5. Results and discussion

4. Methods and materials

Table 1. Sampling sites on Tweelopiespruit.

348 Water Quality

In this research, the quantitative research design was used. The research methods combined statistical analysis of retrospective (historical) data and batch analysis of water samples from the sites. Experimental analysis was performed on two batches of water samples, one in August and the other in September. Analysis was performed using the same analytical and standard methods which were used for the historical data in order to validate the historical

Figure 9. Sampling points along Tweelopiespruit (Software platform: ESRI [10]. Source of shapefiles: Internet).

Sampling point Description Latitude Longitude F1S1 Upstream of R24 at Randfontein Estates on Tweelopie −26.10752 27.72268 F2S2 Willow tree in KGR on Tweelopie −26.10653 27.72227 W1S3 Hippo Dam in KGR on Tweelopie −26.09917 27.72128 F6S7 Cemetery Spring (1) (Spring 1) in KGR on Tweelopie −26.09671 27.71932 F8S9 Lodge Spring (2) (Spring 2) at broad crest in KGR on Tweelopie −26.08527 27.70886 F10S11 Northern fence in KGR −26.07620 27.69963 F11S12 Tweelopie at the N14 intersection −26.06374 27.69589

The results for chosen parameters, i.e., SO4 <sup>2</sup><sup>−</sup> (mg/L), Cl<sup>−</sup> (mg/L), Ca2+ (mg/L), Mg2+ (mg/L), Na<sup>+</sup> (mg/L), K<sup>+</sup> (mg/L), Fe (mg/L), pH (pH units), and EC (m Sm−<sup>1</sup> ) are shown for all monitoring points in Figures 10–20; using trends that were plotted on MS Excel, for each sampling site according to their geocoordinates, starting with F11S12. While monitoring continues and is active at these sites since the 1970s, it is noted that there is a general trend toward increase in parameter concentration. For an environmentally sensitive micro-catchment, which also houses the Cradle of Humankind in its downstream ecosystem, efforts should be done to reduce the study area parameter concentrations in order improve the ecosystem. Because these are combination graphs for a mixture of parameters, individual units of measure could not be indicated on the y-axis of the graphs, hence the use of the label"parameter test value."

pH trends (Figure 17) for all monitoring points are lowest at the highest point (F1S1) but also is very unstable on all the other points because the environment itself is prone to nonpoint AMD pollution.

Figure 10. F11S12 monitored parameters for 2003–2011.

Figure 11. F10S11 monitored parameters for 2003–2008.

Just like the spiking values for pH, Figure 18 indicates variable trends for sulfate along Tweelopiespruit.

However, the figure also indicates the conservative nature of sulfate as it shows lowest concentration at the sampling point farthest from the AMD sources along the river (F11S12 and F10S11) and highest trends close to old mine shaft activities (F1S1 and F2S2). Sulfate does not mobilize easily and is therefore deposited along the stream soon after its entry. Figure 19 shows that iron is typically high at the upper reaches of the river (F1S1), indicating the major source of AMD and a potential priority point for mitigation and management efforts to control AMD in the micro-catchment.

Figure 12. F8S9 monitored parameters for 2003–2008.

Figure 13. F6S7 monitored parameters for 2003–2009.

Just like the spiking values for pH, Figure 18 indicates variable trends for sulfate along

However, the figure also indicates the conservative nature of sulfate as it shows lowest concentration at the sampling point farthest from the AMD sources along the river (F11S12 and

Tweelopiespruit.

parameter test value

350 Water Quality

11/14/2003

Figure 10. F11S12 monitored parameters for 2003–2011.

5/14/2004

11/14/2004

5/14/2005

11/14/2005

5/14/2006

11/14/2006

5/14/2007

Years

11/14/2007

Calcium Chloride Conduc�vity Iron Potassium Magnesium Sodium pH Sulphate

5/14/2008

11/14/2008

5/14/2009

11/14/2009

5/14/2010

11/14/2010

5/14/2011

Parameter test value

11/14/2003

3/14/2004

Figure 11. F10S11 monitored parameters for 2003–2008.

7/14/2004

11/14/2004

3/14/2005

7/14/2005

11/14/2005

Magnesium Sodium pH Sulphate

3/14/2006

7/14/2006

Years Calcium Chloride Conduc�vity Iron Potassium

11/14/2006

3/14/2007

7/14/2007

11/14/2007

3/14/2008

7/14/2008

Calcium indicates a high concentration in the upper reaches of the river, too, as indicated in Figure 20.

