Distribution of silicones in water, sediment and fish in Japanese rivers

A new analytical method for assaying polyorganosiloxanes (silicones) in environmental samples is presented. The method utilizes petroleum for solvent extraction of the sample (water, sediment, biological tissue) together with inductively coupled plasma detection of the extracted organic silicones. The detection limit for silicones in the final methyl isobutyl ketone sample/extract is approximately 0.01 ppm, and the method is applied to samples from various Japanese rivers to quantify silicones in several environmental materials. Silicones are reported from river waters (up to approximately 50 ppb), riverine sediments (up to 6 ppm), and as an extractable component of fish tissue (up to approximately 0.9 ppm).     

Complementary accumulation of selenium and mercury in fish muscle

The concentrations of total selenium and total mercury in the muscle of striped mullet from four stations in the Northern Tyrrhenian Sea and one in the Black Sea were analyzed. If the sum of the concentrations of mercury and selenium (expressed as nmoles/g) is plotted against the age of the specimens, a single function describes all of the results.The explanation suggested by the authors is that SeHg receptors exist and increase with the age of the animal. These receptors may be occupied by mercury in proportion to its concentration in the environment.     

Active seismic monitoring of hydraulic fractures in laboratory experiments

In scaled laboratory tests, we perform acoustic measurements in a time-lapse sequence to separate the fracture response from the background signal. Using both compressional and shear waves (that are very sensitive to fluid filled fractures) we can, not only detect the hydraulic fracture, but also characterize its shape and geometry during its growth. We show the application of the technique to propagation and reopening of hydraulic fractures. During fracture growth the acoustic waves excite diffractions at the tip of the fracture. Depending on the acquisition geometry, we detect many events related to surface waves propagating along the fracture. Also, we observe that shear waves detect the migration of the fluid front during reopening of a pre-existing hydraulic fracture, in contrast with the compressional waves which are insensitive to the fluid front during reopening.     

Metal ion adsorption by Phomopsis sp. biomaterial in laboratory experiments and real wastewater treatments

An insoluble material of polysaccharidic nature has been obtained by thermal alkali treatment of the filamentous fungus Phomopsis sp. FT-IR spectrum of the resulting material as well as its nitrogen content suggest that chitosan and glucans are the main components of the biomaterial. Information on Lewis base sites has also been obtained and used as a guideline in the evaluation of the complexing ability against a number of metal ions in aqueous media at pH in the range 4--6. Results indicate that after 24h contact time, up to 870 micromol/g of lead, 390 micromol/g of copper, 230 micromol/g of cadmium, 150 micromol/g of zinc and 110 micromol/g of nickel ions are adsorbed into the material. After approximately 10 min, about 70% of the overall adsorption process has already been completed. Adsorbed metal ions can be recovered by washing with dilute acid. Experiments have been extended to a real wastewater effluent confirming the potential of this biomaterial as a depolluting agent.     

Role of soil-derived dissolved substances in arsenic transport and transformation in laboratory experiments

Dissolved substances derived from soil may interact with both soil surfaces and with arsenic and subsequently influence arsenic mobility and species transformation. The purpose of this study was to investigate arsenic transport and transformation in porous media with a specific focus on the impact of soil-derived dissolved substances, mainly consisting of inorganic colloids and dissolved organic matter (DOM), on these processes. Arsenic transport and transformation through columns, which were packed with uncoated sand (UC) or naturally coated sand (NC) and fed with arsenate (AsV) or monomethylarsonic acid (MMA) spiked influents, were investigated in the presence or absence of soil-derived dissolved substances. The presence of soil-derived inorganic colloids and/or DOM clearly enhanced As transport through the column, with the fraction of As leached out of column (referring to the total amount added) being increased from 23 to 46% (UC) and 21 to 50% (NC) in AsV experiments while 46 to 64% (UC) and 28 to 63% (NC) in MMA experiments. The association of arsenic with DOM and the competitive adsorption between arsenic and DOM could account for, at least partly, the enhanced As movement. Distinct species transformation of As during transport through soil columns was observed. When AsV was the initial species spiked in the influent solutions, only arsenite (AsIII) was detected in the effluents for UC columns; while both AsIII (dominant) and AsV were present for NC columns, with AsIII being the dominant species. When MMA was initially spiked in the influent solutions, all method detectable As species, AsIII, AsV, MMA, and dimethylarsenic acid (DMA) were present in the effluents for both soil columns. These results indicate that risk assessment associated with As contamination, particularly due to previous organoarsenical pesticide applications, should take into account the role of soil-derived dissolved substances in promoting As transport and As species transformation.     

