Contamination and toxicity trends for sediments — Case of the Elbe river

The paper deals with sediment studies in the Upper and Middle Elbe between 1991 and 1996. Hydrological and seasonal factors are discussed with respect to trends in sediment contamination. An investigation programme is described including periodical measurements of inorganic and organic pollutants at monitoring stations as well as in-depth case studies. In these studies reference sites represent background conditions. Heavily contaminated reaches are taken as the worst case scenario. An integrated approach is applied combining chemical and ecotoxicological investigations. Factors are defined which must be taken into account in order to draw reliable conclusions for sediment quality. Contamination trends and trends in sediment toxicity are derived for the river Elbe.     

Adaptation of urban distribution to the fluvial geomorphic environment and the reconstruction of the river system structure by urban distribution in Haihe Plain in the past 2,200 years

The alluvial plain of many of the world's large rivers is generally an area with concentrated urban distribution and a long history of development. In eastern China, the alluvial plains downstream of large rivers such as the Haihe River are the most densely populated and economically developed regions. Beijing, the capital of China, is located on the Haihe Plain. It is a matter of great significance that the region's capacity for livability and sustainable development be improved. Using the river geomorphic data and historical town information, methods of spatial statistical analysis and historical literature research, this paper analyzes the spatial relationship between the distribution of urban centers and the fluvial geomorphology of the Haihe Plain over more than 2,200 years. The research finds that: first, different levels of cities and towns have led to varying choices regarding the fluvial geomorphic environment. Second, in different periods in which different transportations were dominant, the distribution of cities and towns has adapted to the fluvial geomorphology. In the land transportation period, urban settlements mainly concentrated on the diluvial-alluvial fans at the foot of the Taihang Mountain; in the inland shipping period, they focused on gathering at the confluence of rivers on the central plain and along the canals; in the period of global trade, Tianjin, a trade center, established itself at the mouth of the Haihe River. Third, humans intend to rebuild water system structures (such as the Grand Canal) in the context of major water conservancy projects in the basin to meet the needs of the expanding regions and towns. The research shows that the urban development of the Haihe Plain should adapt to the natural regional pattern and establish a solution based on respecting the natural conditions of the basin, to make the regional sustainable development more resilient.     

Towards a rights-based approach in EU international river basin governance? Lessons from the Scheldt and Ems Basins

ABSTRACT

This article finds that the introduction of a rights-based approach in EU transboundary river basin management to remedy observed systemic difficulties and to better achieve legal water quality standards could be a next step in achieving integrated river basin management. However, its effectiveness largely depends on the willingness of member states to share river basin districts to subordinate their separate socio-economic interests to ecological needs, as well as to grant a clear mandate and partly transfer responsibilities and powers to a competent supranational authority.     

Distribution profiles of endocrine disrupting PAHs/APEOs in river sediments: is there a potential ecotoxicological problem?

The endocrinic/mutagenic potencies of the endocrine disrupting chemicals (EDCs) polycyclic aromatic hydrocarbons (PAHs), alkylphyenol ethoxylates (APEOs) and their metabolites are well documented. Less so is the endocrinic ecotoxicological/health risk potential of these persistent organic pollutants (POPs) in river sediments. From approximately 5 x 10(8) m3/y of sewage produced in Israel, approximately 70% are reused, mainly in agriculture, following a conventional activated sludge treatment (AST). A major related question is: does this practice conform to sustainability? We have found the APEOs concentration profiles of Israel's rivers/streams, Mediterranean Sea coastal water and groundwater, to be 12.5-74.6, 4.5-25.0 and trace-20.2 microg/L, respectively. In two "representative" rivers, in the central coastal region of the country, the total concentrations of the PAHs and APEOs were found to be (in the upper layers of their sediments) 1.02-1.59, 1.78-2.30, 1.48-3.12 and 31.27-376.23, 2.40-91.70, 62.99-63.63 microg/g, respectively. The distribution of the PAHs in the co-presence of APEOs in rivers and their sediments, can be rationalized in terms of the hydrophobicity/nonbiodegradability of the former and the hydrophilicity-CMC/nonbiodegradability of the latter. Based on (a) the zebrafish egg production test (ZFEPT) - a long-term exposure of zebrafish to actually found environmental concentrations of EDCs; and (b) the low effectiveness of POPs removal in AST, our preliminary conclusions are that (1) there is a potential ecotoxicological/health risk problem; and (2) the practice of conventional wastewater treatment plants (WWTPs)-treated water reuse is incompatible with sustainability.     

