new general estimation of river pollution using new diatom

Jap. J. Limnol. 44, 4, 329-340, 1983.

New General Estimation of River Pollution Using New Diatom

Community Index (NDCI) as Biological Indicators Based on

Specific Composition of Epilithic Diatoms Communities,

Applied to Asano-gawa and Sai-gawa Rivers in

Ishikawa Prefecture.

Michiaki SUMITA and Toshiharu WATANABE

Abstract

WATANABE (1982) developed an equation to obtain the river pollution index (RPIB) by which he tried to assess the general state of river pollution. This equation is based upon the water quality chart obtained from biological assessment. The water quality chart, however, only indicates the distribution of area with different degrees of water pollution (from 4 to 6 degrees). Accordingly WATANABE (1981) developed the diatom community index (DCI) based on the specific composition of epilithic diatom communities at each station. This index is based on his idea that the degree of water

pollution in rivers actually changes gradually and continuously and that they, therefore, can not be classified into some definite areas with numerical degrees in itself. In this study we developed a numerical index (RPID) to assess the river pollution by using a new

diatom community index (NDCI) based on the specific composition of epilithic diatom communities.

1. Introduction

Both the Asano-gawa and Sai-gawa rivers

run through Kanazawa City (population 420,000) .

The River Asano-gawa flows from Mt. Zunnoyama, which is situated in the

southeastern part of Kanazawa, runs north-ward through the northeastern part of the

city and empties into Lake Kahokugata. The drainage basin has an area of 369.1

km2 and the length of the main stream is

28.9 km. The River Sai-gawa rises from Mt. Naradake, runs through the central

part of the city, joins the River Fushimi gawa, a tributary of the River Sai-gawa it the suburbs, and flows eventually into the

Japan Sea. The drainage area is 256.3 km2 and the length of the main stream is 34.3

km. Kanazawa is famous for its natural beauty

and historical charm. Both the River Asano-gawa and the River Sai-gawa were

used to add limpid beauty to the landscape. Since about 1960, however, river pollution

has become remarkable in the middle and

lower courses of these two rivers, where

water pollution has recently been a serious

problem. The leading cause for the pollution seems to be the very large inflow of domestic sewage caused by the development of Kanazawa city with its growing of pollution.

Other conceivable factors are as follows:

(1) The decrease of flowing water in the middle and lower courses due to the storage in the Sai-gawa and Uchi-kawa

Reservoirs.

(2) The inflow of industrial waste water in the lower courses of the River Sai-

gawa. (3) The inflow of drain water from sewage disposal in the middle courses of the River Asano-gawa. Kanazawa City sewage work began in1973. By 1981, in 65% of the planned area

it had a sewage system, which has begun

to effect good sewage removal.

2. Stations and Method

The river surveys were done at 11 stations in the River Asano-gawa and at 9 stations in the River Sai-gawa involving two tribu-taries, the River Fushimi-gawa and the River Junin-gawa. These stations of the

330 New Diatom Communiy Index

two rivers are the same ones where WATANABE obtained samples in 1973. At the stations from 1 to 7 in the River Asano-gawa and from 1 to 6 in the River Sai-gawa, epilithic algae were collected from flat upper surfaces of submerged stones parallel to the surface of the water, about 15-20 cm deep (Figure 1).

cleaned with sulfuric acid and potassium

permanganate and mounted in Caedax. Species were identified based on the

description of CLEVE-EULER (1951-1955), HUSTEDT (1930, 1927-1966), KAMIJO and WATANABE (1973), KOBAYASI (1964, 1968), PATRICK aild REIMER (1966, 1977) and WATANABE (1971).

3. Results and Discussion

(1) Water temperature and pH The water temperature and the pH observed on surface water at each station are shown in Table 1. The water temper-ature tended to be a little low in the upper course of the river, where they run among the mountains. The pH of the River Sai-

gawa was slightly higher than that . of the River Asano-gawa. The BOD values shown in Figure 2 are the annual averages pub-lished by the Environmental Division of Ishikawa Prefecture from 1976 to 1980 at three chosen stations of the two rivers.

Fig. 1. Sampling stations in the River Asano-

gawa and the River Sai-gawa.