Evidence on behaviour of low concentration DDT in laboratory sorption experiments

In an investigation of ¹⁴C labelled DDT interaction with suspended marine particulate matter, some difficulties in using blank systems occurred due to differences in adsorption by walls of vessels. Great differences were noted for adsorption of DDT onto walls of containers when comparing systems in the presence and absence of suspended particulate matter.The most acceptable results of an investigation for the distribution of DDT between liquid phase and suspended matter were obtained where both the amount of solute adsorbed on suspended matter and the equilibrium concentration in the liquid phase were measured. Where measurements of adsorbed solute on the solid phase were impossible (for instance in kinetics investigations) more realistic results were obtained if the solute was only measured in the liquid phase disregarding blanks.     

Heterotrophic slimes in Irish rivers: Evaluation of the problem

A questionnaire survey was used to determine the frequency of occurrence, extent and duration of slime growth in Irish rivers. Other factors such as the source of slime-promoting effluents, the degree of treatment given to effluents prior to discharge and the effects slime growth was having on watercourses were also examined. 156 outbreaks were recorded throughout Ireland which affected approx. 350 km of channel. Discharges from the agricultural processing industry and domestic sewage were most frequently associated with slime outbreaks. Few of the outbreaks were insignificant in length with 33.7% in excess of 1 km and 13.5% in excess of 5 km. Although 12.6% of outbreaks resulted in no adverse effects on watercourses, major problems reported included the appearance and amenity value being adversely affected (86.4%), smell and deoxygenation (46.6%), damage to fish stocks (37.9%) and problems of sloughed flocs of slime (24.3%). The severity of these adverse effects was directly related to the length of outbreaks. The situation in Ireland is compared to England and Wales.     

Persistent organic pollutants in fish tissue in the mid-continental great rivers of the United States

Great rivers of the central United States (Upper Mississippi, Missouri, and Ohio rivers) are valuable economic and cultural resources, yet until recently their ecological condition has not been well quantified. In 2004-2005, as part of the Environmental Monitoring and Assessment Program for Great River Ecosystems (EMAP-GRE), we measured legacy organochlorines (OCs) (pesticides and polychlorinated biphenyls, PCBs) and emerging compounds (polybrominated diphenyl ethers, PBDEs) in whole fish to estimate human and wildlife exposure risks from fish consumption. PCBs, PBDEs, chlordane, dieldrin and dichlorodiphenyltrichloroethane (DDT) were detected in most samples across all rivers, and hexachlorobenzene was detected in most Ohio River samples. Concentrations were highest in the Ohio River, followed by the Mississippi and Missouri Rivers, respectively. Dieldrin and PCBs posed the greatest risk to humans. Their concentrations exceeded human screening values for cancer risk in 27-54% and 16-98% of river km, respectively. Chlordane exceeded wildlife risk values for kingfisher in 11-96% of river km. PBDE concentrations were highest in large fish in the Missouri and Ohio Rivers (mean > 1000 ng g^− 1 lipid), with congener 47 most prevalent. OC and PBDE concentrations were positively related to fish size, lipid content, trophic guild, and proximity to urban areas. Contamination of fishes by OCs is widespread among great rivers, although exposure risks appear to be more localized and limited in scope. As an indicator of ecological condition, fish tissue contamination contributes to the overall assessment of great river ecosystems in the U.S.     

