Water quality research and evaluation for campus landscape water based on arcgis

Frontier of Environmental Science June 2014, Volume 3, Issue 2, PP.23-28

Water Quality Research and Evaluation for Campus Landscape Water Based on ArcGIS Chunlong Li1#, Gang Yu 1, Xianxi Xiang 2, Li Dai3 1. School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074, China 2. Chongqing HONGwei Environmental Protection Engineering Co. Ltd., Chongqing 401120, China 3. Chongqing Tuke Technology Co. Ltd., Chongqing 400074, China #

Email: cqjtulichunlong@163.com

Abstract In order to understand pollution characteristics and laws of campus landscape water, combined with conventional monitoring index of eutrophication, were analyzed and evaluated by single factor index, nemerow index method, trophic state index method and arcgis spatial method of ArcGis for winter dry season water quality conditions of campus landscape water (Jing Lake) in a university of Chongqing. The results showed that the sites of the chl-a and CODMn exceed 83% and 17%, while TN and TP met the GB3838-2002 water quality standards, TN even up to grade III. The content of chla and TN, TP have a significant linear correlation, and the order of each factor contribute to the eutrophication are chl-a, TP, SD and CODMn, and TN. The artificial lake water quality standard maining sites are in the surface water grade V except 3# region of grade III in winter dry season, has shown moderate eutrophication, needs to be improved.

Keywords: ArcGis; Campus Landscape Water; Trophic State Index; Eutrophication

1 INTRODUCTION Campus environment is the foundation of the school building of spiritual civilization, and the water as a mobile landscape has became the essential landscape elements in contemporary campus environment design.

Small landscape waters created beautiful campus environment, but also satisfied the hydrophilic psychological needs of teachers and students. However, due to the campus landscape water mostly stationary or slow illiquid closed water body, which characteristics are small area, small water environmental capacity, and low self-purification capacity.

Along with the expansion of universities enrollment and student activity frequency, caused water quality gradually decreased or even worsen, become pollution sources of water environment, potential risks of campus life quality.

According to the relevant research results in recent years, university landscape water have emerged different degrees of eutrophication, algal bloom material conditions have existed, seriouly impact the campus landscape and ecological function [1-3].

In this paper, as an artificial lake an example, Jing Lake, which in a University of Chongqing , through the investigation of water quality in winter dry season, used the method of single factor index, Nemero index, comprehensive nutrition state index method and spatial overlay analysis based on ArcGIS method to analyzed the pollution characteristics and to evaluate their nutritional status, in order to master water pollution characteristics and rules of the campus landscape water, to provide scientific basis for the prevention and management of eutrophication and the construction of ecological campus.

2 MATERIALS AND METHODS 2.1 Data Collection and Analysis According to the water environment characteristics and monitoring standards, along the flow direction a circle around the lake laid 6 sampling points (Figure 1). Adopted self-made device at each sampling point in every 7d - 23 http://www.ivypub.org/fes

from October 22 to December 3, 2013, collected 42 samples, the sampling volume was 500ml, the water into clean plastic bottles, index were tested after back to the lab. Sample test indexes mainly include the total phosphorus (TP), total nitrogen (TN), chlorophyll-a (chl-a), chemical oxygen demand (CODMn), transparency (SD), etc.The sample analysis method consulted the book [4].

FIG.1 DISTRIBUTION OF SAMPLING SITES

2.2 Analysis and Evaluation of Water Quality Characteristics The water quality of each index refer to the GB3838-2002 and GHZB 1-1999 standard; evaluation and color characterization through the surface water environmental quality assessment method (The general office of the Ministry of environmental protection no.22, 2011), followed by ArcGIS software for spatial analysis. The Jing Lake shoreline map digitized, inputed attribute code and edited graphics, then built the corresponding graph database, and finally made into thematic maps [5,6].