At the stations in the lower courses of the two rivers, except those mentioned,

water was stagnant, so collection was made

on the concrete enbankment facing water. The diatoms in these samples were

(2) Epilithic organisms (except diatoms) The communities of epilithic organisms at each station were shown in Tables 2 and 3. Zoogloea sp. and Sphaeyotilus natans, species of bacteria, gradually increased down stream in both rivers at stations nearer to Kanazawa - City. They were especially numerous at stations 8 and 9 of tributaries and at station 7 where the water of tributaries flowed into the main stream of the River Sai-gawa. Homoeothyix janthina, a species of Cyanophyceae, was found in the upper and middle courses but not in the lower courses of both rivers

Table 1. Water temperature and pH at each sampling station of the River

Asano-gawa and the River Sai-gawa.

SUMITA and WATANABE 331

SUM.ITA and WATANABE 335

Fig. 2. The change of the annual averages of the BOD from 1973 to 1980 at three chosen

stations of the River Asano-gawa and the River Sai-gawa.

where the water was more polluted. The species was more abundant in the River Asano-gawa than in the River Sai-gawa. The taxon is a representative one in almost all rivers in Japan. Its high frequency of occurrence indicates that the latest water quality of the point is Q-mesosaprobity or oligosaprobity (WATANABE, 1975 a). Oscil-latoria formosa, a species of Cyanophyceae, is more widly distributed than the former species. Stigeoclonium lubricum, a species of Chlorophyceae, is a biological indicator of water quality from Q-mesosaprobity to a-mesosaprobity (WATANABE, 1975 a). This species was found comparatively frequently at many stations of both rivers.(3) Diatoms We identified 19 genera 62 taxa in the River Asano-gawa and 16 genera 55 taxa in the River Sai-gawa. The number of taxa belonging to two genera Navicula and Nitzschia was found to be greater than any number of taxa belonging to the other

genera.

The relative frequency of each diatom taxon at each station was shown in Table

4 and 5. At each station, the taxon with

greatest relative frequency was determined to be the representative taxon here.

4, Biological Assessment of Water

Quality

The biological assessment of water quality in River Asano-gawa and Sai-gawa was undertaken in 1981. Figures 3 and 4 shown the water quality of the River Asano-gawa and Sai-gawa in 1981 in comparison with that of 1973 (KAMIJO and WATANABE, 1973, 1974; WATANABE, 1975b).

In 1981, two stations were added on the

upper courses of the River Asano-gawa. Figure 3 shows that the water quality of

the River Asano-gawa has improved in upper and middle courses but has markedly deteriorated in the lower courses. Figure

4 shows that the water quality of the River Sai-gawa also has the same worsening

tendency in the lower courses.


Fig. 4. The water quality chart by biological assessment of the River Sai-gawa in 1981

(compared with that of 1973).

Fig. 3. The water quality chart by biological assessment of the River Asano-gawa in

1981 (compared with that of 1973),

5. Assessment of River Pollution by Computing Formula Based upon the New Diatom Community Index (NDCI)

(1) Objective Formerly, the degree of river pollution was judged by the average of BOD values obtained at several selected stations of each river. On the other hand, the water quality chart by biological assessment shows the areas in which different degrees of water

pollution are obtained. The chart showing these areas with different degrees of water

pollution in the stream provides important information from the view-point of nature conservation and anti-pollution counter-measures. The water quality chart based on the data obtained at appropriately chosen stations, where water quality changes remarkably due to the inflow of sewage

and tributaries, not only shows the present condition of the river pollution but also may provide us with effective preventive methods against river pollution. Although this water quality chart obtained by the usual biological assessment can show the present condition of river pollution in detail, an accurate comparison of the degree of pollution between rivers different in length is im-

possible by the former method. Therefore the authors attempted to find a new method that could determine the range of the degree of pollution in the water course of the stream and also compare the degrees of

pollution in rivers of different length, using the River Pollution Index (RPIB) in which the maximum rating is loo.(2) Numerical assessment of river pollution WATANABE (1982) developed the following equation for obtaining figures based upon the water quality chart by using the biological assessment.


