Isolation of enteroviruses from water, suspended solids, and sediments from Galveston Bay: survival of poliovirus and rotavirus adsorbed to sediments.

The distribution and quantitation of enteroviruses among water, suspended solids, and compact sediments in a polluted estuary are described. Samples were collected sequentially from water, suspended solids, fluffy sediments (uppermost layer of bottom sediments), and compact sediment. A total of 103 samples were examined of which 27 (26%) were positive for virus. Polioviruses were recovered most often, followed by coxsackie B viruses and echoviruses 7 and 29. Virus was found most often attached to suspended solids: 72% of these samples were positive, whereas only 14% of water samples without solids yielded virus. Fluffy sediments yielded virus in 47% of the samples, whereas only 5% of compact bottom-sediment samples were positive. When associated with solids, poliovirus and rotavirus retained their infectious quality for 19 days. The same viruses remained infectious for only 9 days when freely suspended in seawater. Collection of suspended solids at ambient water pH appears to be very useful for the detection of virus; it has advantages over collecting and processing large volumes of water, with accompanying pH adjustment and salt addition for processing.     

Isolation of enteroviruses from water, suspended solids, and sediments from Galveston Bay: survival of poliovirus and rotavirus adsorbed to sediments

The distribution and quantitation of enteroviruses among water, suspended solids, and compact sediments in a polluted estuary are described. Samples were collected sequentially from water, suspended solids, fluffy sediments (uppermost layer of bottom sediments), and compact sediment. A total of 103 samples were examined of which 27 (26%) were positive for virus. Polioviruses were recovered most often, followed by coxsackie B viruses and echoviruses 7 and 29. Virus was found most often attached to suspended solids: 72% of these samples were positive, whereas only 14% of water samples without solids yielded virus. Fluffy sediments yielded virus in 47% of the samples, whereas only 5% of compact bottom-sediment samples were positive. When associated with solids, poliovirus and rotavirus retained their infectious quality for 19 days. The same viruses remained infectious for only 9 days when freely suspended in seawater. Collection of suspended solids at ambient water pH appears to be very useful for the detection of virus; it has advantages over collecting and processing large volumes of water, with accompanying pH adjustment and salt addition for processing.     

Dependences of 137Cs and 90Sr concentration ratios in fish on the potassium and calcium concentrations in the freshwater reservoirs

Activities of 137Cs and 90Sr, concentrations of the potassium and calcium ions in water and accumulation of the radionuclides in the organisms of various freshwater fish have been measured in the stagnant and semistagnant water reservoirs of Ukraine contaminated as a result of the Chernobyl accident. On the basis of the numerous experimental data for different regions the statistical parameters were derived describing the dependencies of the 137Cs and 90Sr concentration ratios in the muscle tissue of various fish species on the potassium and calcium concentrations in water, respectively.     

Physical and geochemical characteristics of suspended solids,Wilton Creek,Ontario

To understand the nature of sediment-associated nutrient and contaminant transport dynamics in fluvial systems, a stormflow sampling program of suspended solids is reported for one water year in a representative rural diffuse source catchment of southeastern Ontario. Bulk samples of subsieve suspended solids were obtained using field-portable continuous-flow centrifuge apparatus. The physical and geochemical properties of suspended solids show no significant intersite differences over reaches of 1 500–2 000 m, yet display distinctive seasonal trends. Systematic seasonal changes in particle size, organic content, and Ca, P, Mn, Al, Ti, Fe, and K appear to reflect the changing role of partial area hydrology. Ca, P, and Mn are bioaccumulated by stream algae. Mineral signature is relatively constant over the year. This article first appeared in the Canadian Journal of Earth Sciences. Volume 18, pp. 1365–1379 (1981). Permission of the copyright holders to reprint the article is gratefully acknowledged.     

