1. Introduction
Water resource studies can be conducted in a more adequate way if different types of recharge mechanisms are distinguished conceptually and their relative importance in water quality is assessed from the outset [
1,
2,
3]. In addition, basic research on the recharge and quality of waters can provide scientific information to aid the exploitation and protection of these resources [
4]. Understanding the recharge process is also the basis for understanding the sources of recharge and mixing [
5,
6]. Furthermore, recharging is an important factor for governing the geochemical characteristics of groundwater [
7,
8,
9,
10]. Water chemistry and geochemical characteristics can also provide a good basis for describing particular sustainability issues and for transferring knowledge on sources of water and quality of water [
11,
12,
13,
14]. Consequently, derivate approaches, such as the Piper trilinear diagram, are suitable and commonly used to analyze groundwater mixing processes [
15,
16].
Hydrogen and oxygen isotopes are natural tracers of water bodies [
17]. Affected by equilibrium fractionation and dynamic fractionation, different water bodies have different isotopic compositions, which are widely used in indicating the origin and formation of different water bodies, tracing the path of the water cycle, and judging the mutual conversion relationship between different water bodies [
18,
19]. With the development of isotope hydrology, hydrogen- and oxygen-isotope tracing technology has become one of the most important means to study river water cycles [
17].
Jinan is famous for its spectacular springs, of which it has about 130 [
20,
21]. Water for industrial and domestic demand in the city mainly originates from surrounding water resources. However, there has been a continual decline in water quality with increasing socioeconomic development. In addition, the water supply in the city remains insufficient to meet total demand [
22]. Consequently, it is urgent to analyze the characteristics of Jinan’s water resources to promote its sustainable development. The Changqing-Xiaolipu karst groundwater aquifer provides water to Jinan and shows good potential for further development. This aquifer is relatively shallow and contains water of excellent quality. Therefore, water from this aquifer is suitable for industrial, agricultural, and domestic applications. Recent pumping tests have indicated that the Changqing-Xiaolipu area is rich in karst groundwater and that the aquifer has a strong capacity for recharge and recovery [
23]. Therefore, the aquifer shows good potential for further supporting the socioeconomic development of Jinan city. However, there remains a lack of information on the recharge of the Changqing-Xiaolipu aquifer.
The Yellow River, known as the “cradle of Chinese civilization” or the “Mother River”, is the largest source of water in north and northwest China. Although the runoff of the Yellow River accounts for only 2% of total national runoff, it supports 9% and 2% of the total land area and population of China, respectively. The Yellow River also acts as the conduit for a long-distance water transfer to the region [
24,
25]. Therefore, the sustainable utilization of water resources from the Yellow River is key to the socioeconomic development of the Yellow River Basin [
26]. The majority of the Yellow River Basin falls within arid and semi-arid zones in which water resources are limited. The limiting effect of water resources in the Yellow River Basin on development have been exacerbated in recent years by rapid population and economic growth [
27]. Therefore, there is great value in studying the role of the Yellow River in recharging groundwater resources in the Yellow River Basin.
The present study investigated the geochemistry of the Changqing-Xiaolipu aquifer to identify sources of groundwater recharge by evaluating several important geochemical variables. The focus of the present study was on the role of the Yellow River in recharging the Changqing-Xiaolipu aquifer. The results of the present study can act as a reference for the sustainable development of Jinan city under limited water resources.
2. Geological and Hydrogeological Setting
The population of Jinan, the capital of Shandong Province, was 9.2 million in 2021. The city can provide its citizens with 1 million tons of water per day. The Changqing-Xiaolipu aquifer has an area of ~1000 km
2 and is in southwestern Jinan city (
Figure 1a) within a mountainous area of central Shandong Province. The study area is located in the northwest of Tai Mountain, bordering the Yellow River in the north and connecting with the northwest plain of Shandong (
Figure 1a). The topography of the study area decreases from southeast to northwest, which is controlled by the geological structure. The low mountain and hilly area transits to the piedmont inclined plain and the Yellow River alluvial plain. The mountain trend is from southwest to northeast in the horizontal direction, and the flow direction of the Yellow River is nearly parallel to the mountain trend. Therefore, there are different topographical and geomorphic forms between them, and they are also distributed in a parallel strip from southwest to northeast.
