Elemental concentrations and bioaccessibility were determined in background soils collected in Canada as part of the North American Geochemical Landscapes Project. The concentrations of As, Cr, Cu, Co, Ni and Zn were higher in the C-horizon (parent material) compared to 0–5 cm (surface soil), and this observation along with the regional distribution suggested that most of the variability in concentrations of these elements were governed by the bedrock characteristics. Unlike the above-stated elements, Pb and Cd concentrations were higher in the surface layer reflecting the potential effects of anthropogenic deposition. Elemental bioaccessibility was variable decreasing in the order Cd > Pb > Cu > Zn > Ni > Co > As > Cr for the surface soils. With the exception of As, bioaccessibility was generally higher in the C-horizon soils compared to the 0–5 cm soils. The differences in metal bioaccessibility between the 0–5 cm and the C-horizon and among the provinces may reflect geological processes and speciation. The mean, median or 95th percentile bioaccessibility for As, Cr, Cu, Co, Ni and Pb were all below 100 %, suggesting that the use of site-specific bioaccessibility results for these elements will yield more accurate estimation of the risk associated with oral bioavailability for sites where soil ingestion is the major contributor of human health risk.

In 2007,the U.S.Geological Survey,the Geological Survey of Canada,and the Mexican Geological Survey initiated a low-density（1 site per 1600 km2,13323 sites） geochemical and mineralogical survey of North American soils（North American Soil Geochemical Landscapes Project）.Sampling and analytical protocols were developed at a series of workshops in 2003-2004 and pilot studies were conducted from 2004-2007.The ideal sampling protocol at each site includes a sample from 0-5 cm depth,a composite of the soil A horizon,and a sample from the soil C horizon.The 2-mm fraction of each sample is analyzed for Al,Ca,Fe,K,Mg,Na,S,Ti,Ag,Ba,Be,Bi,Cd,Ce,Co,Cr,Cs,Cu,Ga,In,La,Li,Mn,Mo,Nb,Ni,P,Pb,Rb,Sb,Sc,Sn,Sr,Te,Th,Tl,U,V,W,Y,and Zn by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry following a near-total digestion in a mixture of HCl,HNO3,HClO4,and HF.Separate methods are used for As,Hg,Se,and total C on this same size fraction.The major mineralogical components are determined by a quantitative X-ray diffraction method.Sampling in the conterminous U.S.was completed in 2010（c.4800 sites） with chemical and mineralogical analysis currently underway.In Mexico,approximately 66% of the sampling（871 sites） had been done by the end of 2010 with completion expected in 2012.After completing sampling in the Maritime provinces and portions of other provinces（472 sites,7.6% of the total）,Canada withdrew from the project in 2010.Preliminary results for a swath from the central U.S.to Florida clearly show the effects of soil parent material and climate on the chemical and mineralogical composition of soils.A sample archive will be established and made available for future investigations.

A workshop on the role of geochemical data in ecological and human-health risk assessments was sponsored by Health Canada and Environment Canada in 2010. Participants from Geological Survey of Canada developed recommendations for acquiring and analyzing soil geochemical data to support risk assessment and outlined a procedure for estimating geochemical background, released as GSC Open File 6645. The following practices are proposed: 1) the collection of soil samples from pedologic horizons (the C, in particular) rather than depth-based intervals; 2) use of a spatially random sample design; 3) analysis of the less than 2 mm fraction (without ball or ring pulverizing) as a standard. Additionally, analysis of the silt-sized and finer fraction (<0.063 mm) provides more information on the mineral phases and residence sites of elements in soils and the patterns of regional variation; 4) dissolution using the USEPA 3050B aqua regia variant. Additionally, a method for estimating the amount of loosely held 'bioaccessible' amounts of the total-element concentration should be considered (e.g. water leach); 5) archiving of sample splits; and 6) evaluation of chemical data through the insertion, analysis, and monitoring of QA/QC samples. The procedure for estimating geochemical background is based on plotting maps and graphs using the 'rgr' library and functions in R. R is an open source software environment and is available through CRAN mirror sites linked to http://www.r-project.org/. Metadata for 700 geochemical surveys carried out by the GSC and provincial agencies can be accessed through the Geochemical Data Repository at Natural Resources Canada.

