Status of groundwater and river water quality around the location of illegal gold mining activities in Lantung District, Sumbawa

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Volume 10, Number 3 (April 2023):4433-4443, doi:10.15243/jdmlm.2023.103.4433 ISSN: 2339-076X (p); 2502-2458 (e), www.jdmlm.ub.ac.id

Open Access 4433 Research Article

Status of groundwater and river water quality around the location of illegal gold mining activities in Lantung District, Sumbawa

Kevin Philips Barakati¹, Tjahyo Nugroho Adji^2*, Noorhadi Rahardjo²

1 Master of Environmental Management, Universitas Gadjah Mada, Jl. Teknika Utara, Sleman, Yogyakarta, Indonesia, 55281

2 Faculty of Geography, Universitas Gadjah Mada, Sekip Utara, Sleman, Yogyakarta, Indonesia, 55281

*corresponding author: adji_tjahyo@ugm.ac.id

Abstract Article history:

Received 23 November 2022 Accepted 5 January 2023 Published 1 April 2023

The Lantung area is one of the places on Sumbawa Island with a large gold deposit. One of the activities of the Lantung people that has the potential to damage the environment is separating gold from mercury. This study aimed to examine the activity of the gold leaching process and the level of contamination of groundwater and river water due to gold processing from amalgamation by mercury (Hg⁺) waste. In this study, sampling was carried out for each location, namely two samples of wastewater, six samples of river water, and two samples of groundwater, which were then tested in the laboratory on the parameters of mercury and TSS. At the same time, pH was measured in the field. Furthermore, from the survey results, it was found that the use of mercury was ±150-250 mL at each gold processing location. The results showed that all samples from wastewater (tailings), groundwater and river water were contaminated with mercury with levels exceeding the acceptable quality standards. Furthermore, the status of water quality using the Pollution Index (IP) method shows that wastewater is light to moderately polluted, groundwater is lightly polluted, and river water is also lightly to moderately polluted.

Keywords:

gold mining groundwater mercury pollution river

To cite this article: Barakati, K.P., Adji T.N. and Rahardjo, N. 2023. Status of groundwater and river water quality around the location of illegal gold mining activities in Lantung District, Sumbawa. Journal of Degraded and Mining Lands Management 10(3):4433-4443, doi:10.15243/jdmlm.2023.103.4433.

Introduction

The definition of "environment" is based on Law Number (No). 32 (2009)is "the unity of space with all objects, forces, circumstances, and living things, including humans and their behavior, which affect the continuity of life and the welfare of living things." One of the damage and pollution caused by the use of the environment is mining activities (Worlanyo and Jiangfeng, 2021). Gold mining activity by the people is a gold mining business carried out by the local people on a small scale or in mutual cooperation with simple tools for their livelihood (Pokorny et al., 2019).

Illegal gold mining (PETI) activities in Lantung District, Sumbawa, have been going on since 2008.

Mining activities are located around community residential areas with gold processing facilities not far

from the mining location. Gold processing, in this case, is the processing of gold ore which is carried out by an amalgamation process using mercury as a medium to bind and separate gold (Brooks et al., 2017). Environmental pollution due to the use of mercury is groundwater and surface water pollution (Susanti et al., 2018; Belle et al., 2021) because the waste is discharged directly into the ground and drainage, so it has the potential to contaminate groundwater and surface water (rivers).

Krisnayanti (2018) reported that most of the methods for separating gold from rock in Nusa Tenggara Province have changed from amalgamation to cyanidation, which produces less mercury waste and is safe for the environment. However, in the research area (Lantung District), gold miners still use the "old"

method (amalgamation) because the cost is more

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Open Access 4434 economical than the cyanidation process.

