Temporal Variation in Stable Isotopic Composition of Rainfall and Groundwater in a Tropical Dry Forest in the Northeastern Caribbean

2013 ◽  
Vol 17 (27) ◽  
pp. 1-20 ◽  
Author(s):  
Y. Govender ◽  
E. Cuevas ◽  
L. D. S. Sternberg ◽  
M. R. Jury
Keyword(s):  
Puerto Rico ◽  
Isotopic Composition ◽  
Temporal Variation ◽  
Groundwater Recharge ◽  
Meteoric Water ◽  
Dry Forest ◽  
Water Line ◽  
Isotopic Signatures ◽  
Meteoric Water Line ◽  
Stable Isotopic

Abstract Karst topography links rainfall to groundwater recharge; therefore, possible changes in the hydrology can play an important role in ecosystem function especially in tropical dry forests where water is the most limiting resource. This study investigates the temporal variation in isotopic composition (δ18O and δD values) of rainwater and groundwater in the Guánica Dry Forest of southwestern Puerto Rico. The study not only establishes a dataset of oxygen and hydrogen isotopic composition of rainwater to assist in local ecohydrological studies but also establishes the origin of rainfall in the semiarid region of the island. The geographical position of Puerto Rico in the northeastern Caribbean causes the study site to receive marine air masses from the North Atlantic Ocean and Caribbean Sea. This research documents the monthly to annual variability in stable isotopic composition of rainwater and estimates the source of groundwater recharge in the Guánica Dry Forest. To calculate the local meteoric water line (LMWL), the authors analyzed the isotopic signatures of rainwater, collected at near-monthly intervals from January 2008 to December 2011. The LMWL (δD = 7.79δ18O + 10.85) is close to the global meteoric water line (δD = 8.17δ18O + 11.27). Isotopic signatures of rainwater for the Guánica Dry Forest are consistent with southeastern Caribbean, where rainfall is of marine origin with an annual cycle contributed by sea surface temperature (SST) and significant intermonthly fluctuations due to rainfall and winds during tropical weather events. The d-excess values in the period of data collection (2008–11) respond to the rainfall–evaporation balance, with little seasonal cycle and strong pulsing events. Comparison of rain and groundwater isotopic compositions in the United Nations Educational, Scientific and Cultural Organization (UNESCO) Man and the Biosphere Programme (MAB) Guánica Dry Forest indicates that groundwater recharge is confined to rainfall events of more than 90 mm. Imbalances between rainfall and drought place cumulative stresses on ecosystems where plants and animals synchronize their growth phenology and reproduction to climatic patterns, especially in areas with variable annual cycles. Therefore, it is useful in ecohydrological studies to determine the origins and temporal dynamics of rainfall and groundwater recharge in the Caribbean, where predictions of climate models indicate drying trends.

Stable isotope tracers as diagnostic tools in studying water sources in a humid bamboo watershed during the plum rainfall events

Water Policy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 368-381
Author(s):  
Jianfeng Gou ◽  
Simin Qu ◽  
Peng Shi ◽  
Dachen Li ◽  
Xueqiu Chen ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Temporal Variation ◽  
Soil Water ◽  
Meteoric Water ◽  
Water Sources ◽  
Rainfall Events ◽  
Water Line ◽  
Isotopic Variation ◽  
Meteoric Water Line

Abstract This study investigates the temporal variation of stable isotopic composition in precipitation, soil water, and streamflow water during the plum rainfall events in an upland headwater watershed which is mainly covered with bamboo. The results show that the isotopic composition of various water sources exhibit significant temporal variation. The local meteoric water line is established by using the relationship between the stable isotope of oxygen-18 and deuterium, which is slightly different from the meteoric water line of China. The isotopic temporal variation of precipitation is closely related to exchange effect between raindrops and environmental vapor, evaporation fractionation and rainfall intensity. The isotopic variation of shallow soil water is mainly determined by canopy interception, ground evaporation and the mixing with pre-event water; as for the isotopic variation of deep soil water, it is virtually influenced by pre-event water. The most enriched isotopic composition of streamflow and deuterium excess (d-excess) differences between streamflow and rainfall both indicate that streamflow is recharged not only by event water but also by pre-event water. Hence, a better understanding of precipitation formation and the hydrological response under the plum rainfall system may be instructive for the management of water resources in humid watersheds in southern China.

scholarly journals Isotopes of oxygen-18 and deuterium in precipitation in Slovakia / Izotopy kyslíka-18 A deutéria v zrážkach na Slovensku

