Environmental assessment of gold mining and needs for sustainable technologies. Peter Goethals, Colin Janssen, Filip Tack and Gijs Du Laing

Transcription

1 Environmental assessment of gold mining and needs for sustainable technologies. Peter Goethals, Colin Janssen, Filip Tack and Gijs Du Laing

2 Contents Gold mining technologies The DPSIR environmental assessment concept Assessing the environmental impacts of gold mining Potential routes towards sustainable gold mining and gold consumption Research and policy-support needs

3 Gold mining technologies Artisanal and smallscale mining Industrial and large-scale mining Source: Chibunda, 2008 Source: CATAPA website GOUD:EERLIJK?

4 Gold mining technologies Artisanal and smallscale mining Often direct high risks for human health of gold miners Waste often directly discharged in environment Industrial and largescale mining Due to large scale, potential risks for environmental disasters Often waste disposal and high water and energy consumption

5 Contents Gold mining technologies The DPSIR environmental assessment concept Assessing the environmental impacts of gold mining Potential routes towards sustainable gold mining and gold consumption Research and policy-support needs

6 The DPSIR environmental assessment concept Driving forces: hard to stop, rather adapt methods Pressures States: no endpoint!!! Impacts Responses: at different levels (prevention, endoff-pipe, )

7 DPSIR and environmental/ecosystem services (Source: Diversitas, 2010)

8 The DPSIR environmental assessment concept Environmental (and social-economic) impacts and responses are depending on mining as well as other activities (impacts but also services: e.g. food and drinking water production, ) Environmental assessment needs a more integrated and system-relevant approach, where compliance to a set of environmental standards is just one of the elements

9 Contents Gold mining technologies The DPSIR environmental assessment concept Assessing the environmental impacts of gold mining Potential routes towards sustainable gold mining and gold consumption Research and policy-support needs

10 Assessing the environmental impacts of gold mining Major pollution variables (mainly based on Eisler, 2000) Water and energy consumption Case-study illustrating the variability and complexity of the impacts

11 Major pollution variables Mercury Mixing of ground ores with metallic mercury to produce gold amalgam, that leaks out goldamalgam from ore In second step evaporation of mercury High impact on nervous system and kidneys of artisanal miners Distribution in the environment and food chain (plants, fish, cattle)

12 Major pollution variables Cyanides (e.g. 80 million kg used in USA for gold mining) Used for extraction of gold from ores via leaching process Often times safe concentrations in receiving waters (safe levels 3-5 microgram/liter) Fish most sensitive (5 microgram/liter effects on swimming and reproduction, mortality around 20 microgram/liter)

13 Major pollution variables Turbidity Mainly result of soil particles which get in suspension during places mining The increased turbidity has a negative effect on the photosynthesis (energy import) in the stream, and can consequently affect the whole ecosystem. Also habitat loss is often an extra negative stress, as a result of the coverage of cobles, stones and grind, resulting in difficulties for reproduction (lithophylic spawners), missing food for grazers, lack of hiding habitats.

14 Major pollution variables Acidity Result of reaction of sulfide in rocks, with water and oxygen, leading to sulfuric acid Severe impact on most plants and animals, but in lower acidity ranges already effects on micro-organisms, snails and crustaceans, which are often playing a key role in the food chain (degradation of organic material, prey of fish)

15 Major pollution variables Associated metals (Copper, Lead, Cadmium, Arsenic) Strongly depending on ore composition Combined toxicity effects Accumulate in the environment

16 Assessing the environmental impacts of gold mining Major pollution variables Water and energy consumption Case-studies illustrating the variability and complexity of the impacts

17 Water and energy consumption (Source: Mudd, 2007)

18 Water and energy consumption (Source: Mudd, 2007)

19 Water and energy consumption Highly variable data, related to variability of processes and concentration of gold in ores, depth of mining activities, Water consumption should also be put in the context of local availability of water resources and the extra effect of contamination of these via mining activities

20 Assessing the environmental impacts of (gold) mining Major pollution variables Water and energy consumption Case-study illustrating the variability and complexity of the impacts

21 Case study (Tanzania and Victoria lake) In Tanzania most small scale gold mines are concentrated around lake victoria area (Lake Victoria Gold Fields) Gold processing takes place mainly at river banks which in turn drain into lake victoria Approximately, 12 tonnes of mercury are estimated to be released in lake Victoria basin annually (Source: PhD of Raphael T. Chibunda, Promoted by Prof. C. Janssen)

22 Hg (Air) Atmosphere Hg deposition Hg in tailings and rain runoffs MeHg Water column Sediment MeHg Hg MeHg MeHg MeHg? (Source: PhD of Raphael T. Chibunda, Promoted by Prof. C. Janssen)

23 Case study (Tanzania and Victoria lake) Study was done at Nungwe Village (fishing village) of Geita District, Mwanza region Tanzania Structured questionnaires were used to collect information about fish consumption pattern, in combination with fish analyses (Source: PhD of Raphael T. Chibunda, Promoted by Prof. C. Janssen)

24 Case study (Tanzania and Victoria lake) 0.6 Hg levels (µg/g ww) Catfish Tilapia Nile perch Lungfish Sardine Frequently consumed fish (Source: PhD of Raphael T. Chibunda, Promoted by Prof. C. Janssen)

25 Mercury exposure (* values higher than WHO standards) Fish Consum p rate (g/kg bwt/da y MeHg (µg MeHg/ g ) One day Consumption frequency ( days/week) Two days Three days Seven days Nile perch * 2.85* 6.65* Tilapia * 4.79* Sardine Lungfish Catfish * 2.96* 6.90* Average * 3.80* (Source: PhD of Raphael T. Chibunda, Promoted by Prof. C. Janssen)

26 Case study (Tanzania and Victoria lake) This case study illustrates the impotance of direct and indirect effects of gold mining on the environment and human health Also social economic aspects can become very important, as fish from Lake Victoria might probably not be sold on the international market (Source: PhD of Raphael T. Chibunda, Promoted by Prof. C. Janssen)

27 Contents Gold mining technologies The DPSIR environmental assessment concept Assessing the environmental impacts of gold mining Potential routes towards sustainable gold mining and gold consumption Research and policy-support needs

28 Potential routes towards sustainable gold mining and gold consumption Customer and market awareness (perception of gold) Improved mining technologies and related policy development (need for research and education): better recycling methods on mining sites as in the market (e.g. urban mining), integrated environmental impact assessment and sustainability analyses

29 Contents Gold mining technologies The DPSIR environmental assessment concept Assessing the environmental impacts of gold mining Potential routes towards sustainable gold mining and gold consumption Research and policy-support needs

30 Research and policy-support needs Independent and integrated monitoring and data(sharing): Better risk and impact assessment: direct and indirect effects Comparison of methods: efficiency, environmental impacts, relation with human health, Mitigation of impacts and pollution prevention (treatment methods): getting insights in the overall picture

31 Research and policy-support needs Multidisciplinary research: Geology Chemistry Hydrology Ecotoxicology Ecology Environmental technology Human health Economy Sociology Law Integrated (environmental) modelling and assessment

32 Research and policy-support needs Sustainability definition(s) and benchmarking of methods: Criteria Targets Standards Basis for education and certification customer and market awareness sustainable policies and best available technologies development