Sedimentation and distribution of gamma-emitting radionuclides in bottom sediments of southern Lake Päijänne,Finland, after the Chernobyl accident

The rates of sedimentation of fallout nuclides were determined by means of sediment traps during 28 months after the Chernobyl accident in southern Lake Päijänne, Finland. The spatial distribution of the radionuclide content of the lake bottom was studied on 35 sediment cores in winters 1987/88 and 1988/89. The results were compared with simultaneous observations of the radionuclide content of the water and seston. The role of different transfer mechanisms in the elimination of radionuclides from the water column is discussed.The values recorded for the flux to the lake sediments were on average of the same order of magnitude as the initial deposition on the lake surface (Cs-137 65 kBqm^–2). The radionuclide flux to the sediments was rapid during the first months after the accident. After that the elimination of dissolved nuclides from the water mass became significantly slower. The highest flux rate was that of Ce-144 and the lowest that of Rh-106 (Ru-106). Of the radiocesium, about half of the initial inventory was transferred to the sediments after the first observation year.The content of radionuclides showed considerable spatial variation on the lake bottom (Cs-137 7–280 kBqm^–2). Direct adsorption of radiocesium explains unexpectedly high concentrations on shallow erosion bottoms. There was a clear tendency for the concentrations to increase with depth, as a result of the focusing effect. Sediment resuspension had a significant impact on the total flux of radionuclides to deepwater sediments. Estimates were made of the resuspended flux of radionuclides.     

Cs-134/137 contamination and root uptake of different forest trees before and after the Chernobyl accident

Summary The Cs-134/137 activities were measured from different tree organs of spruce, larch and sycamore maple. Two locations in South Bavaria were monitored during a period of 2.5 years following the Chernobyl accident. Samples taken in 1985 allow to determine the Cs-137 contamination before the accident. Increasing Cs-137 activities from older to younger needle years ofPicea abies caused by root-uptake of the global weapons' fallout are due to the high phloem mobility of this element and the remaining of the needles at the tree for about 6–7 years. In contrast, the Cs-137 activity was much smaller in leaves of larch and sycamore maple. After the Chernobyl accident, the higher contamination of spruce > larch > sycamore maple is dependent on the roughness of bark, absolute bark surface and the existence of leaves during the deposition of Chernobyl-derived radioactivity. The Cs-134/137 activity (Bq/kg d.w.) was about 25-times higher in bark compared to wood ofPicea abies and 1.5–4.7 times higher in directly contaminated twig-axes than in leaves. Till the end of the investigation the major contamination of the shoots was due to direct deposition of cesium on the trees. A maximum of 5–15% of the total activity of the directly contaminated branches of the plants was calculated to be part of root-uptake, depending on the amount of initial retention. 20% of the translocated cesium into new leaves of larch and about 50% into sycamore maple resulted from root-uptake 2.5 years after the accident.     

The distribution of the radionuclides in the main components of lake ecosystems within the Chernobyl NPP exclusion zone

The results of the studies devoted to the distribution of radionuclides 90Sr, 137Cs, 238Pu, 239 + 240Pu and 241Am in 1998-2003 in main components of Glubokoe Lake and Dalekoe-1 Lake located within Krasnensky flood lands of the Pripyat River (inner exclusion zone of the Chernobyl NPP) were analysed. The data about the radionuclide content in bottom sediments, in water, in seston, in macrozoobenthos (including bivalvia molluscs), in gasteropods molluscs, in higher aquatic plants and in fish are presented.     

Monte-Carlo prediction of changes in areas of west Cumbria requiring restrictions on sheep following the Chernobyl accident

