Spatial variation and environmental assessment of soil organic carbon isotopes for tracing sources in a typical contaminated site

Accepted Manuscript Spatial variation and environmental assessment of soil organic carbon isotopes for tracing sources in a typical contaminated site

Qingjun Guo, Guangxu Zhu, Tongbin Chen, Jun Yang, Junxing Yang, Marc Peters, Rongfei Wei, Liyan Tian, Xiaokun Han, Jian Hu PII: DOI: Reference:

S0375-6742(16)30422-8 doi: 10.1016/j.gexplo.2016.12.009 GEXPLO 5872

To appear in:

Journal of Geochemical Exploration

Received date: Revised date: Accepted date:

7 May 2015 22 July 2015 7 December 2016

Please cite this article as: Qingjun Guo, Guangxu Zhu, Tongbin Chen, Jun Yang, Junxing Yang, Marc Peters, Rongfei Wei, Liyan Tian, Xiaokun Han, Jian Hu , Spatial variation and environmental assessment of soil organic carbon isotopes for tracing sources in a typical contaminated site. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Gexplo(2016), doi: 10.1016/j.gexplo.2016.12.009

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ACCEPTED MANUSCRIPT Spatial variation and environmental assessment of soil organic carbon isotopes for tracing sources in a typical contaminated site Qingjun Guoa,*, Guangxu Zhua,b, Tongbin Chena, Jun Yanga, Junxing Yanga, Marc Petersa, Rongfei Weia, Liyan Tiana, Xiaokun Hana, Jian Huc

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a

Center for Environmental Remediation, Institute of Geographic Sciences and

China State

Key

Laboratory

of

Environmental

Geochemistry,

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b

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Natural Resources Research, Chinese Academy of Sciences, Beijing 100101,

Institute

of

*

Corresponding Author

Email address: [email protected]

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Fax: +86-10-64889455

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Tel: +86-10-64889455

ABSTRACT

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Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China

The environment of Beijing as the capital city of China is highly affected by

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industrial pollution. The area of the Capital Iron & Steel Factory of Beijing is a typical example for industrially contaminated sites in the Beijing area. In the

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present study, we collected topsoil and section samples from the Capital Iron & Steel Factory site and its surrounding area in high resolution, which were analyzed on organic carbon concentrations and carbon isotopic compositions. The results reveal both anthropogenic and natural contributions of carbon to these soils. Three profiles from the vicinity and two profiles from the area surrounding the steel company display vertical patterns in soil organic carbon concentrations and isotopic compositions that resemble more commonly observed downward gradients in soil carbon chemistry and indicate microbial carbon turnover. 1

ACCEPTED MANUSCRIPT δ13CSOC values in the transverse distribution change towards either more

13

C

or 12C depleted values with distance to the center of the steel factory area. The study discloses that coal and/or coal combustion products represent the dominant source of soil organic carbon in the industrial region, and the affection decreases with increasing distance to the center of the industrial area.

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Organic matter of the soil from the surrounding area of the industrial site is mainly derived from coal or coal combustion products as well as C3 and C4

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plants.

An assessment of the transverse and vertical distribution of the concentrations

from

industrial

sites

and

the

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and isotopic compositions of bulk organic carbon in topsoil and soil profiles surrounding

area

combined

with

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three-dimensional spatial distribution and variation analysis were applied to identify the degree, sources, and processes of industrial pollution.