2012 ◽  
Vol 60 (4) ◽  
pp. 265-276 ◽  
Author(s):  
Ladislav Holko ◽  
Michal Dóša ◽  
Juraj Michalko ◽  
Martin Šanda
Keyword(s):  
Isotopic Composition ◽  
Air Temperature ◽  
Meteoric Water ◽  
Precipitation Amount ◽  
Data Series ◽  
Water Line ◽  
Temperature And Precipitation ◽  
Meteoric Water Line ◽  
The Mean ◽  
Available Information

The article synthesizes available information on isotopic composition of precipitation in Slovakia (the Western Carpathians). Monthly δ18O data from eleven stations and period 1988-1997 were used to investigate correlations among the stations, altitude, air temperature and precipitation amount effects. The mean annual altitude and air temperature gradients of δ18O in precipitation were 0.21‰/100 m and 0.36‰/1°C, respectively. Maps of spatial distribution of mean annual δ18O in precipitation based on both gradients were constructed. The two maps do not significantly differ for the majority of Slovakia. δ2H data were available for only three stations. Local meteoric water line derived for the station with the longest data series (δ2H = = 7.86δ18O + 6.99) was close to the Global Meteoric Water line. Its parameters in periods 1991-1993 and 1991-2008 did not change. The study indicates that a more detailed monitoring of isotopic composition of precipitation in mountains should be carried out in the future. The highest station exhibited very small seasonal variability of δ18O in precipitation compared to other Slovak stations. The second highest mountain station had significantly higher deuterium excess than the neighboring stations located in the valley. In some analyses the data from the nearest stations situated abroad (Vienna, Krakow) were used.

Isotopic composition of precipitation in a topographically steep, seasonally snow-dominated watershed and implications of variations from the global meteoric water line

2016 ◽  
Vol 30 (24) ◽  
pp. 4582-4592 ◽  
Author(s):  
Daniel J. Tappa ◽  
Matthew J. Kohn ◽  
James P. McNamara ◽  
Shawn G. Benner ◽  
Alejandro N. Flores
Keyword(s):  
Isotopic Composition ◽  
Meteoric Water ◽  
Water Line ◽  
Meteoric Water Line ◽  
Global Meteoric Water Line

scholarly journals Last glacial millennial-scale hydro-climate and temperature changes in Puerto Rico constrained by speleothem fluid inclusion δ<sup>18</sup>O and δ<sup>2</sup>H values

2021 ◽  
Author(s):  
Sophie F. Warken ◽  
Therese Weissbach ◽  
Tobias Kluge ◽  
Hubert Vonhof ◽  
Denis Scholz ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Fluid Inclusion ◽  
Meteoric Water ◽  
Convective Activity ◽  
Drip Water ◽  
Water Line ◽  
Last Glacial ◽  
Meteoric Water Line ◽  
The Last Glacial ◽  
Millennial Scale

Abstract. We present speleothem fluid inclusion δ18Of and δ2Hf values from Larga Cave, Puerto Rico, that covers the interval between 46.2 to 15.3 ka before present on millennial scale, including the Last Glacial Maximum (LGM) and several stadial and interstadial cycles. The dataset can be divided in two main clusters of stable isotope compositions of the fluid inclusion water with respect to the global meteoric water line which coincide with strong variations in the water content of the stalagmite. In particular, this clustering is found to be climate related, where the first cluster comprises samples from cold and dry periods, such as Heinrich and Greenland stadials, as well as parts of the LGM, which exhibit very high δ18Of and δ2Hf values. We interpret this enrichment as caused by evaporation inside the cave due to enhanced cave ventilation during these colder and drier times. In contrast, in most samples corresponding to warmer and wetter Greenland interstadials, but also for some from Heinrich Stadial 2 and 3, the δ18Of and δ2Hf values plot on the meteoric water line and modification of fluid inclusion water due to “in-cave” evaporation is found negligible. Consequently, variations of last glacial hydro-climate and temperature in the western tropical Atlantic can be constrained. In general, δ18Of values from fluid inclusions are up to 3 ‰ higher than those of modern drip water, which is interpreted as a weaker atmospheric convective activity during the last glacial period. In addition, reconstructed temperatures suggest an average cooling of c. 3 °C during the LGM compared to modern cave temperature. During Heinrich Stadials 2 and 3, reconstructed cave temperatures yield an additional cooling of 2.9 ± 2.6 °C and 4.4 ± 0.6 °C, respectively. Higher δ18Of values of these samples further suggest that the drip water was dominated by orographic rainfall and/or cold fronts, along with weak or even absent convective activity. In contrast, during interstadial phases, reconstructed temperatures reached nearly modern values, and convective activity was comparable or only slightly weaker than today.