The ages of formations of the study area range from the Archean to Quaternary (
Figure 1b), and its basement geology is composed of granites and metamorphic Neoarchean gneisses (Taishan group). The main outcropping strata in the study area include Cambrian carbonate rocks, Ordovician marine carbonate rocks, and Permian sandstone and mud rocks. The strata are overlain by Quaternary sediments. Observation wells have confirmed that the aquifer consists of Ordovician carbonate rock. The geology of the Changqing-Xiaolipu area has a monocline structure dominated by faults [
24], which control the geological and hydrogeological conditions.
Meteorological data for Jinan city indicate an annual average temperature of 13.7 °C, with the highest and lowest temperatures observed in July and January with averages of 26.3 °C and −1.2 to −1.8 °C, respectively. The mean annual rainfall of the study area is 651 mm, with 50–60% of rainfall occurring from July to August. The mean annual potential evaporation of the study area is 1818.6 mm, far exceeding mean annual rainfall. Many rivers flow through the study area, with the Yellow River being the largest.
3. Method and Analyses of Samples
Samples of the karst groundwater and water of the Yellow River were collected in 2019 to 2021, totaling 76 and 3 samples, respectively. All samples were analyzed for compositions of major elements, whereas 8 and 1 samples of karst groundwater and Yellow River water were analyzed for oxygen and hydrogen isotopes, respectively. Four groundwater samples were measured for isotopes of carbon (14C).
Temperature and pH were measured in the field. Samples were refrigerated before transport to the various laboratories. Water samples were filtered using 0.45 μm membrane filters and stored in clean polyvinyl fluoride bottles sealed with wax. Chemical analyses of samples were conducted in laboratories at the Shandong Provincial Geo-mineral Engineering Exploration Institute and the Qingdao Geo-Engineering Surveying Institute, China. The compositions for anion and cation in karst groundwater and Yellow River water were determined by conventional analytical procedures (APHA 2012). Ca2+ and Mg2+ were analyzed in volumetric titration methods using EDTA. K+ and Na+ concentrations were determined using a flame photometer (ELEX 6361, Eppendorf AG, Hamburg, Germany). AgNO3 and HCl were used to measure Cl−, HCO3−, and CO32− concentrations. The colorimetric method was applied to analyze SO42− and NO3− using a spectrophotometer (UV 1600 PC).
Stable isotopes of oxygen, hydrogen, carbon, and 14C were analyzed at the Beta Analytic Inc. laboratory. Both oxygen and hydrogen isotope ratios were determined using a Finnigan MAT 253 mass spectrometer with an error of <0.2‰ for both δ18O and δD. The 14C concentrations were determined by accelerator mass spectrometry (Artemis facility, UMS LMC14) on Fe-graphite targets prepared at the IDES Laboratory. The results are reported in percent modern carbon (pMC), with the uncertainty for each sample stated.
4. Results
4.1. Groundwater Chemical Characteristics
Table 1 provides a summary for site descriptions, physical parameters, and element concentrations for karst groundwater and Yellow River water. The pH of the karst groundwater ranged from 7.4 to 8.3, with a mean of 7.8. Groundwater temperature varied from 15 to 25 °C, with a mean of 16 °C. Total dissolved solids (TDS) of groundwater varied from 394 to 1700 mg/L, with a mean of 677 mg/L. Of the groundwater samples, 97% had a TDS < 1000 mg/L, thereby falling within the category of fresh water [
28]. The pH of Yellow River water ranged from 8.2 to 8.6, with a mean of 8.4, whereas temperature ranged from 15 to 26 °C, with a mean of 19 °C, and TDS ranged from 530 to 707 mg/L, with a mean of 605 mg/L.
The major cations of karst groundwater samples were Ca
2+ and Mg
2+ (
Figure 2). The order of cations in karst groundwater in terms of concentration was Ca
2+ > Mg
2+ > Na
+ > K
+, with Ca
2+, Mg
2+, and Na
+, contributing 66%, 22.9%, and 11% of the total cationic charge (TZ
+ = Na
+ + K
+ + 2Mg
2+ + 2Ca
2+ in meq/L), respectively. Major anions of karst groundwater were HCO
3− and NO
3− (
Figure 2), and the order of anions in terms of total molar anion concentrations was HCO
3− > NO
3− > SO
42− > Cl
−, with HCO
3−, NO
3−, SO
42−, and Cl
−, contributing 39%, 37%, 13%, and 11% of the total anionic charge (TZ
− = Cl
− + 2SO
42− + NO
3− + HCO
3− in meq/L), respectively. The karst groundwater samples were mostly of the Ca·Mg-HCO
3·SO
4 type.