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Keywords: Contaminated site, sources, soil organic carbon isotope,

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1. Introduction

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three-dimensional spatial analysis, the Capital Iron & Steel Factory, Beijing

Rapid economic development in China in the past decades characterized by an irresponsible treatment of the natural heritage has led to heavy pollution of

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China’s urban and rural environment in most parts of the country (Wong et al.,

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2006; Morel and Heinrich, 2008). Soil has been polluted by contaminants from air, water and solid waste through migration, retention and deposition. Toxic substances enter the soil and accumulate with time until they represent a serious risk for humans' health and the environment (Chen et al., 2005). Legacy sites are mainly located in the suburbs of cities and are usually highly polluted by industrial emissions (Luo et al., 2012a, 2012b). During the process of urbanization these contaminated sites will be transformed from industrial to commercial, residential or municipal land. These sites are characterized by a high development value, but also by high environmental and social risks. 2

ACCEPTED MANUSCRIPT Hence, it is important to assess the environmental quality of these former industrial sites. Variable soil δ13CSOC values and their evolution over time are controlled by carbon inputs from vegetation and by biological decay processes (Nadelhoffer and Fry, 1988; Garten et al., 2000). Soil organic matter can carry the isotope

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signals of wet and dry deposition, fossil fuel combustion residues, environmental changes and human activities (Ehleringer et al., 2000; Zhu et al.,

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2005; Bai et al., 2012), so that carbon isotopes and carbon abundance can be used to quantify SOC turnover rates, reconstruct the plant-soil community

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history (Balesdent et al., 1987; Choi et al., 2001; Sanaiotti et al., 2002; Krull et al., 2007; Boutton et al., 2009a), trace the sources and fate (degradation,

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migration and transformation) of soil organic carbon, analyze functional and structural characteristics of ecosystems and their responses to human

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activities and environmental changes (Amundson et al., 1998; Boutton et al., 1999; Ehleringer et al., 2000; Pataki et al., 2003, 2007; West et al., 2010; Bai

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et al., 2012), and provide constraints for carbon cycling models (e.g.,

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Ehleringer et al., 2000; Stevenson et al., 2005; Norra et al., 2005; Boeckx et al., 2006; Weihmann et al., 2007; Zhu and Liu, 2008; Guo et al., 2013). At present, environmental contamination at former industrial sites is a serious

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economic problem in China (Chen, 2005；Zhou et al., 2007). It is suggested that the soil in the area of the Capital Iron & Steel Factory is

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polluted by heavy metals due to smelting and other industrial activities over the past 100 years. So far, only a few reports have focused on the distribution of heavy metals and isotopes (Yuan et al., 2013; Guo et al., 2013) in the soils of this area. In order to reveal and distinguish both anthropogenic and natural contributions, analyses of the spatial distribution of organic carbon and heavy metals in the soil is a significant task (Cicchella et al., 2005; Acosta et al., 2011; Guillén et al., 2011; Mrvić et al., 2011; Wu et al., 2011; Li and Feng, 2012; Lu et al., 2012; Yuan et al., 2013). Beijing is the capital and one of the business centers of China, and has a 3

ACCEPTED MANUSCRIPT well-developed industrial sector. However, around 2008, more than 400 factories were closed and moved to other cities due to the Olympic Games. Therefore, many abandoned and legacy sites have to be assessed and remediated. The Capital Iron & Steel Factory was founded in 1919 and covered 8.56

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square kilometers. The area contained sintering, iron making, refining and coal-fired power plants, and produced an output of 30 million tons of iron per

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year. It became one of the largest factories in China. Since the end of 2010, the company has been completely closed and moved to Chaofeidian, Hebei

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Province. In future, the entire former industrial area of the Capital Iron & Steel

remediation of the contaminated land.

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Factory will be transformed into parks, commercial and residential areas after

Hence, in the present study organic carbon abundances and stable carbon

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isotopes as well as three-dimensional spatial variation analyses on samples from the topsoil and soil profiles collected in the Capital Iron & Steel Factory

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zone and its surrounding area were conducted in order to characterize soil

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carbon turnover, and to identify the source(s) and fate of soil organic carbon.