Abundance and distribution of benthic macroinvertebrates in offshore soft sediments in Western Lake Huron, 2001–2007

Invasive species have had major impacts on the Great Lakes. This is especially true of exotic dreissenid mussels which are associated with decreased abundance of native macroinvertebrates and changes in food availability for fish. Beginning in 2001, we added a benthic macroinvertebrate survey to the USGS-Great Lakes Science Center's annual fall prey fish assessment of Lake Huron to monitor abundance of macrobenthos. Mean abundance of Diporeia, the most abundant benthic taxon in Lake Huron reported by previous investigators, declined greatly between 2001 and 2007. Diporeia was virtually absent at 27-m sites by 2001, decreased and was lost completely from 46-m depths by 2006, but remained present at reduced densities at 73-m sites. Dreissenids in our samples were almost entirely quagga mussels Dreissena bugensis. Zebra mussels Dreissena polymorpha were virtually absent from our samples, suggesting that they were confined to nearshore areas shallower than we sampled. Loss of Diporeia at individual sites was associated with arrival of quagga mussels, even when mussel densities were low. Quagga mussel density peaked during 2002, then decreased thereafter. During the study quagga mussels became established at most 46-m sites, but remained rare at 73-m sites. Length frequency distributions suggest that initial widespread recruitment may have occurred during 2001–2002. Like other Great Lakes, Lake Huron quagga mussels were associated with decreased abundance of native taxa, but negative effects occurred even though dreissenid densities were much lower. Dreissenid effects may extend well into deep oligotrophic habitats of Lake Huron.     

Occurrence and distribution of organochlorine pesticides and polycyclic aromatic hydrocarbons in surface sediments from Qinghai Lake,northeast Qinghai–Tibet plateau,China

Organochlorine pesticides (OCPs) and polycyclic aromiatic hydrocarbons (PAHs) were analyzed in surface sediment samples collected from Qinghai Lake, the largest lake in China, which is situated in the northeast Qinghai–Tibet plateau at an altitude of 3200 m. The concentrations of these pollutants ranged from 0.02 to 1.00 ng/g for hexachlorocyclohexanes (HCHs), from not detected to 0.86 ng/g for dichlorodiphenyltrichloroethanes (DDTs), from 0.26 to 1.73 ng/g for OCPs, and from 366 to 966 ng/g for PAHs. The predominance of α-HCH suggests that long-range atmospheric transport is an important source for HCHs. A low α- to γ-HCH ratio (3.87 on average) indicates the possible usage of lindane in the drainage basin. The high percentage of p,p′-DDE and p,p′-DDD and the low percentage of o,p′-DDT indicated significant degradation from previous inputs, and no recent inputs of dicofol derived DDT. Based on the analysis of the component ratios, PAHs were found to be primarily from the combustion of biomass and coal-based fossil fuels. Using the Canadian sediment guidelines, PAHs are of greater ecological concern than OCPs in Qinghai Lake.     

What's in a name? Taxonomy and nomenclature of invasive gobies in the Great Lakes and beyond

The species identities, scientific names, and relationships of Eurasian gobies that invaded the Laurentian Great Lakes – and other species that are predicted to invade in the future – are evaluated here using recently resolved DNA characters. The Round Goby and the Freshwater Tubenose Goby entered the Great Lakes ca. 1990 via ballast water originating from Black Sea ports. The Round Goby spread extensively throughout the Great Lakes and adjacent rivers, whereas the Freshwater Tubenose Goby recently began to expand its range. Both species also are widely invasive in Eurasia, dispersing via canals and shipping. Several of their relatives – the Monkey, Racer, and Bighead gobies – also are invasive in Eurasia, and are predicted to invade the Great Lakes. We discuss results from phylogenetic analyses of DNA sequences from 4 mitochondrial and nuclear gene regions, and provide a revision of their scientific nomenclature. The Freshwater Tubenose Goby was redefined as Proterorhinus semilunaris, which is markedly different and distinctive from the Marine Tubenose Goby Proterorhinus marmoratus. The genus Neogobius, as formerly defined, contained multiple evolutionary lineages and incorrect scientific names. We thus restricted Neogobius to just 4 species—including the Round Goby Neogobius melanostomus and the Black Sea Monkey Goby Neogobius fluviatilis. Several previously recognized subgenera, which were incorrectly grouped in Neogobius, were elevated to the level of genera. Notably, the Racer Goby became Babka gymnocephalus and the Bighead Goby now is Ponticola kessleri. These changes made the names consistent with their true relationships and species characters, which are essential for identifying and characterizing these gobies in invasive and native habitats.     

