Effects of Social and Economic Development of Regions Surrounding Chao Lake on Water Quality Change of Chao Lake

Tengfei ZHAO，Qingqing WANG，Xiaoxian TANG，Xijun LlU，Yunhua ZHANG

1.School of Resources and Environment，Anhui Agricultural University，Hefei 230036，China；

2.Environmental Monitoring Center of Chaohu Authority，Hefei 238000，China；

3.School of Forestry&Landscape Architecture，Anhui Agricultural University，Hefei 230036，China；

4.School of Life Sciences，Anhui Agricultural University，Hefei 230036，China

Effects of Social and Economic Development of Regions Surrounding Chao Lake on Water Quality Change of Chao Lake

Tengfei ZHAO1，Qingqing WANG1，Xiaoxian TANG2，Xijun LlU3，Yunhua ZHANG4*

1.School of Resources and Environment，Anhui Agricultural University，Hefei 230036，China；

2.Environmental Monitoring Center of Chaohu Authority，Hefei 238000，China；

3.School of Forestry&Landscape Architecture，Anhui Agricultural University，Hefei 230036，China；

4.School of Life Sciences，Anhui Agricultural University，Hefei 230036，China

The research analyzed social and economic development around Chao Lake as well as changes of water quality in Chao Lake and explored the relationships of local population and GDP with water chemical oxygen demand（COD），total phosphorus （TP），total nitrogen （TN），chlorophyll and eutrophication index.The results showed that population around Chao Lake and GDP kept growing from 2001 to 2013，and water quality was improving.In addition，correlation analysis indicated that except of water eutrophication，GDP and population showed inverse correlation with other indices，demonstrating that water quality has been effectively controlled in Chao Lake recently.

Surrounding Chao Lake areas；Water quality of Chao Lake；Social and economic development；Correlation analysis

I n the pastdecades，much progress has been made on economy of regions surrounding ChaoLake.However，environment pollution arrives in quick succession of Chao Lake wetlands，accelerating water eutrophication［1-2］.For example，treatment on Chao Lake pollution drew attention from central，and local governments since the 9thFive-year Plan and Chao Lake has been listed as one of key treatment rivers and lakes，with progress.Recently，most researches available focus on assessment index system of Chao Lake［4-6］.

On August 22，2011，the prefecture-level city was announced to be a county-level city in central Anhui Province，under Hefei’s administration［7］.What’s more，Chaohu Authority has been established for comprehensive development covering Binhu District. Therefore， further research should be conducted whether Chao Lake，the 5thlargest freshwater lake with moderate eutrophication，would undergo the new round development surrounding lakes.The research analyzed the effects of population and economy on water quality of Chao Lake in order to reveal the rules of social and economic development with Chao Lake water quality and provide theoretical references for treatment and protection on Chao Lake

Chao Lake

Chao Lake is one of the five largest freshwater Lakes in China in central Anhui Province under Hefei’s administration.It is situated between the Yangtze River and Huai River，belonging to the left bank river system of the downstream of Yangtze River. Chao Lake is an importantwater source for industrial and agricultural production，as well as for domestic water，and a crucial base for fishery［8］. The water replenishment relies on surface runoff and rainfall，stretching over Hefei，Chaohu，Feixi，Feidong and Lujiang.Since establishment of Zhao-he Floodgate，Chaohu Floodgate，and Yuxi Floodgate，Chao Lake became a typical semi-closed eutrophic lake in the 1980s［9］.In the 1990s，eutrophication started deteriorating and bluegreen algae propagated，so that Chao Lake has become one of freshwater lakes the most seriously affected by eutrophication.Consequently，drinking water and industrial and farming water are affected either.It is obvious that eutrophication of Chao Lake has been a key factor influencing social and economic developmentin regions surrounding Chao Lake.

Data Source and Analysis

Social and economic development data were from Anhui Statistical Yearbook and water quality of Chao Lake from Environmental Monitoring Center of Chaohu Authority.The correlation analysis was conducted with SPSS16.0.

Social and Economic Development in Regions Surrounding Chao Lake

In recent decades，population in the regions surrounding Chao Lake is increasing fast with urbanization and population shift.For instance，population in the region was 5.477 million in 2001 and grew to 6.353 million in 2013（Fig.1）.It is clear that the population growth rate averaged 13.3‰，which is far higher than provincial mean natural growth rate of 7‰.

On the other hand，the regions surrounding Chao Lake represent 6.86%of Anhui Province in terms of area，but take up to 23%of Anhui GDP.Therefore，it is the qualified regions in the region with high competitiveness.As shown in Fig.2，GDP of the regions surrounding Chao Lake advanced so fastfrom 45.354 to 436.923 billion yuan from 2001 to 2013，with annual growth rate at 20%，which kept higher than annual mean rate of Anhui.

Analysis on Water Quality of Chao Lake

It is recorded that Chao Lake ecoenvironment always maintained well before the 1950s，but wetlands nearby started decreasing thereafter because of land reclamation from lakes.For instance，wetlands nearby Chao Lake reduced by about 200 km2during 1955-1985［1］，accelerating silting rate and depriving of interception function of wetlands.From the 1980s，nutrient load started growing in Chao Lake and eutrophication emerged with industrialization and urbanization.