Additionally, the Governor of Nusa Tenggara Barat Regulation No. 18 (2016) states that the Lantung District is included in the pollution area with high total mercury (Hg⁺) concentrations in tailings. High levels of Hg⁺ contamination can pose a risk to health and the environment (Krisnayanti et al., 2012) because most people in the Lantung District use groundwater as the primary source of drinking water and for domestic needs. Furthermore, the objectives of this study were to examine the activities of the gold leaching process and evaluate the quality status of groundwater and river water, which has the potential to be polluted by amalgamation waste (Hg⁺) in Lantung District.

Materials and Methods Site description

Geomorphologically, the research location is a valley between hills, making the position lower with the constituent rocks dominated by Breccia-Tuff (Sudrajat, 1998). According to the Schmidt-Ferguson climate classification, the study area is a D (moderate) climate with an average rainfall of 1300-1400 mm/year. The groundwater condition in the research location has a groundwater depth of 3-4 m for dug wells, while for drilled wells, it reaches a depth of 70 meters. Hydrological conditions are characterized by the Tiu Bangin River and Padesa River, which flow throughout the year (perennial). The two rivers are recharged by the surrounding aquifer (effluent). The soil type in the research location is lithosol which is shallow soil that develops on hard rock and has not experienced development due to erosion and steep slopes. The dominant type of land use is "palawija," or seasonal crops with a cropping pattern system that follows the distribution and pattern of rainfall (de Ruijter et al., 2012).

Tools and materials

Research equipment to support the implementation of research activities at the preparation, research, and field survey stages, as well as when processing data, is presented in Table 1.

Field work

Primary data collection involved description (observation and measurement), recording, and plotting data on a base map. Field observations thoroughly covered places around the gold processing area and places related to the research topic. At this stage, samples of river water, groundwater, and gold processing wastewater were taken to determine the level of contamination from the results of amalgamation activities). Water sampling in the field was carried out on 26-27 June 2022 at minimum discharge conditions (dry season). Samples of amalgamation waste, river water, and groundwater

were collected based on SNI 6989-59-2008 by Badan Standardisasi Nasional (2008).

Table 1. Tools and materials.

Equipment/material Result Satellite

images, topographic map, geological map, soil map

Map of location research, map of tracks research, Site

description Equipment field

including GPS, tape meter, interview checklist, camera, bottle samples

Position and elevation of sampling point, interview data, groundwater level, the water quality of groundwater, river, and wastewater

Notebook, calculator, software Arcgis 10.2

Data analysis of water quality status

Amalgamation wastewater was taken at the outlet where the waste resulting from gold separation comes out, whereas river water samples were taken at locations before being exposed to waste and after being polluted by waste. Meanwhile, groundwater samples were taken from one drilled well, and one dug well because there were only two drilled wells and two dug wells.

Data analysis

The data obtained in the field were analyzed descriptively-qualitatively to get an accurate value of the various factors of groundwater contamination due to gold amalgamation activities. The analysis provides an overview, pattern, and distribution of each study object, so spatial analysis is also needed through mapping techniques with the help of Geographic Information System software (Arcgis 10.2).

Gold amalgamation activity analysis

To explore the factors that affect environmental sustainability due to gold processing activities, purposive sampling interviews were conducted with informants related to this activity. Interviews with the community (informants) were carried out at a radius of 1-50 m from the gold processing site. The distribution of interviewed informants is presented in Table 2.

Analysis of groundwater, river, and wastewater pollution levels

Determination of the status of water quality/pollution is carried out using the Pollution Index (IP) method. If Lij represents the concentration of water quality parameters listed in the water allotment standard (j), and Ci represents the concentration of water quality parameters (i) obtained from the results of water analysis at a water intake location, then PIj is the Pollution Index for the allotment (j) is a function of Ci/Lij.

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Open Access 4435 Table 2. The number and distribution of informants.