Can we characterize river corridor evolution at a continental scale from historical topographic maps? A first assessment from the comparison of four countries

National historical map resources are assessed in four European countries to characterize river corridor features and associated channel changes, as well as identify issues limiting or promoting geomorphic assessment procedures at a continental scale. A geomorphic audit that launches potential data for diagnosis from reach to continental scales could offer a good resource for biology and ecology managers of river authorities or government agencies and engineers. The assessment compares the resources available by country in terms of period covered, spatial scale, history and chronology, and representation of the fluvial corridor features. We then applied the Historical Maps Vectorization Toolbox, initially developed for vectorizing river corridors from French maps, to detect and extract flow channels, unvegetated bars and riparian vegetation patches from historical topographical maps. We found that (a) it is difficult to apply an audit of channel changes to the whole continental scale because map legends differ between countries due to geographic and political specificity; (b) there exists an opportunity to get assessment information in all countries at reach or national scale where map resources are available; (c) the highest potential is observed in Switzerland and Belgium where there is high quality national map coverage from the 19th century; and (d) the algorithm Historical Maps Vectorization Toolbox applied to map resources works well with any of the countries, and its widespread application is encouraging.     

Biomarkers of algal populations in phytoplankton,filamentous algae,and sediments from the eastern basin of Lake Erie 2003–2005

Algal carotenoids (n:16) and chlorophylls (n:7) were determined in phytoplankton (n:60), filamentous algae (n:14) and sediments (n:44), collected from two nearshore sites in eastern Lake Erie (Van Buren Point (VBP), 6.5 m; Point Gratiot (PG), 17 m), during summer and fall of 2003, 2004 and 2005. The most prominent biomarkers for diatoms (fucoxanthin), cryptophytes (alloxanthin), chlorophytes (chlorophyll-b) and cyanobacteria (zeaxanthin) revealed temporal variations in phytoplankton community composition, which were correlated to water temperatures: i) seasonal succession, from diatoms with some cryptophytes in June (cool), to an increased percentage of chlorophytes and cyanobacteria in August and September (warm); ii) differences between 2004 (cool; cryptophytes more abundant) and 2005 (warm; chlorophytes more abundant). Filamentous algae (chlorophytes, epiphytic diatoms; some cyanobacteria) varied in condition, according to levels of chl-a, pheopigments, and class biomarkers: high, at VBP (growing; decaying; bont/E suspect); low, at PG (mostly dead). Relative to phytoplankton, sediments were depleted in several biomarkers (chl-a; diadino-, neo- and violaxanthin) but enriched with others, particularly at PG (pheopigments; diatoxanthin; canthaxanthin, echinenone; alloxanthin). Sediment composition was characterized by strong differences between sites (chl-a, chl-b and fucoxanthin nearly 10-fold greater at VBP than PG) and increasing accumulation of biomarkers from year-to-year. A linear log–log function, relating total carotenoids to total chlorophylls (intercept −0.516, slope 1.054, r² 0.96), implied increased biodegradation among specimen types: levels of pigments (pmol/g ww) decreased three orders of magnitude, from phytoplankton, through filamentous algae, to sediments. Deviation from a 1:1 relationship indicated 1.7-fold depletion of carotenoids relative to chlorophylls at mid-range.     