scholarly journals Study on the isotopic compositionof rainwater in Long Khanh city,Southeast of the Mekong Delta region

2021 ◽  
Vol 63 (8) ◽  
pp. 14-18
Author(s):  
Quang Tri Bui ◽  
◽  
Thi Thu Huong Huynh ◽  
Uyen Thi Pham ◽  
Thi Bich Chi Duong ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Meteoric Water ◽  
Mekong Delta ◽  
Reference Value ◽  
Isotope Ratios ◽  
Global Scale ◽  
Delta Region ◽  
Water Line ◽  
Average Value ◽  
Meteoric Water Line

The 2H/1H and 18O/16O isotope ratios in rainwater bring a lot of information about the fractionation of water molecules in the hydrosphere. The relationship between the isotope ratios of rainwater in an area characterised by the local meteoric water line, which is known as a reliable reference value for studies related to the identification of the recharge source of groundwater and climate change investigations. This study aims to establish a local meteoric water line in Long Khanh city (LK LMWL) in the period of 2020-2021, which is considered as a basis for research on the origin of groundwater in the area of Long Khanh city and subsequent studies on the origin of groundwater in the Southeast of the Mekong Delta region and the Dong Nai river basin. Results show that δ2H in rainwater ranges from -73.64 to 0.36 (‰ VSMOW) with an average value of -49.74‰ (n=19) and that figure of δ18O ranges from -10.91 to -1.59 (‰ VSMOW) with a mean of -7.68‰ (n=19). Due to the amount and specific meteorological conditions of the region, δ2H and δ18O in rainwater are enriched in the dry season but deplete in the rainy season. The LK LMWL follows a model of δ2H=(7.89±0.38)xδ18O + (10.28±2.93) (R2=0.96, n=19), which shows that the isotopic composition of δ18O in rainwater is more enriched than the isotopic composition of δ2H. The deuterium excess (d-excess) of rainwater in the region is found to be 10.28±2.93‰, which is comparable to those for the global scale of 10‰.

scholarly journals A new local meteoric water line for Inuvik (NT, Canada)

2021 ◽  
Author(s):  
Michael Fritz ◽  
Sebastian Wetterich ◽  
Joel McAlister ◽  
Hanno Meyer
Keyword(s):  
Isotopic Composition ◽  
Meteoric Water ◽  
Environmental Geochemistry ◽  
Sampling Period ◽  
Water Line ◽  
Meteoric Water Line ◽  
Oxygen And Hydrogen Isotopes ◽  
Western Arctic ◽  
Stable Oxygen ◽  
Data Gap

Abstract. The paper presents a new local meteoric water line (LMWL) of precipitation stable oxygen and hydrogen isotopes from Inuvik in the Western Canadian Arctic. Data were obtained over 37 months between August 2015 and August 2018 resulting in 134 measurements of the isotopic composition of both types of precipitation, snow and rain. For 33 months of the sampling period each month is represented at least two times from different years. The new LMWL from Inuvik is characterized by a slope of 7.39 and an intercept of –6.70, and fills a data gap in the Western Arctic where isotopic composition data of precipitation are scarce and stem predominantly from before the year 1990. Regional studies of meteorology, hydrology, environmental geochemistry and paleoclimate will likely benefit from the new Inuvik LMWL.

scholarly journals National Stable Isotope Baseline for Precipitation in Malawi to Underpin Integrated Water Resources Management

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1927
Author(s):  
Limbikani C. Banda ◽  
Michael O. Rivett ◽  
Anold S. K. Zavison ◽  
Sydney Kamtukule ◽  
Robert M. Kalin
Keyword(s):  
Developing Countries ◽  
Meteoric Water ◽  
Land Development ◽  
Water Line ◽  
Meteoric Water Line ◽  
Spatial Coverage ◽  
Stable Isotopic ◽  
Isotopic Characterization ◽  
Isotopic Baseline ◽  
Water Isotope

