Suspended particulate grain size dynamics and their implications for trace metal sorption in the Don River

We examined particle size distributions of suspended particulate matter (SPM); physical and environmental influences on the observed distributions; and relationships between particle size and geochemical partitioning of metals, over the fall and winter period in a small urban river (Don River, Toronto, Ontario, Canada). For this dataset, the majority of particles (80%) in suspension were less than 10 µm in size. In addition, while total SPM concentrations showed a positive trend with increasing discharge (Q); the proportions of particles found within given size classes were independent of both SPM concentration and Q. Temperature was the only measured environmental variable related to the particle concentrations within size classes. As water temperature increased, the concentration of particles in the smallest size class (1–4 µm) decreased, while the concentration of silt and/or algae sized particles (10–50 µm) increased. Increasing water temperatures may promote bacterial attachment to particles and their subsequent flocculation into larger sized particles. Decreasing concentrations of leachable (most labile) Cd, Zn and Mn were associated with increasing concentrations of the largest particles (70–150 µm) in suspension. In contrast, higher reducible (oxides) associated concentrations of Cd, Zn and Mn occurred with increasing concentrations of smaller particles (1–10 µm) in suspension. Both of these trends are speculated to reflect the importance of particle surface area for metal sorption reactions.     

A trace metal problem in pond oyster culture

Oysters reared in power station cooling water were found to have accumulated high concentrations of copper and zinc. The reasons for such elevated metal concentrations and the relevance of these observations to shellfish culture have been examined and emphasize the care that must be taken to avoid unwitting contamination of culture ponds.     

Organochlorine pesticide and trace metal monitoring of Russian rivers flowing to the Arctic Ocean: 1990-1996

Information is presented on the concentrations of organochlorine pesticides (HCHs and DDT residues) and trace metals (Fe, Cu, Zn and Ni) in waters of 15 large Russian rivers flowing to the Arctic Ocean during 1990-1996. Estimates of the corresponding annual fluxes are made. Other contaminants (Hg, Pb, Cr, Mn, beta-HCH and dihydroheptachlor) were examined briefly. Concentration data are presented as averaged annual means for each of the seven years with the ranges, standard deviations and numbers of samples. Also given are data on locations, the methods of analysis and limited quality assurance data. Data on discharges to the Northern Seas for the more frequently monitored contaminants are given for rivers accounting for >70% of the total northerly flows. Scaled-up fluxes to account for unmonitored rivers as well are given for each sea; totals over the period were: Fe, 1452; Cu, 15; Zn, 59 (x 10(3) t yr(-1)); alpha-HCH, 25; gamma-HCH, 44 (t yr(-1)). Ni was monitored at too few rivers to estimate its total Russian flux. The fluxes for the HCHs considerably exceed previous estimates and indicate that the Arctic Ocean is not in balance as much as was previously believed.     

Selection and criteria for biological indicator species for Arctic monitoring

The estuarine ecosystems are considered as key objects in the Arctic monitoring. Crustacean Saduria entomon, bivalve Portlandia aestuariorum and Cyrtodaria curriana, whitefish Coregonus muksun, C. autumnalis and C. sardinella sardinella and sculpin Triglopsis polaris (= Myoxocephalus quadricornis) are proposed for monitoring of Arctic estuaries. Review of AMAP list of species was carried out. Some species, as included in the World and National ‘Red Books’ and thus being under legislation (polar bear, atlantic and Laptev sea subspecies of walrus, falcon Falco rusticolus) must be left out of the list of species-monitors. The same is applied as in the case of species which often feed on human waste (glaucous gull, fulmar). Instead of using the rare and valuable carnivorous species, appropriately their prey is used as monitors.     

A reassessment of trace metal budgets in the Western Mediterranean Sea

This paper presents inputs and output fluxes of dissolved metals (As, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) into and out the Western Mediterranean. These flux estimates are based on the most recently published concentrations and fluxes for the atmosphere, the rivers and the straits. Comparison of the different sources shows the predominance of the inputs through the straits over other sources. The river input is smaller than the atmospheric input except for As. For all elements except Fe, output flux and input flux are balanced; iron budget indicates transfer from the dissolved to the particulate phase.     