The major cations of Yellow River water samples were Ca
2+ and Na
+. The rank of cations in terms of total concentration was: Ca
2+ > Na
+ > Mg
2+ > K
+, with Ca
2+, Na
+, and Mg
2+, contributing 40%, 30%, and 28% of total cationic charge, respectively. The major anions of Yellow River water were SO
42− and Cl
− (
Figure 3b), and the order of anions in terms of total molar concentrations was SO
42− > Cl
− > NO
3− > HCO
3−, with SO
42−, Cl
−, NO
3−, and HCO
3−, contributing 33%, 27%, 20%, and 20% of the total anionic charge, respectively. The Yellow River water samples were of the Ca·Na·Mg-SO
4·Cl type.
The chemical composition of groundwater can be altered by the weathering process and aquifer matrix [
5]. The Gibbs diagram, displaying TDS vs. (Na + K)/(Na + K + Ca) and Cl/(Cl + HCO
3), can effectively determine groundwater geochemistry [
29]. In this study, most groundwater samples were spread in the evaporation and rock–water interaction fields (
Figure 3). This finding demonstrated that the bulk of the samples was governed by rock dominance processes and evaporation [
5], and this result also implies that evaporation and rock dominance processes have significant influences on groundwater quality [
5].
4.2. Saturation Indices
All karst groundwater samples contained calcite and dolomite concentrations at saturation or above, indicating the possibility of calcite and dolomite precipitation. The gypsum concentration in karst groundwater samples did not reach the saturation index (SI), indicating the possibility of gypsum dissolution. The halite concentrations of all karst groundwater samples were below the SI (SI
halite < 0). The Yellow River water showed the same saturation properties as karst groundwater, indicating precipitation of calcite and dolomite and dissolution of gypsum and halite (
Figure 4).
4.3. Isotopic Characteristics of Water in the Changqing-Xiaolipu Area
Both the Yellow River water and karst groundwater samples showed similar low variation in stable isotope content (
Figure 5), with δ
18O ranging from −8.93 to −7.07‰ (mean of −8.2‰) and δD ranging from −64.7 to −52.7 ‰ (mean of −59.8‰) (
Table 2).
14C of karst groundwater ranged from 84.2 to 96.7 pMC. δ
18O and δD of Yellow River water were −8.83‰ and −64.7‰, respectively, whereas
14C was 90.7 pMC (
Table 2).
5. Discussion
5.1. Origin and Recharge of Groundwater
Both δ
18O and δD are important indicators of sources of groundwater recharge and can help with understanding the water cycle [
33]. δ
18O and δD of karst groundwater were distributed far from the LWML and close to those of the Yellow River water and water from the recharge area in the southern mountain region (
Figure 5). These results indicated that the groundwater in the recharge area in the southern mountain region is mostly recharged by infiltration of Yellow River water or through infiltration of local rainfall. However, the variations in the karst groundwater table depth were closely related to the depth of the Yellow River table and showed no correlation with rainfall (
Figure 6). In addition,
14C of karst groundwater ranged from 84.2 to 96.7 pMC, whereas that of Yellow River water was 90.7 pMC, indicating that the karst groundwater is not old and that there was a minor degree of mixing between the Yellow River water and groundwater before 1390 BP [
34]. Therefore, the present study proposes that the karst groundwater is recharged by the groundwater in the southern mountain region and is subsequently modified by mixing with water of the Yellow River.
5.2. Hydrochemical Evidence for Mixing between Yellow River Water and Karst Groundwater and Its Quantification
No samples showed halite concentrations at or above saturation, thereby excluding the possibility of halite precipitation under current conditions (
Figure 4). Hence, Cl
− is used to behave relatively conservatively in the mixing model [
35]. The relationship between Cl
−/HCO
3− molar ratios and Cl
− showed a predominantly linear pattern (
Figure 7), suggesting mixing between Yellow River water and groundwater in the groundwater recharge area in the southern mountain region. The results show that the mixing of Yellow River water and karst groundwater is one of the processes leading to groundwater salinization. However, deviation of some samples from this line indicated the involvement of other processes. The relationship between the concentrations of SO
42− and Cl
− depicted in
Figure 8a suggests that most data points of karst groundwater are near the mixing trend, also indicating the mixing process of these waters. The relationship between Na
+ and Cl
− was indicative of this mixing (
Figure 8b). In general, the major ion/Cl ratios increasingly approximated the observed mixing lines as salinity increased (
Figure 8), which can be attributed to the total solute load from mixing overwhelming the properties of other processes.