Following the 1986 Chernobyl accident radiocaesium levels in sheep meat in some upland areas of the United Kingdom were above the national intervention limit. West Cumbria was one of these areas and restrictions are currently still in place. In addition to deposition from the Chernobyl accident, Cumbria has been subject to radiocaesium deposition from atmospheric nuclear weapons tests, the 1957 Windscale accident and routine releases from the Sellafield nuclear reprocessing plant. A Monte-Carlo approach has been used to try to predict areas in west Cumbria where radiocaesium activity concentrations in lamb meat would require the imposition of restrictions at different times after the Chernobyl accident. The approach models the transfer of radiocaesium from soil to vegetation, based upon soil organic matter, and from vegetation to lamb meat. Spatial inputs are soil organic matter and total post-Chernobyl (137)Cs and (134)Cs deposition; a ratio of Chernobyl (137)Cs to (134)Cs deposition has been used to differentiate Chernobyl and pre-Chernobyl (137)Cs deposition. Comparisons of predicted radiocaesium transfer from soil-vegetation and the spatial variation in lamb (137)Cs activity concentrations are good and predicted restricted areas with time after Chernobyl compare well to the restricted areas set by UK government. We predict that restrictions may be required until 2024 and that in some areas the contribution of pre-Chernobyl (137)Cs to predicted lamb radiocaesium activity concentrations is significant, such that restrictions may only have been required until 1994 as a consequence of Chernobyl radiocaesium deposition alone. This work represents a novel implementation of a spatial radioecological model using a Monte-Carlo approach.     

Modeling underwater light climate in relation to sedimentation,resuspension, water quality and autotrophic growth

The underwater light climate ultimately determines the depth distribution, abundance and primary production of autotrophs suspended within and rooted beneath the water column. This paper addresses the underwater light climate, with reference to effects of suspended solids and growth responses of autotrophs with emphasis on phytoplankton.Effects of the most important factors contributing to the absorption and scattering of light in surface waters were described. A comparison between spectral and scalar approaches to underwater light climate modeling was made and examples of linear approximations to light attenuation equations were presented. It was demonstrated that spectral and scalar photosynthesis models may converge to similar values in spectral-flat, high photon flux environments, but that scalar PAR models may overestimate biomass-specific production by 70%. Such differences can lead to serious overestimates of habitat suitability for the growth and survival of submersed macrophytes, particularly in relatively turbid, coastal waters.Relationships between physical and optical properties of suspended sediments were described theoretically, and illustrated with modeling examples and measurements. It was found that the slowly settling particulate fraction contributed substantially to the suspended solids concentration, and greatly to light attenuation within the water column. It was concluded that distinguishing particles by fall velocity and concomitant light attenuation properties in the modeling of underwater light conditions allowed the establishment of useful, although not simply linear, relationships.In eutrophic, shallow lakes, the largest contribution to light attenuation often originates from phytoplankton on a seasonal basis (months–years), but from suspended solids behavior on a shorter time scale (days–weeks), particularly when water bodies are wind-exposed. Temporal and spatial variabilities in wave height, suspended solids concentrations, and light attenuation within the water column, and their importance for autotrophic growth were described, and illustrated with a case study pertaining to Markermeer, The Netherlands. The influence of underwater light conditions on phytoplankton succession was briefly discussed and illustrated with a case study pertaining to Lake Veluwe, The Netherlands. It was concluded that modeling the underwater light climate in a water body on a few sites only can indicate how important various components are for the attenuation of light, but based on the current state of the art, it can not be expected that this will provide accurate predictions of the underwater light climate, and of phytoplankton and submersed macrophyte growth.     

Use of Aquatic Plants and Algae for Decontamination of Waters Polluted with Chlorinated Alkanes

The transformation of carbon tetrachloride (CT) and hexachloroethane (HCA) by aquatic plants and freshwater algae was investigated. Stressed, axenic, and physiologically healthy freshwater plants all transformed the two chlorinated alkanes, yielding similar breakdown products. Experiments conducted with dead plants were used to indirectly test the hypothesis that dead aquatic plants maintain and possibly contribute to the dehalogenase activity observed in organic-rich sediments. After exposure of the aquatic plants and algae to HCA- and CT-dosed solutions, a rapid sorption (or sequestration) step followed by a slow transformation lasting several hours thereafter was observed. The kinetics data were adequately described by two first-order rate equations; pseudo-first-order sorption rate coefficients were calculated for the initial rapid adsorption and transformation steps. The identified metabolites extracted from plants indicated that more than one pathway, possibly requiring different reactants, mediated the phytotransformation reactions. Mass balance estimations confirmed that >80% of the parent chemical was sequestered, transformed, and/or assimilated by the biomass. The metabolic activity observed with dead plants and algae suggests that photoautotrophs maintain this activity at death, and the active agents could become bound to the sediment-organic matrix as plants die, decay, and are buried in sediment. The results of this study suggest the potential usefulness of aquatic plants and freshwater algae in the removal of chlorinated alkanes from water and remediation of aquatic environments.     