As shown in Fig.3，water in east of Chao Lake underwent light eutrophication and in west was moderate eutrophication.The eutrophication index was in the range of 56.7 to 66.77.In general，the water was moderate in eutrophication.It can be concluded from Fig.3 that water in Chao Lake underwent two heavy fluctuations in 2003 and 2008，respectively，and west of Chao Lake maintained heavy eutrophication.

As shown in Fig.4-Fig.6，permanganate index，total P and total N were shown during 2001-2003 of Chao Lake.Specifically，permanganate index was decreasing in east and west of Chao Lake，as well as the whole Lake and rose dramatically in 2006，followed by decreasing.During 2001-2013，total P kept decreasing in east of Chao Lake but increasing in the west. In contrast，in the west of Chao Lake，totalP contentunderwentmany changes，such as growing in 2001-2003 followed by decreasing in 2006，increasing again before the second drop in 2009，as well as last rising in 2011. Generally speaking， the changes of total P in Chao Lake are much similar to that in the west of Chao Lake.As for total N，it kept decreasing generally，and only grew in2006 for the east of Chao Lake.In west of Chao Lake，however，total N maintained increasing during 2001-2003 and reached the peak in 2003，followed by decreasing in 2006；the content grew again and dropped in 2009；the last growth was shown in 2011.It can be concluded that the change of total N in Chao Lake was similar to that of the west of Chao Lake.

Chlorophyll is a component of algae and the content has been closely linked to the species，number as well as water environment.Therefore，the content of chlorophyll in water reflects water quality in certain extent.As shown in Fig.7，the content maintained stable in the east of Chao Lake in 2001-2013 below 10 mg/m3，and higher in the west of Chao Lake，especially in 2003 when a peak was shown at 91.20 mg/m3，followed by two subpeaks in 2008 and 2012.In conclusion，the change of chlorophyll content in Chao Lake are similar to that in the west of the Lake.

Analysis on the Effects of Social and Economic Development in the Regions nearby Chao Lake on Water Quality of Chao Lake

The correlation analysis was shown about social and economic development with water quality of Chao Lake during 2001-2013（Table 1）.

It can be concluded from Table 1 that eutrophication of Chao Lake was deteriorating with GDP growth in the regions nearby Chao Lake，with low significance.Besides，GDP of the regions nearby Chao Lake showed inverse correlation with permanganate？index，total P，total N and chlorophyll，but the correlation was not so significant with chlorophyll content.

It can be concluded from Table 1 that population in the regions nearby Chao Lake was of insignificant correlation with eutrophication ofChao Lake，showing inverse correlation with permanganate？index，total P，total N and chlorophyll，but the correlation was not so significant with chlorophyll content.

Suggestions

The research proved that water pollution in Chao Lake was effectively controlled in 2001-2013，but social and economic development has insignificant effects on water quality，indicating that treatment projects on Chao Lake pollution play key roles since the 9thFive-year Plan.Still，water quality is still moderate eutrophication of Chao Lake.

Therefore，it is recommended to reinforce comprehensive management on rivers and lakes surrounding Chao Lake.Specifically，it is recommended to carry out construction on ecological county，town and village by scattered treatment on rural sewage and reduce chemical fertilizer to effective controlnon-point source pollution nearby Chao Lake.Furthermore，it is necessary to strengthen agricultural eco-environment conservation，restore original wetlands and reduce pollutants from surface runoff.Finally，it is crucial to enhance monitoring and management on environment protection and improve conservation nearby Chao Lake，as well as obsolete traditional chemical enterprise，printwork，electroplate factory，brewery and cement plant.In general，the principle of whoever causes pollution is responsible for its treatment should be insisted on in order to explore and advance ecological compensation mechanism.

Table 1 Correlation analysis on Chaohu GDP with population and water quality

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Responsible editor：Xiaoxue WANG

Responsible proofreader：Xiaoyan WU

环巢湖地区社会经济发展对巢湖水质变化的影响

赵腾飞1，王晴晴1，唐晓先2，刘西军3，张云华4*
（1.安徽农业大学资源与环境学院，安徽合肥230036；2.巢湖管理局环境保护监测站，安徽合肥 238000；3.安徽农业大学林学与园林学院，安徽合肥230036；4.安徽农业大学生命科学学院，安徽合肥230036）

分析了2001～2013年环巢湖地区的社会经济发展状况以及在此期间巢湖水体的水质变化情况。应用相关性分析方法分析了环巢湖地区人口、GDP与巢湖水体COD、TP、TN、叶绿素和富营养化指数之间的关系。结果显示，2001～2013环巢湖地区的人口和GDP呈现逐年增长的趋势，巢湖水体水质总体趋于好转。相关分析表明除了与环巢湖地区GDP与巢湖水体富营养化呈现正相关（不显著）以外，环巢湖地区GDP、人口与巢湖水质其他指标呈现负相关。这表明近十几年来巢湖水体环境质量总体得到了有效控制。

环巢湖；巢湖水质；社会经济发展；相关性分析

安徽省省级环境保护科研项目（编号：2014-004）。

赵腾飞（1991-），男，河南洛阳人，硕士研究生，研究方向：环境生态学。*通讯作者，E-mail：yunhua9681@163.com。

2015-10-04

Supported by Anhui Environmental Protection Scientific Research Program（2014-004）.

*Corresponding author.E-mail:yunhua9681@163.com

Received:October 4，2015 Accepted:November 16，2015

修回日期 2015-11-16