A dataset of water quality monitoring in Taihu Lake (2001 – 2006)

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A dataset of water quality monitoring in Taihu Lake (2001 – 2006)

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A dataset of water quality monitoring in Taihu Lake (2001 – 2006)

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A dataset of water quality monitoring in Taihu Lake (2001 – 2006)

Xu Jinduo1, Ma Ronghua1*, Wang zhen1, Hu Jiajun1

1. Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China

*Email: rhma@niglas.ac.cn

Abstract: This dataset is provided by TaiLLER (Taihu Laboratory for Lake Ecosystem Research) of Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences. It contains 8 routine monitoring sites data which were sampled from 2001 to 2006. Longitudinal water quality monitoring data can response exactly the development trend of water quality changes and provide data support for studies on eutrophication of lake water environment, water environmental protection, pollution control and management. We take international standard data processing methods and quality control systems to ensure the observation data quality. We publish these data publicly and provide online access service for them. These data provide support for the limnological research.

Keywords: Taihu Lake;water quality;water chemistry; monitoring data

Dataset Profile

Chinese title

2001~2006年太湖水体物理及水体化学监测数据集

English title

A dataset of water quality monitoring in Taihu Lake (2001 – 2006)

Corresponding author

Ma Ronghua(rhma@niglas.ac.cn)

Data Author (s)

Xu Jinduo, Ma Ronghua

   Source (s) of funding

National Earth System Science Data Sharing Infrastructure, Scientific and Technological Data Resource Integration and Sharing Project of Chinese Academy of Science, National Ecosystem Research Network of China

Time range

2001 – 2006

Geographical scope

Taihu Lake

Data format

*.xlsx

Data size

0.16 MB

Data service system

<http://www.sciencedb.cn/dataSet/handle/13>

Dataset composition

The dataset contains the latitude and longitude data of water quality observation station in Taihu Lake and water physical and chemical observation data of Taihu Lake from 2001 to 2006. The physical and chemical indicators include water temperature, transparency, pH, suspended matter, conductivity, alkalinity , dissolved oxygen, permanganate index, the 5-day biochemical oxygen demand, total phosphorus, total nitrogen, ammonia nitrogen, phosphate, nitrate nitrogen, nitrite nitrogen, etc.

1. Introduction

Located in the southern margin of the Yangtze River Delta[1], Taihu Lake also has names of Zhenze, Juqu and Lize in ancient times. It is one of the five largest freshwater lakes in China, with an area of 2,427.8 km2 and a water area of 2338 km2 as well2, which plays an important role in regional and socio-economic development. In recent years, due to the rapid economic development and irrational exploitation and utilization, the water quality of Taihu Lake has deteriorated along with the obvious trend of eutrophication and the degradation of ecosystem3. In order to facilitate long-term, systematic and stable field observation experiments and studies on large-scale shallow lakes represented by Taihu Lake, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences founded the Taihu Lake Ecosystem Research Station (the Taihu Lake Station), which mainly focuses on basic and applied research of lakes and creating large-scale dataset on lakes4. The longitudinal data observed can be used in major science issues research, such as substance conversion and energy flow in eutrophic lakes, the effects of physical, chemical and biological processes on cyanobacteria bloom, mechanisms of lake eutrophication and water pollution, and lake eutrophication, swampiness and ecological catastrophe.

The Taihu Lake Station (Figure 1) consists of two parts. The base (31°24'N, 120°13'E) is located on the shore of Meiliang Lake of Taihu Lake in Binhu district, Wuxi city, Jiangsu province, and the branch is an aquatic agriculture experiment station located in Suzhou city, the east part of Taihu Lake4. Since its establishment in 1991, the station has been continuously collecting water physical and chemical indicators of Taihu Lake. From 1991 to 1995, eight sampling sites were laid on the lake in the northern part of Taihu Lake covering 1000 km2. From 1995 to 2004, more sites are set to monitor the entire lake. This dataset is the physical and chemical data of water bodies collected by 8 routine monitoring sites in Taihu Lake Station from 2001 to 2006.

Figure Geographical location of Taihu Lake

2. Data collecting and processing

The water physical and chemical data of Taihu Lake station collected from 2001 to 2006 involve 8 routine monitoring sites, which are as follows: THL00 (Taihu Station No.0, 120.22°E, 31.54°N), THL01 (Taihu Station No.1, 120.19°E, 31.51°N), THL03 (Taihu Station No.3, 120.19°E, 31.48°N), THL04 (Taihu Station No.4, 120.19°E, 31.44°N), THL05 (Taihu Station No.5, 120.19°E, 31.41°N), THL06 (Taihu Station No.6, 120.13°E, 31.50°N), THL07 (Taihu Station No.7, 120.18°E, 31.34°N)和THL08 (Taihu Station No.8, 120.17°E, 31.25°N). The physical and chemical data of Taihu Lake water body were observed at a fixed interval of once per month. The physical data include indicators of transparency, water depth, water level etc. The chemical data elements include total phosphorus, total nitrogen, phosphate, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen, dissolved oxygen, biochemical oxygen demand etc.