Variations of photosynthetic activity and growth of freshwater algae according to ozone contact time in ozone treatment

The activity of freshwater algae in drinking water supply at various ozone contact times was investigated to evaluate ozonation processes used for sterilization of algae. O production rates of algae just after ozonation were severely retarded even by short ozone contact. The algal growth rate was also declined with increase of ozone contact time and completely inhibited by ozonation for 60 min. These results implied that the usual treatment time applied in conventional ozonation processes is not sufficient but at least 60 min of ozonation is required for a complete sterilization of freshwater algae in drinking water source.     

淡水藻类在监测水质和净化污水中的应用

淡水藻类作为水体中的初级生产者,分布广泛,适应性强,在水生生态系统食物链中占据着十分重要的地位,在水质监测中起着关键的作用。通过对藻类生长与水环境之间的相互关系进行简要的概述,探讨了pH值和氮磷对淡水藻类的生长的影响,以及淡水藻类的生长对外界环境的影响。藻类不但应用于水质监测,而且还能去除水体中的氮、磷等营养物质和其它有机物,对自然水域中的污水有良好的净化作用。重点论述淡水藻类在水质监测和污水净化中的作用以及利用淡水藻类来处理污水的方法。并提出了保护水资源的相关建议,为综合监测和治理水环境提供一定的理论依据和支持。     

Physiological response of Epipremnum aureum for cobalt-60 and cesium-137 translocation and rhizofiltration

In this study, three separate experiments were carried out to explore the potential of Epipremnum plants for Co-60 and Cs-137 uptake and rhizofiltration from solutions. Experiment I was carried out to screen the effects of different concentration (0-10 mM) of stable Co and Cs salts on some physiological components of the Epipremnum over 20 d. Data from the experiment showed that 1 mM of either Co or Cs had no adverse effects on the chlorophyll, soluble sugar, and protein of Epipremnum. Over 20 d at a high concentration (10 mM), some effects of Co or Cs were detectable but were not inhibitory. Experiment H showed an increase in the concentration ratios (CRs) of carrier-free Co-60 and Cs-137 relative to their concentration in the solution. Transport indexes (TIs) of Co-60 only increased with increasing its concentration in the solution. CRs increased with time and more than 50% of Co-60 and Cs-137 was detected at 5 d. Based on the data obtained from experiments I and II, both stable Co and Cs were used as carriers for Co-60 and Cs-137 to study their uptake and translocation in Experiment III. It was found that the Epipremnum plant had bioconcentration factors (BCFs) of 10.69 and 2.26 for Co and Cs, respectively. However, TI was 13.8 for Co and 35.6 for Cs. The accumulation of Co-60 and Cs-137 in the roots of Epipremnum might offer a method for Co-60 and Cs-137 rhizofiltration.     

Molecular dynamics study of the swelling patterns of Na/Cs-, Na/Mg-montmorillonites and hydration of interlayer cations

Over the last two decades, the swelling properties of montmorillonite (MMT) have been studied in many experimental and simulation works, but less attention has been given to MMT containing a mixture of monovalent/monovalent and monovalent/bivalent cations in the interlayer spaces. We carried out a molecular dynamics simulation of the swelling patterns of Na-, Mg-, Na/Cs-, Na/Mg-MMT in an isobaric isothermal ensemble (NPT) at T = 300 K and p = 1 atm. The simulation reproduced a swelling pattern of Na-, Mg-, Na/Cs-, Na/Mg-MMT and the swelling curves obtained showed the difference between the hydration mechanisms of the type of MMT used in this study. We also found out that the differences in size and hydration energy of Na, Cs and Na, Mg ions have strong implications on the structure of interlayer water. This has led to the difference in the swelling curves of the simulated Na-, Mg-, Na/Cs- and Na/Mg-MMT. For Na/Cs-MMT, the hydration energy of Na cations increased compared to that in Na-MMT, the hydration energy of Cs cations decreased in Na/Cs-MMT compared to that in Cs-MMT and also for Na/Mg-MMT, the hydration energy of Na cations increased compared to that in Na-MMT and that of Mg cations decreased in comparison with that in Mg-MMT. The diffusion coefficient of Cs cations obtained in this simulation was higher than that of Mg and Na cations in Cs-, Mg- and Na-MMT, respectively. Cesium cations have been seen to have a low hydration energy compared to Na and Mg cations and can be used as a good inhibitor of Na-MMT swelling process.     