For the most groundwater samples, the Yellow River water mixing proportions were estimated to increase from 10% to 30% of the mixed waters. This mixing pattern is of great significance for evaluating the extent to which the Yellow River recharges the Changqing-Xiaolipu water resource.
5.3. Water Quality Assessment
Water quality assessment and management is one of the most important aspects of water management. This has attained significant global importance over the years in view of growing concerns and awareness of environment- and health-related impacts. Water from the Changqing-Xiaolipu karst aquifer is mainly used for domestic water supply. Over 97% of the karst groundwater samples fell within the TDS and pH domestic water standards prescribed by the Ministry of Health (2006). High domestic water contents of sulfate can result in diarrhea, dehydration, and weight loss in humans, whereas high nitrate concentrations can result in birth defects, hypertension, and high-Fe hemoglobin [
36]. The domestic water limits for sulfate and nitrate in China are 250 and 20 mg/L, respectively. Most of the karst groundwater samples exceeded the permissible domestic, industrial, and agricultural water standards for nitrate. This phenomenon may be caused by the nitrate occurring in the reservoir. Therefore, the karst groundwater should be pretreated to reduce the nitrate concentration. In addition, approximately 4% and 84% of the Yellow River samples exceeded the permissible domestic water standards for sulfate and nitrate, respectively, indicating that this water is not suitable for domestic use. The water of the Yellow River is also highly saline, further precluding its suitability for consumption by humans and animals. Thus, groundwater in the southern mountain region is an important freshwater source for human domestic use. Achieving sustainable development of water resources in this area in the future will require further pollution prevention and control.
6. Conclusions
The present study used a combination of hydrodynamic, hydrochemical, and stable isotopic data to identify the role of the Yellow River in recharging the Changqing-Xiaolipu aquifer. This aquifer in the Yellow River Basin, eastern China shows complex groundwater table dynamics. The analytical results of major ions in karst groundwater exhibited the trends of Ca2+ > Mg2+ > Na+ > K+ and HCO3− > NO3− > SO42− > Cl−, respectively. These trends showed that the karst groundwater was mostly of the Ca·Mg-HCO3·SO4 type. In addition, the obtained physicochemical parameters in Yellow River water revealed that ionic sequences of Ca2+ > Na+ > Mg2+ > K+ and SO42− > Cl− > NO3− > HCO3− associated with the Ca·Na·Mg-SO4·Cl water type. The hydrogeochemical facies of karst groundwater revealed the influence of evaporation and rock–water interaction on the groundwater quality. The data for isotopes (δ18O, δD, and 14C) and major ion/Cl− ratios highlighted the beneficial influence of diverted water from the Yellow River to recharging the aquifer system. Although the Yellow River contributes 10–30% of the karst Changqing-Xiaolipu aquifer, this river should be considered when characterizing the chemistry and budget of groundwater. Most of the karst groundwater in this area has good water quality and is suitable for domestic use, but more attention should be paid to the high concentrations of nitrate and sulfide in the aquifer water in the future.
Author Contributions
Conceptualization, D.Y. and J.Y.; methodology, D.W.; software, Y.H.; validation, B.S., L.Z. and H.C.; investigation, D.W.; resources, D.W.; data curation, D.W.; writing—original draft preparation, D.Y.; writing—review and editing, R.L.; funding acquisition, R.L. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the National Natural Science Foundation of China (Grant No. 42102076) and the Shandong Provincial Natural Science Foundation (ZR2021QD037).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Some or all data that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
We especially thank the anonymous reviewers and Huaizhi Shao in Shandong University of Technology for their valuable and constructive comments.
Conflicts of Interest
The authors declare no conflict of interest.
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Figure 1.
(a) Map showing the geology of the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. The black box encompasses the Changqing-Xiaolipu aquifer. The black line between A and B is the section line. (b) Cross section of the Changqing-Xiaolipu aquifer.
Figure 1.