No Type of informant Total person Question component 1 Gold Processor 13 1. Activities in gold processing

2. Have a concern about the environment

3. Knowing the impact of mercury on the environment 2 Community 6 1. Disturbed with the processing of gold

2. How long coexisted with gold processing

3. Knowing the impact of mercury on the environment

3 Village Head 3

1. Affected by the processing of gold

2. Knowing the impact of mercury on the environment 3. Efforts have been made to reduce the impact of

environmental pollution

PIj = Ci

Lij 2 + (Ci Lij)2 2 where:

PIj = Pollution Index for certain designations (j)

Lij = concentration of water quality parameters

Ci = concentration of laboratory test results

(Ci/Lij)M = maximum Ci/Lij value (Ci/Lij)R = mean Ci/Lij values

Water quality status can be determined based on calculating the Pollution Index (IP) score. The class value of groundwater pollution potential is divided into 4 pollution classes, namely:

0≤PIj≤1.0 = meet the water quality standard 1.0<PIj≤5.0 = lightly polluted

5.0<PIj≤10 = moderately polluted PIj>10 = heavily polluted Sampling and laboratory analysis

Laboratory analysis was carried out on wastewater, river water, and groundwater samples. All samples are tested for TSS, pH, and mercury (Hg⁺) levels. The determination of mercury (Hg⁺) levels was carried out using the dithizone colorimetry method, which forms complexes with metal ions and produces a colored solution whose intensity depends on the mercury concentration in the sample. Before the above procedure, the sample was digested using the Nitric Acid Digestion method according to Standard Method 3030-E regarding Nitric Acid Digestion of Metal Samples (APHA, 1998). Meanwhile, the Total Suspended Solid (TSS) test method is carried out gravimetrically to obtain a TSS estimate calculated based on the difference between total dissolved solids and total solids. The pH parameter was measured in situ using a HANNA-H198130 water checker. The analysis results of the level of contamination of wastewater, river water, and groundwater are then

compared according to the applicable laws and regulations. Locations for sampling wastewater, river water, and groundwater are presented in Table 3.

Table 3. Sampling coordinate.

No Location Latitude Longitude

1 Gold Tailing A

8°45'32.79"

117°30'56.18"

2 Gold Tailing

B 8°45'26.02" 117°31'38.49"

3 Upstream A 8°46'42.21" 117°31'44.42"

4 Midstream A 8°45'32.88" 117°30'58.27"

5 Downstream

A 8°44'36.54" 117°30'16.99"

6 Upstream B 8°46'1.77" 117°32'6.62"

7 Midstream B 8°45'12.26" 117°31'30.51"

8 Downstream

B 8°44'37.83" 117°31'15.25"

9 Dug well 8°45'36.18" 117°30'51.83"

10 Borehole well 8°45'38.22" 117°31'21.12"

Furthermore, the trajectory map (Figure 1) was used to make it easier to determine the sampling location. The track map comes from topographic maps and overlaid satellite images. This track map contains sampling points and observations of soil and rock types. The trajectory map is also used to analyze the source of pollution and where it leads.

Results and Discussion

Sources of groundwater and river pollution

The source of mercury pollution in gold processing in Lantung District, Sumbawa, comes from the activity of separating gold ore by the amalgamation process. In this process, the gold is separated from the binder where an amalgamation process carries out the gold ore, which is already in the form of fine grains, namely the process of binding gold metal from the ore using mercury (Hg⁺) water in a tube called a "gelundung"

(Figure 2). Mercury will automatically bind to gold (Veiga et al., 2006; Soe et al., 2022). Tailings or gold washing waste from the amalgamation process, which

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Open Access 4436 contains much mercury, is directly disposed of to the

environmental agency without being processed first so that the wastewater allows environmental pollution.

Separation of gold using the amalgamation method using mercury (Hg⁺) raises river and groundwater pollution problems (Esdaile and Chalker, 2018). Some

mercury bound to the gold is filtered and will separate the gold and mercury. The remaining dirty gold will usually be burned to get pure gold. Burning in the open will cause mercury vapor emissions, resulting in air pollution. The steam from burning gold will be wasted on the environment.

Figure 1. Sampling position and research trajectory.

Figure 2. Binding gold metal by "gelundung".