In environmental and human health protection, the role for geoscience may be expressed by how it enhances certainty in the hazard potential models that support risk assessment. For geochemical hazards, certainty reflects how well geoscience simplifies variability in the element concentrations and in the environmental conditions associated with exposure pathways. Through mineralogy, geoscience establishes natural geochemical background variability in terms of provenance, process, and past, and it links hazard potential to the physical and chemical transformation due to weathering and soil formation. The interpretation of hazard potential may be expressed by how analytical protocol, expressed by grain size and strength of acid decomposition, combines with geological factors, expressed by (1) mineralogy and mineral partitioning and (2) environmental cofactors, including moisture, pH, buffering capacity, and porosity. With this type of knowledge, geoscience enhances the potential to identify covariant relations between hazard indicators and disease, and to resolve potential causal factors.

The Climate Change Geoscience Program (CCG) at the Earth Science Sector (ESS) contributes to adapting to environmental impacts from climate change through the provision of critical earth science information to support policy and regulation decisions. The interaction between the development of a scientific knowledge base and the development of appropriate policy decisions is fundamental to achieving meaningful outcomes. The program's fundamental role lies in providing a suitable base of geoscience knowledge, accomplished by identifying the knowledge needs and gaps through collaboration with stakeholders. Specifically the geoscience in the CCG Program focuses on those environmental variables that will be most impacted and altered by a changing climate namely the cryosphere (permafrost, glaciers and snow cover), water (availability trends and impacts as well as water level changes) and vulnerable landscapes (particularly coastal areas and northern ecosystems). Significant changes to these components of the environment will affect Canadians, their prosperity and ability to benefit from their environment. Scientific activities will quantify the environmental impacts using leading edge techniques that provide excellent knowledge and predictive insights. The scientific knowledge base is being delivered through a mix of earth observation, both remote and in-situ, and quantitative assessments of landscape and ecosystem response. Projects are multi-disciplinary respecting the multi-dimensionality of environmental issues and the need to study the interaction between variables. Northern vulnerability is particularly highlighted in the program as evidence for more rapid climate change and accelerating impacts in northern Canada has been cited as a critical driver in the government's Northern Strategy which also recognizes environmental degradation, vulnerable infrastructure, and transportation as areas requiring attention. The outcome will be achieved through engagement in the current round of national and international assessments, in particular through the Intergovernmental Panel on Climate Change (IPCC) as well as the International Polar Year (IPY).

In eastern Canada, natural arsenic concentrations in bedrock, soil, and water exceed levels associated with acceptable human health risk, and they are linked with enhanced risk for disease. Despite complex and varied exposure pathways, geoscience supports health risk assessment by informing on regional-scale variation in relative geochemical hazard potential, and by providing a stable environmental reference framework that guides decision making. For New Brunswick, a preliminary arsenic hazard model based on bedrock type, mineral composition, geological history, and regional geochemical data supports a two-level hazard code classifi cation, but may be improved to four-level by incorporating information compiled in higher resolution geological maps. In an exploratory, collaborative project with the New Brunswick Department of Health, a revised model will be tested as a predictor for arsenic in well water, an environmental media more closely associated with exposure pathways, and for spatial variation in occurrences of human cancers known to be arsenic related.

A Geographic Information System (GIS), in concert with statistical analysis tools, are used to study the statistical and spatial relationships between mercury (Hg) and dissolved organic carbon (DOC) concentrations in a variety of media in Kejimkujik Park, south-central Nova Scotia, where high Hg concentrations have been found in loons and fish. The sampled media includes soil, humus, till, vegetation and water. Humus and the Ah soil horizon exhibit the highest concentrations of Hg, followed by till and water. The GIS analysis of the various media and the integration of Hg anomaly maps using a simple boolean additive model, has established that anomalous Hg concentrations occur in specific areas within the park. The area around Big Dam Lake over the contact zone between leucogranites and Goldenville rocks, and an area around Big Red Lake over biotite/muscovite-bearing granitoid rocks especially high in K, appear to be anomalous. Anomalous Hg and DOC concentrations in water prima- rily occur southeast of Kejimkujik Lake over sulphide-bearing Halifax Formation slates. These rocks may be a prefer- ential source of Hg (biotite and sulphides as a sink for Hg). More importantly, the granitoids and slates may be more conducive to the formation of wetland environments that are characterized by lower pH and increased DOC. These fac- tors are, perhaps, the main drivers in the bioaccumulation of Hg in the park.