2. Geographic setting

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Beijing (39°20’ – 40°90’N, 115°20’ – 117°20’E) is situated at the northern tip of

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the North China Plain. In its west, north and northeast, the city is surrounded by mountains. The Bohai Sea is located around 150km to the southeast of Beijing, which is characterized by a typical monsoon-influenced climate, with windy and dry winters due to the north-west Asian monsoon (Siberian anticyclone), and generally humid and hot summers due to the South-East Asian monsoon (Wu et al., 2010; Guo et al., 2013).The study area is represented by the former industrial site of the Capital Iron & Steel Factory Zone and its surrounding area, Shijingshan District, in the west of Beijing (Fig. 1). 4

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3. Sampling and analytical Methods 3.1

Sampling

The study area comprises approximately 58.31 km2 and extends from the center of the Capital Iron & Steel Factory area to outward direction. A 2 × 2 km

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grid for sampling was established. Topsoil core samples (0-10 cm, n = 71) inside the former plant zone (one sample per 200 meter, n=23) and the

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surrounding area (one sample per 300 meter, n=48) were collected as shown

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in Figure 1.

Eight section samples (Guo et al., 2013) have been collected in the industrial

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zone (A, B and DLC) and in the surrounding area (FCK, 469) as well as the non-industrial area (Yongledian, Tongzhou and Guadi) of Beijing.

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Four coal and seven plant samples were collected from the Capital Iron & Steel Factory area. Two plants (The dog’s tail grass, Hard grass) were C4 plants, and the rest (A tree stem, Large leaves, Holly stems, Cypress, Holly

3.2

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leaves) were C3 plants (Guo et al., 2013).

Analytical Methods

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Dried Soil samples were pulverized using an agate mortar. The concentration of soil organic carbon (SOC) was determined by the difference between the

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concentrations of total carbon (TC) and total inorganic carbon (TIC). These concentrations were measured using Infrared spectroscopy following liberation of carbon dioxide from soil samples via combustion at 1350°C (TC) or hydrochloric acid-digestion (TIC). Analyses were performed using a CS Mat 5500 (carbon and sulfur elemental analyzer) at the Institut für Geologie und Paläontologie in Münster, Germany and IR spectroscopy using a CS Mat (carbon and sulfur elemental analyzer) at the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences in Beijing, China. Reproducibility as determined through replicate measurements was 5

ACCEPTED MANUSCRIPT better than 1% relative. The isotopic composition of organic carbon (δ13CSOC) was measured via sealed-tube combustion (e.g., Strauss et al. 1992) and subsequent mass-spectrometric analysis using a ThermoFinnigan Delta Plus at the Institut für Geologie und Paläontologie in Münster, Germany and a ThermoFinnigan

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MAT 253 at the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences in Beijing, China.

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The stable organic carbon isotope is expressed in ‘‘delta’’ (δ) notation to indicate differences between the isotopic ratio of the sample and accepted

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δ13CSOC=

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standard materials expressed as

where δ13CSOC is reported in permil (‰) difference to the Vienna PDB standard (VPDB). Reproducibility as determined through replicate measurements was

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better than 0.15‰.

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A model of the spatial distribution and 3D distribution of carbon concentration and δ13CSOC was developed based on the significance of the land

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management variables. The model of the spatial distribution of δ13CSOC is shown in Fig. 3. Separate plots are provided for the 0–5 cm (Figs. 3 and 4 new)

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soil depths.

Descriptive statistics were computed with SPSS for Windows, version 19.0 and Origin for Windows, version 8.0.

4. Results Analytical results are given in Tab. 1. (1) Top soil: A. Samples from the industrial area show highly variable soil organic carbon concentrations between 0.9 and 14.6 wt.-% (avg.: 4.63±3.3%, n=23) (Table 1; Fig. 2). Soil organic carbon isotope data display rather 6

ACCEPTED MANUSCRIPT invariable δ13C values between -24.1 and -25.8‰ (avg.: -24.7±0.5‰, n=22) (Table 1; Fig. 2); B. Samples from the area surrounding the industrial zone reveal highly variable soil organic carbon concentrations between 1.2 and 11.3 wt.-% (avg.: 4.1±2.3%, n=48) (Table 1; Fig. 2). Soil organic carbon isotope data display values between -22.3 and -26.7‰ (avg.: -24.4±0.8‰, n=46)