Based on Figure 3, it is known that one of the sources of mercury pollution in groundwater and river water may come from the gold processing process at the separation stage of amalgam with mercury (Hg⁺) from tailings fine sand. The potential for river water pollution is greater because it comes from the tailings waste of separating gold ore which is not carried out according to the correct method.

Figure 3. Amalgam filtering.

Meanwhile, an example of the condition of a gold- washed tailings storage pond is presented in Figure 4, while a flow chart of gold processing activities is shown in Figure 5.

Types of gold processing activities

The types of activity in gold processing in Lantung District are workers with the duties of stone pounders,

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Open Access 4437 spindle processors, gold screeners, and amalgam

burners. The amount of mercury used/day/gold processor is ± 25 mL/cub. In 1 gold processing location, there are 6-10 spools, and if in 1 day a gold processor can process gold 2 times, then the average use of mercury can be 150-250 mL at each gold processing location (Barakati, 2022). Complete personal protective equipment for workers in gold processing is still lacking. None of the gold processing workers uses it. People who work as gold processors are 25-40 years old. The community is not disturbed by the gold processing activities, and they live alongside gold processors. In this case, gold processors have no concern for the environment due to the lack of information they receive regarding the impacts/dangers resulting from mercury on the

environment/health (Johari et al., 2016). Figure 4. Tailings storage pond.

Figure 5. Flowchart of gold processing activity.

Pollution level based on pollution index (IP)

Analysis of the pollution level of wastewater, groundwater, and river water was obtained from the results of laboratory tests and analysis using the pollution index method for each sample which was

then calculated and given a score for each parameter.

Evaluation of the critical level of the quality of wastewater, groundwater, and surface water is carried out by calculating the pollution index value using the Water Pollution Index method (Minister of State for the Environment Decree No. 115, 2003).

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Open Access 4438 Wastewater quality evaluation

The results of water quality measurements in gold waste A are for TSS of 139.5 mg/L, while in gold waste B is 43.87 mg/L. The results of laboratory tests for the pH of wastewater A were 7.58, while the pH value of wastewater B was 7.27. Laboratory test results for mercury in wastewater A were 0.0119 mg/L, and in wastewater B, they were 0.0669 mg/L. Based on Minister of State for the Environment Decree No. 202 (2004), the maximum mercury level is 0.005 mg/L.

The test results significantly obtained exceeded the

quality standards. This wastewater sample was taken from 2 settling ponds located at the gold separation site. This settling pond is helpful in storing amalgamated wastewater. Wastewater that is stored in settling ponds is channelled into the river when an overflow occurs, and if there is no overflow, the wastewater is only allowed to seep into the ground, and some of it is channelled into the river body. The results of calculating the Pollution Index (IP) value obtained a value of 1.83 (lightly polluted) for wastewater A (Table 4), and wastewater B obtained an index value of 9.99 or moderately polluted (Table 5).

Table 4. IP calculation results in waste ponds A.

Parameter Value Quality Standards (Li) Ci/Li

TSS 139.5 mg/L 200 mg/L 0.69

pH 7.58 6-9 0.05

Mercury 0.0119 mg/L 0.005 mg/L 2.38

(Ci/LiX)R 1.04

(Ci/LiX)M 2.38

Pollution Index (PIj) 1.83

Status Lightly polluted

Table 5. IP calculation results in waste ponds B.

TSS 43.87 mg/L 200 mg/L 0.21

pH 7.27 6-9 0.15

Mercury 0.0669 mg/L 0,005 mg/L 13.38

(Ci/LiX)R 4.58

(Ci/LiX)M 13.38

Status Heavily polluted

Figure 7. Sampling of tailings wastewater.

