(1)Carbon cycle in the epigenic karst processes. A network to investigate carbon cycle in karst of different ecological conditions of the world was set up. Monitoring techniques were improved for a better understanding on the behaviours of carbon migration on the interfaces between atmosphere, vegetation, soil, carbonate rock and water. Limestone denudation rates at different parts of the world, as a basic data for estimation of carbon sink in karst processes are accumulated. A karst denudation map for Irkutsk region of Siberia covering 400,000km² was compiled. The preliminary estimation on carbon uptake from atmosphere by carbonate rock dissolution ranges between (2.2-6.08)´ 10⁸t/a according to different authors.

(2)Deep source CO₂ from karst areas. The indications of deep source CO₂ emission from karst regions were not only discovered in plate margin such as the Tethys and Pacific realm, but also in intraplate region, such as mainland China. Moreover , deep source CO₂ was found related to oil-gas reservoirs. Following the early stage investigation of CO₂ emission on Tethys realm at Tibet of China, Turkey and Italy, the Project has extended this exploration to Vietnam at east, and Spain and France to the west. 1370 hot springs were registered on Tibet Plateau in an attempt to find out their relation with CO₂ emission. In the intraplate parts of mainland China, CO₂ emission are found widespread in most of its 28 major active faults. 20 big CO₂ reservoirs of deep inorganic source were discovered where the active faults are covered by thick sediments. In Pacific realm, CO₂ emission was studied at Hualien County, eastern coast of China’s Taiwan Is. This research had also been extended to South Spitsbergen, where S-E Lauritzen noticed a karst spring at Trollosen of geothermal origin. In some carbonate rock oil-gas reservoirs of Russia and other countries, CO₂ is produced along with H₂S as a result of reduction by hydrocarbon of sulphates mixed in carbonate rock strata. The processes take place under high pressure of tectonic movement, and can thus intensify karstification in the overlying carbonate rock.

(3)Paleoenvironment reconstruction with karst records. The past achievements of the Project in this direction are characterized by wide geographic coverage, improving techniques and resolution. Important paleoenvironment informations were provided by karst sediments from five continents including many countries, such as Australia, New Zealand, China, Japan, Turkey, Israel, Saudi Arabia, Norway, UK, Poland, Belgium, France, Czech, Spain, USA, Canada, Bahamas, Brazil, Argentina, Morocco, Tanzania, S. Africa, Botswana, and Namibia. The techniques used include Uranium series dating, C¹⁴ dating, AMS C¹⁴ dating, TIMS, TL, fission track, paleomagnetism, luminescene microbanding, trace elements and stable isotope. The resolution ranges between millennial to seasonal according to the characteristics of the speleothem and the techniques used. In the core project PAGES of IGBP, a special initiative to use speleothem as paleoenvironmental proxy has been launched (Speleothem PEP, or SPEP) for its PEP III Transect (Europe to Africa).

2. Achievements of the Project in 1998

The new development on the three objectives of the Project this year could be summarized as deeper understanding on the characteristics of carbon cycle in karst dynamic system; more new techniques used in paleoenvironmental reconstruction with karst records which led to reveal some events of paleoenvironmental change with high resolution; and more problems of societal benefits were studied.

2.1.1 Carbon cycle in the epigenic karst processes

More monitoring sites in USA, UK, Italy, Australia, Luxembourg, Canada(Labrador) put into operation this year, in addition to those already set up in the early stage of the Project which keep providing new data. The understanding on the behaviours of carbon cycle in epigenic karst system has extended to arctic and alpine regions.

(1)Carbon cycle in Arctic karst. In Spitsbergen, observation on dissolution rate of carbonate rock has been continued for 18 years on selected catchments with different hydrological conditions, i.e, uplifted marine terrace, permafrost, and glacier-covered. The observation was done in both polar summer and polar winter. The carbon uptake from atmosphere by karst processes was estimated as (20.4-23.5)´ 10⁵gC/km^2× a for a permafrost catchment (Fugleberget Basin, 1.28km²). The uptake for a glacial catchment is much higher, being 53.09´ 10⁵gC/km^2× a(Werenskiold Basin, 44km²), but for a smaller basin as Kvisla, it could be as high as (94.43-109) ´ 10⁵gC/km^2× a. Based on the observation data from Spitsbergen, a model of chemical denudation processes was obtained. It will facilitate estimating not only the carbon removal by karst processes for all the 46 catchments of Hornsund Fjord at SW Spitsbergen covering 1270km², but also for similar estimation at other arctic karst of the world (W.E.Krawczyk, Poland).