2.3 Evaluation Standards and Methods Referenced lakes eutrophication assessment method, comprehensive evaluation of the degree of nutrition for Jing Lake by trophic state index method, and the artificial lake trophic state graded a series of digital 0~100, comprehensive nutrition index below 30 for poor nutrition, 30~50 for middle nutrition, more than 50 for eutrophication, included 50~60 for light eutrophication, 60~70 was middle eutrophication, more than 70 for severe eutrophication [7]. Trophic state index calculation formula as follows[8].

TLI(COD Mn )= 10[ 0.109+ 2.66ln(COD Mn )]

(1)

TLI(Chl - a)= 10[ 2.5 +1.08ln(Chl - a)]

(2)

TLI(SD)= 10[ 5.118- 1.94ln(SD)] TLI(TP)= 10[ 9.436+ 1.624ln(TP)] TLI(TN)= 10[ 5.453+ 1.694ln(TN)] TLI( )=

(3) (4) (5)

m

W j ×TLI(j)

(6)

j=1 m

W j = rij2 /

 rij 2

(7)

j=1

In the formula, TLI (CODMn), TLI (Chl-a), TLI (SD), TLI (TP) and TLI (TN) are the trophic state indexes respectively based on potassium permanganate index, chlorophyll-a, transparency, total phosphorus, total nitrogen basis; relative weights of trophic state index Wj for the j parameter, Rij is the correlation coefficient between the j parameter and the reference parameter Chl-a; TLI (∑) for comprehensive nutrition state index, TLI (j) for the nutrition state indexas of the j parameters.

3 RESULTS AND DISCUSSION 3.1 Spatial and Temporal Distribution of Each Index - 24 http://www.ivypub.org/fes

Transparency（cm）

1) Transparency 50 40 30 20 10 0 10/22

1#

2#

3#

4#

10/29

11/5

11/12

11/19

5#

6#

Date 11/26

12/3

FIG.2 TRANSPARENCY CHANGES OF CAMPUS LANDSCAPE WATER

The figure 2 shown that the transparency of the artificial lake, there was no significant difference among varied with the change of the weather, the average transparency between 29.7 ~ 38.6 cm. The transparency of 3 # area is the highest 38.6 cm; main lakes is lowest; all sampling point to maintain at about 30 cm. The main reason is that the water quality entering the lake is still relatively poor, the flow rate very slowly. Lake water flowing by gravity into the 3# area, in this process through a distance waterfall reoxygenation, plus the 3# regional planted some aquatic plants (such as the water lily, lotus ,etc.), so the water transparency of 3# area more higher than other sampling points, proved that aquatic plants has a certain improvement on water transparency. From the monitored results, the transparency of Jing Lake is still relatively low, mainly due to the content of plankton and suspended material is rich.

2) Chlorophyll-a

Chlorophyll a（mg/m3 ）

140

1#

2#

3#

4#

5#

6#

120 100 80 60 40 20 0 10/22

Date 10/29

11/5

11/12

11/19

11/26

12/3

FIG.3 CONTENT SPATIOTEMPORAL DISTRIBUTION OF CHL-A

The figure 3 shown that the the overall content of chlorophyll-a of campus artificial lake all sampling points is higher, most of the area beyond the 65 mg/m3, shown that phytoplankton biomass of the artificial lake is very rich, with a strong primary productivity. By used a single factor index method evaluation found that the single factor index of chlorophyll-a in the range of 0.52～1.87, and each sampling point of chlorophyl-a content was greatly influenced by the variable weather. Sunny day (November 19) reached the maximum sample value was mainly due to algae grow and multiply rapidly at a temperature suitable conditions that the shallow depth of winter, adequate light, high oxygen content. Used the sample mean made thematic map can be clearly drawn, most of the region has a red warning; only the 3# area to met the water quality standard of landscape water, appeared orange signal warning; The number of Jing Lake sampling points exceeded the water quality standard was 5, exceeded standard rate was 83%.

