ofm me 2013-016: bedrock acid rock drainage potential map of …€¦ · shaded relief image...
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Nova Scotia Department of Natural ResourcesMineral Resources Branch
1 0 1 2 3 4 km
Open File Map ME 2013-016
Bedrock Acid Rock Drainage Potential Map of the LaHave Islands Area, NTS Sheet 21A/01,
Lunenburg County, Nova Scotia
L. L. Trudell and C. E. White
64°30'
44°15'
64°30'
44°00'
64°00'
44°15'
64°00'
44°00'
NTS Sheet 21A/01 OFM ME 2013-016
Gulf ofSt. Lawrence
Bay of FundyNova Scotia
Atlantic Ocean SableIsland
NewBrunswick
P.E.I.
60°W
60°W
64°W
64°W
46°N 46°N
44°N 44°N
This map represents the fourteenth in a series of 25, 1:50 000 scale maps,highlighting the acid-generating potential of bedrock in southwestern Nova Scotiaif exposed and/or physically disturbed. A corresponding digital product (DP ME484) and an information circular (IC ME 067) are available on the DNR website.
This map is part of an undergraduate Honours thesis project with DalhousieUniversity School of Planning, examining how to make geologic informationaccessible to an audience of planners and non-geologists.
Descriptive Text
GIS databases, cartography and reproduction by Laura Trudell, Angie Ehler,Brian Fisher and Jeff McKinnon of the Nova Scotia Department of NaturalResources, 2013. The GIS databases and map were developed usingArcGIS® 10.
Universal Transverse Mercator Projection (UTM), Zone 20, Central Meridian63°00' West. North American Datum (NAD) 1983 Canadian Spatial ReferenceSystem (CSRS) 98.
Base and digital data derived from the Nova Scotia Topographic Database(NSTDB). Copyright Her Majesty the Queen in Right of the Province of NovaScotia. The NSTDB is available from Service Nova Scotia and MunicipalRelations (SNSMR), Land Information Services Division (LIS), Nova ScotiaGeomatics Centre (NSGC), Amherst, Nova Scotia.
Shaded relief image derived from a 25 m Digital Elevation Model of the Provinceof Nova Scotia, DP ME 56, version 2, 2006. Azimuth of 0°, sun angle of 45° anda vertical exaggeration of 5.
Map Notes
Disclaimer
Selected References
Recommended Citation
20P/11
20P/05 20P/06
20P/12 20P/10
20P/13 20P/14 20P/15
21A/11
21B/01 21A/04 21A/03 21A/02 21A/01
20O/08
21B/08 21A/05 21A/06 21A/07 21A/08
20O/09
21A/12 21A/10 21A/09
20O/16
64°W
64°W
64°30'W
64°30'W
65°W
65°W
65°30'W
65°30'W
66°W
66°W
66°30'W
66°30'W
44°30'N44°30'N
44°N44°N
43°30'N43°30'N
The information on this map may have come from a variety of government andnongovernment sources. The Nova Scotia Department of Natural Resourcesdoes not assume any liability for errors that may occur. Site specificlithogeochemical analyses are necessary to confirm the occurrence of acid-generating bedrock.
Trudell, L. L. and White, C. E. 2013: Bedrock acid rock drainage potential map ofthe LaHave Islands Area, NTS Sheet 21A/01, Lunenburg County, Nova Scotia;Nova Scotia Department of Natural Resources, Open File Map ME 2013-016,scale 1:50 000.
Scale 1:50 000
Crown Copyright © 2013, Province of Nova Scotia, all rights reserved.
Halifax, Nova Scotia2013± 0 100 200 km
Map area . . . . . . . . . .
Current extent . . . . . . .
NTS map sheets . . . . .
We thank Nova Scotia Department of Natural Resources for the permission touse unpublished data. Dr. Patricia Manuel, Dalhousie University School ofPlanning professor, is thanked for her advice and guidance with theundergraduate thesis project. We thank the participating planners for theirhelpful comments throughout the map production process, which led to thepublishing of this derived map product.
Acknowledgments
0 20 40 km
Selected References (continued)
Please note: latitudes and longitudes represent the corner coordinates of the mapped NTS sheet and not the corners of the map frame.
* Note: Compiled legend and symbols list for Open File Maps ME 2013-003 to 2013-027. All symbols may not appear on each map.