The effects of depuration,size and sex on trace metal levels in bay mussels

The effects of depuration, size and sex on the concentrations of Mn, Ni, Cu, Zn and Cd were determined for gonadal and somatic tissues of Mytilus edulis from Yaquina Bay, Oregon. After depuration, Mn levels decreased significantly in both tissues while Cu and Ni concentrations increased in somatic tissues. The latter finding may have been associated with a stress response manifested by the appearance of new byssal threads and attachment to the vessel. Larger, and presumably older, mussels contained higher concentrations of Ni, Cu and Cd in their somatic tissues while smaller animals had greater somatic levels of Mn. There were no significant differences in gonad concentrations between the two size groups. Manganese and Zn levels were greater in the gonads of female mussels and Cd was more concentrated in the somatic tissues of females.     

Late Mesozoic palaeomagnetism from Spitsbergen; implications for continental drift in the Arctic

Thermal and alternating-current demagnetization combined with ore microscopy and measurements of the temperature dependence of saturation magnetization have been carried out on some Mesozoic, probably Cretaceous, basaltic lavas from two areas (Seidfjell and Sørlifjell) at Spitsbergen. The experimental studies suggest that the Seidfjell locality has undergone extensive oxidations, which resulted in remagnetization. The estimated palaeomagnetic pole for this area is 77°N 107°E, which suggests a remagnetization, probably some time in the Late Tertiary. On the other hand the experimental data from the Sørlifjell locality suggest that the magnetization is primarily of deuteric origin. The mean palaeomagnetic pole position for this latter formation is at 75°N 235°E, which is significantly different from previously published European Mesozoic data. However, closing the Neo-Arctic basin by rotating Spitsbergen towards the Lomonosov Ridge, makes the suggested Cretaceous pole coincide with poles of similar age from North-America. This suggests that the estimated pole from Sørlifjell is a good approximation for a Late Mesozoic palaeomagnetic pole for Europe and it also confirms that the process of continental separation in the Arctic has taken place in Tertiary time.     

Dissolved metal contamination in the East River-Long Island sound system: potential biological effects

A suite of dissolved trace metals (Ag, Cd, Cu and Pb), inorganic nutrients (NO(3), PO(4)), and chlorophyll a was measured along a 55 mile transect from the East River into western and central Long Island Sound. The main objectives of this study were to determine the relative levels of contamination from sewage, and to assess its possible biological impact on local waters. The East River-Long Island Sound system receives large volumes of treated sewage and industrial effluent as a result of the heavy urbanization of the area. Despite these strong environmental pressures, this study is among the first to report dissolved metal levels from that region. Consistent with the locations of anthropogenic sources, a strong east-west concentration gradient was observed for Ag, Pb, NO(3) and PO(4) with the highest levels found in the East River. In contrast, dissolved Cd and Cu were relatively constant throughout the area of study, suggesting that sewage sources have a more limited influence on the levels of those metals. Remobilization from contaminated sediments may represent the primary source of Cd and Cu to the Long Island Sound under low-runoff conditions in summer. Chlorophyll a concentrations, used as an indicator of total biomass, were also low in the East River. These low chlorophyll concentrations could not be explained by nutrient or light limitation, water column stratification, or to advection of phytoplankton out of the river during tidal flushing. These preliminary results suggest a potential toxic effect of sewage on the biological communities of the East River.     

Sensitivity of coastal waters to anthropogenic trace metal emissions

Trace metal concentrations in the waters of the Gulf of St. Lawrence and the Scotian Shelf and their sensitivity to changes in the composition of the major contributor of fresh water, the St. Lawrence River, are assessed. Comparison of the levels of trace metals in eastern Canadian coastal waters with those in other coastal waters of the world reveals that the former area generally has lower trace metal concentrations and is, therefore, probably less contaminated than elsewhere. The increased anthropogenic activity in the St. Lawrence drainage basin required to increase the levels of trace metals in receiving coastal waters by detectable amounts is discussed. We demonstrate that faster and more reliable warning of changes due to anthropogenic activity will be revealed through river monitoring than through monitoring of coastal waters. Changes in the marine environment can then be assessed through a thorough understanding of the geochemical behaviour of trace metals in nearshore waters.     

Longitudinal dispersivity data and implications for scaling behavior

Longitudinal dispersivity (alpha) data were compiled from 109 different authors for different types of geological media. The data were subdivided into different subsets. Dispersivity values for consolidated media were subdivided as basalts, granites, sandstones, and carbonate rocks, while unconsolidated sediments were subdivided into three reliability classes. The data sets provided here may provide ground water practitioners a preliminary guide to estimate dispersivity values at various scales and to guide and verify theories on scaling behavior. Based on the data set presented here, the relationship that empirically best described the dispersivity data in regard to scale of measurement was in the form of a power law. The scaling exponent for consolidated and unconsolidated geological media varied between 0.40 and 0.92, and 0.44 and 0.94, respectively. Higher reliability subsets of data for the unconsolidated sediments and more frequently tested rock formations indicate that the scaling exponent is at the lower end of the observed range, close to 0.5. No significant difference in scaling exponent was found among different media, and no clear evidence exists for the presence of an upper bound or asymptotic behavior on the relationship for any of the analyzed media.     