Total nitrogen （mg/L）

3) Total Nitrogen 4 3.5 3 2.5 2 1.5 1 0.5 0 10/22

1#

2#

3#

4#

5#

10/29

11/5

11/12

11/19

11/26

6#

Date 12/3

FIG.4 CONTENT SPATIOTEMPORAL DISTRIBUTION OF TN - 25 http://www.ivypub.org/fes

The figure 4 shown that the total nitrogen content of the campus artificial lake between 0.96 ~ 1.66 mg/L, most areas has in the grade IV of surface water environmental quality standards. Through single factor index evaluation found that the index of each sampling point range between 0.23 ~ 1.73, sunny day (November 19) has a high content of nitrogen may be released by endogenous nitrogen in sediment. As can be seen from the total nitrogen thematic map, the lake water quality in good condition, 1 # area with high content of total nitrogen (grade Ⅴ), presented the orange alert; the total nitrogen contents of 3 # area was the lowest (grade Ⅲ), green warning; The rest of the region were grade Ⅳ, presented yellow warning. 3# area water quality was the greatest, was mainly due to planted waterlily, lotus and other aquatic plants, and bred a greater number of brocade carp, crucian carp and other planktonic animal.

Main lakes area bred only brocade carp and crucian carp, water quality deterioration in the 3# area.The main reason is that aquatic plants and zooplankton ecological purification system for purification of the polluted water is better than single zooplankton purification system [9,10], so 3 # area water quality was better than other sections.

4) Total Phosphorus Total phosphorus （mg/L）

1#

2#

3#

4#

5#

6#

0.3 0.25 0.2 0.15 0.1 0.05 Date

0 10/22

10/29

11/5

11/12

11/19

11/26

12/3

FIG.5 CONTENT SPATIOTEMPORAL DISTRIBUTION OF TP

The figure 5 shown that the whole quality of campus artificial lake in grade IV or V, average value between 0.083 ~ 0.106 mg/L, so the spatial distribution of total phosphorus content was more balanced. The mean single factor index of each point in the range of 0.42 to 0.53, the whole artificial lake total phosphorus content in the grade IV or V, did not exceed the standard value. Through total phosphorus thematic map, 2# and 5# area water quality presented orange alert; the other area water quality met the grade Ⅳof water quality standard, presented yellow warning.

Because the lake in the beautiful environment of the campus, non-point source pollution is not obvious, which is mainly influenced by the weather, water stage fluctuation, the ability of sediment adsorption and other natural elements[11]. The n/p ratio greater than 7.2, P may became the limiting nutrient.The total phosphorus content directly affects the water quality condition, so the control of total phosphorus content has a positive impact on the lake water environment quality.

（mg/L） Potassium permanganate index

5) Potassium Permanganate Index 1#

2#

3#

4#

5#

6#

25 20 15 10 5 0 10/22

Date 10/29

11/5

11/12

11/19

11/26

12/3

FIG.6 CONTENT SPATIOTEMPORAL DISTRIBUTION OF CODMN

As shown in the Figure 6, the campus artificial lake potassium permanganate index gradually returned to the original level after decreased, the change trend of each sample point almost unanimously, potassium permanganate index was reduced in a short period is mainly due to the dilution effect caused by rainfall. Most areas (1#~5#) can met the water quality standard of landscape water, but 6# area has exceeded the standard evaluted by the single factor index method, the rate of exceed the standard was 17%.1 # ~ 5 # areas can met the water quality - 26 http://www.ivypub.org/fes

requirements, but are close to the upper limit of water quality grade Ⅴ (15 mg/L), appeared orange alert. The 6 # area has exceeded the national standard, presented the red alert. The evaluation results shown that the lake organic material content will be increase when in the rich nutrient season, easily lead to potassium permanganate index higher than grade V. Monitoring data shown the artificial lake organic material content was high, easily lead to the water quality reached the red warning if not take preventive measures.

