Abstract
In January 2013, a high concentration of hexavalent chromium was detected in the meltwater at an urban park in Tokyo. A chromate manufacturing plant operated at this location until 1972. The highest concentration value showed was in excess of up to 740 times the Japanese regulation value (0.05 mg L−1). Although 40 years have passed since dumping, highly polluted groundwater is still found today. Heavy rain or snowfall is a trigger for the outbreak of Cr(VI) pollution in this area.
Introduction
Chromium is generally present in the trivalent and hexavalent oxidation states in the environment. Hexavalent chromium [Cr(VI)] compounds were widely used in industry for coloring, leather tanning, and metal plating. However, Cr(VI) is highly toxic to human beings and is known as a carcinogen. The WHO has reported that a lethal dose of water soluble Cr(VI) is 50–70 mg kg−1 of body weight [1]. Therefore, Cr(VI) is regulated in the environment, food, daily necessities, and industrial products in many countries. In Japan, Cr(VI), which is classified as an environmental pollutant, is strictly regulated by the Poisonous and Deleterious Substances Control Act, and an acceptable environmental regulation value is prescribed.
Until 1972, a chromate manufacturing plant operated in the Komatsugawa area, Edogawa ward, Tokyo. The chromium slag generated during manufacturing was disposed underground. The total amount of the chromium slag generated from 1940 until the plant’s closure is estimated to be 573,000 t. The disposal spot is known to contain 327,500 t of total chromium slag [2]. The slag was disposed in the Koto and Edogawa wards in Tokyo, and in Ichikawa city, Chiba, and so on. The environmental pollution caused by the disposed slag and resultant Cr(VI) has become a serious problem [3–5].
Kyu-nakagawa River divides Ojima-Komatsugawa Park into two areas: the western and eastern areas, which lie in the Koto and Edogawa wards, respectively (Fig. 1). The chromium slag is buried underneath Gathering Field, Wind Field, and Free-use Field of this park. In an attempt to deal with the chromium slag, the Tokyo Metropolitan Government applied a reduction to Cr(III) by FeSO4 treatment, and the industrial waste that contains the chromium slag was covered with soil. Since the chromium slag is covered with a large amount of soils, the field on this park is higher than the surrounding ground levels. In addition, the slag was partitioned by steel sheet piles to prevent leakage into the groundwater [2]. However, since then, Cr(VI) has often been found in groundwater around the park [3]. Recently, it was reported that Cr(VI)-contaminated groundwater flowed from Free-use Field (Jiyu-no-hiroba) in February and March 2011 [6], and from Gathering Field (Wansaka-hiroba) in April 2012. In this study, we examined Cr(VI) pollution in the meltwater, snow, soil and its causes at Ojima-Komatsugawa Park.
Location of Ojima-Komatsugawa Park (filled star) and sampling points (filled circle)
Materials and methods
Sample collection and pretreatment
Samples were collected around Ojima-Komatsugawa Park. The surface soil (0–5 cm) samples were collected on November 27, 2012, and meltwater, snow, and surface soil (0–5 cm) were collected on January 14–16, 2013. The sampling points are shown in Figs. 1 and 2. Figure 2 shows the sampling points at the northern site in the Gathering Field in the park and the vertical picture of the sampling location. Each sample was collected at the foot of the covered soil, as shown in Fig. 2. The samples were collected and stored in glass vials. After sampling, the soil samples were extracted with 4 mol L−1 HNO3 for 42 h at 25 °C, and the extracted solutions were centrifuged at 4000 rpm for 15 min and filtrated with a 0.22 μm membrane filter. The meltwater and snow samples were filtrated with a 0.22 μm membrane filter. These filtrate solutions were used for analysis.
Sampling points at a northern site in Gathering Field in Ojima-Komatsugawa Park and the vertical picture of the sampling location on the right side. The point no. 9 is outside this photograph area
Analytical methods
The total Cr concentration was measured by inductively coupled plasma atomic emission spectroscopy (720ICP-OES, Agilent Technologies). The Cr(VI) concentration was measured by 1,5-diphenylcarbazide (DPC) absorption spectrophotometry using a UV/VIS spectrophotometer (U-2900 Double Beam Spectrophotometer, HITACHI) at 542.0 nm [7]. The Cr(VI) standard solutions were prepared with chromium standard solution (Wako Pure Chemical Industries, Ltd.), and were appropriately diluted with pure water. The DPC solution was prepared with 0.5 g 1,5-diphenylcarbonohydrazide dissolved in 50 mL of water/acetone (2:3, v/v).