What controls distribution of larval and juvenile yellow perch? The role of habitat characteristics and spatial processes in a large,shallow lake

The goal of this study was to determine the relative contribution of environmental and spatial processes governing the distribution of larval and juvenile yellow perch (Perca flavescens) in two shallow embayments of a large fluvial lake on the St. Lawrence River system. We tested the hypotheses that: i) larval distribution is not related to habitat characteristics, presumably due to their relatively low swimming capacity, whereas ii) these environmental variables drive juvenile distribution, reflecting a more active habitat selection. This study is one of the first attempts to partition the relative roles of environmental and spatial factors in shaping the distribution of a freshwater fish through its early ontogeny. We show that larvae were not spatially aggregated within the embayments and that habitat characteristics, mainly related to aquatic vegetation, played an important role in explaining their distribution. In contrast, juvenile abundances were not significantly related to habitat characteristics, despite being spatially structured over multiple scales. Contrary to our predictions, habitat association was stronger for larvae than for juveniles which were aggregated independent of habitat characteristics. Increased swimming capacities may thus facilitate the aggregation of juveniles rather than strengthening their association with habitat, at least at the scales considered here (ca 3 km²). These results shed a new light on the factors governing larval and juvenile yellow perch distribution, suggesting that active habitat choice might begin earlier than previously thought.     

Return of adult anadromous allis shad (Alosa alosa L.) in the river Seine,France: A sign of river recovery?

In the past, the diadromous fish fauna of the river Seine comprised 11 native species. From the second part of the 19th century, the progressive modification of the river for navigation purposes and the increase of domestic and industrial pollution led to a general decline of migratory stocks and the extinction of several species. Among them, allis shad (Alosa alosa) was previously widespread in the Seine basin, but disappeared at the beginning of the 20th century. In July 2004, several individuals of shad were observed in the river Seine upstream of Paris (410 km from the sea), one of them was identified as an allis shad that had clearly spawned (thin fish and large scale erosion). A second allis shad was caught in a more downstream location (180 km from the sea) in November 2007 and a spawning mark was found on scales demonstrating clear evidence of reproduction. Recent occurrences of this species are discussed in relation to the present conditions of water quality and migration in the Seine watershed and recent evolution of the species' distribution in the northwestern part of France. Copyright © 2009 John Wiley & Sons, Ltd.     

On the beautiful diverse Danube? Danubian floodplain forest vegetation and flora under the influence of river eutrophication

The aim of this study was to investigate and compare the flora and vegetation of three well‐preserved hardwood floodplain forest areas along the river Danube and to discuss whether possible differences between the floodplain forests can be linked to river eutrophication. Flora and vegetation data from three study areas located on the Upper, Middle and Lower Danube in Central and Eastern Europe were compared using univariate and multivariate statistical methods. Special attention was paid to floristic composition, plant functional types, and ecological indicator values. We found that the three studied hardwood floodplain forests appeared to be rather different regarding floristic composition and herb‐layer vegetation. Despite the high beta diversity, the distribution of the plant functional types indicated generally equal habitat conditions, which were quite stable. The diversity of herb‐layer vegetation decreased downstream, while the indicators of nutrient availability pointed to increasing nutrient supply. The factor light apparently played a minor role for herb‐layer diversity. There is a remarkable congruence between the results of our floodplain vegetation analysis and the longitudinal river eutrophication patterns as described in the literature. We conclude that the nutrient input into Danubian hardwood floodplain forests increased downstream, resulting in higher nutrient availability for plants. This promoted especially the growth of tall and competitive forbs, which outcompeted other plant species. Even if the importance of the various eutrophication patterns is difficult to quantify, our study provides evidence that anthropogenic eutrophication has a distinct effect on the flora and vegetation of Danubian hardwood floodplain forests. Copyright © 2010 John Wiley & Sons, Ltd.     

How would the Rogun Dam affect water and energy scarcity in Central Asia?

The construction of the Rogun Dam in the Amu Darya Basin to increase upstream energy generation creates potential trade-offs with existing downstream irrigation, due to the different timing of energy and irrigation water demands. The present analysis, based on a hydro-economic optimization model, shows that cooperative basin-wide maximization of benefits would lead to large increases in upstream hydropower production and only minor changes in downstream irrigation benefits. However, if upstream stations, including Rogun, are managed unilaterally to maximize energy production, hydropower benefits might more than double while irrigation benefits greatly decrease, thereby substantially reducing overall basin benefits.     

