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Tuesday, August 5, 2008

Impacts of Hyperacid Water from The Ijen Crater Lake, East Java

Ecological and Human Health Impacts of Hyperacid Water from the Ijen Crater Lake, East Java, Indonesia

Budi Widianarko1, Ansje Löhr2

1Faculty of Agricultural Technology, Soegijapranata Catholic University,
Jl. Pawiyatan Luhur IV/1 Semarang 50234, INDONESIA
(E-mail:
widianarko@unika.ac.id; Tel.:62-24-8441555; Fax.:62-24-8445265)

2Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1085,
NL-1081 HV Amsterdam, The Netherlands

Abstract
The Ijen crater lake in East Java, Indonesia is one of the world’s largest natural reservoirs of hyperacid water (30-40x106 m3). This hyperacid water has a pH less than 0.3 and contains extremely high concentrations of many elements. It is the source of extremely acidic and metal polluted river Banyupahit (45 km). The river water, with a pH between 2.5 and 3.5, has been used by the inhabitants of the watershed area for domestic as well as agricultural purposes. This paper describes the impacts of the effluent of the Ijen Crater lake on the ecosystem as well as on human health. Based on analyses of metal (using ICP-MS) and other elements it was found that the river water contains a high load of SO4, NH4, PO4, Cl, F, Fe, Cu, Pb, Zn, Al and other potentially toxic elements. Metal concentrations in the river water exceed the Indonesian and international quality standards. The food-webs in the acidic parts of the river are highly underdeveloped. No invertebrates were present in the acidic water, and at pH 2.3 to 3.3 only chironomids were found. A lower pH was also found in soils irrigated with acid water compared to those irrigated with neutral water. This leads to decreased yields of cultivated crops. Increased levels of metals, especially Cd, Co, Ni and Mn were found in various foodstuffs, but still under the maximum permissible levels. Fluoride exposure is of the utmost concern as manifested in high prevalent of dental fluorosis among local residents.
Key Words: Crater Lake, Hyperacid, Ecosystem, Human

I. Introduction
Volcanic crater lake is one of natural sources of environmental pollution. Lakes developed in volcano craters can become highly acidic due to the influx of volcanic gases, leading to one of the most extreme natural environments on earth. Water from volcanic crater lake with a pH value as low as 0.0 has been reported1. Acid crater lakes present in many parts of the world, e.g. in Japan, Mexico, Italy, Costa Rica, New Zealand, Argentina and Indonesia2-6.

In Indonesia, environmental pollution due to natural sources is rarely studied. This can partly be explained by the fact that the country’s pollution control regime is more oriented toward anthropogenic pollution. Most existing legislation only cover pollution caused by human activities, especially industry7.

This paper deals with an hyperacid pollution of volcanogenic origin in Indonesia, i.e. the hyperacid water of the Banyupahit-Banyuputih river originates from the crater lake Kawah Ijen in East-Java. This very low pH water carries a significant load of pollutants, so it has raised a great deal of concern8. Actually, volcanogenic acidification is also found in other areas in Indonesia, such as the Patuha volcano in West Java which has been acidifying the water of a tributary of the Citarum river9 , however the Banyupahit-Banyuputih river is of special concern since the hyperacidic water is used for irrigation in the 3,564 ha of agricultural land in Asembagus area. Sugar cane and rice are the main crops cultivated in the area. In addition, the water is also used by approximately 50,000 local inhabitants for drinking and other domestic purposes.

As indicated by Delmelle10 the hyperacid water can have negative impacts on the agricultural land. In addition to its acidity, Heikens11 mentioned that water of the Banyupahit-Banyuputih river contains fluoride up to 15 mg/l, which is above the Canadian guideline value for irrigation water of 1 mg/l12. Water from many wells in the area also contain fluoride at concentrations above the WHO guideline value of 1.5 mg/l for drinking water13. Field observation showed that a large portion of the human inhabitants in the area suffers from tooth fluorosis, a problem which has been recognized since as early as a quarter of century ago14.
The aim of the present paper is to provide an actual description of the impacts of hyperacid water from the Kawah Ijen crater lake on ecosystem and its human inhabitants.