Results and discussion
Concentration of total Cr and Cr(VI)
Samples of meltwater, snow, and soil were collected in November 2012, and January 2013. The concentrations of total Cr and Cr(VI) in each sample are shown in Table 1. In January 2013, we investigated Cr(VI) pollution in Ojima-Komatsugawa Park. High concentration of Cr(VI) was detected in Gathering Field. In the collected meltwater samples, Cr(VI) concentrations were 16.9–37.0 mg L−1, except for sample nos. 5 and 6. Sample nos. 3 and 4 showed the highest Cr(VI) concentrations, 37.0 and 36.5 mg L−1, respectively. These values were in excess of up to 740 times the Japanese regulation value (0.05 mg L−1). Sample no. 7 was collected near the area where Cr(VI)-contaminated groundwater was reported in February and March 2011 [6]. We expected to redetect Cr(VI) at this location; however, this was not the case, suggesting that Cr(VI) detection varies by sampling point.
Yellowish snow was found in places at a northern site in Gathering Field. We suspected that snow was colored with the peculiar yellow color of Cr(VI). The yellowish snow was analyzed by on-site simplified qualitative analysis based on the diphenylcarbazide visual colorimetric method, and Cr(VI) was detected. Therefore, we collected yellowish snow (no. 8) and normal white snow as a blank (no. 9). The Cr(VI) concentration of the yellowish snow sample was 11.8 mg L−1, on the other hand, the total Cr concentration in the blank sample was 0.012 mg L−1, and no Cr(VI) was detected. The meltwater samples collected near the yellowish snow (nos. 1 and 2) also showed high Cr(VI) concentration, 23.4 and 16.9 mg L−1, respectively. Therefore, it can be concluded that this yellow color originated from Cr(VI).
In the soil sample collected at the point where the meltwater samples with high Cr(VI) concentration were collected (no. 16, Fig. 2), the total Cr concentration was very high, and the concentration of Cr(VI) was relatively high (330 and 2.19 mg L−1, respectively). In sample nos. 14 and 15, Cr(VI) was not detected, however, the total Cr concentration was high, 37.1 and 35.7 mg L−1, respectively. The Cr(VI) concentration in these samples is low despite the high total Cr concentration because Cr(VI) was reduced to Cr(III) by organic matter in the soil and FeSO4 [8], which was sprinkled as a reductant in April 2012. In addition, we have reported that the reduction to Cr(III) started just after Cr(VI) was adsorbed to soil; 20 % of the total Cr(VI) was reduced to Cr(III) in 24 h [9]. As Cr(VI) can be reduced to Cr(III) in soil immediately, soil polluted with a flowing Cr(VI) solution was reduced to Cr(III) at this location. As a result, the total Cr concentration showed high values. Although sample nos. 14 and 15 were collected on different dates, the total Cr concentration in these samples is approximately the same. This indicates that, at this location, Cr(VI) had not flown out between November and January 2013. In sample nos. 10–13, which were collected at Wind Field and another location in Gathering Field, the total Cr concentration was low, and Cr(VI) was not detected. The high total Cr concentration of nos. 14–16 indicates that Cr(VI) had been leaking at this location in the past.
Relationship between weather condition and elution of Cr(VI)
Cr(VI) was not detected on the fine weather sampling day in November (Table 1). This fine weather lasted until the next sampling day. However, on the next sampling day (January 14), there was heavy snowfall, and the precipitation observed was 68 mm. On this snowy day, a high Cr(VI) concentration was detected in the snow and meltwater. The field of this park is higher than the surrounding ground levels because the soil covering the Gathering Field is 6 m high. Furthermore, the location at which the highest Cr(VI) concentration was detected was at the end of the slope. The interval of the slope was 2 m in the vertical direction, and the altitude is the lowest in the Gathering Field, as shown in Fig. 2.
In another case, at the chromium slag disposal site in Ichikawa city, Chiba, Cr(VI) was detected in the covered soil surface and groundwater even after application of the reduction treatment, where the surface (<20 cm) of the slag was mixed with FeSO4 and covered by more than 1 m of soil [4, 5]. Four months after the reduction treatment, Cr(VI) was detected at values ranging from 876 to 2450 mg kg−1 at the surface of the covering soil and 6.1 mg L−1 in groundwater. In addition, 5 years later, Cr(VI) was detected at values ranging from 33.2 to 684 mg kg−1 at the soil surface. In 1976, Chiba prefecture reported that Cr(VI) could move in both chromium slag and covered soil [10]. These reports indicated that not all Cr(VI) in the chromium slag was reduced to Cr(III) by the reduction treatment, and that the covered soil and groundwater are still polluted with Cr(VI). Moreover, Cr(VI) is known to have high mobility because Cr(VI) is oxyanion in solution. In contrast, Cr(III) does not readily migrate in many environments and rapidly precipitates as Cr(OH)3 or FexCr1−x(OH)3, because it is chelated by organic molecules that are adsorbed to mineral surfaces [11–14]. Similarly, in our study area, it is suggested that not all Cr(VI) in the chromium slag has been reduced to Cr(III). The Cr(VI) that has not been reduced can move in both slag and covered soil, and can be released. However, how Cr(VI) is released from the slag or soil has not been clarified.