(a) Map showing the geology of the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. The black box encompasses the Changqing-Xiaolipu aquifer. The black line between A and B is the section line. (b) Cross section of the Changqing-Xiaolipu aquifer.
Figure 2.
Piper plots showing proportions of major ions in karst groundwater and Yellow River water for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province.
Figure 2.
Piper plots showing proportions of major ions in karst groundwater and Yellow River water for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province.
Figure 3.
Karst groundwater facies and their controlling mechanisms along the Changqing-Xiaolipu aquifer.
Figure 3.
Karst groundwater facies and their controlling mechanisms along the Changqing-Xiaolipu aquifer.
Figure 4.
Saturation indices (SI) for halite, calcite, dolomite, and gypsum for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. All samples were processed using PHREEQC version 2.8 (U.S. Geological Survey, Reston, VA, USA). Note: the blue circle is karst groundwater and the red circle is the Yellow River.
Figure 4.
Saturation indices (SI) for halite, calcite, dolomite, and gypsum for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. All samples were processed using PHREEQC version 2.8 (U.S. Geological Survey, Reston, VA, USA). Note: the blue circle is karst groundwater and the red circle is the Yellow River.
Figure 5.
δD-δ
18O plot of the karst groundwater and the Yellow River water for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. GMWL, global meteoric water line. The data of the Yangtze River and Amazon River are from [
30,
31,
32].
Figure 5.
δD-δ
18O plot of the karst groundwater and the Yellow River water for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. GMWL, global meteoric water line. The data of the Yangtze River and Amazon River are from [
30,
31,
32].
Figure 6.
Variations in groundwater table depth and depth of the Yellow River (2011 to 2012) from measurements at typical wells in response to rainfall for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. Note: H5 and H3 are the two sample sites along the Yellow River.
Figure 6.
Variations in groundwater table depth and depth of the Yellow River (2011 to 2012) from measurements at typical wells in response to rainfall for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. Note: H5 and H3 are the two sample sites along the Yellow River.
Figure 7.
Hydrochemical relationships between the concentrations of Cl− and Cl−/HCO3− for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. The line represents mixing between the two endmembers: the Yellow River (red triangle) and groundwater from the groundwater recharge area in the southern mountain region (red square). Numbers along the mixing line show the percentage (%) of the Yellow River at 10% increments under simple mixing behavior. Concentrations are expressed in meq/L.
Figure 7.
Hydrochemical relationships between the concentrations of Cl− and Cl−/HCO3− for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. The line represents mixing between the two endmembers: the Yellow River (red triangle) and groundwater from the groundwater recharge area in the southern mountain region (red square). Numbers along the mixing line show the percentage (%) of the Yellow River at 10% increments under simple mixing behavior. Concentrations are expressed in meq/L.
Figure 8.
Hydrochemical relationships between the concentrations of Cl
− and SO
42− (
a), Na
+ (
b), Ca
2+ (
c), and Na
+/Cl
− (
d) for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. The line, two endmembers, and number along the mixing line have the same meanings as those in
Figure 7.
Figure 8.
Hydrochemical relationships between the concentrations of Cl
− and SO
42− (
a), Na
+ (
b), Ca
2+ (
c), and Na
+/Cl
− (
d) for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province. The line, two endmembers, and number along the mixing line have the same meanings as those in
Figure 7.
Table 1.
A summary of the hydrochemical properties of karst groundwater and Yellow River water from the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province.
Table 1.
A summary of the hydrochemical properties of karst groundwater and Yellow River water from the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province.