(2)More knowledges about the characteristics of carbon cycle in epigenic karst system. Automatic monitoring on the CO₂ fluxes in Altamira and Tito Bustillo caves, Northern Spain reveal that there are two types of CO₂ variation: seasonal change controlled by rainfall and ventilation; and short term variations controlled by the fluctuation of atmosphere pressure. When the atmosphere pressure is high (in dry period), the CO₂ content in soil will decrease, but it will increase to extreme high in cave air (up to 6000ppm). In contrast, when the atmospheric pressure decreases, a fall of CO₂ in cave air is observed (less than 1500ppm). Moreover, the ²²²Rn content in soil and cave air behaved the same as CO₂ (M.Hoyos, Spain). In Marble Mt, Northern California, USA, CO₂ in soil covering Subalpine Karst (1700-1900m asl) has been monitored. It is found related to snowmelt, with peaks varied between 1% and 4% according to different ecological conditions: red-fir, dry meadow, wet meadow, or rock fissure (Jerry D Davies, USA). The sensitivity of CO₂ content variation in karst system to environmental factors (bushfire, rainfall) observed in Belize made the traditional ideas of taking carbon cycle in karst as long-term, slow process questionable (Michel Day, USA). All this new findings will help better estimation on CO₂ flux in karst processes.

(3)New estimation on carbon uptake from atmosphere. Three methods to estimate CO₂ uptake from atmosphere by karst processes were suggested, including limestone denudation rate; hydrochemical and Diffuse Boundary Layer(DBL) approaches (Liu Zaihua, China; Kazuhisa Yoshimura, Japan; W.B.white, and John Mylroie, USA). Some authors made new estimation of global annual carbon uptake as (1.1-6.08)´ 10⁸t/a.

2.1.2 Deep source CO₂ in karst areas

(1)The origins of deep source CO₂. According to d ¹³C analyses for CO₂ gas from typical geothermal springs at Kangding, Zhongdian, Huanglong and some other points in China’s Tethys realm, the emissions are identified as partly from mantle, and partly from metamorphism of carbonate rocks. Moreover, the mixture ratios are estimated, for example, for Huanglong, 77% from mantle, 23% from metamorphism; for Zhongdian geothermal spring, 36% from mantle, and 64% from metamorphism. In Rocky Mt area, carbon and noble gas isotopic analyses for CO₂ gas from a low temperature spring (9.8-16.5ºC, the Manitou Springs, Colorado) of Paleozoic carbonate rock aquifer got the similar conclusion, where magmatic CO₂ accounts for 7-14% (Alan L Mayo, USA).

(2)Maps of CO₂ emission. A map series for deep source CO₂ emission from China’s Tibet Autonomous Region and its neighbouring Qinghai, Sichuan and Yunnan Provinces was compiled at the scale of 1:10,000,000. It was compiled on the basis of hydrochemical data of 680 geothermal springs, and includes three maps: 1) A map of CO₂ content in geothermal springs, with five categories of springs shown on the map, which are distinguished according to their CO₂ content: >1500mg/l; 1500-1000mg/l; 1000-500mg/l; 500-100mg/l; <100mg/l. 2) A map of relationship between active faults and hot springs in Tibet, scale 1:8,000,000. 3) A map of deep source CO₂ emission intensity in Tibet and neighbouring provinces. The region is divided into 6 categories according to intensity of CO₂ emission: 500-100g/l; 100-50g/l; 50-10g/l; 10-5g/l; 5-1g/l; and 1-0g/l. The annual emission of deep source CO₂ is estimated to be 2.68 ´ 10⁵t/a (Yang Lizheng, China). Taking into account the distortion which may be brought about by water sampling points where some part of CO₂ already lost, it may match the result of D M Kerrick (1994) who did the estimation by macroscopic tectonic history model.

2.1.3 Paleoenvironment reconstruction with karst records

Following the use of new techniques, such as ¹⁰Be, ²⁶Al, TIMS, ²¹⁰Pb and DNA, new paleoenvironment informations including paleohydrology, paleovegetation, in addition to paleoclimate, and higher resolution were got in reconstructing the course of environmental change.

(1)Paleohydrology. Taking the Mammoth Cave area as an example, cosmogenic nuclides ¹⁰Be (half-life 1.5 million yr) and ²⁶Al (half-life 0.71 million yr) were used to date the quartz grain in the cave sediments. The results indicate that sediments within the uppermost 40 meters of the cave system date to approximately 2.5 million years ago, coincident with the onset of northern hemisphere glaciation. These sediments are supposed to have been laid down as a result of massive aggradation of the nearby Green River. Sediment dates from lower passages of the cave system indicate that Green River incision has lowered the regional water table at a rate of roughly 30m/My(D E Granger and D Fabel, USA).