Sublethal effects of contamination on the Mediterranean sponge Crambe crambe: metal accumulation and biological responses

The effect of low levels of pollution on the growth, reproduction output, morphology and survival of adult sponges and settlers of the sponge Crambe crambe were examined. We transplanted sponges from a control area to a contaminated site and measured the main environmental variables (chemical and physical) of both sites during the study period. Except some punctual differences in particulate organic matter, silicates, nitrates, and water motion, most environmental variables in the water were similar at both sites during the study months. Mainly copper, lead and OM concentrations in the sediment, and water motion were significantly higher at the polluted site and may be implicated in the biological effects observed: decrease in the percentage of specimens with embryos, increase in shape irregularity and decrease in growth rate. Individuals naturally occurring at the polluted site and those transplanted there for four months accumulated ten times more copper than either untouched or transplant controls. Although lead concentration in sediment did not differ between sites, native specimens from the contaminated site accumulated this metal more than untouched controls. Vanadium concentration also tended to increase in the sponges living at or transplanted to the contaminated site but this difference was not significant. C. crambe is a reliable indicator of metal contamination since it accumulates copper, lead and vanadium in high amounts. At the contaminated site, sponge growth, fecundity and survival were inhibited, whereas sponge irregularity ending in sponge fission was promoted. All these effects may compromise the structure and dynamics of the sponge populations in sheltered, metal-contaminated habitats.     

The initial assessment of trace metal pollution in coastal sediments

Coastal sediments are important hosts for pollutant trace metals, but analytical difficulties can prevent them being included in routine environmental monitoring programmes. In order to identify a suitable approach to the problem, an established simple technique has been evaluated for the initial assessment of trace metal pollution in coastal sediments. The technique, which involves leaching the samples with cold 0.5 N HCl, has been applied to surface sediments from two Greek gulfs and has been shown to provide a rapid, inexpensive way of initially establishing the gross degree to which a sediment population has been subjected to trace metal pollution from the overlying waters.     

Seasonal variation in the trace metal content of Mytilus edulis

The possible seasonal variation in the trace metal content of the mollusc Mytilus edulis has been studied by analysing cadmium, cobalt, copper, lead, manganese, mercury, nickel and zinc in 560 individuals collected from the same mussel bed over a period of two years. A clearly discernible effect of size on metal concentration was detected. However, no seasonal trends could be seen in the data.     

Scavenging of thorium isotopes in the Arctic regions: implications for the fate of particle-reactive pollutants

The sources of inorganic pollutants to the Arctic areas are reviewed using previously published results. The removal of particle-reactive pollutants is discussed using thorium scavenging as an analog. The scavenging of 234Th from the upper water column (approximately 100 m) and sediment inventory of 230Th from the deep Arctic waters is compared to different ocean basins in the subarctic areas. Such a comparison shows that 234Th is in equilibrium with its parent, 238U, in certain regions of the Canada Basin of the Arctic Ocean, while it is deficient in other regions of the arctic as well as in sub-polar ocean basins. This implies that the particle-reactive pollutants in the deep Arctic of the Canada Basin are less likely to be removed from the deep waters and will eventually be transported out of this area. We have utilized the 230Th inventory in sediments from the Arctic area to determine the removal rates of particle-reactive nuclides. The 230Th inventory in the deep Arctic Ocean of the Canada Basin is much lower than the Norwegian Sea and the Fram Strait of the Arctic as well as all other sub-polar world oceans. These observations suggest that any pollutants into the deep Arctic areas of the Canada Basin are less likely to be removed locally and may be transported out of this area. In those areas, the colloidal material could potentially play a major role in the removal of particle-reactive contaminants.     

A review of algorithms for detecting volcanic hot spots in satellite infrared data

Since the 1980s, application of thermal infrared satellite data for volcano monitoring has rapidly evolved to become a proven operational tool. Due to the large quantities of data provided by sensors in polar and geostationary orbits, as well as the sheer number of active volcanoes on earth, processing and managing such data sets requires an enormous amount of workforce. A number of algorithms have been developed to facilitate detection, location, and tracking of hot spots of active volcanoes. A collation and review of hot spot detection algorithms developed and applied by the volcanological community reveals three main types which have been applied to date: contextual, fixed threshold, and temporal. The founding algorithms for these three classes are VAST, MODVOLC, and RST, respectively. Through comparison with manually based detections, the performance of each algorithm was tested for sustained lava flows (Etna and Stromboli), strombolian activity (Stromboli), lava dome growth and collapse (Augustine), and fumarole fields (Vulcano). It is shown that, as the number of correctly identified anomalies increases, so too does the number of false positives. Although each of the algorithms operates well within the limits and criteria of their design requirements and application, under current data restraints, no algorithm can be expected to perform perfectly.     