The chromium slag under the ground at Ojima-Komatsugawa Park included sodium chromate [4, 10], which is soluble in water. In addition, the detection of Cr(VI) was dependent on weather conditions because the Cr(VI) was not detected on the fine weather. We estimate that rainwater or meltwater triggers Cr(VI) release because it can elute Cr(VI) from the slag or soil. Cr(VI) in the soil and/or slag is eluted by rainwater, then eluted Cr(VI) moves through the soil to groundwater. It is suggested that continuous or heavy rainfall causes Cr(VI) to pollute groundwater, since the soil’s capacity to absorb rainwater becomes saturated. As a result, the groundwater level increases, and the groundwater flows out with eluted Cr(VI) solution. In case of intermittent or light rain, soil can absorb rainwater and the capacity of rainwater absorption of the soil is not saturated. Therefore, it is considered that a heavy rain or snowfall is a trigger of the outbreak of Cr(VI) pollution in this area. Moreover, the eluted Cr(VI) solution flows from higher to lower depths through drainage and in groundwater [15], which explains why higher Cr(VI) concentrations have been detected at lower points. Therefore, concentrated Cr(VI) is easy to be detected at the lowest point and continuous high precipitation triggers the outbreaks of Cr(VI) pollution in this area.
Conclusion
We investigated Cr(VI) pollution in Ojima-Komatsugawa Park. Until 1972, slag from a chromate manufacturing plant was disposed underground at this location. High levels of Cr(VI) contamination in meltwater were detected in January 2013. The highest concentration value was in excess of up to 740 times the Japanese regulation value (0.05 mg L−1). Results indicate that both heavy rain and snowfall cause elution of Cr(VI), which results in the ongoing pollution in Ojima-Komatsugawa Park.
References
- 1.
World Health Organization (1988) Chromium (Environmental Health Criteria; 61). World Health Organization, Geneva
- 2.
Tokyo Metropolitan Government (1977) 6kkakuromu kousai niyoru dojyoosenn taisaku houkokusho (in Japanese). Tokyo Metropolitan Government, Tokyo
- 3.
Kubota M, Asami T, Minamisawa K, Tsuchihashi K (1995) Chromium pollution of soils and sediments in the Komatsugawa area, Tokyo, Japan (in Japanese). Man Environ 21:15–18
- 4.
Asami T (1973) Environmental pollutions by chromium slag brought to the reclamated land by filling (in Japanese). J Sci Soil Manure Jpn 44:223–225
- 5.
Asami T, Sampei H (1977) Environmental pollution by chromium slag brought to the reclamated land by filling (part 2) (in Japanese). J Sci Soil Manure Jpn 48:323–328
- 6.
Ozaki H, Ichinose H, Tetsuda Y, Matsushima Y, Kawano F, Watanabe I (2011) Extreme chromium concentration in strong alkaline exudates that might have related with The Great East Japan Earthquake (in Japanese). People Environ 37:18–22
- 7.
Japanese Standards Association (2010) JIS K0102:2008 Testing methods for industrial wastewater (in Japanese). Japanese Standards Association, Tokyo, pp 260–267
- 8.
Wittbrodt PR, Palmer CD (1996) Effect of temperature, ionic strength, background electrolytes, and Fe(III) on the reduction of hexavalent chromium by soil humic substances. Environ Sci Technol 30:2470–2477
- 9.
Hori M, Shozugawa K, Matsuo M (2011) Improvement of speciation analysis for chromium by X-ray absorption fine structure and estimation of the reduction of hexavalent chromium in soil (in Japanese). Bunseki Kagaku 60:379–387
- 10.
Ninagi M (1979) Kuromuniyoru Dojoosen (in Japanese). In: Shibuya M (ed) Dojoosen no kikou to kaiseki. Sangyoutosho, Tokyo, pp 100–128
- 11.
Rai D, Sass BM, Moore DA (1987) Chromium(III) hydrolysis constants and solubility of chromium(III) hydroxide. Inorg Chem 26:345–349
- 12.
Sass BM, Rai D (1987) Solubility of amorphous chromium(III)–iron(III) hydroxide solid solutions. Inorg Chem 26:2228–2232
- 13.
James BR, Bartlett RJ (1983) Behavior of chromium in soils: V. Fate of organically complexed Cr(III) added to soil. J Environ Qual 12:169–172
- 14.
James BR, Bartlett RJ (1983) Behavior of chromium in soils: VI. Interactions between oxidation-reduction and organic complexation. J Environ Qual 12:173–176
- 15.
Satoh K, Furuno K, Hara Y, Okuda T, Takanashi Y, Nirei H (1983) The mechanism of groundwater pollution by Cr6+ at the Shimofusa Plateau, Chiba Prefecture (in Japanese). Mem Geol Soc Jpn 23:105–113
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Hori, M., Shozugawa, K. & Matsuo, M. Hexavalent chromium pollution caused by dumped chromium slag at the urban park in Tokyo. J Mater Cycles Waste Manag 17, 201–205 (2015) doi:10.1007/s10163-014-0243-0
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Keywords
- Hexavalent chromium
- Pollution
- Chromium slag