2.1 Water physical data of Taihu Lake

The physical elements of lake water are important parameters of lake ecosystem5. The monthly observed water physical indicators include water depth, temperature, transparency, suspended matter and conductivity. Water temperature is observed by water thermometers, which are verified annually. Transparency is determined by plug discs with each point measured 3 times for a mean value; suspended matter is weighed after drying in an oven, and this procedure is repeated until achieving a measurement error of less than 1 / 10000g; conductivity is monitored using a conductivity meters, which are calibrated every 3 months (Table 1).

Table 1  Taihu Station water quality monitoring instruments and quality control[4]

Projects

Analysis Methods

 Instruments

Quality Control

Water temperature

Water temperature meter method

Surface water thermometer

Calibrate the water thermometer each year

Transparency

Plug method

Plug disc

The Plug disc is painted each year and each point is measured 3 times and the mean is taken

Suspended matter

Drying method

Drying oven, 1/100000 electronic scales

Bake for 3 hours followed by cooling in the dryer and then weight. Later bake the solids for half an hour and cool them in the dryer and weigh again until the satisfactory results come with an error less than 1/10000 g

Conductivity

Conductivity meter method

DDS-11C conductivity meter

periodic calibration

2.2  Water chemical data of Taihu Lake

The chemical elements of water in Taihu Lake from 2001 to 2006 include total phosphorus, total nitrogen, phosphate, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen, dissolved oxygen, permanganate index, biochemical demand oxygen, suspended matter, total nitrogen, pH, four kinds of cations, chloride, sulfate, water temperature, transparency, conductivity and other indicators of monthly observed data. Among these data, alkalinity, dissolved oxygen, permanganate index, biochemical oxygen demand factor are measured by using 10 ml microburette after the concentration is calibrated; total phosphorus, phosphate, total nitrogen, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen are determined by ultraviolet spectrophotometry; sulfate, chlorides, kalium, natrium, calcium and magnesium are measured by ion chromatography (Table 2).

Table 2  Taihu Station water quality monitoring instruments and quality control4

Projects

Analysis methods

 Instruments

Quality control

pH

pH composite electrode method

PHS-3TC

Replace the electrode every year and use the standard buffer solution for calibration every time

Alkalinity

Acid-base titration

10 ml microburette

 Calibrate using the standard  concentration of HCl solution every quarter

Dissolved oxygen

Iodometry

10 ml microburette

Calibrate using the standard concentration of sodium thiosulfate

solution each time  

Permanganate index

Acid process

10 ml microburette

Calibrate each time, using the standard concentration of potassium permanganate solution

Biochemical oxygen demand

(BOD)