II. The Location
The Indonesian archipelago has 129 active volcanoes, approximately 13% of the world's total active volcanoes. There are 21 active volcanoes and seven crater lakes, on Java alone15. The Ijen volcanic area is situated in the eastern tip of Java (Figure 1). The Ijen crater is an active stratovolcano (2,346 m above sea level) located on the rim of the caldera, which contains a turquoisecoloured lake. Up to now, the crater is still active, it is under the continual control of the Volcanological Survey of Indonesia (VSI). In case of an eruption, the lake will pose a potential threat to a vast area covering three regencies, i.e. Bondowoso, Banyuwangi and Situbondo16.
The Ijen system consists of a 16-km-wide caldera, the Ijen plateau, with an altitude between 850 and 1500 m. The active volcano Ijen is located on the southeast side of the caldera belt. The Ijen crater lake, one of the world’s largest (30-40 x 106 m3) pools of hyperacidic volcanic water (pH < 0.3)17. The area is subject to a tropical climate, characterized by dry and rainy seasons, with a much higher precipitation in the caldera than in the coastal areas. Rain intensities on a daily basis in the caldera can be as high as 100 mm. In 1921, a dam was built on the western crater belt to control the water level in the lake and to regulate the outflow of hyperacidic water in the downstream area,. For several decades, the dam’s sluices have not been used as the water level remained below the dam18. However, water from the lake was and still is leaking. The acidic water leaks through the rock basement at several points below the dam. This water is the main source of the Banyupahit river, with a total discharge of only 50 l/s at its origin. A 45 km long stream, the Banyupahit river (“Bitter River”) flows westward along the volcanic slopes and passing through two small villages, Paltuding and Watucapil. Downstream of Watucapil a spring contributes moderately acid and polluted water lead an increase of discharge up to hundreds l/s.

Figure 1. Map of the Ijen ecosystem, showing the location of the Kawah Ijen crater lake The river is diluted mainly by two tributaries within the Ijen caldera, the rivers Kali Sat and Kali Sengon, both near the village of Blawan. After dilution by the Kali Sengon, the river is called Banyuputih river (“White River”) and flows down a 50 m high waterfall at the caldera rim after which it flows through a steep, narrow gorge. The pH of the water increases to 2.5 – 3.5 when the river leaves the plateau. After leaving the Ijen caldera, the Banyuputih river flows through the largest single expanse of forest on Java (60,000 ha). This forest is part of the Ijen-Malang-Raung nature reserve that covers an area of 130,000 ha. Only a little dilution of the river water between the waterfall and a downstream irrigation dam at Liwung has been observed visually, but information on chloride concentrations showed that more dilution occurs, most probably at the floor of the waterfall. At the downstream, twenty kilometers from the caldera rim the river water is used for irrigation and domestic purposes. Most of the river water is channeled into the existing irrigation system at the village of Liwung. The original riverbed follows its way to the Strait of Madura and serves as an overflow discharge channel when flash floods occur during the rainy season. Asembagus is one of seventeen districts in the Situbondo regency. The district of Asembagus is laid at an elevation of 0 to 1,000 m above sea level. It has approximately 130,000 inhabitants spread over subdistricts Asembagus (46,127), Banyuputih (47,760) and Jangkar (35,168). Total area of Asembagus is 11,874 square kilometers, 70% of which is upland with slopes of more than 40%. The agricultural land in Asembagus is approximately 5,500 hectares (3,000 hectares of irrigated rice field and 2,500 hectares of dry agricultural land). Agriculture is the most important economic sector in Situbondo, involving 60% of the total productive age group of the population. The four most important agricultural products of Situbondo are maize, rice, sugar cane and mango19.

III. Pollutants
Measurements of pollutants contents of water from the Ijen crater lake and the Banyupahit-Banyuputih river, as well as from the neutral Kali Sengon river were conducted in 2000. A detailed account of the samplings and chemical analyses of water can be found in previous publication8. The procedures of chemical analyses were summarized below. At each sampling site, pH and conductivity were measured in triplicate using a Multi-line P4 (WTW) aquatic field kit. Nitrate was measured using the cadmium reduction method (Hach method 8171); sulphate using the Sulfa Ver 4 method (USEPA method 375.4, Hach method 8051); chloride using the mercuric thiocyanate method (Hach method 8113); reactive phosphorus was measured using the molybdovanadate method (Hach method 8114). TOC was measured with a Dohrmann DC-190 TOC analyser; trace-elements by a HP4500 ICP-MS; major-elements (Ca, Al, Fe) by a Varian Liberty II ICP; F, Na and K with the Dionex DX120 ion chromatograph. Total suspended solids (TSS) were measured by filtering 500 ml of sample over a 0.22 µm pore-size filter. For the analysis of alkalinity and acidity, water samples were collected and stored at 4ºC before analysis. Acidity was determined by titration to pH 8.3 (APHA 1995) with NaOH (Merck, Darmstadt, Germany, p.a., 99% pure). Alkalinity was measured by titration to a pH of 4.3 (APHA 1995) with H2SO4 (Merck, Darmstadt, Germany, p.a., 95.0% pure).