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(Table 1; Fig. 2); (2) Soil sections samples, four coal samples and seven plant samples were

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reported(Guo et al., 2013);

(3) Soil δ13C was significantly and positively correlated with SOC

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concentrations (r2 =0.1331) (Fig.5) in the industrial zone and negatively correlated with SOC concentrations (r2 =0.11) (Fig.5) in the surrounding area

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of the industrial zone;

(4) The ArcGIS spatial distribution maps and the spatial 3D distribution maps

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developed from the grid points revealed that soil TC (Figs. 3a and 4a), TIC (Figs. 3b and 4b) and TOC (Figs. 3c and 4c) were gradually increasing from

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northwest to southeast of the area and decreasing with increasing distance to

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the center; soil δ13C was rather invariable from the center of the industrial area, gradually increasing or decreasing with increasing distance to the center of the factory area (Figs. 3d and 4d);

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The maps based on the grid points disclosed that soil (Fig. 3e) was rather invariable from the center of the industrial area, gradually increasing or

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decreasing with increasing distance to the center of the factory area (Fig. 3e).

5 Discussion

Isotope analyses of organic carbon in soil are an appropriate method for tracing the sources and fate (degradation, migration and transformation) of soil organic carbon, and provide constraints for carbon cycling models (e.g., Enting et al.,1995; Ehleringer et al., 2000; Norra et al., 2005; Stevenson et al., 2005; Zhu et al., 2005; Boeckx et al., 2006; Weihmann et al., 2007; Zhu and Liu, 7

ACCEPTED MANUSCRIPT 2008; Guo et al., 2013). It is significant for the study that δ13CSOC and TOC concentration in soils as a function of distance and depth in industrial region and surrounding area with different distances. The sampling area of the 71 top soil samples (this study) and eight profiles (Guo et al., 2013) include the industrial zone and the surrounding area, which

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are characterized by industrial and non-industrial environmental conditions. Soils from the industrial area have been affected by industrial emissions for

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around 90 years, and particularly some soil samples taken close to some plants in the industrial area have likely experienced a long history of

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contribution by anthropogenic pollutants, such as heavy metals, organic waste and industrial C.

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Organic carbon isotope results have been used to distinguish both natural and anthropogenic contributions of carbon to soils, such as coal, rocks and plants

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(C3 and C4 plants) (e.g., Bender, 1971; Smith and Epstein,1971; O’Leary, 1981; Ågren et al., 1996; Yi, 2005; Guo et al., 2013). C3 plants reveal δ13C

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values around -27‰, and C4 plants around -13‰. Seven plant samples from

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the steel company area display δ13C values between-15.4 to -15.1‰ (three C4 plants) and between -30.0 and -26.7‰ (four C3 plants), respectively (Guo et al., 2013). Organic carbon isotopic compositions of Chinese coal and of coal

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collected in the Capital Iron & Steel Factory area vary between -25.5 and -23.5‰ (Duan,1995) and between -25.1 and -23.6‰ (Guo et al., 2013), respectively.

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Organic carbon isotopic compositions from topsoil samples from a non-industrial area in Beijing vary between -23.6 and -22‰ (Guo et al., 2013), which can be considered as background values of natural soils in Beijing. Samples from the industrial area show highly variable soil organic carbon concentrations between 0.9 and 14.6 wt.-% (Tab. 1; Fig. 2), and the average values are higher than those of samples from the surrounding area with values between 1.2 and 11.3 wt.-% (Fig. 2). It is evident that the concentrations of SOC of the top soil horizons in the industrial area (esp. plant area) are generally high, much more variable and decrease with increasing distance to 8

ACCEPTED MANUSCRIPT the center of the industrial zone. Soil organic carbon concentrations are highly variable (avg.: 4.6±3.3%, n=23), esp. soil organic carbon concentrations (SOCC) around several plants exhibit relatively high values between 8 and 14.6 wt.-% (Figs. 2 and 6). The soil organic carbon concentrations of the samples from the area surrounding the industrial zone (including the former

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residential area for factory workers) are lower than those from the industrial area, but highly variable (avg.: 4.1±2.3%, n=48) (Figs. 2 and 6, Table 1).