Modelling the dispersion of radionuclides following short duration releases to rivers: Part 2. Uptake by fish

This paper evaluates and generalizes state-of-the-art approaches for dynamic modelling of bioaccumulation in fish resulting from short duration liquid discharges of radionuclides ((3)H, (14)C, (60)Co, (134)Cs, (137)Cs, (65)Zn, (89)Sr, (90)Sr, (125)I, (131)I, (241)Am, isotopes of Pu and U) to rivers. Based on a review of model parameter values, predictions are made of maximum and time-integrated activity concentrations in fish. A simplified version of the model was developed and presented as "look-up" graphs. The influence of various environmental parameters on model output was evaluated by sensitivity analysis. Maximum and time-integrated concentrations in fish may be predicted for rivers based on the river volumetric flow rate and water temperature. It is demonstrated that the dynamic model gives lower and more realistic predictions of maximum concentrations in fish than the simpler "Concentration Factor" approach. However, for time-integrated concentration in fish, and estimation of radiation dose to humans from consumption of the fish, the Concentration Factor approach gives similar predictions to the dynamic model.     

Mercury contamination in fish from gold mining areas in Indonesia and human health risk assessment

This study investigates the effects on fish and assesses human health hazards from mercury released in two gold mining areas in Indonesia: Tatelu (North Sulawesi Province) and Galangan (Katingan District, Central Kalimatan Province). In Tatelu, 154 fish specimens of 10 freshwater species were collected, as well as five marine species from the fish market. The mean concentration of total mercury in muscles of freshwater fish from this area was 0.58+/-0.44 microg/g, with more than 45% of fish having Hg levels above the WHO guideline for human consumption of 0.5 microg/g. In Galangan, where 263 fish specimens of 25 species were collected, the total mercury in muscles averaged 0.25+/-0.69 microg/g. Excluding data from flooded open pits in sub-area P4, mean Hg levels in fish from Galangan were 2 to 4 times lower than 0.5 microg/g, while fewer than 10% of fish from Galangan exceeded WHO guidelines. The Hazard Quotient (HQ) was applied to both areas to determine the threat of MeHg exposure for communities in both areas. The HQ is a risk assessment indicator which defines the ratio of exposure level to a single substance in relation to a reference dose. Samples from Tatelu (excluding marine species) had an HQ above one, while those from Galangan resulted in values of 2.4 for the whole area and 9.9 for sub-area P4, pointing to potentially harmful fish consumption for the local population. By using the single-compartment model to estimate mercury levels in blood and hair from daily intake dose, sub-area P4 showed the highest levels, higher than the upper limit guideline for pregnant women, but still lower than threshold levels associated with observed clinical effects.     

PAHs in soils: contemporary UK data and evidence for potential contamination problems caused by exposure of samples to laboratory air

Archived (1951–1974) and contemporary (1993) surface soil samples collected from the same 46 locations widely distributed over the UK have been analyzed for 12 polynuclear aromatic hydrocarbons (PAHs). Contemporary soils were analyzed wet, ensuring that contamination, losses or alteration of PAHs in the samples was minimal. Archived soils had been air-dried prior to storage. The ΣPAH concentration of the contemporary and archived soils range from approx. 20 μg kg⁻¹ to 7.4 mg kg⁻¹ (mean = 1.1 mg kg⁻¹) and from approx. 160 μg kg⁻¹ to 7.1 mg kg⁻¹ (mean = 2.1 mg kg⁻¹), respectively. Comparison of the concentrations of PAHs in the archived and contempcrary soils revealed no significant trends for compounds heavier than benzanthracene. For some of the lighter molecular weight compounds the concentrations were notably higher in the archived soils than in the contemporary soils. Two soils of contrasting PAH content (0.08 and 9.8 mg kg⁻¹) were used in an experiment to compare the effects of air-drying on soils with relatively low and high PAH concentrations. Subsamples of soil (10 g) were placed into foil trays and exposed to laboratory air for up to 64 days. A clear increase in theiconcentration of the lighter molecular weight compounds (acenaphthene, fluorene, phenanthrene) occurred in both soils. No marked changes were observed for the heavier molecular weight PAH compounds. This experiment suggests that the higher concentrations of the lower molecular weight compounds measured in the archived soil samples is due to contamination during air drying.     

