Butyltins, trace metals and morphological variables in surf scoter (Melanitta perspicillata) wintering on the south coast of British Columbia, Canada

From 1998 to 2001 we examined spatial and temporal variation in uptake of contaminants by surf scoters (Melanitta perspicillata) in the Georgia Basin region of the Pacific coast of Canada. Samples were collected during late fall and early spring at industrialized and reference locations, carcasses examined, and tissues collected for histology, biomarkers, and contaminant analyses. Scoters from both Vancouver and Victoria harbours had significantly higher hepatic concentrations of summation operatorbutyltins than birds from a reference site. In adult male surf scoters, hepatic summation operatorbutyltins increased over the winter at two sites (p=0.02, n=26), while mercury increased (p=0.03, n=15) and selenium decreased at one site (p=0.001, n=15). Body condition decreased over the winter at both the treatment site, Howe Sound (p<0.0001, n=12), and the reference site, Baynes Sound (p=0.02, n=15). Multiple regression analysis using Akaike's Information Criteria (AIC(C)) showed an association between hepatic butyltin concentrations and overall body condition (p=0.06, r=-0.237).     

Exposure pathways of anticoagulant rodenticides to nontarget wildlife

Second-generation anticoagulant rodenticides are widely reported to contaminate and poison nontarget wildlife, primarily predatory birds and mammals. Exposure pathways, however, have not been well defined. Here, we examined potential movement of rodenticides from deployment of bait to exposure of small mammals and other biota. At two adjacent working farms, we placed baits containing either brodifacoum or bromadiolone. We monitored movement of those compounds to the surrounding environment by collecting small mammals, birds, and invertebrates. Similar collections were made at a third agricultural setting without active bait deployment, but located among intensive livestock production and regular rodenticide use by farmers. Livers and whole invertebrate samples were analyzed for rodenticides using a sensitive LC-MSMS method. Norway rats (Rattus norvegicus) from both baited and non-baited farms had residues of brodifacoum or bromadiolone, implicating rats as an important exposure pathway to wildlife. Among 35 analyzed nontarget small mammals, a single vole had high hepatic residues (18.6 μ/g), providing some indication of a small mammal pathway. One song sparrow (Melospiza melodia) sample from a baited farm contained 0.073 μg/g of brodifacoum in liver, while 0.39 μg/g of diphacinone was measured in a pool of carrion beetles (Dermestes spp.) from the non-baited farm area, implicating avian and invertebrate components in exposure pathways. Regurgitated pellets of barn owl (Tyto alba) selected randomly from baited farms contained no detectable rodenticide residues, while 90 % of owl pellets collected from a variety of farms, and selected for the presence of rat fur, contained detectable anticoagulant residues. We recorded behavior of a captive sample of a representative songbird, the house sparrow (Passer domesticus); they readily entered bait stations and fed on (unloaded) bait.     

Field olfactometry assessment of dairy manure land application methods

Surface application of manure in reduced tillage systems generates nuisance odors, but their management is hindered by a lack of standardized field quantification methods. An investigation was undertaken to evaluate odor emissions associated with various technologies that incorporate manure with minimal soil disturbance. Dairy manure slurry was applied by five methods in a 3.5-m swath to grassland in 61-m-inside-diameter rings. Nasal Ranger Field Olfactometer (NRO) instruments were used to collect dilutions-to-threshold (D/T) observations from the center of each ring using a panel of four odor assessors taking four readings each over a 10-min period. The Best Estimate Threshold D/T (BET10) was calculated for each application method and an untreated control based on preapplication and <1 h, 2 to 4 h, and approximately 24 h after spreading. Whole-air samples were simultaneously collected for laboratory dynamic olfactometer evaluation using the triangular forced-choice (TFC) method. The BET10 of NRO data composited for all measurement times showed D/T decreased in the following order (a = 0.05): surface broadcast > aeration infiltration > surface + chisel incorporation > direct ground injection Sshallow disk injection > control, which closely followed laboratory TFC odor panel results (r = 0.83). At 24 h, odor reduction benefits relative to broadcasting persisted for all methods except aeration infiltration, and odors associated with direct ground injection were not different from the untreated control. Shallow disk injection provided substantial odor reduction with familiar toolbar equipment that is well adapted to regional soil conditions and conservation tillage operations.     