3.2 The Temporal and Spatial Distribution Characteristics of Comprehensive Quality Single factor index;Nemerow index

Chl-a

TN

TP

Potassium permanganate index

Nemerow index

1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 Date

0.00 10/22

10/29

11/5

11/12

11/19

11/26

12/3

FIG.7 CONTENT SPATIOTEMPORAL DISTRIBUTION OF THE OVERALL WATER QUALITY

Figure 7 shown that the nemerow index of campus artificial presented the first decreased and then increased and finally decreased, indicated the changes of water quality. At the same time, change trend of the nemero index almost in line with chlorophyll-a, shown that the main factor affected the campus artificial lake water was chlorophyll-a. The main reason was the N/P ratio of the campus landscape water between 10~20, in the growth ratio ideal range, and they has linear relation with chlorophyll a (R2 = 0.9233 and 0.8754). From the spatial distribution of water quality, most areas shown orange alert of different concentration, in moderately polluted; only 3 # area water quality was better, shown green warning. From the analysis of monitoring data, the artificial lake water quality situation was not optimistic, eutrophication was more serious, the relevant departments should take effective measures to control and protect Jing Lake water as soon as possible.

3.3 Assessment of Water Quality Eutrophication According to several average sampling data, evaluated nutritional status of the campus artificial lake by comprehensive nutritional status index, the evaluation results were shown in table 1.

TABLE 1 EUTROPHICATION ASSESSMENT RESULTS Pionts

TLI(SD)

TLI(TN)

TLI(TP)

TLI(CODMn)

TLI(Chl-a)

TLI(∑)

level

1# 2# 3# 4# 5# 6#

71.94 72.88 69.66 74.10 74.74 74.10

63.12 60.35 53.84 60.94 58.45 57.33

53.94 57.91 56.64 55.96 57.91 56.47

72.79 70.15 69.75 72.87 73.03 73.19

70.48 71.46 69.82 71.50 72.22 71.67

66.67 66.87 64.37 67.34 67.60 66.90

Moderate eutrophication Moderate eutrophication Moderate eutrophication Moderate eutrophication Moderate eutrophication Moderate eutrophication

The weight of each factor were chlorophyll-a of 26.6%, total phosphorus of 18.8%, total nitrogen of 17.9%, transparency was 18.3%, potassium permanganate index of 18.3%, shown the order of each factor contributed to the eutrophication were chl-a, TP, SD and CODMn, and TN. Meanwhile, the evaluation results shown that the TLI (∑) of 6 sampling points were between 64.37~67.60, close to the severe eutrophication, indicated that the lake water quality was poor, eutrophication was serious.

4 CONCLUSIONS 1) Through to manual sampled a campus landscape water (Jing Lake) of a university in Chongqing, used single factor index method and the spatial overlay analysis of ArcGIS.The results shown that, chlorophyll-a and potassium - 27 http://www.ivypub.org/fes

permanganate index exceeded the standard value, the rate of exceed the standard were 83% and 17%, while TN and TP met the GB3838-2002 water quality standards, TN even up to grade III. The inlet region (1#, 2#) and the main lake area (4#, 5#, 6#) has poor water quality, 3# area water quality was good.

2) Single factor index, nemerow index method, trophic state index method and arcgis spatial method of ArcGis has been used to evaluted the campus landscape water, the results shown that TN, TP have a significant linear correlation, and the order of each factor contributed to the eutrophication were chl-a, TP, SD and CODMn, and TN. The artificial lake comprehensive water quality in the surface water quality grade Ⅲ to Ⅴ during winter dry season, has shown moderate eutrophication status.The comprehensive nutritional index of most points close to the limit value, be easily converted into severe eutrophication status, so the relevant departments should take positive and effective measures to control and protect the Jing lake as soon as possible.

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AUTHORS 1

Chunlong LI (1989- ), Male, Chongqing,

2

Gang YU (1986- ), Male, SIchuan, China, Chongqing Jiaotong

China, Chongqing Jiaotong University

University Graduate Student, Research direction: water pollution

Graduate Student, Research direction:

control technology, E-mail: yg198695@sina.com.

water pollution control technology, E-mail:

3

cqjtulichunlong@163.

Xianxi XIANG (1989- ), Male, HUbei, China, Graduated from

Chongqing Jiaotong University, Research direction: water pollution control technology, E-mail: 520193957@qq.com.

4

Li DAI (1989- ), Male, Chongqing, China, Graduated from

Chongqing Jiaotong University, Research direction: water pollution control technology, E-mail: 760957256@qq.com.

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