near the river, (b) public owned treatment work (POTW) effluents which constitute more than 75% of the flow in the Des Plaines River, (c) or formation of these congeners by debromination of in-place deposits of decabromodiphenyl ether. Average concentration totals (sum of concentrations for seven of the dominant PBDE congeners) were similar on a wet weight bases for the carp (5.39 ng/g wet weight) and large mouth bass (5.25 ng/g) in the Detroit River samples; however, the bass were significantly higher, p = 0.01, when compared on a lipid basis (bass--163 ng/g vs. carp--40.5 ng/g lipid weight). Some of the PBDE congeners were positively correlated with increasing lipid levels in both fish species. Average total PBDE concentrations in the carp from the Des Plaines River (12.48 ng/g wet weight) were significantly higher, p = 0.01, than in carp from the Detroit River. The residues were isolated using standard organochlorine methods for fish and analyzed using gas chromatography/mass spectrometry-negative chemical ionization methods.

Animals↗
PubMed2002

Relationship between ore deposits in river catchments and geochemistry of suspended particulate matter from six rivers in southwest France.

Here we present original data on the geochemical composition of fluvial particulate matter transported by the rivers of the Adour/Garonne basin, which drains one-fifth of the French land surface. Suspended particulate matter from the six main rivers in the basin, sampled at 'normal' flow and during a flood, is compared in terms of: grain size; particulate organic carbon; Fe; Mn; and trace element concentrations (e.g. Zn, Cd, Pb, Cu, Mo, Sn, Ni, Co, Cr, V, As, Hg, U, Th, W, Au, Ag, Ta). Three of the six studied rivers (Garonne, Dordogne and Isle Rivers) are the main tributaries of the Gironde estuary (southwest France), known for Cd pollution. The Adour and Gaves Rivers enter the Adour Estuary and the Charente River reaches the ocean by the Charente Estuary. Our data show, that Cd (and Zn) are not the only trace elements of eco-toxicological relevance transported into the Gulf of Biscay by these six rivers. Potentially toxic elements (e.g. As, Sn, U, Cu, Ag) show elevated concentrations in river particulates entering the estuaries, compared to world average concentrations [Martin and Whitfield, 1983, The significance of the river input of chemical elements to the oceans. In: C.S. Wong, E. Boyle, K.W. Bruland, J.D. Burton, E.D. Goldberg (editors), Trace Metals in Sea Water, Plenum, New York: pp. 265-296]. Comparing SPM sampled during 'normal' discharge and flood, the basin shows a distinct trace element composition of SPM mostly related to ore deposits in the upper basins (Massif Central and Pyreneans). This geochemical signal is partly masked during floods due to changes in grain size, but also due to increased erosion of the lower parts of the basins. This study proves pumping/centrifugation to be the most appropriate sampling/separation technique (recovery, representativity, contamination) by comparing different methods of SPM recovery.

Disasters↗