Group | Water Number | Water Temperature (℃) | pH | K+ | Na+ | Ca2+ | Mg2+ | Cl− | SO42− | HCO3− | NO3− | TDS (mg/L) |
---|
Karst Groundwater | CC6-1 | 16 | 7.7 | 0.44 | 15.0 | 103 | 18.8 | 28.5 | 57.4 | 268 | 61.3 | 569 |
CC6-2 | 16 | 7.6 | 0.50 | 14.3 | 100 | 19.8 | 29.5 | 55.2 | 257 | 61.4 | 555 |
CC6-3 | 16 | 7.7 | 0.50 | 18.6 | 101 | 23.6 | 33.4 | 44.2 | 276 | 62.3 | 575 |
CC6-4 | 16 | 7.7 | 0.60 | 18.6 | 105 | 22.0 | 31.9 | 61.9 | 268 | 64.1 | 588 |
CC8-1 | 16 | 7.7 | 0.56 | 15.0 | 101 | 22.5 | 29.8 | 64.1 | 268 | 77.1 | 594 |
CC8-2 | 16 | 7.6 | 0.50 | 14.3 | 99.53 | 22.0 | 31.1 | 48.6 | 273 | 59.0 | 566 |
CC8-3 | 16 | 7.7 | 0.50 | 18.6 | 97.72 | 23.6 | 39.8 | 46.4 | 273 | 51.6 | 566 |
CC8-4 | 16 | 7.8 | 0.50 | 18.6 | 104 | 22.5 | 33.4 | 64.1 | 276 | 55.3 | 591 |
CC11-1 | 16 | 7.4 | 0.44 | 13.3 | 94.2 | 20.7 | 30.8 | 64.0 | 268 | 48.6 | 547 |
CC11-2 | 16 | 7.7 | 0.50 | 14.3 | 95.9 | 20.3 | 27.9 | 59.7 | 279 | 49.6 | 527 |
CC11-3 | 16 | 7.7 | 0.70 | 18.6 | 95.9 | 20.9 | 27.9 | 53.0 | 270 | 45.5 | 549 |
CC11-4 | 16 | 7.7 | 0.50 | 18.6 | 102 | 22.0 | 34.2 | 53.0 | 281 | 49.3 | 577 |
CC12-1 | 16 | 7.6 | 0.44 | 10.0 | 118 | 20.1 | 28.3 | 81.8 | 257 | 56.5 | 579 |
CC12-2 | 16 | 7.8 | 0.40 | 14.3 | 92.3 | 20.9 | 23.9 | 53.0 | 267 | 43.5 | 531 |
CC12-3 | 16 | 7.8 | 0.50 | 17.1 | 88.7 | 22.0 | 29.5 | 68.5 | 273 | 38.2 | 553 |
CC12-4 | 16 | 7.7 | 0.40 | 18.6 | 95.0 | 20.9 | 32.7 | 59.7 | 278 | 38.5 | 560 |
CX5-1 | 17 | 7.6 | 1.60 | 48.0 | 235 | 37.9 | 32.7 | 59.7 | 350 | 368 | 1308 |
CX5-2 | 15 | 7.5 | 1.30 | 28.6 | 179 | 39.1 | 67.9 | 92.8 | 332 | 223 | 980 |
CX5-3 | 16 | 7.5 | 1.60 | 37.1 | 236 | 41.7 | 111 | 156 | 355 | 301 | 1238 |
CX7-1 | 15 | 7.7 | 0.56 | 14.4 | 94.4 | 18.7 | 35.5 | 18.2 | 310 | 32.7 | 548 |
CX7-2 | 15 | 7.9 | 0.75 | 20.0 | 112 | 17.0 | 22.8 | 61.9 | 300 | 70.7 | 619 |
CX7-3 | 15 | 7.4 | 0.70 | 22.9 | 136 | 22.5 | 35.8 | 55.2 | 406 | 53.4 | 750 |
CX36 | 16 | 7.6 | 0.90 | 48.0 | 165 | 23.6 | 122 | 210 | 265 | 44.1 | 893 |
CX39 | 15 | 7.8 | 0.60 | 15.7 | 78.7 | 17.6 | 25.5 | 42.0 | 271 | 10.2 | 476 |
CX40 | 15 | 7.9 | 0.50 | 10.0 | 67.0 | 13.7 | 15.9 | 11.1 | 256 | 5.50 | 395 |
CX46 | 16 | 7.9 | 0.70 | 14.3 | 75.1 | 15.9 | 21.5 | 44.2 | 255 | 9.54 | 451 |
CX58 | 16 | 7.7 | 0.56 | 14.4 | 67.4 | 20.1 | 22.8 | 1.67 | 304 | 4.21 | 453 |
CX58 | 16 | 7.9 | 0.75 | 12.0 | 71.1 | 21.9 | 29.2 | 42.0 | 255 | 5.59 | 448 |