Result of physico-chemical measurements of the water from upstream to downstream of the Banyupahit-Banyuputih river is presented in Table 1. The pH of water from the crater lake is less than 0.3. Paltuding, close to crater lake, and Watucapil, 8 km downstream, in the most acidic stretch of the river have a pH of 0.7. Blawan is located on the Ijen plateau directly under the confluence of the neutral river Kali Sat with the Banyupahit, which shows a strong increase in pH up to 2.9. The neutral river Kali Sengon, with pH 7.7, confluences with the Banyuputih just before the waterfall, which is the verge of the caldera. Site Hutan, with water of pH 3.2, is located in the forest (not accessible by road) and was sampled in July 2001 during a 4-day expedition8. Twenty km downstream of the caldera rim the river water, with pH of approximately 3.3, is used for irrigation and household purposes in the Asembagus irrigation area. Conductivity of the water seems closely associated with pH. Extremely high conductivity values (up to 110 mS/cm) were found at the most acidic sites, Paltuding and Watucapil. The increase of pH along the first 20 km toward the waterfall corresponds with a decreased conductivity. Very high concentrations of phosphate, chloride, sulphate, nitrate and ammonium measured at the most acidic sites, Paltuding and Watucapil (Table 1). At downstream sites, i.e. Blawan, Hutan and Liwung, concentrations of these substances are one or two orders of magnitude lower. The lowest concentrations of these compounds are found in the neutral Kali Sengon river.

Very high acidity is measured at most acidic sites (around 500 mg CaCO3/l) and decreases from 9.9 at Blawan to 4.7 mg CaCO3/l at Liwung. Alkalinity of the water in the Kali Sengon is 0.95 mg CaCO3/l. At all sites, the oxygen content is close to saturation. No clear pattern is demonstrated by concentrations of total suspended solids (TSS) and total organic carbon (TOC). Lowest TSS is found at Blawan and while the highest is at Liwung. Values of TOC vary between 1.92 mg/l and 6.43 mg/l in the Banyupahit, with the lowest values found at Liwung and the highest at Blawan. In the Kali Sengon, TOC is 5.07 mg/l. Observations in the laboratory suggest that there is significant inter-location variability of the contribution of mineral and organic contents to TSS8.

The concentrations of elements and compounds in the Banyupahit-Banyuputih river exceed water quality standards (Table 2). The concentrations of SO42-, F, Al, Fe and Mn are particularly high. A combination of low pH and high concentrations of many elements/compounds poses a threat to the river ecosystem.

Table 2 shows that most concentrations of metals in water of Banyupahit-Banyuputih river, at the upstream and even downstream sites exceed the maximum permissible levels according to the Indonesian Government Regulation for water used for irrigation and other agricultural purposes and the FAO guideline values for irrigation water. Concentrations of iron and aluminum are extremely high.

IV. Effects on Ecosystem
Ecological risk assessment is a process that assesses the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors21. As an essential component of ecological risk assessment, biological monitoring can describe present biological conditions and provides the means for comparing polluted with unpolluted conditions. Biological monitoring of the macroinvertebrate communities was therefore performed to obtain insight into the ecological characteristics of the ecosystem.

The abundance and diversity of macroinvertebrates, algae and diatoms was extremely low at the acidic sites. The invertebrates and algae found in Kali Sengon, however, characterized a healthy ecological community according to the EPA Q value22. Combination of the high acidity and high load of metals and other elements/compounds is toxic to most organisms (Table 3). Moreover, angiosperms as well as fish species is completely absent along the entire stretch of the Banyupahit-Banyuputih river. A detailed discussion of the results of this biomonitoring can be found in Löhr et al (2005)23. Since the Banyupahit-Banyuputih river passes through the national park a wide variety of animals, such as birds and mammals, including some red list species, might use the water occasionally. As yet, however, the adverse effect on any other wildlife in the national park is still not known.

As mentioned previously, the river water is used for irrigation in the Asembagus agricultural area. Approximately 3,564 hectares of Asembagus irrigation area are irrigated using the hyperacidic water from Banyupahit-Banyuputih river. The continuous input of acidic water leads to a dramatic drop of soil pH up to a around 3.524. Furthermore, the continuous input of acid and inorganic elements has also changed the soil chemistry, causing nutrients losses (e.g. NH4+, Ca2+, K+, Mg2+ etc), strong leaching of Fe and Mn and the accumulation of elements to toxic levels, particularly Al25. Local farmers and irrigation authorities reported a yield loss of rice more than 70 % in recent years, due to the increased acidity of the irrigation water which seems to associate with the decrease of the river’s baseflow discharge8. Low precipitation on the Ijen plateau seems to correspond with low pH of the Banyuputih at Liwung and high dissolved metal concentrations.