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Moreover, the soil organic carbon concentrations of the samples from the nonindustrial area (Guo et al., 2013) are much lower than those from the industrial

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zone and its surrounding area (avg.: 0.6±0.4%, n=46) (Guo et al., 2013). SOC concentrations from the top soil and soil profiles of the industrial zone are

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much more variable and increase with increasing distance and depth compared to the concentrations from other vertical sections and surface soil

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from the non-industrial area (Figs. 2 and 3). As stated before, previous studies of undisturbed natural soil profiles (e.g., Piao et al., 2001; Zhu et al., 2008; Tu

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et al., 2008; Guo et al., 2013) revealed a decrease in soil organic carbon

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concentrations with increasing depth, reflecting its progressive degradation. High SOC concentrations in topsoils as well as deep soil sections, mainly originated from steel production. The concentrations are much higher than

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those of soil from the non-industrial area (Guo et al., 2013) in Beijing (Figs. 2 and 6, Table 1). Hence, high SOC concentrations indicate contamination of

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industrial C.

SOC concentrations increase from northwest to southeast (Fig. 3), and decrease with increasing distance from the center of the Capital Iron & Steel Factory suggesting that organic C in the soils is mainly derived by industrial activities. Concentrations of SOC in local soils can be also affected by the summer and winter monsoon in the Beijing area, so that concentrations of SOC in local soils from southeast to northwest are higher (Fig.3a-3g). The δ13CSOC of the topsoil horizons in the industrial area display rather invariable values between -25.8 and -24.1‰ (avg.: -24.7 ±0.5‰, n=22) and 9

ACCEPTED MANUSCRIPT then decrease or increase with increasing distance to the center of the industrial zone (Figs. 2-6). Furthermore, it is evident that the δ13CSOC values of the topsoil horizons from the area surrounding the industrial zone are generally more variable compared to those of the industrial area (between -26.7 and -22.3‰ (avg.: -24.4 ±0.8‰, n=46)). δ13CSOC variations with increasing depth in soil profiles from the surrounding

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area (avg.: -23±0.6‰, n=21) and from soil profiles from the non-industrial area

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(avg.: -21.9±1.5‰, n=46) are different to the profiles from the industrial zone and reflect (microbial) turnover of soil organic matter (Guo et al., 2013) as well

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as the influence of C3 and C4 plants.

Figures 3 and 4 show that the δ13Corg values of the topsoil horizons generally

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decrease or increase with distance to the center of the Capital Iron & Steel Factory area. In the deeper soil of the three locations (A, B, C, Guo et al., 2013)

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close to the center of the factory area the δ13Corg values of organic matter are similar; soil organic carbon in the three other soil profiles (Guo et al., 2013)

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taken in further distance to the center of the factory area seems to be more

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affected by (bio)degradation processes, as shown by the typical down-section change in the carbon isotopic composition of the soil organic carbon. There exists one possible way how to differentiate carbon pools, such as degradation

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products (DOC) or pyrolysis products etc. Two sections (D,E, Guo et al., 2013) from the area surrounding the industrial zone display variations in δ13Corg and

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SOC concentrations that are intermediate between those from the industrial and non-industrial area. The absence of any variation in δ13CSOC with increasing depth in soils within the industrial area reflects the recalcitrant character of the SOC (Guo et al., 2013). In the Capital Iron & Steel Factory area coal was used for industrial production. In total four coal samples were collected from this area. Total carbon concentrations of the coal range from 70.9 to 78.4 wt.-% (Guo et al., 2013). The δ13Corg values show a variation between -23.6 and -25.1‰. The isotopic composition of soil organic carbon in surface soil as well as the soil 10

ACCEPTED MANUSCRIPT profiles in the area of the Capital Iron & Steel Factory are similar with those of the average carbon isotopic composition for Chinese coal (Duan, 1995) indicating substantial contribution from coal by coal combustion. Furthermore, the distribution area with invariable δ13Corg values and relatively high SOCC was more directly influenced by industrial activities.