River water quality evaluation

The condition of the river water in the study area shows that it flows well, so it is possible to carry out the sampling. Water sampling was carried out in 3 parts, namely the upstream part, which is a location that is not affected by gold waste; the middle part of

the river, which is a wastewater disposal site; and the downstream part, which is an area that has passed the disposal of gold processing waste. Government Regulation No. 22(2021) states that the maximum level of TSS for class II is 50 mg/L, the pH is between 6-9, and the maximum level of mercury (Hg⁺) is 0.002 mg/L. The results of laboratory tests indicate the presence of mercury contamination because the value of laboratory test results exceeds the value of environmental quality standards. Calculation of the water quality status of River A (Padesa River) in the upstream section (Table 6) shows a pollution index value of 8.25 (moderately polluted). Meanwhile, the results of calculations in the middle part of River A (Figure 8) obtained a pollution index value of 5.61 or moderately polluted (Table 7), and in the lower part reaches of River A an index value of 3.71 (lightly polluted, Table 8). Based on the analysis and laboratory tests, it is also known that the pollutant parameter with a high value is mercury (Hg⁺). In this case, the high mercury concentration (Hg⁺) in the upstream area of the Padesa River (A) is probably caused by the runoff of wastewater from processing activities around the upstream of the Padesa River.

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Open Access 4439 Table 6. IP calculation results in the upper of River A.

TSS 2.5 mg/L 50 mg/L 0.05

pH 7.84 6-9 0.22

Mercury 0.0221 mg/L 0.002 mg/L 11.05

(Ci/LiX)R 3.07

(Ci/LiX)M 11.05

Status Moderately polluted

Table 7. IP calculation results in the middle of River A.

TSS 3.5 mg/L 50 mg/L 0.07

pH 8.0 6-9 0.33

Mercury 0.015 mg/L 0.002 mg/L 7.50

(Ci/LiX)R 2.63

(Ci/LiX)M 7.50

Status Moderately polluted

Table 8. IP calculation results downstream of River A

TSS 2.5 mg/L 50 mg/L 0.05

pH 8.57 6-9 0.71

Mercury 0.0098 mg/L 0.002 mg/L 4.90

(Ci/LiX)R 1.88

(Ci/LiX)M 4.90

Figure 8. Sampling of water in River A.

In contrast, the low mercury concentration in the downstream area is due to mercury accumulating with river biota, such as macroinvertebrates, and deposited together with sediments along the Padesa River (Barakati, 2022). This fact is reinforced by the river's

water discharge which is quite large and carries heavy metal material from upstream to downstream, considering the type of flow in the form of a perennial stream, namely a stream that flows throughout the year. The sampling of river B water (Tiu Bangin River) is located in a different area from River A because the river flow is separated by hills, which have different springs, and the location where the gold processing is divided into 2 parts. In this river, sampling was carried out in the river at the time of the gold separation activity (Figure 9). The calculation of the pollution index in River B indicates a quality status between 1.01-2.62 (lightly polluted), as shown in Tables 9, 10 and 11.

Groundwater quality evaluation

Visually, the condition of groundwater in the study area looks clear and odorless. Groundwater in the study area is used for consumption, bathing, and washing clothes. Groundwater quality standards are adjusted to Minister of Health Regulations No. 32 (2017) concerning environmental health quality standards and water health requirements for sanitation hygiene purposes. In this regulation, the maximum

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Open Access 4440 level of mercury (Hg⁺) is 0.001 mg/L. Groundwater in

the study area is considered unsafe for use as drinking water in both shallow dugs (Figure 10) and drilled (deep) wells due to mercury contamination, as shown in Tables 12 and 13.

Figure 9. Sampling of water in River B.

Figure 10. Groundwater sampling.

The dug well, which is located at an altitude of 583 meters above sea level and has a groundwater depth of 3.5 m, causes pollutant substances to quickly reach the water table so that mercury pollution is detected above the quality standard.

Table 9. IP calculation results in the upper of River B.

TSS 2.5 mg/L 50 mg/L 0.05

pH 7.88 6-9 0.22

Mercury 0.007 mg/L 0.002 mg/L 3.50

(Ci/LiX)R 1.25

(Ci/LiX)M 3.50

Table 10. IP calculation results in the middle of River B.