The hepatopancreas of the mangrove crab Neosarmatium africanum: a possible key to understanding the effects of wastewater exposure (Mayotte Island,Indian Ocean)

Environmental Science and Pollution Research - Mangrove crabs are ecosystem engineers through their bioturbation activity. On Mayotte Island, the abundance of Neosarmatium africanum decreased in...     

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Nano zerovalent iron (nZVI) is a promising remediation technology utilizing in situ chemical reduction (ISCR) to clean up contaminated groundwater at hazardous waste sites. The small particle size and large surface area of nZVI result in high reactivity and rapid destruction of contaminants. Over the past 20 years, a great deal of research has advanced the nZVI technology from bench‐scale tests to field‐scale applications. However, to date, the overall number of well‐characterized nZVI field deployments is still small compared to other alternative remedies that are more widely applied. Apart from the relatively high material cost of nZVI and questions regarding possible nanotoxicological side effects, one of the major obstacles to the widespread utilization of nZVI in the field is its short persistence in the environment due to natural reductant demand (NRD). The NRD for nZVI is predominantly due to reduction of water, but other reactions with naturally present oxidants (e.g., oxygen) occur, resulting in situ conditions that are reducing (high in ferrous iron phases and H₂) but with little or no Fe(0). This article reviews the main biogeochemical processes that determine the selectivity and longevity of nZVI, summarizes data from prior (laboratory and field) studies on the longevity of various common types of nZVI, and describes modifications of nZVI that could improve its selectivity and longevity for full‐scale applications of ISCR. © 2016 Wiley Periodicals, Inc.     

Organochlorine contaminants in eggs of seabirds in the Northwest Atlantic, 1968-1984

Eggs of three seabird species, double-crested cormorant (Phalacrocorax auritus). Leach's storm-petrel (Oceanodroma leucorhoa), and Atlantic puffin (Fratercula arctica) were collected at four-year intervals from 1968 to 1984, from colonies in eastern Canada and analyzed for organochlorines. This monitoring study was established to provide data on contamination of the marine environment and possible implications for seabird health. Long-term trend data are presented for PCBs, DDE, dieldrin, HCB, oxychlordane, heptachlor epoxide, HCH and mirex. DDE and PCBs declined significantly in all species from the Bay of Fundy. DDE declined significantly in puffins and petrels while PCBs declined only in petrels from the Atlantic coast of Newfoundland. Generally DDE declined more than PCBs. Dieldrin, oxychlordane, HCH and mirex levels decreased at some locations but were stable at others. Hexachlorobenzene and heptachlor epoxide levels remained steady or increased significantly, depending on the species and location. Organochlorine levels in cormorants from the St. Lawrence River estuary showed no significant trends.     

The effect of complex formation on the adsorption characteristics of heavy metals

In most aqueous environmental systems, inorganic and organic metal complexes represent a significant contribution to the total soluble metal. Metal adsorption is often a highly pH-dependent phenomena. Such behavior can generally be attributed to changes in metal speciation with solution acidity as well as variation in the extent of surface protonation. Thus, because adsorbability may vary drastically between different metal species, (e.g. Cu²⁺ (aq) compared to CuOH⁺) a knowledge of metal species distribution is essential to understanding and interpreting metal adsorption behavior.Organic complexation has been reported to enhance, suppress and have no perceptible effect on trace metal adsorption. Such differences arise because adsorption depends on factors such as the ligand/metal ratio, adsorbability of the free ligand, and various solution parameters (e.g. pH). Most important in determining the effect of complexation on adsorption is the adsorbability of the resulting complexes. Thus, it is difficult to make generalizations about the influence of organic complexation on metal adsorption.Adsorption of metal complexes is frequently reported to be predominantly coulombic in nature; that is, binding of an anionic or cationic complex to an oppositely charged colloidal particle. However, electrostatic forces can often represent an insignificant contribution to the total free energy of adsorption and can be overshadowed by chemical reactions with the surface, hydrogen bonding, and hydrophobic effects.