5. Smell
During the falling tide at spring tide, sludge floatedup and it was smelled

Addled egg smell near the Oto Bridgeat spring tide in Aug. 5th 200953

Sludge is appearing around the Gojo Bridge
Photo by NIT River Survey Group■ Report from the Nagoya Institute of Technology (NIT) River Survey GroupMay 26th, 2nd day of spring tide
Observation of SS and water quality at the Gojo and Naka Bridge
While the water level was high, it was transparent and we could feel the good effect ofwater transmission.
But as water level was getting low, it became black and SS increased drastically. Inaddition, black sludge rose up to the surface along the coast, and it got so smelly.
Although all the surface wasn’t covered by sludge and it seems better than before, theappearance was still bad with terrible smell. We could see that black things were
flowing like ink paintings.
So now, we are planning to find out where, what conditions of water level, and how
long time of the year, these bad phenomenon occurs. In addition, we wonder we could
survey which hours people feel uncomfortable at some bridges. Then it is considered
that, SS and water quality should be improved, if the water level be kept higher at thelower area too.

5.1. Generation Status of Smell①No smell②Smell a little③Smell7
780%

77870%

20100%

7⑤Smell too bad
26

10

1st to 5th Stage
671113

感
潮境界

39

86

30%
20%
10%

58
42
315685木曽川導水新堀川合流

40%

名城水処理

39
Ratio of ③-⑤ ishigher than the others

50%

1593160%

名古屋港

ratio of the odor level(%)

90%④Smell bad( With TRWKR, No rainfall on the day
and the day before )0%Minatoshin Brdg
～ Oseko Brdg

Oseko Brdg ～Matsushige Brdg

Matsushige Brdg
～ Asahi Brdg

Asahi Brdg ～Johoku Brdg.

88

16362299

In case ②“Smell a little” becomes tolerance level of citizens（Ref.）Japanese Offensive Odor Control Act
Control reference quantities at business property line isprovided as the concentration of specified offensive odor
substance corresponding to the odor intensity of 2.5 to 3.5 inIndication Method of 6-Level-Odor IntensityOdorIntensity012345

How it smells
No SmellSmelly engouh to sense itSmelly enough to find out whatkind of smell
Smell easily to realize
Bad Smell
Extremely Bad Smell

Johoku Brdg～
Sanage Brdg

Sanage Brdg～
Sakae Brdg

12114Note） 0％ data is not displayed■How was the odor level?
Ratio of ③-⑤ between Matsushige Bridge - Asahi Bridge
is high.
→ In the evaluation of impression of water pollution, ratioof odor between Matsushige Bridge - Asahi Bridge ishigher than other areas.
This result also shows that ratio of ③-⑤ in this area ishigher than the others54

5.2. Generation Status of Smell in each spanSanage Brdg
～ Sakae Brdg
100%

①No smell②Smell a little

3379

ratio of the odor level(%)

90%
80%

③SmellNumber of Data issmall

60%
50%

9480

7875

30%

( With TRWKR, No rainfall on the day and theday before )（Ref.） Japanese Offensive Odor Control Act
Control reference quantities at business property line isprovided as the concentration of specified offensive
odor substance corresponding to the odor intensity of
2.5 to 3.5 in Indication Method of 6-Level-Odor
Intensity
Odor50Intensity
0150

20%
10%

20%

3451st Stage
Sanage Brdg
～ Minatoshi Brdg
100%90%
ratio of the odor level(%)⑤Smell too bad

25131370%

40%④Smell bad

2nd Stage①No smell

61233％

258②Smell a little

4th Stage④Smell bad

88％

11 28％
10153760%50%③Smell

715％80%70%

3rd Stage

319711■How did the odor level change? （Average level
27％ between Sanage Bridge - Minatoshinbashi Bridge)

3640%
6130%
20%

3948

42

No SmellSmelly engouh to sense it
Smelly enough to find out whatkind of smell
Smell easily to realize
Bad SmellExtremely Bad Smell⑤Smell too bad

Slightly Improved3028

5th Stage

How it smells

3710%

・The odor condition on the 5th stage was slightly
improved compared with the 1st stage conductedat beginning of TRWKR.
・Ratio of ③ to ⑤ on the 1st, 3rd, and 5th stage,
which were held from spring to summer, ishigher than 2nd and 4th stage, which were heldfrom autumn to winter.

0%
1st Stage

2nd Stage

3rd Stage

4th Stage

5th Stage55

5.3. Generation Status of Smell( With TRWKR, No rainfall on theday and the day before )(Sanage Bridge ～ Minatoshinbashi Bridge)

ratio of the odor level(%)

Johoku Brdg
～ Asahi Brdg
100%
1790%
80%70%
3360%
50%
40%
2530%
20%
2510%0%
1st Stage

ratio of the odor level(%)

Asahi Brdg
～ Matsushige Brdg
100%
1190%
1380%
70%
1560%
50%
3740%
30%20%10%0%24
1st Stage①No smell②Smell a little③Smell④Smell bad