Bedrock Potential for Acid Rock DrainageIntroduction
The purpose of this map is to inform landowners, developers and municipal planners about the geological hazard of acid rock drainage (ARD) and to identify where the bedrock in southwestern Nova Scotia is potentially sulphide-bearing and may develop ARD if physically disturbed or exposed. Disturbing the bedrock refers to activities hysically alter and/or xpose that p ethe bedrock, such as drilling, blasting and excavation. This map is intended to be used as a tool for making land-use and environmental planning decision indicating where precaution is needed or further s by ,lithogeochemical analysis is likely required before engaging in activities ,that disturb or expose bedrock.
Overview of Acid Rock Drainage
ARD is a phenomenon that occurs when naturally occurring sulphide
minerals in rocks are exposed to air and water, and react in a chemical
weathering process called sulphide mineral oxidation. During sulphide
mineral oxidation, pyrite (and other sulphide-bearing minerals) react with
oxygen and water to produce iron-oxides and sulphuric acid , whichdischarge into groundwater and streams, rivers or lakes. Waterbodies
impacted by ARD typically have higher acidity (pH levels between 2 and 4), making them corrosive and unable to support many forms of aquatic life.
Acidic waterbodies can negatively impact potable and industrial water
supplies and can cause excessive corrosion in metal and concrete
infrastructure (White and Goodwin 2011; Fox 1997). Furthermore, , et al.,through a process called metal leaching, the acidic waters may break down
other metal-bearing minerals in the rock, causing the release of dissolved
metals (e.g. iron, aluminum, manganese, copper, zinc, cadmium, lead and
other heavy metals), which have adverse effects on human health. ARD can
can render municipal or domestic water supplies unusable and unpalatable,
or aesthetically unpleasant. The oxidation of sulphide-bearing rocks tends to produce elevated iron concentrations leaving an orange discoloration on ,
rocks (Fig. 1), in stream beds (Fig. 2), and when in , water supplies
discolouring laundry and porcelain xtures.fi
ARD occurs naturally at slow rates; exposing or breaking up sulphide-bearing bedrock owever, can accelerate the sulphide , h
mineral oxidation process. Human activity such as highway construction, quarrying, , as well as natural events (e.g. excavating
washouts) are activities that can physically disturb and expose sulphide-bearing bedrock.
Acid Rock Drainage Potential in Nova Scotia
Recent bedrock mapping in the Goldenville and Halifax groups in southern Nova Scotia (White and Goodwin 2011; White , et al.,
2012) has shown that some bedrock formations have the potential to generate ARD. ulphide-bearing slate from the Cunard and S
Acadia Brook formations have the highest potential of generating acidic runoff because these formations contain abundant pyrite, pyrrhotite and other sulphide minerals. Pieces of the weathered sulphide-bearing bedrock may be incorporated into the -bearing
overlying loose surface material. Exposing this type of till or soil can also initiate the process of ARD.
If disturbance in unavoidable, then potentially acid-generating bedrock (and other sulphide-bearing materials) must be managed in
accordance with the Sulphide Bearing Material Disposal regulations ( Section 66 of the Nova Scotia Environment Act made under
1995 ).; Province of Nova Scotia 1995
Classification of Acid Rock Drainage Potential
Recently published geological maps of southwestern Nova Scotia (White 2012) ombined with unpublished digital data and , , cet al.
lithogeochemical data were used as the base for ARD prediction Rock formations were assigned to one of the following three , .
acid-generating potential categories:
High potential that bedrock will generate ARD Moderate potential that bedrock will generate ARD Low potential that bedrock will generate ARD
The ARD potential categories were established on legislative standards for identifying sulphide-bearing material using a similar
lithogeochemical method the British Columbia Research Initial Test (BC-RIT). (White and Goodwin, 2011) as
The overall potential of a rock to generate acid is determined by the ratio of minerals that produce acid, such as sulphides, known
as the acid-producing potential (APP) to the minerals that are able to neutralize it, such as carbonates, known as the acid-,consuming ability (ACA) (White and Goodwin, 2011). Samples from the Bridgewater area (NTS 21A/07) were analyzed to determine their overall potential to generate acid by calculating the APP/ACA ratio hese results extrapolated to . T were the
geological units in southwestern Nova Scotia. Rock samples above the 1:1 ratio were classified as acid-producers or high
potential to generate ARD; samples within the 1:1 and 1:2 ratios have moderate potential to generate ARD; samples below the 1:2
ratio are considered as a non-acid producers or low potential to generate ARD. Whole rock data w used to classify the bedrock - ere
units into acid-generating potential categories on the map based on the method outlined in White and Goodwin (2011).
Summary
The intention of this map is to provide information about the geological hazard of ARD associated risks and identify and its , to
where sulphide-bearing, potentially acid-generating bedrock is located in southwestern Nova Scotia.