Table 6. RPIB based upon water quality chart by biological assessment in the River Asano-gawa and the River sai-gwa.

Table 7. The sum of relative frequencies of the tolerant taxa, indifferent taxa,

intolerant taxa and the value of NDCI at each sampling station of the

River Asano-gawa and the River sai-gawa.

River Asano-gawa

RPIB: River pollution index. Maximum rating is loo.

19m : The percentage of the total length of j9-mesosaprobic water sections

to the total length of the stream surveyed.

am, pp, ap are obtained in the same way as Im. The error is 1/20 of the figures representing the percentage of oligosaprobic water, due to the fact that the oligosaprobic degree was not classified into a-oligosaprobic and ;9-oligosaprobic. The river pollution indexes of the River Asano-gawa and the River Sai-gawa com-

puted from formulas (1) and (2) were in

Table G. This table shows that in 1981 the River Asano-gawa became cleaner but

the River Sai-gawa became more polluted

than in 1973. The River Sai-gawa was cleaner than the River Asano-gawa both

in 1973 and 1981. But they are merely a numerical presentation of areas with five

different degrees of saprobity. The degree

of accuracy of this RPIB is the same as that of the biological chart.

(3) New method of numerical assessment of river pollution using DCI The water quality chart, however, only indicates the distribution of areas with different degrees of water pollution (from


4 to 6 degrees). Accordingly, WATANABE

(1981) developed the Diatom Community Index (DCI) based on the specific com-

position of epilithic diatom communities at each station. This index is based on the notion that the degree of water pollution in rivers actually changes gradually and continuously and that they, therefore, cannot be fundamentally divided into definite areas with numerical degrees. The idea that the taxa of diatom found from oligosaprobic to polysaprobic waters are divided into the following three ecolo-gical groups: (1) Tolerant taxa, (2) In-different taxa, (3) Intorelant taxa (WATA-NABE et al., 1982). DCI can be calculated by the following equation.

axis of ordinate and the lines con-

necting the points.

L: The length of the stream surveyed.

In this case the end of the streams

the last station at the lowest courses.

On the right sides in Figures 5 and 6,

the diatom community represented by the

dominant taxa was shown at each station. As a result, the value of RPI„ of the River Asano-gawa is determined to be 41, and

that of the River Sai-gawa 53. These figures do not necessarily agree

with those of RPI0. For RPI0 is computed

based on the representation of only five degrees of saprobity, where as RPI,a is a

figure obtained directly by using the

specific composition of diatom communities.

DCI: Organic pollution index based on the

diatom community. t Ti: Sum of relative frequency of tolerant i-1

taxa from 1 to 1. 1)1

I j : Sum of relative frequency of in-j=1 different taxa from 1 to m. If the sum of the relative frequency of

intolerant taxa from 1 to n is expressed by

,L/e, then the equation (4) should hold. h=1

Table 7 shows the NDCI of each station on the two rivers in July 1981. Now we change the equation (3) of DCI to the following equation (5).

From the charts shown in Figures 5 and 6, we obtain the following equation

(6).

RPID: The value of the general estimation

of river pollution using DCI. S: The area which is surrounded by the

Fig. 5. The water quality chart by the diatom community index (NDCI) of the River

Asano-gawa and value of RPIi~ of the stream. And representative diatom taxi

at each station.


濁指数(Diatom Community　 Index-DCI)を提

案した.

本研究は,渡辺のDCIを一部修正し,それを用い

た汚染地図を作製したうえで,河川全体の汚濁評価点

(River Pollution Index-RPID)を求めたもので

ある.

References

CLEVE-EULER (1951-1955) : Die Diatomen von Schweden and Finland I-V. K. Sven. Vet.