555884350

57

Number ofdata
is small43

Improved4642

2nd Stage①No smell⑤Smell too bad

3rd Stage②Smell a little

461350③Smell114235

4th Stage

5th Stage

調査数2

調査数13④Smell bad30⑤Smell too bad

411141238461616

Slightly49
deteriorated
50338

2nd Stage

3rd Stage

4th Stage

5th Stage

ratio of the odor level(%)

Matsushige Brdg
～ Oseko Brdg
100%90%80%70%60%50%
40%30%20%10%0%71393②Smell a little⑤Smell too bad

915213717deteriorated

80785933③Smell11111518

Oseko Brdg
～ Minatoshin Brdg
100%
90%80%70%60%50%40%
30%20%10%0%①No smell④Smell bad

29

1st Stage

ratio of the odor level(%)

ratio of the odor level(%)

Sanage Brdg
①No smell ②Smell a little ③Smell ④Smell bad ⑤Smell too bad～Johoku Brdg
100%
2910101590%
953080%
12Improved
3770%
382460%
50%
8240%
6830%
5349
4720%
10%0%
1st Stage
2nd Stage
3rd Stage
4th Stage
5th Stage

2nd Stage①No smell

43

Number of datais small

52

3rd Stage

4th Stage

5th Stage②Smell a little③Smell④Smell bad⑤Smell too bad

Number of data is small
50

100

1001006750

1st Stage

2nd Stage

3rd Stage

4th Stage

5th Stage

調査数2

Smell was improved
between Sanage Bridge - Asahi Bridge■ How did the smell condition change?
・The smell condition on the 5th stage was slightly
improved compared with the 1st stage beginning ofTRWKR.
・Meanwhile, the smell condition between Asahi Bridge– Oseko Bridge was deteriorated.

56

5.4. Kind of Smell in each span
Sakae Bridge～ Sanage Bridge
100%
90%

①Ditch Smell④Pulp Smell

3370%③Addled Egg Smell⑥OtherNumber of data issmall

2080%
ratio of kind of smell(%)②Sludge Smell⑤Beach Smell

502060%50%

10020■How did “kind of smell” change?
（Average of data between SanageBridge – Minatoshinbashi Bridge）

40%
6730%
20%10%

5040

No data0%
1st Stage

2nd Stage

Sanage Bridge～ Minatoshin Bridge①Ditch Smell④Pulp Smell

100%
3280%
1670%

3rd Stage

4th Stage②Sludge Smell⑤Beach Smell

51490%
ratio of kind of smell(%)( With TRWKR, No rainfall on theday and the day before )33332

5th Stage③Addled Egg Smell⑥Other1555544
9127

1560%
50%
40%
6530%

5455

55

3rd Stage

4th Stage

5th Stage・Ratio of “①Ditch Smell” is around50-60 %・Ratio of ”②Sludge Smell” on the 3rdand the 5th stage, which were heldfrom spring to summer, is higher thanthe 2nd and 4th stage, which were heldin autumn to winter・Ratio of ”③Addled Egg Smell” wasincreased on the 5th stage.

20%
10%

No data0%
1st Stage

2nd StageNote） 0％ data is not displayed

57

5.5. Kind of Smell (Sanage Bridge – Minatoshinbashi Bridge)( With TRWKR, No rainfall on the day and the day before )③Addled Egg Smell⑥Other13
6633

23

Number ofdata is small25

2633
63

No data42

Johoku Brdg
～ Asahi Brdg
ratio of kind of smell(%)

9532

1st Stage

100%90%80%70%60%50%40%30%20%10%0%

50
34

2nd Stage①Ditch Smell④Pulp Smell

3rd Stage

4th Stage②Sludge Smell⑤Beach Smell

1111
Number ofdata is small11

4010091

67

60
No dataAsahi Brdg
～ Matsushige Brdg
100%
90%80%70%60%50%40%30%20%10%0%

2nd Stage①Ditch Smell④Pulp Smell

1112

4
370

3rd Stage

4th Stage②Sludge Smell⑤Beach Smell

62
5③Addled Egg Smell⑥Other15832

2nd Stage314

3317755

49

No data

1st Stage

5th Stage

3rd Stage

4th Stage

5th Stage①Ditch Smell④Pulp Smell

Matsushige Brdg
～ Oseko Brdg
100%90%80%70%60%
50%
40%30%20%10%0%1338②Sludge Smell⑤Beach Smell③Addled Egg Smell⑥Other714
5

Number of27
data is small

38

Number ofdata is small

10067

49

43

2nd Stage

3rd Stage

No data

1st Stage

5th Stage③Addled Egg Smell⑥Other9

1st Stage

ratio of kind of smell(%)②Sludge Smell⑤Beach Smellratio of kind of smell(%)

100%
90%80%70%
60%
50%
40%
30%20%10%0%①Ditch Smell④Pulp Smell

Oseko Brdg
～ Minatoshin Brdg
ratio of kind of smell(%)

ratio of kind of smell(%)