Sulphur stable isotopes can distinguish trophic dependence on sediments and plankton in boreal lakes

1. Stable isotopes of carbon are useful for differentiating between freshwater food chains based on planktonic algae or benthic algae, but are reported to be of limited use for identifying food chains based on sedimentary detritus. Because data from marine systems suggest that stable isotopes of sulphur (δ³⁴S values) have potential in this regard, we tested their utility in freshwater lakes.
2. We found that sulphate in the water column of four boreal lakes was enriched in ³⁴S compared to the sulphur in bulk sediments from these lakes. Furthermore, within a given lake, insects known to feed on sediment (directly or via predation) had δ³⁴S values similar to those of sediment, whereas planktonic and benthic invertebrates known to feed on suspended particles had δ³⁴S values similar to those of sulphate in the water column.
3. Using the stable S isotope values of invertebrates that obtain their S from either the sediment or the water column as end members in a two-source mixing model, we show that two fish species obtain their food from both planktonic and sedimentary sources. Furthermore, model results suggest that, as expected, the more benthic-feeding fish species obtains more of its S from the sediment compartment than does the species that feeds in the water-column.
4. Our results suggest that measurements of stable sulphur isotopes provide a means of distinguishing between members of food chains that are based in the water column from those based on sedimentary detritus. As such, they would be a useful complement to stable C isotopes that are used to distinguish between food chains based on planktonic or benthic algae.     

Multi-Scale Controls on Water Quality Effects of Submerged Aquatic Vegetation in the Tidal Freshwater Hudson River

Patches of submerged vegetation can be important sites of primary production and habitat for organisms in many aquatic ecosystems. In the tidal freshwater Hudson River they make up about 6% of the river bottom area. Direct sampling of water masses passing through patches of vegetation and week-long continuous monitoring of water characteristics were used to determine plant effects on dissolved oxygen and suspended sediments. Vegetated areas could have dissolved oxygen concentrations substantially higher than in the main channel and suspended sediments and turbidity were frequently higher in vegetated areas. Patches of Vallisneria americana had variable capacity to maintain super-saturated oxygen concentrations; patch size accounted for some of the variability whereas larger-scale differences in main-channel influent water also contributed. Differences in turbidity among sites were harder to account for; width of plant beds and abundance of neighboring vegetated areas contributed weakly to predictions of local turbidity. Functional heterogeneity within ecosystems is common and attempts to explain variability may require understanding different controlling factors for different functions and appreciating that factors operate at multiple scales.     

Specific attenuation coefficients of optically active substances and their contribution to the underwater ultraviolet and visible light climate in shallow lakes and ponds

Sunlight penetration through the water column is controlled by the amount and kind of materials dissolved and suspended in the water. Understanding UV penetration in its complexity is essential for the prediction of the impact of UV radiation on aquatic ecosystems. However, only limited data are available on the penetration of UVR into shallow waters rich in inorganic suspended solids and chromophoric dissolved organic matter (CDOM). The same is true for the specific attenuation coefficients of light-absorbing components at the UV waveband. This study analyses the role of CDOM, algal-free suspended solids and algae in the formation of underwater UVR and PAR climate in 30 water bodies from clear gravel pit lakes trough the shallow Lake Balaton to turbid soda pans. Irradiance-depth profiles were obtained at 305, 313, 320 nm (UV-B), 340, 380, 395 nm (UV-A) and 400–700 nm (PAR) with a Biospherical PUV-2500 radiometer. Vertical attenuation coefficients (K _d) were calculated. Water samples were taken for the laboratory measurement of the concentration of light-absorbing components: algae as chlorophyll a (CHL), chromophoric dissolved organic matter as colour (CDOM), and algal-free suspended solids (TSS-Alg) parallel with the in situ light measurements. Specific attenuation coefficient values were calculated by multiple regression analysis (n = 140). The obtained specific UV attenuation coefficient values of CHL, CDOM and TSS-Alg made it possible to establish light attenuation at different wavelengths based on the knowledge of the concentration of these light-absorbing components.     