Does hatchery rearing of lake trout affect their reproductive behavior in the wild?

Stocking of hatchery-reared fishes has been used with variable success as a management action to promote the recovery of populations and species. The practice has been controversial for several reasons, including uncertainty about whether the hatchery rearing experience may affect reproduction after release. Fine-scale acoustic telemetry was used during three spawning seasons to test whether hatchery rearing affects the reproductive behavior of lake trout using a spawning shoal complex in northern Lake Huron. Within sex, wild- and hatchery-reared fish behaved similarly, but significant behavioral differences occurred between sexes. Lake trout of both sexes moved synchronously onto the spawning shoals at the completion of autumn thermal turnover and occupied the same spawning sites (confirmed visually by presence of fertilized eggs) on the shoals. Male lake trout tended to congregate directly on spawning sites, with duration of occupancy varying greatly among years. Female lake trout spent less time on spawning shoals than males and congregated less at spawning sites on shoals. Most fish visited multiple spawning sites among shoals per season, with many making multiple transits among individual spawning sites. We found no evidence to support the hypothesis that hatchery rearing impairs spawning behavior of lake trout and, therefore, conclude that behavior deficiencies on the spawning ground are likely not an impediment to rehabilitation of lake trout in northern Lake Huron. Our study narrows the field of possible impediments to lake trout rehabilitation in the Great Lakes and provides insights that expand the conceptual model of lake trout spawning behavior.     

Do policy and institutional factors explain the low levels of smallholder groundwater use in Sub-Saharan Africa?

This article examines the policy and institutional constraints on smallholder adoption of groundwater irrigation practices in Sub-Saharan Africa. The analysis departs from the unilateral focus on the promotion of technologies and probes not only the issues of groundwater governance but also those policies related to other enabling factors such as access to credit, energy and agricultural pricing policies and land-tenure security. The paper argues that the region may be missing an opportunity by not ensuring at least neutral policy towards agricultural groundwater development and addressing other constraints which hold back not only agricultural groundwater use but smallholder agriculture development in general.     

Application of a water–energy–food nexus framework for the Duero river basin in Spain

This paper proposes a framework for the identification, assessment and analysis of the water–energy–food nexus at a basin scale. This methodology is applied to the Duero river basin in Spain to detect the most important conflicts derived from water, food and energy interdependencies. Some of the most important issues are the limitations posed by rising energy prices for irrigated agriculture due to modernization, limitations to water treatment, and the possible emergence of new water demands for energy by hydraulic fracturing for oil and gas and enhanced bioenergy.     

Spatial and temporal variation in distribution of larval lake whitefish in eastern Lake Ontario: Signs of recovery?

The lake whitefish (Coregonus clupeaformis) is one of the native Lake Ontario fishes that declined severely over the past century. Recent evidence of larval lake whitefish production in a historic spawning area (Chaumont Bay) might signal a recovery of this species in New York waters. We surveyed coastal and open water areas to evaluate densities and estimate total abundance of larval lake whitefish in Chaumont Bay. Other historic spawning areas and embayments with appropriate spawning and nursery habitat were also surveyed, but only a few larvae were found outside of Chaumont Bay. Lake whitefish larvae were found in every embayment sampled within Chaumont Bay, with larval densities of nearly 600/1000 m² in some samples. Greatest abundances occurred in the northern sectors and near the mouth of the bay. Open water densities were generally less than half that of nearshore sites. The total bay-wide estimate for 2005 was approximately 644,000 lake whitefish larvae, but dropped to 230,000–400,000 in 2006 and 2007, respectively. Mean larval growth rates (0.36 mm/day) did not differ by year, but were consistently higher in early May than in late April. Lake whitefish production in Chaumont Bay is encouraging for this species, but the cause and persistence of the decline after 2005 can be determined only by continued monitoring. Other possible bottlenecks of survival may exist at juvenile and adult stages and could significantly affect recruitment dynamics. This species is sensitive to normal climatic fluctuations and increased variability associated with global climatic change could make winter nursery conditions unfavorable for this species.     