Akad. Handl. 2 (1) : 1-155, 3 (3) : 1-143, 4 (1) : 1-149, 4 (5) : 1-240, 5 (4) : 1-217,

J. Cramer.FUKUSHIMA, H. and T. KOBAYASHI (1975) : Dia-

toms as the biological indicator. p.54-60 In: Environmental problems commitee meeting

in Japanese Journal of Ecology (ed.), Envi- ronmental and Biological Indicators 2. Kyoritu Shuppan. (in Japanese)

HUSTEDT, F. (1930) : Bacillariophyta In: A. PASCHER (ed.), Die Szisswasserflora Mittelen-

ropas, 10. Gustav Fischer.HUSTEDT, F. (1927-1966) : Die Kieselalgen Deut-

schland, Osterreichs and der Schweiz mit Berucksichtingung der ubringen Lander Europas sowie der angrenzenden Meeresge- biete I-III. RABENHOST's Kryptogamen-Flora,

7.

Fig. 6. The water quality chart by the diatom community index (NDCI) of the River

Sai-gawa and value of RPID of the stream. And representative diatom taxa

at each station.

The figure RPID, thus obtained presumably

has a more practical and intrinsic value

for the general assessment of the water

quality of rivers than RPIB.

摘要

筆者の一人渡辺(1982)は,従来の生物学的水質判

定法に基づく汚染地図から,河川汚濁を100点満点法

によって総合評価する方式を提案した.しかし,従来

の汚染地図は,貧腐水性から強腐水性までの,数段階

の汚濁階級の分布を示したものであった.

一方,河川の汚濁度の推移は,本来幾つかの階級に

分けられるものではなく,連続的に異なるものである

との考えから,渡辺(1981)は,珪藻群集に基づく汚

KAMIJO, H. and T. WATANABE (1973) : On the diatoms from Lake Kahoku-gata and its

inflows. Sci. Rep. Kanazawa Univ. 18 (2) : 97-153.

KAMIJO, H. and T. WATANABE (1974) : Biological study of the pollution of the Asano-gawa

River, Ishikawa Prefecture. Jap. J. Water Treat., 10: 32-38. (in Japanese)KOBAYASI, H. (1964) : Diatoms from River Ara- kawa (2). Bull. Chichibu Museum Nat.

Hist. 12: 66-77. (in Japanese) KOBAYASI, H. (1968) : A survey of the fresh water in the vicinity of Tokyo. Jap. J. Bot., 20 (1) : 93-122.PATRICK, R. and C. W. REIMER (1966, 1977) The Diatoms of United States I-II. Acad. Nat. Sci., Philadelphia. WATANABE, T. (1971) : The attached diatoms

from the Takami River (near Mizugase), Nara Prefecture. Ann. Rep. Noto Mar. Lab., 11: 9-20.WATANABE, T. and H. KAMIJO (1973) : The attached diatoms from the Sai-gawa River, Ishikawa Prefecture. Ann. Sci. Kanazawa

Univ., 10: 77-106. (in Japanese) WATANABE, T. (1975 a) : Algae as the biological

indicator (except Diatoms) p.61-89 In: Envi-


ronmental problems commitee meeting in Japanese Journal of Ecology (ed.), Environ-mental and Biological Indicators, 2. Kyoritu Shuppan. (in Japanese)

WATANABE, T. (1975 b) : Organisms of rivers and lakes in Ishikawa Prefecture. Natural envi-

ronmental of Ishikawa Prefecture, 5: 1-23.

(in Japanese)WATANABE, T. (1981) : A new approach to water

quality estimation using the specific composition of the benthic diatoms in epilithic forms based on the discuss to several pro-

blems on indicator organisms. J. Environ. Poll. Cont., 1 7 (5) : 13-18. (in Japanese)WATANABE, T. (1982) : Numerical assessment of

river pollution based on the water quality chart. Research Report of Environmental

Science, B 121-R-12-10: 92-95. (in Japa-nese)

WATANABE, T., M. TOHEI and H. KADOTANI (1982) : Tolerant and indifferent epilithic

diatoms to the organic pollution in the river. Research Report of Environmental Science,

B 121-R-12-10: 48-73. (in Japanese)

(著者:墨田廸彰,明峰高校,石川県小松市;渡辺

仁治,奈良女子大学理学部,奈良市北魚屋西町;Mi-

chiaki SUMITA, Meiho High School, Ishikawa Prefecture 923; Toshiharu WATANABE, Biological Institute, Faculty of Science, Nara Women's University, Nara 630)

Accepted: 11 June 1983

new general estimation of river pollution using new diatom

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