Suspended sediments and nutrients in water ebbing from seagrass-covered and denuded tidal mudflats in a southern Australian embayment

The concentrations of suspended solids, nitrogen (NH₄⁺, NO₃⁻, NO₂⁻), phosphorus (total phosphorus, PO₄⁻³) and silicate were measured in water ebbing from seagrass-covered tidal mudflats and from adjacent ungrassed mudflats in Western Port, Victoria, Australia. Ebb water was collected on six occasions during January and February (summer) and once during July (winter). From both types of mudflats the concentrations of suspended solids, phosphorus and silicate increased during the last hour of ebb tide with maxima in concentrations reached 0.5 to 1 h before slack water ebb. During the last 1.5–2.5 h of ebb tide the suspended solids, phosphorus and silicate concentrations were higher in water ebbing from denuded mudflats than from seagrass-covered mudflats. The concentration of nitrogen remained low in water ebbing from both types of mudflats during the day, but increased significantly during a night-time ebb; light-dependent biological uptake of nitrogen is implicated. It is suggested that denudation of seagrass-covered tidal mudflats would lead to increased efflux of suspended solids, phosphorus and silicate from sediments to overlying water.     

Benthic Diatoms as Indicators of Stream Sediment Concentrationin Hong Kong

Diatoms are photosynthetic unicellular, eukaryotic, microorganisms (algae) that are distinguished by their silicified (SiO₂‐nH₂O) cell walls. They have often been employed to assess salinity, pH, and nutrient conditions. Our data suggest that, they may also be used to assess suspended solid levels in streams. The ratio of motile to attached benthic diatoms from five different stream sites in Hong Kong was correlated with the level of suspended solids for each of these sites. Sites with high concentrations of suspended solids had a high percentage of motile diatoms on their rocks while sites with low concentrations of suspended solids had a high percentage of attached (non‐motile) diatoms on their rocks. When water carried by a stream has a high concentration of suspended solids, benthic diatoms in the stream are often covered in a layer of silt. Those diatoms that are motile are able to get on top of this silt layer while attached diatoms cannot. If the silt layer is not washed away, the attached diatoms perish and the percentage of motile diatoms increases. Thus, streams with high concentrations of suspended solids display a higher proportion of motile diatoms than do clear water streams with low concentrations of suspended solids. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Do saline taxa evolve faster? Comparing relative rates of molecular evolution between freshwater and marine eukaryotes

The major branches of life diversified in the marine realm, and numerous taxa have since transitioned between marine and freshwaters. Previous studies have demonstrated higher rates of molecular evolution in crustaceans inhabiting continental saline habitats as compared with freshwaters, but it is unclear whether this trend is pervasive or whether it applies to the marine environment. We employ the phylogenetic comparative method to investigate relative molecular evolutionary rates between 148 pairs of marine or continental saline versus freshwater lineages representing disparate eukaryote groups, including bony fish, elasmobranchs, cetaceans, crustaceans, mollusks, annelids, algae, and other eukaryotes, using available protein‐coding and noncoding genes. Overall, we observed no consistent pattern in nucleotide substitution rates linked to habitat across all genes and taxa. However, we observed some trends of higher evolutionary rates within protein‐coding genes in freshwater taxa—the comparisons mainly involving bony fish—compared with their marine relatives. The results suggest no systematic differences in substitution rate between marine and freshwater organisms.