Sanage Brdg
～Johoku Brdg

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%0%

①Ditch Smell④Pulp Smell

4th Stage②Sludge Smell⑤Beach Smell

5th Stage③Addled Egg Smell⑥Other50

Number ofdata is small
50

No data

1st Stage

2nd Stage

3rd Stage

4th Stage

5th StageNote） 0％ data is not displayed■ How did “kind of smell” change?
・Ratio of ”②Sludge Smell” between Asahi Bridge andMatsushige Bridge on the 3rd and 5th stage, which were
held from spring to summer, is higher than the 2nd and4th stage, which were held in autumn to winter・”③Addled Egg Smell” was reported on the 5th Stagebetween Sanage Bridge and Matsushige Bridge. Ratio of
this smell is higher in downstream area.
58

5.6. Kind of Smell in Each Span
( With TRWKR, No rainfall on the day and the day before )2nd to 5th Stage
100%
90%

70%

50

60%
50%
40%20%

5052

Minatoshin Brdg ～Oseko Brdg

Oseko Brdg ～Matsushige Brdg

“Ditch Smell”Increase73
5010%0%
Matsushige Brdg ～Asahi Brdg

Asahi Brdg ～Johoku Brdg.

Johoku Brdg～Sanage Brdg

1892746

庄内川導水

30%

“Ditch Smell”decrease
61③Addled Egg Smell⑥OtherInjection of TRWKR

ratio of kind of smell(%)

80%

Number ofdata is small①Ditch Smell②Sludge Smell④Pulp Smell⑤Beach Smell
2Addled egg smell slightly increased
4
7“Beach Smell” 841183452219322233“Sludge Smell” Increase
25

Sanage Brdg～
Sakae Brdg

Note） 0％ data is not displayed59

5.6. Kind of Smell in Each Span
■What kind of smell？
・Ratio of “Ditch Smell” in downstream of Johoku Bridge increased （50 % →70 %）.
・Between Jｙohoku Bridge – Oseko Bridge, ratio of “Ditch Smell” decreased(70 % → 50 %) and “Sludge Smell” increased (20 % → 30 %） towarddownstream.
・”Ditch Smell” was reported between Matsushige Bridge – Oseko Bridge.
・”Addled Egg Smell” was reported in downstream of Sanage Bridge. Ratio of
this smell increased a little between Johoku Bridge – Matsushige Bridge.
→It was found that ratio of “Ditch”, “Sludge”, and “Addled Egg” smell washigh between the Asahi Bridge – Matsushige Bridge, where ratio of odor in theevaluation of water pollution was worse than other spans. “Sludge Smell”
occurs especially when sludge rise up from river bed to surface and rolls up atlow tide. And “Addled Smell” is regarded to occur when it is hit by blue tide.

Column – Smell Now we explain “Smell” surveyed by the time of the 5th stage.
“Odor Level” is organized and classified in each span. （see 5.1.)
As this result, ratio of “Smell” and “Smell bad” was higher than other spans.
Next, “Odor Level” is organized and classified in each stage and each span. （see5.2、5.3.)
Results show that odor of the 5th stage was slightly improved from the 1st stage
held beginning of TRWKR and that ratio of “Smell”- ”Smell extremely bad” washigher in spring to summer season than in autumn to winter season.
In addition, in the 5th stage, smell was improved from the 1st stage between
Sanage Bridge – Asahi Bridge, and while odor was deteriorated between Asahi
Bridge – Oseko Bridge.
Finally, “Kind of smell” is organized and classified. （see 5.4、5.5、5.6.）
Between Sanage Bridge – Minatoshinbashi Bridge, ratio of “Ditch Smell” washigh (50-60 %). And it was reported that ratio of “Sludge Smell” in spring tosummer season was higher than in autumn to winter season reported. Besides,
ratio of “Addled Egg Smell” increased on the 5th Stage.
60

Among the spans, ratio of “Ditch Smell” near Johoku Bridge was the highest andgot lower toward downstream (70→ 50 %), while ratio of “Sludge Smell” washigher toward downstream (20→ 30 %).
Meanwhile, It was found that ratio of “Ditch”, “Sludge”, and “Addled Egg” smellwas high between Asahi Bridge to Matsushige Bridge, where ratio of odor was
higher than other spans in the evaluation of water pollution.
“Sludge Smell” occurs especially when sludge rise up from river bed into surface
and rolls up at low tide. And “Addled Smell” is regarded to occur when it is blue
tide*.
Note） It is considered that sludge smell occurs by the influence of sludge turbidity,water quality, temperature, tide* and so on.
＊Influence of tide（Example） drawdown of water level ： Sludge on the water surface let its smell
diffuse into the air
high flow velocity： Sludge rolls up and its smell diffuse into the air from thewater surface.

＊Blue tideBlue tide is the phenomenon that water surface color changes into creamy-blue or
creamy-white.
When oxygen is decreased by organics decomposition and hypoxic water masscomes into being、sulfate ion inside becomes reduced by sulfate reducer(anaerobes bacteria) and changes into sulfide ion.
Water containing sulfide ion generates hydrogen sulfide(H2S), which smells likeaddled eggs, and fine particles of sulfur or sulfur oxides (SOx) by reacting withoxygen in the air. These fine particles float around in the water and change water
surface color into creamy-blue or creamy-white by the reflection of sunshine.