Eutrophication Evaluation and Influencing Factors of Daheiting

Reservoir

Lihui

Cao

1,2 a

, Xubo Lv

, Kun Lei

, Libiao Yang

2,* d

and Dianwu Wang

1,* e

College of resources and Environmental Sciences, Hebei Agricultural University, Baoding, Hebei, 071000, China

Chinese Academy of Environmental Sciences, Beijing, 100012, China

Keywords:

Eutrophication, Evaluate, Factors, Daheiting Reservoir.

Abstract:

Taking Daheiting Reservoir as an example, the water quality changes were studied by investigation and field

sampling, and the water eutrophication and the main influencing factors were evaluated and analyzed in view

of the gradually serious eutrophication of the water body in China. And the results were shown as below: DO

concentration did not reach class II water standards only in the dry season. TN was inferior to class V in dry

and normal season, and class IV in wet season; TP water quality was inferior to class V in dry and normal

season, class III in July in wet season and not exceed the standard in August in wet season. COD

exceeded

the standard only during normal and wet water periods in August, and the water quality was class III. In dry

season, the water body was slightly eutrophic; in normal water period, the water body was slightly to

moderately eutrophic; in the wet season, the water body was slightly eutrophic in July and moderately

eutrophic in August. Principal component analysis showed that temperature, nitrogen and phosphorus

nutrients were the main influencing factors and do, pH and COD

were the main manifestation factors of

water eutrophication.

1 INTRODUCTION

Reservoirs were one of the important sources of urban

drinking water in China. However, most reservoirs

have a series of problems, such as short water

exchange cycle, high basin erosion intensity and anti

seasonal fluctuation, which lead to great instability of

reservoir water quality and potential risks of water

environment (Da, 2020; Wang,2010). The problem of

water eutrophication was preliminarily explored in

the early 20th century (Poikane, 2014), now it has

become the focus of attention. Water eutrophication

destroys aquatic ecosystems all over the world,

foreign countries began to investigate lake

eutrophication in the 1960s, and established relevant

evaluation and prediction models. Due to its complex

mechanism, wide range and difficult treatment, it has

become a hot spot of water ecological security (Qin,

2010, Lu, 2003). The intensification of water

https://orcid.org/0000-0003-0903-4621

https://orcid.org/0000-0002-5392-5897

https://orcid.org/0000-0001-8343-3087

https://orcid.org/0000-0002-7444-5112

https://orcid.org/0000-0003-3408-6992

eutrophication not only has an adverse impact on

social harmony and stability, but also does serious

harm to people's production and life. Therefore,

scientific and reasonable water quality evaluation and

determination of water eutrophication status were of

great practical significance for water pollution control

and water environment management planning

(Meyer-Reil, 2000, Liu, 2020).

In November 2016, April, July and August 2017,

this paper monitored 10 indicators including water

temperature, total nitrogen, total phosphorus, active

phosphate and Chl.a, evaluated water eutrophication,

and clarified the main influencing factors of water

eutrophication, in order to provide a theoretical basis

for water pollution control of Daheiting reservoir.

244

Cao, L., Lv, X., Lei, K., Yang, L. and Wang, D.

Eutrophication Evaluation and Inﬂuencing Factors of Daheiting Reservoir.

DOI: 10.5220/0011197700003443

In Proceedings of the 4th International Conference on Biomedical Engineering and Bioinformatics (ICBEB 2022), pages 244-248

ISBN: 978-989-758-595-1

2 MATERIALS AND METHODS

2.1 Overview of the Study Werea

Daheiting reservoir, located in Qianxi County,

Tangshan City, is one of the backbone projects of

Luanhe River Diversion Project Group. The inflow

rivers mainly include Luanhe main stream, Sahe

River, etc. The region has a warm temperate

continental semi humid monsoon climate with four

distinct seasons and obvious dry and wet seasons. The

average annual temperature is 10.1 ℃, the average

annual precipitation is 804.2mm, the total storage

capacity is 337 million m3 and the effective storage

capacity is 224 million m3. The normal pool level is

133.0m and the dead water level is 121.5m. It is a

large type II annual regulation reservoir. 15 sampling

points were evenly arranged in the water werea from

dam front to reservoir tail in Daheiting reservoir

werea, as shown in Figure 1. The water quality

sampling time is November 2016 (dry season), April

2017 (normal season), July and August 2017 (wet

season).

Figure 1: Schematic diagram of sampling points in

Daheiting reservoir.