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The variable δ13Corg values and lower SOC concentrations suggest that the soil organic matter from the topsoils and soil profiles from the non-industrial

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area shows (microbial) turnover of soil organic matter (Guo et al., 2013) and influence by C3 and C4 plants. Moreover, the rather invariable δ13Corg values

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and high SOC concentrations in topsoil and soil profiles from the area surrounding the industrial zone mainly originated from the direct contribution of

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coal or the emissions from coal burning as well as C3 and C4 plants (Fig. 6) suggesting an influence of both anthropogenic activities and natural

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processes.

A spatial distribution model by carbon isotopes of topsoils reflects the

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distribution of organic carbon in soil from the industrial and non-industrial zone

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(Figs.3 and 4). The monsoon from the southeast in summer and from the northwest in winter (Fig. 3a-3g) probably affected the distribution of the δ13CSOC values.

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Our results suggest that topsoil as well as deep soil (down to 100cm depth) of the main industrial area has been seriously polluted by industrial activities.

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Consequently, in order to prevent serious risks for the health of the population the contaminated area has to be intensely remediated before further actions, such as the transformation of the former industrial site into parks, commercial and residential areas, are carried out.

6. Conclusions The concentration and organic carbon isotopic composition of bulk soil from 71 top soil samples collected in the industrial zone of the Capital Iron & Steel 11

ACCEPTED MANUSCRIPT Factory and its surrounding area reveal both natural and anthropogenic contributions of organic carbon to these soils. This research presented a method to model the spatial distribution of the carbon stable isotopic compositions. SOC concentrations increase from northwest to southeast, and decrease with increasing distance from the center of the industrial zone to the surrounding area. A significant change in the transverse distribution of the

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δ13CSOC values towards more positive or negative values occurs with

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increasing distance to the center of the Capital Iron & Steel Factory area. Stable carbon isotopes suggest coal and/or coal combustion products as the

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dominant sources of organic carbon in surface soil and soil profiles in the industrial region, and the influence of these sources decrease with increasing

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distance to the center of the industrial area. In the surrounding area, soils were more directly influenced by the anthropogenic activities and natural processes.

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This study demonstrates that the combination of the transverse and vertical distribution of organic carbon and its isotopic composition in surface soil and

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soil profiles from a former industrial site with its surrounding area as well as

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non-industrial regions can provide a deeper insight into the sources and the fate of soil organic carbon. Specifically, an anthropogenic input of organic carbon into soil by coal and coal combustion products could be identified and a

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further assessment of the soil quality is useful for later remediation measures

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and an appropriate environmental management in this area.

Acknowledgements Analytical work was performed at the Institut für Geologie und Paläontologie, Westfälische Wilhelms-Universität Münster, Germany, and the Institute of Geographic Sciences and Natural Resources Research, CAS. Harald Strauss, Artur Fugmann, Andreas Lutter and Jianli Wang are thanked for their help in the laboratory. GQ acknowledges financial support by 973 Program (Nr. 2014CB238906), the One Hundred Talents Program of the Chinese Academy 12

ACCEPTED MANUSCRIPT of Sciences, the Alexander von Humboldt Foundation, the National Natural Science Foundation of China (NSFC Nos. 41450110460).

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Geochemistry, 27, 171-177.

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ACCEPTED MANUSCRIPT Figure Captions Fig. 1 Geographic setting and location of soil samples, Beijing city, China Fig. 2 Distribution of carbon isotopic composition and SOC of this study Fig. 3 ArcGIS spatial distribution of (a) TC, (b) TIC, (c)TOC, (d)TOC/TC, (e) δ13C

bars represent the concentrations of

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Fig. 4 Spatial 3D plots of (a)TC, (b) TIC, (c)TOC, (d) δ13C, the height of the (a)TC, (b) TIC, (c)TOC and the

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composition of (d) δ13C, and the location in the x,z plane is the coordinate location.