The dynamics of coastal landslides: insights from laboratory experiments and theoretical analyses

Laboratory experiments have been carried out to study the dynamics of landslides commencing sub-aerially and ending inside a water basin. A comparison between experiments with and without water shows differences in the final deposits. In the subaqueous experiments the grains did not spread out from the mass in the same way as in the subaerial movement. It is suggested that air can be trapped inside the mass which, released during the final stage of the underwater mass propagation, modifies the buoyancy forces. Other effects observed during the air to water transition include the “jumping” and “tilting” of grains. It is concluded that the air to water transition plays a key role in the dynamics of combined subaerial/subaqueous landslides. The information obtained from the experiments may also be useful in the consideration of tsunami generation and the sedimentological analyses of landslide deposits.     

Seasonal, interannual, and long-term variation in sport fish contamination, San Francisco Bay

This study documents changes in contamination over time at seasonal, interannual, and decadal time scales for sport fish collected in San Francisco Bay. Samples from seven fish species were prepared according to common consumption practices (muscle fillets either with or without skin) and analyzed for trace metals (mercury and selenium) and trace organochlorine contaminants (PCBs, DDTs, chlordanes, and dieldrin). In 2000, sport fish samples exceeded human health screening values for mercury, PCBs, DDTs, selenium, and dieldrin but did not exceed screening values for chlordanes. On a seasonal time scale, white croaker (Genyonemus lineatus) exhibited significantly lower PCB and lipid concentrations in spring, and a general increase in concentrations in other seasons. When monitoring data were compared among 1994, 1997, and 2000, analysis of variance indicated that concentrations of mercury, PCBs, DDTs, and chlordanes varied significantly among years for several fish species. Interannual variation in DDTs often correlated to changes in sampled fish size or lipid content among years. Interannual variation in mercury and PCBs was evident in striped bass (Morone saxatilis) but absent in shiner surfperch (Cymatogaster aggregata), leopard shark (Triakis semifasciata), and white croaker. The higher interannual variability of striped bass contaminant concentrations may result from migratory behavior and wide home ranges. Chlordanes significantly declined between 1994 and 2000 in white croaker and striped bass. Of the historical data analyzed (1986-2000), only DDT concentrations in white sturgeon (Acipenser transmontanus) showed evidence of a significant decline. Neither PCBs nor selenium showed evidence of a trend in white sturgeon. Between 1970 and 2000, mercury concentrations in striped bass showed no evidence of a trend. The absence of recent trends in mercury may result from the presence of widespread and historic sources, with use reductions occurring in the early 20th century. In contrast to mercury, apparent recent declines in fish tissue DDT and chlordane concentrations may result from use curtailment in the 1970s and 1980s.     

Method for obtaining root nodules of the Baikal relict legumes in laboratory pot experiments

Abstract

Many relict and endemic legumes are often rare and endangered species, located in remote and almost impenetrable areas. This makes it difficult to study their symbiosis with nodule bacteria. The aim of this work was to obtain root nodules under laboratory conditions of Hedysarum zundukii, Oxytropis popoviana, Oxytropis triphylla, Oxytropis tragacanthoides, Astragalus chorinensis and Glycyrrhiza uralensis belonging to the Miocene-Pliocene relicts, usually growing in restricted habitats of the Baikal Lake region. A pot experiment was conducted with soils and seeds collected in distribution areas of these legumes. The collected soils had low content of N and P, suggesting importance of nitrogen-fixing symbiosis for successful maintenance of plant populations. The symbiotic nodules were observed on roots of all plant species tested and 52 bacterial strains assumed as root nodule bacteria (rhizobia) were isolated from nodules. The proposed method avoids collection of native plants and prevents decrease in plant populations. The isolated bacteria will be used to search for ancestral genes responsible for the specificity and efficiency of rhizobia-legume symbiosis and can contribute to the conservation of rare and endangered species of relict legumes in the Baikal region.     

Chemical contaminants, health indicators, and reproductive biomarker responses in fish from rivers in the Southeastern United States

