scholarly journals Effects of Farming Activities on the Temporal and Spatial Changes of Hydrogen and Oxygen Isotopes Present in Groundwater in the Hani Rice Terraces, Southwest China

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 265
Author(s):  
Chengjing Liu ◽  
Yuanmei Jiao ◽  
Dongmei Zhao ◽  
Yinping Ding ◽  
Zhilin Liu ◽  
...  
Keyword(s):  
Stable Isotope ◽  
High Intensity ◽  
Southwest China ◽  
Isotope Composition ◽  
Agricultural Watershed ◽  
Spatial Effects ◽  
Elevation Gradients ◽  
Groundwater Circulation ◽  
Spatial Changes ◽  
Temporal And Spatial

Landform changes caused by human activities can directly affect the recharge of groundwater, and are reflected in the temporal and spatial changes in groundwater stable isotope composition. These changes are particularly evident in high-intensity farming areas. In this study, we tested and analyzed groundwater stable isotope samples at different elevations of rice terraces in a typical agricultural watershed of the Hani Terraces, a World Heritage Cultural Landscape in southwest China. Thus, we determined the characteristic variations and factors that influence the temporal and spatial effects on groundwater stable isotopes in the Hani Terraces, which are under the influence of high-intensity farming activities. The elevation gradients of δ18O and δ2H in groundwater are significantly increased due to farming activities. The values were 0.88‰ (100 m)−1 and −4.5‰ (100 m)−1, respectively, and they changed with time. The groundwater circulation cycle is approximately three months. We also used the special temporal and spatial variation characteristics of the groundwater isotopes as a way to evaluate the source and periodic changes of groundwater recharge. In addition, high-intensity rice farming activities, such as ploughing every year from October to January can increase the supply of terraced water to groundwater, thus ensuring the sustainability of rice cultivation in the terraces during the dry season. This demonstrates the role of human wisdom in the sustainable and benign transformation of surface cover and the regulation of groundwater circulation.

scholarly journals Speleothem Stable Isotope Records from Eastern Europe & Turkey

2018 ◽  
Author(s):  
Zoltán Kern ◽  
Attila Demény ◽  
István Gábor Hatvani
Keyword(s):  
Stable Isotope ◽  
Eastern Europe ◽  
Oxygen Isotope ◽  
Temporal Resolution ◽  
Isotope Composition ◽  
Precipitation Amount ◽  
Temporal Distribution ◽  
Elevation Gradients ◽  
The Holocene ◽  
Carbon And Oxygen Isotope

The region of Eastern Europe & Turkey contributed to the SISAL (Speleothem Isotopes Synthesis and AnaLysis) global database with stable carbon- and oxygen isotope time-series from 18 entities from 14 cave systems. The currently available oldest record from this region is the ABA-2 flowstone record (Abaliget Cave; Hungary) reaching back to MIS 6. The temporal distribution of the compiled 18 entities points out a ~20-kyr-long period, centering around 100 ka, lacking speleothem stable isotope record in the region. The regional subset of SISAL_v1 records displays a continuous coverage for the past ~90 kyr for both δ18O and δ13C, with a mean temporal resolution of ~12 yr for the Holocene, and >50 yr for the pre-Holocene period. The highest temporal resolution both for the Holocene and the pre-Holocene was achieved in the So-1 record (Sofular Cave; Turkey). Assessing the data, an important split was found regarding the climatic interpretation of speleothem δ18O. While the oxygen isotope composition of more continental formations is thought to reflect mainly temperature variations and changes in moisture transport trajectories, it may strongly reflect fluctuations of precipitation amount in the southern part of the region. Variations of δ13C primarily interpreted as humidity changes reflecting dry/wet periods across the region. Elevation gradients from three non-overlapping time periods from the region - for the last 5kyr - indicated systematically prevailing elevational gradients around -0.26‰ 100m-1 in δ18O. The regional comparison of SISAL_v1 speleothem δ18O and the temporal distribution of coarsely crystalline cryogenic cave carbonate occurrences back to 45ka does not appear to confirm the finding that occurrence of the latter coincides with the warming from stadial to interstadial conditions.

scholarly journals Temporal and spatial changes of water quality and management strategies of Dianchi Lake in southwest China

2013 ◽  
Vol 10 (12) ◽  
pp. 15409-15432 ◽  
Author(s):  
T. Zhang ◽  
W. H. Zeng ◽  
S. R. Wang ◽  
Z. K. Ni
Keyword(s):  
Water Quality ◽  
Pollution Control ◽  
Southwest China ◽  
Management Strategies ◽  
Control Measures ◽  
Current Status ◽  
Dianchi Lake ◽  
Chl A ◽  
Spatial Changes ◽  
Temporal And Spatial

Abstract. Temporal and spatial changes to the water quality of Dianchi Lake in Southwest China were investigated using monthly monitoring data from 2005 to 2012. Based on the analysis of total phosphorus (TP), total nitrogen (TN), and chlorophyll a (Chl a) concentrations, it was determined that, in Caohai Lake, the annual concentrations of these variables ranged from 0.19–1.46, 6.11–16.79, 0.06–0.14 mg L−1, respectively. In addition, the annual concentrations of TP, TN and Chl a in Waihai Lake ranged between 0.13–0.20, 1.82–3.01, 0.04–0.09 mg L−1, respectively. Cluster Analysis (CA) classified the 10 monitoring sites into two groups (group A and group B) based on similarities of water quality characteristics. Our data revealed that the current status of water quality within Caohai Lake was much worse than that of Waihai Lake. Water quality was seriously degraded during the economic boom near the period of the "Eleventh Five-Year Plan" (2005–2010), and gradually improved from 2010 to 2012 because of the "standard emission directive to industry". The main factors that influenced the spatial and temporal changes to water quality were natural factors including lake evolution and regional characteristic as well as human factors such as pollution load into the lake and management strategies that were already adopted. Some activities and regulations were implemented to enhance the lake environment by controlling wastewater emissions and establishing regulations to protect the lakes in the Yunnan Province. However, problems with institutional fragmentation (horizontal and vertical), simple treatment methods, low-intensity investment in pollution control, and lack of meaningful endogenous pollution control strategies were still present in the lake management strategy. To solve these problems, suitable control measures are needed, especially considering the current old-age status of Dianchi Lake. The fundamental improvement of the water quality within Caohai Lake was dependent on the measures taken in the upper reaches of the Caohai Watershed, including further recovery of submerged plants, resource utilization by floating plants and the reinforcement of sediment disposal. Management strategies for endogenous pollution in Waihai Lake were mainly dependent on restocking algae-eating fish and the ecological restoration of macrophytes. In this way, the swamping trend and the ageing process that is occurring in Dianchi Lake can be stunted.