2.2 Evaluation and Analysis Method

2.2.1 Water Sample Collection and

Monitoring

The water sample is collected with a 2L stainless steel

water collector, put into a 500ml Brown reagent

bottle, and immediately add concentrated H

for

acidification and preservation. The water temperature

and dissolved oxygen are measured by YSI multi

parameter water quality detector, the transparency is

measured by plug plate, the pH is measured by

portable water quality analyzer, and the temperature,

transparency and pH value are recorded on site. Other

indexes shall be determined according to the fourth

edition of monitoring and analysis methods for water

and wastewater (P A, 2002).

2.2.2 Evaluation Method

Carlson comprehensive nutritional status index (TLI)

method is used for evaluation, and the calculation

formula is:

TLI()=𝑊𝑗







𝑇𝐿𝐼(𝑗)

Where, TLI (∑) is the comprehensive nutritional

status index, WJ is the relevant weight of the

nutritional status index of the j-th parameter, TLI (J)

is the nutritional status index of the j-th parameter,

and N is the number of evaluation parameters.

The comprehensive nutritional index TLI < 30 is

poor nutrition, 30 ≤ TLI ≤ 50 is medium nutrition, 50

< TLI ≤ 60 is mild eutrophication, 60 < TLI ≤ 70 is

moderate eutrophication, and TLI > 70 is severe

eutrophication.

3 RESULTS & DISCUSSION

3.1 Water Quality Analysis of

Daheiting Reservoir

The water quality was evaluated according to the

environmental quality standard for surface water

(GB3838-2002). In November 2016, the average

concentration of do was 4.805 mg/L, which was class

IV water, and did not exceed the standard in other

periods; The average concentration of PO

-P was

0.288 mg/L at the beginning of the study period, and

gradually decreased to 0.005 mg/L at the end of the

study period. The mean values of TN concentrations

Eutrophication Evaluation and Inﬂuencing Factors of Daheiting Reservoir

245

in the four periods were 2.541, 3.508, 1.184 and 1.374

mg/L respectively, exceeding the standard by 5.08,

7.02, 2.36 and 2.74 times respectively; In November

2016, April 2017 and July 2017, the average TP

concentration was 0.268, 0.217 and 0.047 mg/L

respectively, exceeding the standard by 10.72, 8.68

and 0.88 times respectively. In August, TP did not

exceed the standard, and the water quality was

upgraded from inferior class V to class II water; NH3-

N concentration did not exceed the standard in four

periods. In April and August 2017, the average

COD

concentration was 5.308 and 5.639 mg/L

respectively, exceeding the standard by 1.33 and 1.41

times respectively. In other periods, it did not exceed

the standard, and the water quality was class III water.

3.2 Eutrophication Evaluation of

Daheiting Reservoir

The eutrophication state of Daheiting reservoir in dry

season is shown in Figure 2, the comprehensive

trophic state index ranges from 47.46 to 58.49, with

an average of 51.58. 25% of the water bodies belong

to mesotrophic state, 75% of the water bodies were

slightly eutrophic, and the comprehensive trophic

state is evaluated as slightly eutrophic. The normal

water period can be seen from Figure 3, the

comprehensive nutritional status index ranges from

54.80 to 63.01, with an average of 58.33. 100% of the

water body reaches the degree of eutrophication, and

the comprehensive nutritional status is evaluated as

mild to moderate eutrophication. In the wet season in

July, the comprehensive nutritional status index

ranges from 47.32 to 54.80, with an average of 51.17.

37.5% of the water bodies belong to mesotrophic

status, 62.5% of the water bodies belong to mild

eutrophication, and the comprehensive nutritional

status is evaluated as mild eutrophication; In August,

the comprehensive nutritional status index ranged

from 43.93 to 58.51, with an average of 46.47. 66.7%

of the water bodies were in mesotrophic status, 33.3%

of the water bodies were in mild eutrophication, and

the comprehensive nutritional status was evaluated as

mesotrophic. Xue et al. (Yun, 2020) found that the

eutrophication degree of Dongting Lake decreased

successively in summer, autumn, spring and winter,

and Dongting Lake was mainly in medium trophic

state. In the study on eutrophication evaluation of

dajinzhong reservoir, Wang et al. (Wang, 2019) found

that the overall water quality of the reservoir is in a

slightly eutrophic state, and individual wereas were in

a moderately eutrophic state, and the comprehensive

nutritional state index is related to the wet season and

dry season, and the comprehensive nutritional state

index is high in the wet season. In this study, It may

be that the tributary pollutants enter the reservoir

werea, resulting in the accumulation of pollutants,

and the concentration of TN and TP exceeds the

standard seriously, resulting in the aggravation of the

degree of eutrophication. With the continuous

discharge of water from the reservoir and the

influence of rainfall, the concentration of TN and TP

gradually decreases until the TP concentration does

not exceed the standard in the wet season, and the

comprehensive nutritional state of the reservoir water

is medium nutrition.