CX58 | 16 | 8.0 | 0.60 | 15.7 | 71.6 | 21.4 | 35.7 | 29.3 | 278 | 8.01 | 475 |
C7-1 | 15 | 7.8 | 0.66 | 16.6 | 80.5 | 18.1 | 30.4 | 63.9 | 262 | 7.99 | 502 |
C7-2 | 15 | 8.0 | 0.88 | 16.0 | 76.1 | 18.2 | 24.1 | 33.1 | 255 | 11.7 | 448 |
C7-3 | 15 | 8.2 | 0.70 | 17.1 | 80.5 | 15.9 | 27.9 | 39.8 | 268 | 12.6 | 478 |
C7-4 | 15 | 7.8 | 0.60 | 1.56 | 77.8 | 18.2 | 27.4 | 12.2 | 278 | 11.1 | 439 |
C19-1 | 16 | 7.9 | 1.11 | 24.7 | 84.2 | 18.2 | 21.6 | 102 | 229 | 22.8 | 515 |
C19-2 | 16 | 8.1 | 0.80 | 19.3 | 94.6 | 22.5 | 38.1 | 95.2 | 231 | 28.9 | 542 |
C28-1 | 16 | 8.1 | 0.60 | 20.0 | 53.0 | 37.5 | 9.52 | 68.3 | 304 | 5.06 | 515 |
C28-2 | 16 | 8.0 | 1.11 | 12.0 | 128 | 22.5 | 25.4 | 117 | 263 | 83.3 | 664 |
C29 | 16 | 7.7 | 2.32 | 20.0 | 97.2 | 18.23 | 33.0 | 108 | 221 | 50.2 | 566 |
C31 | 16 | 7.9 | 1.11 | 14.0 | 106 | 18.8 | 29.2 | 79.5 | 261 | 43.9 | 566 |
C230 | 16 | 7.7 | 0.63 | 22.4 | 235 | 43.7 | 79.9 | 159 | 357 | 285 | 1201 |
CK1-1 | 15 | 7.7 | 0.56 | 16.6 | 133 | 31.0 | 43.1 | 60.9 | 334 | 109 | 750 |
CK1-2 | 15 | 7.9 | 0.75 | 20.0 | 104 | 21.9 | 40.6 | 61.9 | 295 | 38.2 | 595 |
CK1-3 | 16 | 7.7 | 0.70 | 20.0 | 123 | 28.0 | 45.4 | 77.3 | 329 | 73.5 | 712 |
CK1-4 | 15 | 7.7 | 0.30 | 18.6 | 127 | 27.3 | 54.8 | 56.1 | 342 | 57.0 | 696 |
T69 | 16 | 7.7 | 0.70 | 14.3 | 96.8 | 17.6 | 22.3 | 66.3 | 248 | 39.2 | 519 |
T80 | 16 | 7.9 | 0.67 | 16.0 | 93.5 | 21.9 | 37.2 | 39.1 | 291 | 16.4 | 531 |
T85 | 16 | 7.8 | 0.88 | 20.0 | 106 | 15.8 | 15.2 | 113 | 238 | 45.1 | 566 |
T94-1 | 16 | 7.4 | 13.1 | 65.0 | 284 | 35.7 | 190 | 263 | 403 | 191 | 1462 |
T94-2 | 25 | 7.5 | 12.6 | 75.0 | 271 | 38.6 | 201 | 278 | 424 | 194 | 1512 |
T94-3 | 17 | 7.6 | 12.8 | 70.0 | 291 | 35.7 | 202 | 252 | 389 | 238 | 1491 |
T96 | 17 | 8.1 | 0.80 | 20.0 | 128 | 30.7 | 61.9 | 84.0 | 239 | 193.8 | 758 |
T97 | 16 | 7.9 | 0.50 | 14.3 | 74.2 | 18.1 | 23.8 | 17.9 | 268 | 9.43 | 441 |
T99 | 16 | 7.8 | 0.44 | 7.5 | 82.4 | 23.8 | 20.2 | 9.76 | 340 | 6.18 | 505 |
T101 | 17 | 7.6 | 0.40 | 22.9 | 167 | 28.5 | 64.5 | 163 | 284 | 128 | 876 |
T105 | 16 | 7.4 | 5.43 | 100 | 304 | 43.4 | 275 | 243 | 310 | 400 | 1701 |
T105 | 17 | 7.6 | 5.00 | 86.7 | 239 | 37.3 | 207 | 217 | 292 | 258 | 1342 |
T112 | 16 | 7.6 | 1.68 | 44.0 | 159 | 45.8 | 93.2 | 198 | 378 | 58.3 | 978 |
T112V | 16 | 7.7 | 0.89 | 53.3 | 109 | 24.1 | 90.8 | 134 | 257 | 12.4 | 682 |
