3. COD
Chemical Oxygen Demand. COD describes the level of water pollution by organic
compounds in marine and lake water. It is the amount of oxygen required to react (oxidize)an organic compound in water. The higher COD value means the higher level of pollution.

The Yuri-no-kai Research Group

Goyosui-ato Gaien Aigokai Research Group

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3.1. Longitudinal change of COD(Span average: with TRWKR, no rain)

Improvement

10 109764987131116151411

Improvement1413121110

Improvement

9 9910

Improvement

The number ofsample is less.

The number ofsample is less.

3 2 5 2 2

14 34 32 9 28

27 63 55 19 27

12 17 14 2 13

Minatoshinbashi
Breidge - OsekoBridge

Oseko Bridge Matsushige Bridge

Matsushige Bridge - Asahi Bridge - Johoku
Asahi Bridge
Bridge31 34 41 10 30

Johoku Bridge Sanage Bridge→
Injection point of TRWKR

COD(mg/L)

15

3rd Stage 1st Apr. - 30th Jun. 2008→
Meijo Treatment Plant

9Confluence of→Shinhorikawa River

The number ofsample is less.
→
Nagoya port

14121086420

2nd Stage 8th Sep. - 16th Dec. 2007
5th Stage 1st Apr. - 30th Jun. 200910 99 9The number ofsample is less.
4 9 13 2 8→Confluence of the Shonai River

1st Stage 22nd Apr. - 30th Jun. 2007
4th Stage 28th Sep. - 16th Dec. 2008201816Sanage Bridge Sakae Bridge■How has longitudinal COD changed?
・COD between Sanage bridge and Oseko bridge in 5th stage has got lower (=improved) than that of 1st stage (rightafter TRWKR).
・COD between the Sanage Bridge and the Johoku Bridge was 10mg/L. It got higher as down the stream
・COD in 1st, 3rd and 5th stage (from spring to early summer) was 8mg/L - 15mg/L. That in 2nd and 4th stage (fromfall to winter) was 7mg/L - 13mg/L.
→ COD at downstream of Sanage bridge from spring to early summer has been higher than that from fall towinter (except the result between Oseko bridge and Minato-shin bridge which has scarce data).

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3.2. Effect of TRWKR(1st stage - 5th stage, No rain)

The number of sample is less.
20864
208→Nagoya port

COD (mg/L)

10314

Minatoshinbashi
Number of Breidge - OsekoBridge
sample139918112

Oseko Bridge Matsushige Bridge

3013206

Matsushige Bridge Asahi Bridge

14121248

Asahi Bridge Johoku Bridge→Meijo Treatment Plant

1112151038→
Injection point of TRWKR

14Confluence of→Shinhorikawa River

16118

Johoku Bridge Sanage Bridge

10102267→
Confluence of the Shonai River

With TRWKR
Without TRWKR

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COD has been improved
between the Sanage bridge and the Asahi bridge

Sanage Bridge Sakae Bridge■Comparing COD values “with TRWKR” to “without TRWKR”, is there
any difference?
→ COD value has been improved between Sanage bridge and Asahi bridge byTRWKR.
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Column - COD COD describes the level of water pollution by organic compounds. The higher COD valuemeans the higher level of pollution.
We, HSC organized change of COD to catch up point-by-point or stage-by-stage. (ref. 3.1.)
As a result, we found that COD between the Sanage Bridge and the Oseko Bridge in the 1ststage (right after TRWKR) has got lower than 5th stage and that COD from spring to earlysummer was higher than from fall to winter.
This trend is same as transparency and correlate with an impression about water pollution. Itmeans that COD backs up change of sensuous impressions about water pollution.
Then we organized COD data classified according to whether TRWKR was run. (ref. 3.2)
As a result, COD between the Sanage Bridge and the Asahi Bridge “with TRWKR” hasbeen lower than that “without TRWKR”.

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