Physically disturbing and exposing sulphide-bearing rocks can ARD. Determining if sulphide-bearing bedrock is present accelerate
should to be considered during the planning stage of development and construction in order to avoid negative environmental and human health effects as well as to reduce costly remediation. he way to prevent ARD is knowing where sulphide-bearing T best
bedrock is located and avoid disturbing and exposing it. to /or
Additional Information For more information about ARD, please refer to nformation . Additional information includes the factors that I Circular ME 067
influence ARD, the human activities that initiate ARD, and the effects of ARD that impact human health, the environmental and
infrastructure.
. Figure 1 Small, bronze-coloured, cubic, pyrite crystals are visibly embedded in this slate. The rusty-coloured iron staining indicates ongoing sulphide oxidation and ARD (photo by G. Prime, NSDNR) .
. Figure 2 Sulphide mineral oxidation of the surrounding pyritic-slate bedrock discharges iron-oxides into this stream, discolouring it red (photo by G. Prime, NSDNR).
Nova Scotia Environment 2007b; Natural watershed municipal surface water supply areas;Nova Scotia Environment, Water Resources Management Unit, scale 1:10 000.
Nova Scotia Environment, Water and Wastewater Branch and Nova Scotia Department ofNatural Resources, Mineral Resources Branch 2006; Municipal Water Supply WellsDatabase
Province of Nova Scotia 1995. Environment Act: Sulphide-bearing Material DisposalRegulations. Retrieved from http://gov.ns.ca/just/regulations/regs/env5795.htm. Dateaccessed: January 2013.
Trudell, L. L. and White, C. E. 2013: Digital Bedrock Acid Rock Drainage Potential Data forthe Southwestern Area of Nova Scotia; Nova Scotia Department of Natural Resources,Digital Product ME 484; http://www.gov.ns.ca/natr/meb/download/dp484.asp [ISN:23257]†
White, C. E. and Goodwin, T. A. 2011; Lithogeochemistry, petrology, and the acid-generating potential of the Goldenville and Halifax groups and associated granitoid rocks inmetropolitan Halifax Regional Municipality, Nova Scotia, Canada; Atlantic Geology; v. 47,p. 158-184.
White, C. E., Fisher, B. E., McKinnon, J. S., and Ehler, A. L. (compilers) 2012: DigitalGeological Data Generated as Part of Geological Mapping of the Meguma Terrane ofSouthwestern Nova Scotia (1998-2010), Shelburne, Digby, Yarmouth, Annapolis, Queens,and Lunenburg Counties, Nova Scotia; Nova Scotia Department of Natural Resources,Digital Product ME 127; http://www.gov.ns.ca/natr/meb/download/dp127.asp [ISN:23256]
† Internal Search Number (ISN) is a unique identifier used in NovaScan - the Nova Scotia Geoscience Maps andPublications Database. The ISN can be used to retrieve a digital version of the listed citation -http://www.gov.ns.ca/natr/meb/default.asp
Fox, D. L. 1999: Prediction of acid rock drainange (ARD) from sulphidic slatesusing GIS analysis of mineralogical, geochemical, magnetic and geologicalparameters a test case in southern Nova Scotia; unpublished Ph. D. thesis,Dalhousie University, 294 p.
Health Canada 2010: Guidelines for Canadian Drinking Water Quality, SummaryTable. Retrieved fromhttp://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/2010-sum_guideres_recom/index-eng.phpDate accessed: January 2013.
Nova Scotia Environment 2007a; updated 2010: Primary and secondarywatersheds; Nova Scotia Environment, Water Resources Management Unit,scale 1:10 000.
Symbols*
Current extent . . . . . . .
Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rock in water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Municipal drilled well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arterial highway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Trunk highway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Collector highway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hard surface road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loose surface/resource access road . . . . . . . . . . . . . . . . . . . . .
Trail, footpath, cart track . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Railway (active, inactive) . . . . . . . . . . . . . . . . . . . . . . . .
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Coastline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
River, stream . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Municipal boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Watershed (primary, secondary) . . . . . . . . . . . . . . . . . .
Transmission line (multi, single line) . . . . . . . . . . . . . . .
Municipal surface water supply area . . . . . . . . . . . . . . . . . . . . . . . . . . . .
National Park . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wetlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lake/ocean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
! ! !
! ! !! ! !
Jul 31, 2013
Open File Map ME 2013-016
Legend *
Potential for acid rock drainage (ARD) from bedrock that is exposed or physically disturbed
High potential that bedrock will generate ARD. . . . . . . . . . . . . . . .
Moderate potential that bedrock will generate ARD . . . . . . . . . . . .
Low potential that bedrock will generate ARD . . . . . . . . . . . . . . . .