Figure 14. W1S3 monitored parameters for 2003–2010.

Figure 15. F2S2 monitored parameters for 2003–2008.

W1S3 indicates higher values for calcium and could be subject for further investigation regarding the type of water that passes by that monitoring point. For example, calcium contributes to water hardness which affects mobility of other related ions and anions in the water and sediments.

Figure 16. F1S1 monitored parameters for 2003–2008.

Calcium indicates a high concentration in the upper reaches of the river, too, as indicated in

Figure 20.

352 Water Quality

Parameter test value

11/13/2003

4/13/2004

Figure 14. W1S3 monitored parameters for 2003–2010.

9/13/2004

2/13/2005

7/13/2005

12/13/2005

Magnesium Sodium pH Sulphate

5/13/2006

10/13/2006

3/13/2007

Years Calcium Chloride Conduc�vity Iron Potassium

8/13/2007

1/13/2008

6/13/2008

11/13/2008

4/13/2009

9/13/2009

2/13/2010

Parameter test value

11/13/2003

Figure 15. F2S2 monitored parameters for 2003–2008.

3/13/2004

7/13/2004

11/13/2004

3/13/2005

7/13/2005

11/13/2005

3/13/2006

Years

7/13/2006

Calcium Chloride Conduc�vity Iron Potassium Magnesium Sodium pH Sulphate

11/13/2006

3/13/2007

7/13/2007

11/13/2007

3/13/2008

7/13/2008

Figure 17. pH trending for all monitoring points.

The study area is critical in its strategic position because, apart from preserving its endowed environments, it is also because of its proximity to the Vaal Basin, which is the heartland of South Africa's economic activities as indicated in the digital elevation map (see Figure 21). Thus, measures and actions focusing on managing Tweelopiespruit pollution could also potentially benefit the Vaal System.

Figure 18. Sulfate trending for all monitoring points.

Figure 19. Iron trending for all monitoring points.

Assessment of Impacts of Acid Mine Drainage on Surface Water Quality of Tweelopiespruit... http://dx.doi.org/10.5772/65810 355

Figure 20. Calcium trending for all monitoring points.

The study area is critical in its strategic position because, apart from preserving its endowed environments, it is also because of its proximity to the Vaal Basin, which is the heartland of South Africa's economic activities as indicated in the digital elevation map (see Figure 21). Thus, measures and actions focusing on managing Tweelopiespruit pollution could also poten-

tially benefit the Vaal System.

Sulphate (mg/L)

354 Water Quality

9/1/2002

Figure 18. Sulfate trending for all monitoring points.

1/14/2004

Iron (mg/L)

9/1/2002

Figure 19. Iron trending for all monitoring points.

1/14/2004

5/28/2005

5/28/2005

10/10/2006

10/10/2006

F11S12 F10S11 F8S9 F6S7 W1S3 F2S2 F1S1

Years

2/22/2008

7/6/2009

11/18/2010

Years F11S12 F10S11 F8S9 F6S7 W1S3 F2S2 F1S1

2/22/2008

7/6/2009

11/18/2010

Figure 21. Overlaid monitoring points along Tweelopiespruit on micro-catchment A21D.

### 6. Conclusions

Pollution in the Krugersdorp Game Reserve is very significant as indicated by the chemical analysis' results for the monitoring points. Treatment of the polluted effluent does not seem to have an impact on the effluent for the study period up to 2008.

This research could benefit from the land use change detection, especially from satellite images which could show the devastating effects of the AMD on the environment within the Tweelopiespruit micro-catchment. These satellite images, freely available from the USGS website, could inform on the worsening situation in the micro-catchment.

It can be noted that peace-meal treatment works at the Randfontein site do not seem to have made a noticeable impact on pollution of the "dead" Tweelopiespruit, from AMD. The watershed, spanning the Witwatersrand System and the Upper reaches of the quaternary catchment A21D, is a hot spot for environmental disaster that is set to impact outer ecosystems for many years to come, and South Africa will have to pay for non-stringent environmental legislation, which was in place before the 1990s. The research results and conclusions aim to provide a baseline for critiquing ongoing research in the Tweelopiespruit micro-catchment in order to assist with answering the research questions that were initially raised against each objective. The use of satellite and remote sensing methods are recommended for further research.