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Fig. 5 Cross-plot of SOC and δ13Csoc in the Capital Iron & Steel Factory area (A) and δ18Ocarb and Mn/Sr (weight ratio) (B). Diamonds display values

triangles the Dongergou section

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from the Penglaiba section, squares the Wushi phosphorite section and

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Fig. 6 SOC concentration and organic carbon isotopic composition delineate contributions from natural sources as well as coal and coal combustion

Table Caption

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Table Content and organic carbon isotopic composition of surface soil samples

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from Beijing Steel company area

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ACCEPTED MANUSCRIPT Table 1 Table Content and organic carbon isotopic composition of surface soil samples from Beijing Steel company area samples

δ13Corg(VPDB,‰)

TS(%) TC(%) TIC(%) TOC(%)

Longitude

Latitude

(1)Inside of the industrial area -24.5

0.04

6.60

1.86

4.72

116.1219444444 39.9372222222

2

-23.5

0.04

4.16

1.79

2.37

116.1143888889 39.9372222222

3

-24.6

0.03

4.55

1.37

3.18

116.1086944444 39.9305833333

5

-24.9

0.08

6.11

1.21

4.90

116.1204722222 39.9246666667

0.05

3.58

0.88

2.71

116.1489166667 39.8958888889

0.04

4.27

1.09

3.18

116.1583888889 39.8873333333

20

-23.5

0.02

2.66

0.93

1.72

116.1328055556 39.9093333333

21

-23.9

0.03

3.31

1.62

1.69

116.1279444444 39.9101666667

23

-23.3

0.02

2.44

0.86

1.57

116.1254722222

25

-25.0

0.20

4.89

2.01

2.88

116.1716944444 39.8931944444

26

-25.0

0.42

7.35

2.93

4.43

116.1633333333 39.8946944444

28

-25.3

0.48

8.07

2.95

5.12

116.1556666667 39.8988611111

29

-24.3

0.55

6.87

1.53

5.34

116.1637222222 39.8906666667

30

-24.8

0.19

4.98

1.84

3.14

116.1707777778

31

-24.3

0.24

5.54

2.02

3.51

116.1773055556 39.8913055556

34

-24.9

0.07

4.16

1.74

2.42

116.1983888889

37

-24.0

0.15

8.96

0.97

7.99

116.2000277778 39.8814722222

39

-22.8

0.04

2.50

0.06

2.44

42

-22.3

43

-23.8

48

-23.6

49

-24.5

52

116.212

39.9085

39.89075

39.88775

39.8770555556

0.02

1.91

0.72

1.18

116.1991944444 39.8780555556

0.03

2.73

0.59

2.13

116.1938611111 39.8820555556

0.05

2.72

0.16

2.56

0.10

3.89

1.60

2.29

116.1696111111 39.8755277778

-24.4

0.33

3.08

1.60

1.48

116.1850833333 39.8701388889

55

-24.4

0.16

11.28

0.87

10.41

116.1986111111 39.8953611111

58

-24.8

2.77

1.04

1.73

-24.6

0.08

4.32

0.90

3.43

116.1876388889 39.9014722222

116.15675

0.03

66

-24.7

0.10

6.13

0.57

5.56

116.1546666667 39.9249444444

68

-24.9

0.13

9.60

1.06

8.53

116.1505277778 39.9310277778

0.03

2.63

0.62

2.02

116.1445277778

65

69

116.20075

39.8750555556

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-22.6

D

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1

39.9171666667

39.93125

73

-24.3

0.04

3.42

0.61

2.81

116.1250277778 39.9384722222

75

-24.5

0.08

6.02

0.31

5.71

116.1269444444 39.9317222222

77

-24.1

0.10

6.54

1.50

5.04

116.1317222222 39.9273055556

79

-24.4

0.08

6.85

0.70

6.15