Dilution and seeding method

10 ml microburette

Calibrate each time, using the standard concentration of sodium thiosulfate

solution, and control time and temperature precisely

Total phosphorus

Molybdenum-antimony anti-spectrophotometric method

UV-240lPC ultraviolet spectrophotometry

 Calibrate and compare with the analytic results of standard sample control

Phosphate

Molybdenum-antimony anti-spectrophotometric method

UV-240lPC ultraviolet spectrophotometry

Calibrate and compare with the analytic results of standard sample control

Total nitrogen

ultraviolet spectrophotometry

UV-240lPC ultraviolet spectrophotometry

Calibrate and compare with the analytic results of standard sample control

Nitrate nitrogen

spectrophotometric method with phenol disulfonic acid

UV-240lPC ultraviolet spectrophotometry

Calibrate and compare with the analytic results of standard sample control

Nitrite nitrogen

N(1-naphty1)-ethylenediamine dihydrochloride spectrophotometric method

UV-240lPC ultraviolet spectrophotometry

 Calibrate and compare with the analytic results of standard sample control

Ammonia nitrogen

Nessler's reagent colorimetric method

UV-240lPC ultraviolet spectrophotometry

Calibrate and compare with the analytic results of standard sample control

Sulfate

chromatography of ions

DX-100 ion chromatography

Calibrate and compare with the analytic results of standard sample control

Chloride

chromatography of ions

DX-100 ion chromatography

 Calibrate and compare with the analytic results of standard sample control

Kalium

chromatography of ions

DX-100 ion chromatography

Calibrate and compare with the analytic results of standard sample control

Natrium

chromatography of ions

DX-100 ion chromatography

Calibrate and compare with the analytic results of standard sample control

Calcium

chromatography of ions

DX-100 ion chromatography

 Calibrate and compare with the analytic results of standard sample control

Magnesium

chromatography of ions

DX-100 ion chromatography

 Calibrate and compare with the analytic results of standard sample control

3. Sample description

The dataset of water quality monitoring in Taihu Lake in the period of 2001 – 2006 are arranged in two Excel data files: “Water Quality Data of Taihu Lake Station Observation Site.xlsx” and “Water Body Physics and Water Body Chemical monitoring data of Taihu Lake 2001-2006.xlsx”. The fomer data file, describes the space point information of 8 water quality routine monitoring sites of Taihu Lake (Table 3); The latter data file contains two sheets, which are “Water Physical Monitoring Data of Taihu Lake 2001-2006” and “Water Chemical Monitoring Data of Taihu Lake 2001-2006”. The two Excel documents contain physical and chemical data acquired monthly by the 8 sites from 2001 to 2006 (in the forms of Table 4 and Table 5, respectively). In the chemical monitoring, some observation stations left several data items empty, such as dissolved total nitrogen, dissolved total phosphorus, permanganate index, silicate and alkalinity, due to differences in manual sampling and instrument failure. Some indicators, such as BOD5, were not included in the regular monitoring system until 2006. But relevant data from 2006 are still presented in the dataset for data integrity.

Table 3  Sample data in Taihu Lake water quality observation stations

Field name

Dimension

Data type

Example

Observation Station Number

 

Characters

1

Observation Station Code

 

Characters

THL00

Observation Station Name

 

Characters

Taihu Lake Station No.0

East Longitude

°

Floating-point numbers

120.219,44

North Latitude

°

Floating-point numbers

31.539,68

Table 4  Sample of the physical monitoring data sheet

Field name

Dimension

Data type

Example

Observation station number

 

Characters

1

Observation station code

 

Characters

THL00

Year

 

Short type

2006

Month

 

Short type

1

Water depth

m

Floating-point numbers

1.4

Water temperature

Floating-point numbers

7.8

Transparency

m

Floating-point numbers

0.5

Suspended matter

mg/L

Floating-point numbers

29.88

Conductivity

µS/cm

Floating-point numbers

775

Table 5  Sample of the chemical monitoring data sheet

Field name

Dimension

Data type

Example

Observation station number

 

Characters

1

Observation station code

 

Characters

THL00

Year

 

Short type

2003

Month

 

Short type

1

pH

 

Floating-point numbers

8.31

Total nitrogen

mg/L

Floating-point numbers

5.58

Total phosphorus

mg/L

Floating-point numbers

0.114

Chlorophyll a

μg/L

Floating-point numbers

14.28

Pheophytin

μg/L

Floating-point numbers

3.21

Permanganate index

mg/L

Floating-point numbers

6.21

Dissolved oxygen

mg/L

Floating-point numbers

11.88

BOD5

mg/L

Floating-point numbers

3.87

Ammonia nitrogen

mg/L

Floating-point numbers

2.45

Nitrite nitrogen

mg/L

Floating-point numbers

0.041

Nitrate nitrogen

mg/L

Floating-point numbers

1.198

Dissolved total nitrogen

mg/L

Floating-point numbers

5.09

Phosphate

mg/L

Floating-point numbers

0.011

Dissolved total phosphorus

mg/L

Floating-point numbers

0.039

Alkalinity

mmol/L

Floating-point numbers

2.51

Kalium ion

mg/L

Floating-point numbers

7.63

Natrium ion

mg/L

Floating-point numbers

69.3

Calcium ion

mg/L

 Floating-point numbers

54.9

Magnesium ion

mg/L

Floating-point numbers

12.31

Fluoride ion

mg/L

Floating-point numbers

0.49

Chloride

mg/L

Floating-point numbers

61.2

Sulfate

mg/L

Floating-point numbers

90.2

Silicate

µmol/L

Floating-point numbers

63.5

Alkalinity (on CaCO3 basis)

mg/L

Floating-point numbers

140.8

Silicate (on Si basis)

mg/L

Floating-point numbers

3.81

4. Quality control and assessment

The quality control process of original observation data and refined data include examination and organization of source data, examination, transformation and inputs of single data points, writing, examination and inputs of metadata.

Source data are audited for obvious problems, such as file formatting errors and damages during storage, and others in file formats, standard field naming, dimensions and data integrity. Single data points are inspected to correct errors and remove anomalies.