Avian embryonic development does not change the stable isotope composition of the calcite eggshell

2011 ◽  
Vol 23 (2) ◽  
pp. 339 ◽  
Author(s):  
G. Maurer ◽  
S. J. Portugal ◽  
I. Boomer ◽  
P. Cassey
Keyword(s):  
Stable Isotope ◽  
Embryonic Development ◽  
Developmental Stages ◽  
Isotope Composition ◽  
Trophic Relationships ◽  
Avian Embryo ◽  
Stable Isotope Composition ◽  
Spatial Use ◽  
Temporal And Spatial ◽  
Insight Into

The avian embryo resorbs most of the calcium for bone formation from the calcite eggshell but the exact mechanisms of the resorption are unknown. The present study tested whether this process results in variable fractionation of the oxygen and carbon isotopes in shell calcium carbonate, which could provide a detailed insight into the temporal and spatial use of the eggshell by the developing embryo. Despite the uncertainty regarding changes in stable isotope composition of the eggshell across developmental stages or regions of the shell, eggshells are a popular resource for the analysis of historic and extant trophic relationships. To clarify how the stable isotope composition varies with embryonic development, the δ13C and δ18O content of the carbonate fraction in shells of black-headed gull (Larus ridibundus) eggs were sampled at four different stages of embryonic development and at five eggshell regions. No consistent relationship between the stable isotope composition of the eggshell and embryonic development, shell region or maculation was observed, although shell thickness decreased with development in all shell regions. By contrast, individual eggs differed significantly in isotope composition. These results establish that eggshells can be used to investigate a species’ carbon and oxygen sources, regardless of the egg’s developmental stage.

scholarly journals Temporal and spatial changes of water quality and management strategies of Dianchi Lake in southwest China

2014 ◽  
Vol 18 (4) ◽  
pp. 1493-1502 ◽  
Author(s):  
T. Zhang ◽  
W. H. Zeng ◽  
S. R. Wang ◽  
Z. K. Ni
Keyword(s):  
Water Quality ◽  
Pollution Control ◽  
Southwest China ◽  
Management Strategies ◽  
Control Measures ◽  
Current Status ◽  
Dianchi Lake ◽  
Chl A ◽  
Spatial Changes ◽  
Temporal And Spatial

Abstract. Temporal and spatial changes to the water quality of Dianchi Lake in southwest China were investigated using monthly monitoring data from 2005 to 2012. Dianchi Lake is divided into two parts, Caohai Lake and Waihai Lake, by a man-made dike. Caohai Lake lies at the north of Dianchi Lake, while Waihai Lake is the main water body of Dianchi Lake and accounts for 96.7% of the whole area of the lake. Based on the analysis of total phosphorus (TP), total nitrogen (TN), and chlorophyll a (Chl a) concentrations, it was determined that, in Caohai Lake, the annual concentrations of these variables ranged from 0.19–1.46 mg L−1, 6.11–16.79 mg L−1, 0.06–0.14 mg L−1, respectively. In addition, the annual concentrations of TP, TN and Chl a in Waihai Lake ranged between 0.13 and 0.20 mg L−1, 1.82 and 3.01 mg L−1, and 0.04 and 0.09 mg L−1, respectively. Cluster analysis (CA) classified the 10 monitoring sites into two clusters (cluster A and cluster B) based on similarities of water quality characteristics. Our data revealed that the current status of water quality within Caohai Lake was much worse than that of Waihai Lake. Water quality was seriously degraded during the economic boom near the period of the "Eleventh Five-Year Plan" (2005–2010), and gradually improved from 2010 to 2012 because of the "standard emission directive to industry". The main factors that influenced the spatial and temporal changes to water quality were natural factors including lake evolution and regional characteristic as well as human factors such as pollution load into the lake and management strategies that were already adopted. Some activities and regulations were implemented to enhance the lake environment by controlling wastewater emissions and establishing regulations to protect the lakes in the Yunnan Province. However, problems with institutional fragmentation (horizontal and vertical), simple treatment methods, low-intensity investment in pollution control, and lack of meaningful endogenous pollution control strategies were still present in the lake management strategy. To solve these problems, suitable control measures are needed, especially considering the current old-age status of Dianchi Lake. The fundamental improvement of the water quality within Caohai Lake was dependent on the measures taken in the upper reaches of the Caohai Watershed, including further recovery of submerged plants, resource utilization by floating plants and the reinforcement of sediment disposal. Management strategies for endogenous pollution in Waihai Lake were mainly dependent on restocking algae-eating fish and the ecological restoration of macrophytes. In this way, the swamping trend and the ageing process that is occurring in Dianchi Lake can be stunted. And the management strategies would be a contribution to the management of water conflicts between mankind and ecosystems in similar lakes.

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