116.1461111111 39.9226944444

80

-24.4

0.11

8.43

1.53

6.90

116.1548333333 39.9213611111

81

-24.3

0.09

6.84

1.04

5.80

116.1573611111

20

39.9175

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-24.8

0.13

11.93

0.67

11.26

116.1647222222 39.9080555556

85

-25.0

0.10

5.71

0.88

4.82

116.1638611111 39.9166666667

86

-24.6

0.09

8.20

1.43

6.77

116.1638333333 39.9216111111

87

-24.5

0.06

3.98

0.98

3.00

116.1844166667 39.9234166667

90

-24.6

0.04

2.32

0.58

1.74

116.1852777778 39.9306944444

96

-24.7

0.04

3.30

0.25

3.05

116.1635277778 39.9268888889

97

-26.7

0.07

3.50

0.18

3.32

99

-24.7

0.07

5.00

1.14

3.85

100

-25.2

0.12

7.65

0.76

6.88

101

-24.4

0.07

4.18

1.16

3.02

116.1714166667 39.9157222222

102

-24.9

0.07

6.40

1.19

5.20

116.1771944444 39.9111944444

105

-23.0

0.24

2.84

1.21

1.62

116.1830833333 39.9021111111

106

-24.7

5.51

5.46

1.37

4.13

116.1828611111 39.8959444444

39.9151666667

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116.1765

6.02

1.46

4.55

116.1563722222 39.9154194444

0.03

4.74

1.04

3.70

116.1486055556 39.9153277778

-24.4

0.02

5.10

1.30

3.80

116.1421666667 39.9124333333

167

-25.8

0.01

1.19

0.27

0.92

116.1535194444 39.9009222222

168

-24.6

0.01

1.68

0.42

1.26

116.1680666667 39.8974222222

169

-24.4

0.04

5.26

1.33

3.92

116.1667222222 39.9010555556

170

-25.3

0.24

8.12

1.92

6.20

116.1743055556 39.9012777778

171

-25.5

0.02

2.22

0.56

1.66

116.1747222222

172

-25.2

0.04

3.67

0.82

2.84

116.1575555556 39.9038333333

173

-24.4

174

-24.2

175

-24.1

176

-24.5

177

39.89925

0.04

3.28

0.85

2.43

116.1619722222 39.9006944444

0.08

5.03

1.22

3.81

116.1541388889 39.9075833333

0.05

4.23

1.00

3.22

116.1513333333

0.07

7.92

1.92

5.99

116.1450833333 39.9164444444

-25.1

0.02

2.32

0.57

1.74

116.1435555556 39.9132777778

178

-24.1

0.10

10.59

2.51

8.08

116.1558

39.919

179

-24.2

10.98

2.79

8.19

116.1598

39.9141

-24.5

0.04

3.85

0.87

2.98

116.154

39.9149

39.913

0.06

181

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MA

165

116.1832777778 39.9166111111

0.09

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-24.9

39.9318888889

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(2)Outside of the industrial area 164

116.16275

-24.7

0.12

7.57

1.80

5.78

116.1418

39.922

182

-24.9

0.01

1.25

0.29

0.96

116.1771

39.8998

183

-24.5

0.55

19.07

4.41

14.66

116.1484

39.9142

184

-24.6

0.27

4.64

1.13

3.51

116.144

39.9224

185

-24.3

0.12

7.71

1.77

5.93

116.1543

39.9171

186

-24.7

0.17

13.82

3.51

10.31

116.162

39.9112

180

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Highlight

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(1) Carbon isotope is shown for evaluating environmental quality; (2) Utilizing the transverse and vertical Spatial distribution of isotopes for polluting sources; (3) Distinguishing industrial from non-industrial soils from three-dimensional spatial variation;

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(4) Revealing both natural and anthropogenic contributions of organic carbon to soils.

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