Figure 2  Quality control process

In routine observation projects carried out by the Taihu Lake lab, a systematic quality control process (Figure 2) is established at the data input stage to ensure the integrity and consistency of the stored data. At the observation stage, professionals with long-term working experience in the lab are responsible for making observations and maintaining equipment.

Quality control processes at the steps of data organization and storage are mainly divided into two steps:

(1) Integrate, sort and convert various source data into one unified format;

(2) Remove random and systematic errors through a series of quality control methods. The methods contain extremum inspection and internal consistency check to ensure data quality. Metadata are filled in by data observation and reorganization personnel from the Taihu Lake lab in accordance with the lab’s standard formats (in data name, time range, field descriptions, observation methods, and intellectual property, etc.) and reviewed by professional researchers hired from specific fields.

5. Usage notes

The long-term monitoring and accumulation of water quality data of Taihu Lake, which indicate the changing trends of pollutants in Taihu Lake, provide basic information for cyanobacteria monitoring, forecasting, and warning in Taihu Lake, and scientific basis for water environment management, water quality evaluation and planning of Taihu Lake6.

The dataset can be accessed at Science Data Bank website (http://www.sciencedb.cn/dataSet/handle/13), Lake-Watershed Science Data Center (http://lake.geodata.cn), and China Lake Database (http://www.lakesci.csdb.cn). Readers can query and download data, and use an online visual tool of data (http://lake.geodata.cn/LakeDB).

Queries can be done by selecting an observation station in the map (Figure 3) and choosing certain field names. In the dataset, after selecting one observation station, readers can choose a period of time they want, and simply click the “Submit” button. Readers can also select multiple water quality elements at the same time in the “Chart” tab (Figure 4) and click the “Download” button to download the queries in an Excel document. In the “Graph” tab, when readers pick one water quality element and click the “Draw” button, a curve graph will show the changing trend of the element (Figure 5).

Figure 3  Choose an observation station in the map for water quality data query

Figure 4  Taihu Lake water quality data query

Figure 5  Taihu Lake water quality graph-drawing

Acknowledgments

We would like to thank the Taihu Lake Laboratory Ecosystem Research Station of Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences for its generous support and assistance, and appreciate the funding offered by National Earth System Science Data Sharing Infrastructure, National Science & Technology Infrastructure of China, Chinese Ecosystem Research Network (CERN) and the 12th five-year-plan Scientific and Technological Data Resource Integration and Sharing Project of the Chinese Academy of Sciences.

References

1. Wang Sumin, Dou Hongshen. Records of Lakes in China. Beijing: Science Press, 1998.

2. Qin Boqiang, Luo Liancong. Changes in eco-environment and the causes for Lake Taihu, China. Quaternary Sciences 24 (2004): 561 – 568

3. Li Wei, Cui Lijuan, Zhao Xinsheng et al. Relationship between Soil Animal Community Structure and Soil Physical and Chemical Properties in Lake Taihu Lakeshore, China. Acta Ecologica Sinica 35 (2015): 944 – 955.

4. Qin Boqiang, Hu Chunhua. Ecosystem Observation and Research Dataset of China - Ecosystems in Lakes, Wetlands and Gulfs in Taihu Lake of Jiangsu Province (1991-2006). Beijing: China Agriculture Press, 2010.

5. He Jun, Gu Xiaohong, Liu Guofeng. Aquatic Plants in East Lake Taihu and Their Interaction with Water Environment. Journal of Lake Sciences 20 (2008): 790 – 795.

6. Qin Boqiang. Progress and prospect on the eco-environmental research of Lake Taihu. Journal of Lake Sciences 21 (2009): 445 – 455.

Data citation

Xu J, Ma R. A dataset of water quality monitoring in Taihu Lake (2001 – 2006). Science Data Bank. DOI: 10.11922/sciencedb.170.13.

Authors and contributions

Xu Jinduo, MSc, Engineer; research area: database building, data sharing, and cartography and geographic information systems. Contribution: construction and operation of Lake-Watershed Science Data Center.

Ma Ronghua, PhD, Researcher; research area: data sharing and remote sensing of lake water environment. Contribution: operation and management of Lake-Watershed Science Data Center.

Wang Zhen, BS, Engineer; research area: database construction. Contribution: data organization and quality control in this Taihu Lake database project.

Hu Jiajun, BS, Engineer; research area: cartography and geography information system. Contribution: database building in this Taihu Lake database project.

 

How to cite this article: Xu J, Ma R, Wang Z et al. A dataset of water quality monitoring in Taihu Lake (2001 – 2006). China Scientific Data 2 (2016). DOI: 10.11922/csdata.170.2015.0014.

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