Stormwater management network effectiveness and implications for urban watershed function: A critical review

Deleterious effects of urban stormwater are widely recognized. In several countries, regulations have been put into place to improve the conditions of receiving water bodies, but planning and engineering of stormwater control is typically carried out at smaller scales. Quantifying cumulative effectiveness of many stormwater control measures on a watershed scale is critical to understanding how small‐scale practices translate to urban river health. We review 100 empirical and modelling studies of stormwater management effectiveness at the watershed scale in diverse physiographic settings. Effects of networks with stormwater control measures (SCMs) that promote infiltration and harvest have been more intensively studied than have detention‐based SCM networks. Studies of peak flows and flow volumes are common, whereas baseflow, groundwater recharge, and evapotranspiration have received comparatively little attention. Export of nutrients and suspended sediments have been the primary water quality focus in the United States, whereas metals, particularly those associated with sediments, have received greater attention in Europe and Australia. Often, quantifying cumulative effects of stormwater management is complicated by needing to separate its signal from the signal of urbanization itself, innate watershed characteristics that lead to a range of hydrologic and water quality responses, and the varying functions of multiple types of SCMs. Biases in geographic distribution of study areas, and size and impervious surface cover of watersheds studied also limit our understanding of responses. We propose hysteretic trajectories for how watershed function responds to increasing imperviousness and stormwater management. Even where impervious area is treated with SCMs, watershed function may not be restored to its predevelopment condition because of the lack of treatment of all stormwater generated from impervious surfaces; non‐additive effects of individual SCMs; and persistence of urban effects beyond impervious surfaces. In most cases, pollutant load decreases largely result from run‐off reductions rather than lowered solute or particulate concentrations. Understanding interactions between natural and built landscapes, including stormwater management strategies, is critical for successfully managing detrimental impacts of stormwater at the watershed scale.     

Effects of biological sediment mixing on the210Pb chronology and trace metal distribution in a Long Island Sound sediment core

An experiment was designed to assess the relative importance of sediment accumulation and bioturbation in determining the vertical distribution of nuclides in estuarine sediments. A diver-collected core, 120 cm long, was raised from central Long Island Sound and analyzed down its length for:²¹⁰Pb and²²⁶Ra;^{239, 240}Pu; and Mn, Zn, Cu, and Pb. Sampling for chemical analysis was guided by X-radiography of the core. Excess²¹⁰Pb (relative to²²⁶Ra) is roughly homogeneous in the top 2–4 cm of the core, then decreases quasi-exponentially to zero at (or above) 15 cm.^{239, 240}Pu and excess Zn, Cu, and Pb, relative to background values at greater depths in the core, are distributed like excess²¹⁰Pb in the top 10–15 cm. The absence of Mn enrichment at the top of the core, in contrast to other cores raised from this station, suggests that 1–3 cm of sediment was lost by erosion at the site of this core sometime prior to sampling. Below 15 cm excess²¹⁰Pb and excess Zn, Cu, and Pb are found only in the bulk sample from 25 to 30 cm and in clearly identifiable burrow fillings dissected from 70 cm and 115 cm depth. Infilling of large burrows, excavated and then abandoned by crustaceans, is therefore a mechanism for transfer of surficial material to depth in these sediments.The bioturbation rate in the top several centimeters at this station has been determined previously using²³⁴Th (24-day half-life). The distribution of^{239, 240}Pu can be used to estimate a bioturbation rate for the underlying layer (to ～10 cm depth); this rate is found to be 1–3% of the maximum mixing rate for the top 2–3 cm. Using these two mixing rates in a composite-layer, mixing + sedimentation model, the distribution of excess²¹⁰Pb in the top 15 cm was used to constrain the sediment accumulation rate, ω. While the apparent rate of sediment accumulation (assuming no mixing below 2–4 cm) is 0.11 cm/yr, the model requires ω < 0.05 cm/yr. Thus in an area of slow sediment accumulation, a low rate of bioturbation below the surficial zone of rapid mixing causes an increase of at least a factor of two in apparent accumulation rate.