Largemouth bass (Micropterus salmoides) and common carp (Cyprinus carpio) were collected from 13 sites located in the Mobile (MRB), Apalachicola-Flint-Chattahoochee (ARB), Savannah (SRB), and Pee Dee (PRB) River Basins to document spatial trends in accumulative chemical contaminants, health indicators, and reproductive biomarkers. Organochlorine residues, 2,3,7,8-tetrachlorodibenzo-p-dioxin-like activity (TCDD-EQ), and elemental contaminants were measured in composite samples of whole fish, grouped by species and gender, from each site. Mercury (Hg) and polychlorinated biphenyls (PCBs) were the primary contaminants of concern. Concentrations of Hg in bass samples from all basins exceeded toxicity thresholds for piscivorous mammals (>0.1 microg/g ww), juvenile and adult fish (>0.2 microg/g ww), and piscivorous birds (>0.3 microg/g ww). Total PCB concentrations in samples from the MRB, ARB, and PRB were >480 ng/g ww and may be a risk to piscivorous wildlife. Selenium concentrations also exceeded toxicity thresholds (>0.75 microg/g ww) in MRB and ARB fish. Concentrations of other formerly used (total chlordanes, dieldrin, endrin, aldrin, mirex, and hexachlorobenzene) and currently used (pentachlorobenzene, pentachloroanisole, dacthal, endosulfan, gamma-hexachlorocyclohexane, and methoxychlor) organochlorine residues were generally low or did not exceed toxicity thresholds for fish and piscivorous wildlife. TCDD-EQs exceeded wildlife dietary guidelines (>5 pg/g ww) in MRB and PRB fish. Hepatic ethoxyresorufin O-deethylase (EROD) activity was generally greatest in MRB bass and carp. Altered fish health indicators and reproductive biomarker were noted in individual fish, but mean responses were similar among basins. The field necropsy and histopathological examination determined that MRB fish were generally in poorer health than those from the other basins, primarily due to parasitic infestations. Tumors were found in few fish (n=5; 0.01%); ovarian tumors of smooth muscle origin were found in two ARB carp from the same site. Intersex gonads were identified in 47 male bass (42%) representing 12 sites and may indicate exposure to potential endocrine disrupting compounds. Comparatively high vitellogenin concentrations (>0.35 mg/mL) in male fish from the MRB, SRB, and PRB indicate exposure to estrogenic or anti-androgenic chemicals.     

CO2 sequestration by magnesite mineralisation through interaction of Mg-brine and CO2: integrated laboratory experiments and computerised geochemical modelling

ABSTRACT

Several Carbon Capture and Storage (CCS) techniques have been studied including injections of carbon dioxide (CO₂) into the mature and/or depleted hydrocarbon reservoirs and deep saline aquifers. This work aims to test storing CO₂ into the magnesium-rich evaporite strata and also into the stratigraphic intervals containing Mg-rich brines. The test simulates Mg-carbonation of the synthetic solution obtained from the Mg-evaporite mineral, bischofite – both experimentally in the laboratory condition and also through computerised geochemical simulation. The laboratory experiments, which resulted in the crystallisation of anhydrous magnesite, were analysed. The TOUGHREACT^TM, Geochemist’s Workbench^TM (GWB) and PHREEQC^TM software simulated the experiments as computerised geochemical model and tested the results for natural geological conditions. The geochemical simulations successfully demonstrate the immense CCS potential for the Mg-evaporite (as well as the sedimentary strata charged with Mg-evaporitic brine) at their subsurface geological occurrences at elevated pressure-temperature and high salinity.     

Evaluation of a bacterial algal control agent in tank-based experiments

A bacterial-based bioremediation product, LakeRelief™ by Novozymes (Waterguru LakeRelief, 2011), was tested in a series of experiments between October 2008 and March 2009 to evaluate its suitability as a short-term intervention technique to reduce algal blooms in the Swan-Canning River system. Results from fibreglass tank experiments (1100 L) suggested that the product did not actively attack and lyse algal cells. The product decreased NH₄ and NO_x concentrations in treated tanks, both aerated and non-aerated. Product application decreased PO₄ concentrations in non-aerated tanks but not in aerated tanks. The product appeared to suppress algal growth in non-aerated tanks over short periods (several days). Algal growth regularly diminished after product application but reappeared shortly afterwards. Aeration had a negative effect on bacterial proliferation in the tanks, possibly through alteration of environmental conditions (e.g. water mixing). As a consequence of the environmental conditions in the tanks being counterproductive to the development of a representative microbial composition, several aspects regarding the product’s effectiveness could not be assessed satisfactorily in the tank experiments. The importance of long-term nutrient immobilisation into a well developed food web and the subsequent nutrient removal through removal of the top order organisms is highlighted.     