Temporal and spatial differences in deposition of organic matter and black carbon in Lake Michigan sediments over the period 1850–2010

Inorganic carbon (IC), total organic carbon (OC), and black carbon (BC) were analyzed in eight sediment cores obtained from deep water (>30 m) sediments in the Chippewa and south Chippewa basins, as well as Green Bay in Lake Michigan. These cores were segmented at high resolution and radio-dated to reconstruct a detailed history of deposition to the lake both spatially and temporally since ca. 1850 CE. To help interpret the depositional record, cores were also characterized for stable isotopes (¹³C and ¹⁵N), as well as particle size distribution, density, organic matter (OM), and other parameters. Fine (silt and clay) sediment particles contained OM of primarily lacustrine algal biomass origin. Sedimentation fluxes showed large increases in OM and OC fluxes through much of the lake during the onset of industrialization and the period of rapid industrialization to onset of Great Lakes environmental legislation. In contrast, fluxes and loading of BC increased dramatically in the southern basin until the 1930's, then decreased substantially after the 1940's. This observation was due largely to results from site M009 nearest the steel mills and industrial zones of Chicago and northern Indiana. Together, whole lake loadings of OM and BC provide evidence that changing industrial activity and legislation intended to curb air pollution in the Great Lakes region have had a fairly rapid and dramatic impact. In contrast, legislation intended to decrease eutrophication through reductions in nutrient loading to the lake have not had a similar impact on sedimentation of OM in the lake.     

Trends in the distribution and abundance of Hexagenia spp. in Saginaw Bay,Lake Huron, 1954–2012: Moving towards recovery?

Since at least the 1940s, multiple anthropogenic disturbances to the Laurentian Great Lakes have had detrimental effects on benthic habitats and biota including decimating the environmentally sensitive burrowing mayfly genus Hexagenia around the mid-1950s. While remediation efforts have facilitated recovery of some populations, benthic surveys in Saginaw Bay, Lake Huron in the last 50 years have only occasionally discovered Hexagenia nymphs. Recently, adult Hexagenia swarms have been reported near the bay; therefore, we corroborated the local presence of Hexagenia adults and evaluated the current status of Saginaw Bay Hexagenia nymphs. We quantified adults during mayfly emergence events in 2010 at three Tawas City, Michigan, USA area locations, and found > 17 Hexagenia/m²/site. We quantified nymphs from Ponar grab samples collected at 57 sites in Saginaw Bay between 2009 and 2012, and found 1.5 nymphs/m² overall with nymphs present at 15.8% of sites sampled, their greatest documented distribution in Saginaw Bay since 1956. Additionally, we mapped bay sediment composition and related sampling site abiotic conditions with both Hexagenia presence and abundance using Zero-Inflated Poisson regression. Model results indicate that the probability of observed Hexagenia absence being true absence is positively related to both sediment sandiness and surficial dissolved oxygen concentration while Hexagenia abundance is greatest where surficial temperatures are ~ 18.6 °C and is also related to sediment sand content. The documentation of nearby adults and in bay nymphs may indicate the beginning of a Hexagenia return to Saginaw Bay, and, therefore, a possible improvement of the ecosystem's benthic health.     

Distribution of Contaminants in Clams and Sediments from the Huron-Erie Corridor. II–Lead and Cadmium

The St. Clair River is a major center for the Canadian petrochemical industry, while the shoreline of the Detroit River is heavily urbanized. The extent of lead and cadmium discharge from these sources was assessed by determining contaminant concentrations in unionid clams (Lampsilis radiata siliquoidea) and sediments from 102 sites in Lake St. Clair and from the Canadian side of the Detroit and St. Clair rivers. Overall, lead and cadmium levels in sediments averaged 20.5 and 0.18 mg kg⁻¹ dry weight, respectively. These concentrations are lower than those reported in prior studies, but the decline is likely a consequence of shifts in sampling methodology and site location. Lead concentrations in clams (7.1 mg kg⁻¹) averaged only one half those in the sediments, whereas cadmium concentrations were 30 times higher in clam tissues than in the surrounding sediments. There was a significant positive correlation between lead and cadmium concentrations in sediment, and between the concentrations of both metals and the amount of organic carbon present. There was no correlation between the level of either lead or cadmium in clams and levels in the sediments from which they were collected. Patterns of variation in contaminant concentrations support the conclusion that industries along the Canadian side of the St. Clair River are the primary source of both lead and cadmium.