T112b | 16 | 7.8 | 0.78 | 26.8 | 110 | 23.2 | 59.9 | 82.6 | 293 | 13.6 | 611 |
T113 | 17 | 8.1 | 1.10 | 86.7 | 76.0 | 24.7 | 96.4 | 150 | 194 | 8.57 | 652 |
PT1-1 | 16 | 7.6 | 0.85 | 20.7 | 132 | 29.7 | 58.9 | 107 | 303 | 66.5 | 718 |
PT1-2 | 16 | 7.7 | 0.80 | 19.3 | 131 | 27.0 | 56.7 | 97.0 | 296 | 64.8 | 693 |
PT1-3 | 16 | 7.7 | 0.81 | 19.8 | 129 | 27.5 | 56.7 | 98.3 | 303 | 65.0 | 700 |
PT1-4 | 16 | 7.5 | 0.76 | 20.8 | 129 | 26.9 | 55.7 | 98.9 | 306 | 63.0 | 701 |
165 | 16 | 7.8 | 0.70 | 20.0 | 138 | 28.5 | 57.1 | 110 | 276 | 92.8 | 737 |
SJ | 16 | 8.0 | 0.38 | 3.64 | 130 | 8.51 | 11.4 | 3.84 | 241 | 47.8 | 555 |
QL1 | 16 | 7.8 | 0.20 | 15.7 | 128 | 22.5 | 36.9 | 95.2 | 247 | 110.3 | 671 |
G2-1 | 16 | 7.8 | 0.69 | 17.9 | 95.8 | 19.1 | 37.6 | 61.5 | 277 | 29.5 | 553 |
G2-2 | 16 | 7.4 | 0.83 | 20.0 | 103 | 21.3 | 40.1 | 64.4 | 296 | 29.6 | 593 |
G2-3 | 16 | 7.9 | 0.72 | 14.2 | 96.4 | 18.8 | 36.5 | 60.0 | 272 | 28.2 | 542 |
G2-4 | 16 | 7.6 | 0.72 | 18.6 | 91.7 | 15.8 | 32.9 | 60.6 | 272 | 25.9 | 531 |
G2-5 | 16 | 7.9 | 0.95 | 11.3 | 95.4 | 17.6 | 33.5 | 61.2 | 269 | 25.9 | 527 |
G2-6 | 16 | 7.8 | 0.76 | 19.3 | 88.2 | 16.2 | 25.1 | 69.8 | 260 | 27.9 | 522 |
G2-7 | 16 | 7.8 | 0.91 | 16.6 | 90.2 | 16.2 | 26.7 | 47.2 | 256 | 20.6 | 488 |
XTS | 25 | 8.3 | 1.30 | 22.9 | 73.3 | 23.1 | 45.4 | 104 | 146 | 28.6 | 454 |
HHS | 16 | 7.7 | 0.50 | 18.6 | 102 | 20.9 | 33.4 | 55.2 | 276 | 54.1 | 577 |
Yellow River | H5 | 17 | 8.2 | 4.00 | 93.3 | 65.2 | 31.8 | 114 | 155 | 213 | 18.7 | 707 |
H6 | 26 | 8.6 | 6.57 | 31.4 | 75.1 | 33.5 | 66.1 | 122 | 124 | 54.5 | 531 |
H11 | 15 | 8.5 | 3.71 | 70.0 | 75.1 | 26.3 | 118 | 210 | 63.1 | 1.29 | 577 |
Table 2.
18O, D and 14C in karst groundwater and Yellow River water for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province.
Table 2.
18O, D and 14C in karst groundwater and Yellow River water for the Changqing-Xiaolipu area, southwestern Jinan city, central Shandong Province.
Group | Sample Number | 18O (‰) | D (‰) | 14C (pMC) |
---|
Karst Groundwater | CL1 | −8.41 | −63.67 | 84.2 |
CX4 | −7.07 | −52.70 | 95.3 |
G2 | −8.65 | −63.04 | |
T84 | −7.96 | −58.09 | |
T89 | −8.57 | −60.39 | |
T93 | −8.27 | −59.85 | |
T105 | −7.70 | −56.35 | 96.7 |
X5 | −8.93 | −64.66 | |
Yellow River | H5 | −8.83 | −65.00 | 90.7 |
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