Comparison between controlled laboratory experiments and discrete particle simulations of the mechanical behaviour of rock

Discrete particle modelling offers the possibility for performing grain-scale modelling of rock mechanical behaviour. An important step in turning this kind of numerical modelling into a more quantitative tool is to perform a calibration of the numerical model against controlled laboratory experiments. In this paper, a strategy for calibration is outlined and results from tests with artificial rock-like materials are presented. The rock-like materials consist of spherical grains (glass beads) while the numerical simulations were performed with PFC^3D (PFC: Particle Flow Code), which uses spherical particles as its basic elements.

Stress dependent P- and S-wave velocities in uncemented assemblies of glass beads were computed using a Hertzian contact law, and a satisfactory correspondence with laboratory data was obtained without any fitting parameters. The discrete particle model was able to reproduce the observed dependence of unconfined strength and Young's modulus on cement content. The initial experiments presented here demonstrate the potential of using discrete particle modelling as a numerical laboratory for studies of rock mechanical behaviour.     

Copper pharmacokinetics in fish gills—II body size relationships for accumulation and tolerance

In water contaminated with copper, juvenile and adult sunfish were found to accumulate copper in their gills. The time-course of accumulation was characterized by: (a) an initial fast, and (b) a subsequent slow phase. Biphasic kinetics were attributed to metabolic alterations associated with the toxicant's presence. The accumulation rate during the slow phase was determined to be 8.2 x 10⁻³ μg Cu(g fish)⁻¹ h⁻¹ for sunfish weighing 3.3 g, and values decreased disproportionately with body weight. Once the fish were transferred to uncontaminated water, copper was rapidly eliminated from the gills. Clearance was monophasic: the instantaneous clearance rate being a function of the copper concentration in the gills at a given time. The biological half-time was determined to be 1.6 h for fish weighing 3.5 g, and clearance rate constants decreased disproportionately with increasing body weight. It is proposed that clearance may be associated with the repair of gill ultrastructural damage and the rapid recovery from copper intoxication.     

Toxicity and sorption kinetics of dissolved cadmium and chromium III on tropical freshwater phytoperiphyton in laboratory mesocosm experiments

The objective of this study was to assess the interactive effects of Cd and Cr III on tropical phytoperiphyton community growth, metal sorption kinetics, as well as Cd and Cr mixtures toxicity to diatom assemblages in laboratory mesocosm experiments. A natural phytoperiphyton community sampled from the Monjolinho River (South of Brazil) was inoculated into seven experimental systems containing clean glass substrates for phytoperiphyton colonization. The communities were exposed to mixtures of dissolved Cd and Cr concentrations of 0.01 and 0.1 mg.L⁻¹ Cd and 0.05 and 0.2 mg.L⁻¹ Cr. Phytoperiphyton chlorophyll a, ash-free dry mass, growth rate, diatom cell density and diatom community composition were analyzed on samples collected after 1, 2 and 3 weeks of colonization. High Cd concentration (0.1 mg.L⁻¹) affects phytoperiphyton growth while high concentration of Cr (0.2 mg.L⁻¹) decreased the toxic effects of Cd on phytoperiphyton growth demonstrating the importance of studying metal mixtures in field studies. Shifts in species composition (development of more resistant species like Achnanthidium minutissimum (Kützing) Czarnecki, and Nitzschia palea (Kützing) Smith and reduction of sensitive ones like Fragilaria capucina Desmazières, Navicula cryptocephala (Grunow) Cleve, Encyonema silesiacum (Bleisch) Mann, Eunotia bilunaris (Ehrenberg) Mills and Gomphonema parvulum (Kützing) Kützing), of phytoperiphyton communities with increasing Cd and Cr concentrations and exposure duration have been demonstrated in this study making phytoperiphyton communities appropriate monitors of metal mixtures in aquatic systems. Good Cd and Cr accumulation capacity by phytoperiphyton was demonstrated with total and intracellular metal content in phytoperiphyton reflecting the effects of dissolved concentrations of metal in the culture media and exposure duration. Increase in both Cd and Cr reduced sequestration of each other, with generally more Cd being sequestered compared to Cr. Field validation of the observed effects remains an interesting subject for further investigations.