With the resurgence of water-isotope tracing applications for Integrated Water Resource Management in developing countries, establishing a stable isotopic baseline is necessary. Developing countries, including Malawi, continue to struggle with the generation of consistent and long-term isotopic datasets due to non-existent or inadequate in-country water-isotope capacity. Malawi has made significant advances in its quest to establish a stable isotopic baseline through the establishment of the Malawi Network of Isotope in Precipitation. This study provides the first results for the isotopic characterization of precipitation in Malawi with a view to reinforcing understanding of the country’s hydrological cycle. Error-in-variables regression defined a Local Meteoric Water Line as δ2H = 8.0 (±0.3) δ18O + 13.0 (±2.0) using stable isotopic records of 37 monthly samples from 5 stations between 2014 and 2019. Local precipitation (isotopic composition) is consistent with global precipitation expectations, its condensation-forming process occurring under equilibrium conditions and a higher intercept (d-excess) above the 10‰ for Global Meteoric Water Line, implying that air moisture recycling significantly influences local precipitation. Wider variations observed in local precipitation isotopic signatures are largely attributed to different moisture-bearing systems and diverse geographic factors across the country. Additional stations are recommended to improve spatial coverage that, together with longer temporal records, may help understanding and resolving uncertainties such as the altitude effect. This pioneering study is expected to facilitate Malawi’s ambition to achieve integrated use and improved protection of its surface water and groundwater resources in response to mounting climate change, growing population and land-development concerns.

scholarly journals Determination of isotopic composition of rainwater to generate local meteoric water line in Thohoyandou, Limpopo Province, South Africa

Water SA ◽  
2019 ◽  
Vol 45 (2 April) ◽  
Author(s):  
Olatunde S Durowoju ◽  
John O Odiyo ◽  
Georges-Ivo E Ekosse
Keyword(s):  
Isotopic Composition ◽  
Meteoric Water ◽  
Limpopo Province ◽  
Seasonal Effect ◽  
Weighted Mean ◽  
Water Line ◽  
Meteoric Water Line ◽  
Wide Range ◽  
Continental Effect ◽  
Rain Formation

Hydrogen (D) and oxygen (18O) isotopic compositions of precipitation are useful tools to delineate the nature of precipitation, groundwater recharge and climatological investigations. This study investigated the isotopic composition of 12 rainfall occurrences at Thohoyandou, with the objective of generating the local meteoric water line (LMWL) and determining the factors controlling the isotopic composition of the rain. The delta (δ) values for D and 18O of the samples were determined using a Thermo Delta V mass spectrometer connected to a Gasbench. Thohoyandou rainwater showed a wide range of stable isotope values; δD values of the rainwater varied from −76.3‰ to +22.7‰ (SMOW) with a weighted mean of −9.8‰ and δ18O values ranged from −10.78‰ to +3.07‰ (SMOW) with a weighted mean of −2.7‰. δ-values of rainwater were more enriched during winter and more depleted during summer, due to the amount of rainfall and seasonal effect. The LMWL in Thohoyandou is defined by δD = 7.56δ18O + 10.64, which shows a similar slope to the global meteoric water line (GMWL) but with a slightly higher intercept, of 10.64‰ instead of 10‰. This implies that the process of rain formation in Thohoyandou occurred under equilibrium conditions which are not significantly affected by evaporation. The slightly higher d-intercept value above the GMWL reflects an additional supply of recycled moisture across the regions. This implies that there is no continental effect but inland moisture from various water bodies and vegetation.

scholarly journals A new local meteoric water line for Inuvik (NT, Canada)

2022 ◽  
Vol 14 (1) ◽  
pp. 57-63
Author(s):  
Michael Fritz ◽  
Sebastian Wetterich ◽  
Joel McAlister ◽  
Hanno Meyer
Keyword(s):  
Isotopic Composition ◽  
Meteoric Water ◽  
Environmental Geochemistry ◽  
Sampling Period ◽  
Water Line ◽  
Meteoric Water Line ◽  
Oxygen And Hydrogen Isotopes ◽  
Western Arctic ◽  
Stable Oxygen ◽  
Data Gap

Abstract. The paper presents a new local meteoric water line (LMWL) of stable oxygen and hydrogen isotopes in precipitation from Inuvik in the western Canadian Arctic. Data were obtained over 37 months between August 2015 and August 2018 resulting in 134 measurements of the isotopic composition of both types of precipitation, snow and rain. For 33 months of the sampling period each month is represented at least two times from different years. The new LMWL from Inuvik is characterized by a slope of 7.39 and an intercept of −6.70 and fills a data gap in the western Arctic, where isotopic composition data of precipitation are scarce and stem predominantly from before the year 1990. Regional studies of meteorology, hydrology, environmental geochemistry and paleoclimate will likely benefit from the new Inuvik LMWL. Data are available on the PANGAEA repository under https://doi.org/10.1594/PANGAEA.935027 (Fritz et al., 2021).

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