TSS 5.0 mg/L 50 mg/L 0.10

pH 8.07 6-9 0.38

Mercury 0.0051 mg/L 0.002 mg/L 2.55

(Ci/LiX)R 1.01

(Ci/LiX)M 2.55

Table 11. IP calculation results downstream of River B.

TSS 2.5 mg/L 50 mg/L 0.05

pH 7.69 6-9 0.12

Mercury 0.0027 mg/L 0.002 mg/L 1.35

(Ci/LiX)R 0.50

(Ci/LiX)M 1.35

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Open Access 4441 Table 12. Groundwater IP calculation results (dug wells).

TSS 2.5 mg/L 50 mg/L 0.1

pH 6.70 6.5-8.5 0.1

Mercury 0.0016 mg/L 0.001 mg/L 1.6

(Ci/LiX)R 0.6

(Ci/LiX)M 1.6

Table 13. Groundwater IP calculation results (drilled wells).

TSS 2.5 mg/L 50 mg/L 0.10

pH 7.72 6.5-8.5 0.22

Mercury 0.0019 mg/L 0.002 mg/L 1.90

(Ci/LiX)R 0.74

(Ci/LiX)M 1.90

In drilled wells, mercury levels exceed the quality standard. This fact is probably because the drilled well, which is located at an altitude of 587 meters above sea level and has a groundwater depth of about 70 meters, is located next to a gold wash where the waste is

directly discharged to the ground surface. The process of contamination of the drilled wells occurs due to the frequency of infiltrated gold-washing wastewater that has occurred every day for the last 10 years, resulting in groundwater being contaminated with mercury.

Figure 11. Spatial distribution of river water quality status.

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Open Access 4442 Figure 12. Spasial distribution of groundwater quality status.

In determining the status of water quality, dug wells have a pollution index value of 1.2, which is included in the status of lightly polluted, the same as drilled wells having a pollution index of 1.44 (lightly polluted). The contaminated groundwater quality condition requires control to improve water quality so that it can still be utilized according to its designation (Boszke et al., 2002). Here, it is necessary to monitor water quality to determine the status of water quality temporally, which is then used as a basis for evaluating environmental influences and providing input for decision-makers, including giving warnings of pollution levels. Furthermore, in general, although the status of river water quality in the study area is classified as moderately polluted (Figure 11) and groundwater is classified as lightly polluted (Figure 12), the condition of all water sources in the study area is contaminated by mercury (Hg⁺). Accordingly, the impact of mercury on health and the environment needs to be immediately socialized to the community (Krisnayanti et al., 2016). The role of the government as a policymaker must be implemented because the effects of mercury do not have an impact now but accumulate so that the impact on health will only be felt at a later date (Basu et al., 2022).

Conclusion

First of all, gold processing activities that have taken place in Lantung District have been going on since 2008. Gold separation activities are processed using

mercury (Hg⁺) as an amalgamation mixture. The gold processing process starts with crushing the stones to filtering the aggregate with mercury which separates the raw gold. The use of mercury in the gold separation process is ±150-250 mL at each gold processing location. In this case, the entire gold processing process produces waste that pollutes water sources in the study area.

Laboratory test results show that all samples (water in tailings ponds, groundwater and river water) have been contaminated with mercury which exceeds the permissible quality standards. Nonetheless, the water quality status using the results of calculating the value of the Pollution Index (IP) in tailings shows a value range of 1.89-9.99 with light to heavily polluted status. Meanwhile, groundwater has an IP value range of 1.2-1.44 (lightly polluted), while river water has an IP value range of 1.01-8.25 (lightly to moderately polluted). In this case, groundwater is the water component that has the lowest IP value, so it is relatively the least polluted compared to other water sources.

Acknowledgements

The authors thank all the field teams who supported this study in the field data collection. The first author is also grateful to Mr Christover Barakati and Mrs Nurniati Topuh as his parents, who are morally and materially supportive.

The authors also thank the government of Luntung for helping and providing permits and accommodations during research implementation.

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