During the period 1980-1989, the average annual precipitation was 2437 mm with an average of 143 rain days. Much lower average annual precipitation, however, was reported in 1990 –1999, i.e. 1447 mm, with an average of 115 rain days8. Another explanation for the loss in rice yields is aluminum toxicity. Al concentrations in the irrigation water far exceed water quality standards (Table 2). In the Asembagus irrigation water, the total dissolved (filtered over 0.45 µm) Al concentration averaged 64 mg/l. Al is known to cause phytotoxicity at concentrations exceeding 10 mg/l, especially due to phytotoxic Al species such as Al3+ which is dominant at low pH conditions.

V. Effects on Human Health
Human can be exposed to metals in the environment directly via inhalation, soil ingestion, and dermal contact, and indirectly via food products and drinking water. Dietary exposure is dependent on the daily intake. In the Asembagus irrigation area two most important pathways of intake have been identified, i.e. through drinking water (from the river water or wells), and consumption of food crops from land irrigated with the river water11. The acid irrigation water contain Fe, Mn and especially Al with concentrations exceed the guideline values for irrigation water (Table 2). Elevated levels of various elements (especially Cd, Co, Ni and Mn) were measured in crops produced in the Asembagus area, but these concentrations were still within normal ranges11. In a total diet study, the mean total daily intake of a broad range of elements by inhabitants of the Asembagus irrigation area was estimated and compared with the Tolerable Daily Intake (TDI) and the Recommended Nutrient Intake (RNI) values. It was concluded that the intake of essential and non-essential elements was unbalanced, but that the total intake of individual elements did not pose a risk to human health11. However a deficient intake of Ca, Fe and Zn was observed, which is common for a rice- and vegetable based diet. Of all elements and compounds present in the drinking water, fluoride presents the most acute threat for human health.

In the Asembagus area, dental fluorosis (discoloration of teeth as they become porous and brittle) is observed among the majority of the local residents. In general, mild forms of dental fluorosis can be manifest at drinking water concentrations of fluoride of around 1.5 mg/l, whereas skeletal fluorosis (deformities of the skeleton) can occur at above 4 mg/l26. The total daily intake can explain the reported prevalence of dental fluorosis at locations with low concentrations of fluoride in drinking water11. Concentrations of fluoride in the river water and many water wells in the Asembagus area are higher than the guideline value of 1.5 mg/l of the World Health Organization27 for F in drinking water. A hazard map for the area showed not only a high risk for dental fluorosis among children, but also a considerable risk for skeletal fluorosis among adults11. VI. Concluding Remarks In summary, natural pollution caused by the Kawah Ijen crater lake impacts three subsystems: agriculture, human health and the river ecosystem. It is clear that the pollutants concentrations of Banyupahit-Banyuputih river water by far exceeds all standards for drinking, irrigation and river water. However, unlike most polluted river systems, it has only one driving force, i.e. the water from the Kawah Ijen crater lake. Its extreme acidity and high loads of elemental pollutants are the ultimate cause of the agricultural loss, as well as health and ecological deterioration in the area.

Pollution and acidification are directly related to the Kawah Ijen and it seems logical to deal with the problem at its origin. To reduce the effects of pollution, the most desirable option would be to remove the acidic water. In this direction, feasibility of several alternatives for the improvement of the water quality of the Banyupahit-Banyuputih river can be appraised , including (1) closure of seepage points, (2) dilution of the Banyupahit-Banyuputih water, (3) alteration of the flow regime, (4) (pre-) treatment of acidic water, (5)water defluoridation, (6) restoration of soil acidification. Eliminating the acidic water would mitigate social and economic issues and would eliminate agricultural problems. However, both the soil ecosystems in the Asembagus irrigation area as well as the river ecosystem would need a considerable period of time (months) to recover from the acidity28.

Considering the complexity of the problem, however, priorities should be given to increasing the public’s awareness of the problem and to seeking solutions to improve the water quality and the provision of safe drinking water. The serious health risks in the Asembagus irrigation area should be dealt with, first of all by providing an adequate water supply. The provision of drinking water to children is especially important since dental fluorosis develops until the age of 6 to 8 years.

The Ijen problem, however, seems too large a problem for a local government to deal with and, therefore, representatives of the provincial as well as the national government should also be involved. We therefore conclude that a dissemination activity would be the best first step towards risk reduction. Through this activity, awareness of all stakeholders can be raised, which later will enable them to jointly identify options to improve provision of safe drinking water and technological solutions to improve water quality. In this instance, a WOTRO-supported dissemination activity has been in progress.

Acknowledgments
Data used in this paper is obtained mainly from a study supported by The Netherlands Foundation for the Advancement of Tropical Research (WOTRO), residing under the Netherlands Organization for Scientific Research (NWO) (project number WAE 84-465) and the Society for the advancement of research in the tropics (Treub/Maatschappij).

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