Figure 2: Eutrophication status of Daheiting reservoir in November 2016.

100

D10

D11

D12

D13

D14

D15

Value

TLI(TN) TLI(TP)

TLI(CODMn)

TIL（Chla）

TIL（SD）

D10

D11

D12

D13

D14

D15

Value

TIL( ∑ )

ICBEB 2022 - The International Conference on Biomedical Engineering and Bioinformatics

246

Figure 3: Eutrophication status of Daheiting reservoir in April 2017.

Figure 4: Eutrophication status of Daheiting reservoir in July 2017.

Figure 5: Eutrophication status of Daheiting reservoir in August 2017.

3.3 Analysis on Influencing Factors of

Water Eutrophication in Daheiting

Reservoir

Chl. a is a representative indicator of planktonic algae

biomass, so we focus on the correlation between Chl.

a concentration and other environmental factors.

According to the order of correlation degree, it is DO,

SD, PO

-P, temperature, pH, TN, TP and COD

Chl. a has a very significant correlation with do, SD,

-P, temperature, pH, TN and TP, indicating that

TN, TP and PO

-P were the main nutritional factors

for the growth of planktonic algae, and DO, SD,

temperature and pH were the main environmental

factors for the growth of planktonic algae. Tab 1

shows,the cumulative contribution rate of the three

principal components is 86.193%, the contribution

rate of F1 is 39.435%, the contribution rate of F2 is

34.279%, and the contribution rate of F3 is 12.479%.

Tab 2 shows, the load values of temperature, TN, TP

and PO

-P on F1 were large, so F1 can be

characterized by temperature and nitrogen and

phosphorus content. The load values of do and pH on

100

D10

D11

D12

D13

D14

D15

Value

TLI(TN) TLI(TP)

TLI(CODMn)

TIL（Chl.a）

TIL（SD）

D10

D11

D12

D13

D14

D15

Value

TIL( ∑ )

100

D10

D11

D12

D13

D14

D15

Value

TLI(TN) TLI(TP)

TLI(CODMn)

TIL（Chl.a）

D10

D11

D12

D13

D14

D15

Value

TIL( ∑ )

D10

D11

D12

D13

D14

D15

Value

TLI(TN) TLI(TP)

TLI(CODMn)

TIL（Chl.a）

TIL（SD）

D10

D11

D12

D13

D14

D15

Value

TIL( ∑ )

Eutrophication Evaluation and Inﬂuencing Factors of Daheiting Reservoir

247

F2 were large, and only the load value of COD

F3 is greater than 0.80. It is inferred that temperature,

nitrogen and phosphorus nutrients were the main

influencing factors of eutrophication, and DO, pH and

COD

were the main manifestation factors of water

eutrophication.

Table 1: Factor eigenvalues and contribution rate of water

environmental indicators after rotation.

Factor Eigenvalue

Contribution

Rate %

Total

Cumulative %

F1 3.549 39.435 39.435

F2 3.085 34.279 73.714

F3 1.123 12.479 86.193

Table 2: Factor load value after rotation of water environment index.

Facto

Chl.a T

H SD DO PO

-P TN TP COD

F1 -0.366 -0.972 -0.013 0.289 0.008 0.849 0.925 0.893 -0.117

F2 0.657 0.097 0.883 -0.79 0.963 -0.386 0.173 -0.243 0.272

F3 -0.425 0.057 0.226 -0.24 0.125 -0.166 0.194 -0.153 0.853

4 CONCLUSIONS

Based on the results and discussions presented

above, the conclusions are obtained as below:

(1) In dry season, TN and TP exceeded the

standard by 5.08 and 10.72 times respectively, DO

does not meet class II standard, COD

up to

standard; TN, TP and COD

exceeded the standard

by 7.06, 8.68 and 1.33 times respectively in normal

water period, DO up to standard; in the wet season in

July, TN and TP exceeded the standard by 2.36 and

0.88 times respectively, and COD

and DO did not

exceed the standard. In the wet season in August, TN

and COD

exceeded the standard by 2.74 and 1.41

times respectively, and TP and DO did not exceed the

standard.

(2) The water body is slightly eutrophic in dry

season, slightly to moderately eutrophic in normal

season, slightly eutrophic in July and moderately

eutrophic in August in wet season.

(3) The main influencing factors of

eutrophication in Daheiting reservoir were

temperature and nitrogen and phosphorus nutrients,

and the main performance factors were DO, pH and

COD

ACKNOWLEDGMENTS

Key special project of "global change and response"

of national key R&D plan (2016YFA0600902);

National major special project of water pollution

control and treatment science and Technology

(2018ZX07111002).

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