(2)Paleovegetation. A rapid change in d ¹³C in a stalagmite of Guilin area, China is considered to be an indication of vegetation change in the past 200 years. The 13cm high growing stalagmite was taken from Fengyu Cave, 120km south of Guilin. The datings by TIMS, and ²¹⁰Pb approaches were made at Isotope Lab of Minnesota University. A very high resolution d ¹³C analyses (14 readings for every centimeter along the growth axis, i.e, each reading represents 5-10 years) show a sharp rising of d ¹³C(from -12.5‰ up to -5.5‰) after 1780 AD, i.e, the later stage of Emperor Qianlong of the Qing Dynasty. The result repeated well in a second analysis along another section of the same stalagmite. It has been testified that the low d ¹³C reflects a predominance of C₃ plant, whereas the high d ¹³C reflects C₄ plant(herbaceous plant). Accordingly, the sharp rising of d ¹³C at 1780 AD is an indication of deforestation, as a result of massive timbering along with the boost of economy at the time of Emperor Qianlong, one of the most prosperous period of the Qing Dynasty (Li Hongchun, USA). The paleovegetation 20,000 years ago around eastern mountainous area of Las Vegas, USA was identified by DNA analysis (done by the Pääbo Lab. of Munich University, Germany) on coprolite taken back from the Gypsum Cave, 30km east of Las Vegas. The cave was developed in gypsum bed intercalated in Permian limestone, and visited by IGCP 379 participants during its FT-2 excursion of the 28^th IAH Congress. The work at Gypsum Cave was the first successful recovering of DNA from fossil feces (coprolite). Some of the DNA are believed to come from a ground sloth, Nothrotheriops Shastensis lived 20,000 years ago, and extinct from North America 10,000 years ago. Its family is now only available in South America. There are also plant DNA in the coprolite, identified as from 8 plant families including grass, yucca, grapes and mint, which are otherwise not identifiable because of being chewed by sloth beyond recognition. Therefore, the findings provided informations about paleovegetation, and perhaps also about environmental change and the reason of sloth extinction.

(3) More informations about paleoclimate. The 5^th (a-e) and 4^th oxygen isotope stages in Balkan region were identified by uranium series dating and stable isotope analyses (d ¹⁸O,d ¹³C) on a 39.5cm high stalagmite taken from Lithophogus Cave, NW Romania (B.P.Onac, Romania). The Little Ice Age in Guilin area, China, was identified at 1560-1880 AD by d ¹⁸O analyses on the same 13cm high stalagmite taken from Fengyu Cave as mentioned before. The contrast of d ¹⁸O ranges between -7.2‰ and -6.0‰.

2.1.4 Societal benefits

(1)The new understandings on the behaviours of a karst dynamic system achieved by IGCP 379 were used in solving many practical problems including water resources management and pollution of karst aquifers; surface collapse in karst areas; water invasion in tunnels; salt water intrusion in coastal karst. A total of 30 papers presented at the 3 meetings of the Project this year dealt with such issues. In a National Project to solve water problem in NW China’s arid region, the findings of deep source CO₂ helped exploring deep karst water with success.

(2)The Project has been more involved in Global Change study in two ways: assessing the contribution of karst processes to global biogeochemical cycle, especially to the content of CO₂ in the atmosphere; and to collect karst records as paleoenvironmental proxies to test the output of the General Circulation Model. In PEP III of IGBP core project PAGES, the Speleothem PEP (SPEP) has been launched as a special initiative.

(3)In some tropical karsts, the monitoring on the variation of CO₂ in karst dynamic system revealed that in some deep dolines, the atmospheric CO₂ could be doubled than normal, i.e, 600-700ppm. Whether this can be used as a natural CO₂ fertilizer is an object worthwhile for more investigation.

(1)Friends of Karst-IGCP 379 meeting and excursions, Sept. 23-26, 1998, Bowling Green, USA. 120 participants from 15 countries took part in the symposium and excursions at the Mammoth Cave System and the Hawkins River Karst Hydrology and Hydrochemistry Experimental Site which the American Group of IGCP 379 (Dr.Chris Groves) asserted as an experimental site of the Project, and will develop a carbon budget for a Carboniferous limestone Basin covering 160km². 63 papers were presented.

(2)The relevant sessions of the 28^th IAH conference, Sept.27-Oct.2, 1998, Las Vegas, USA, including session TA7 and TA10: karst I; FA32 and FA35: springs and karst II. 42 participants from 19 countries were at the sessions and FT-2 excursion at Las Vegas Valley and the Gypsum Cave archaeology site. 20 papers were presented.

(3)IGCP 379 International Seminar "Karst Processes and the Carbon Cycle", Oct.5-12, 1998 in Guilin, China. 28 participants from 4 countries took part at the seminar and the 4 excursions to the Guilin Karst Experimental Site for carbon cycle study in subtropical regions and the Panlong Cave, Fengyu Cave around Guilin, where speleothems were taken for paleoenvironmental reconstruction with success. 16 papers were presented.

1. Contribution of IGCP 379 "Karst processes and the carbon cycle" to Global Change, Episodes 1998, Volume 21, No.3, by Yuan Daoxian
2. Global Karst Correlation, 308pp, 70 colour photos, Science Press of China, VSP BV, Netherlands, 1998, Editors: Yuan Daoxian, Liu Zaihua
3. Bomb ¹⁴C time history recorded in two modern stalagmites-importance for soil organic matter dynamic and bomb ¹⁴C distribution over continent, Earth and Planetary Science Letters 160 (1998) 795-809, by D. Genty et al
4. Karsts science of 2000, Environment Geology, 1998, 33(4) 313-315, by Yuan Daoxian
5. Special speleothems in cement-grouting tunnel, and their implications of the atmospheric CO₂ sink, Environmental Geology, 1998, 35(4) 258-262, by Liu Zaihua
6. Carbon dioxide fluxes in karstic caves (Altamira and Tito Bustillo caves, Northern Spain). 1998, abstract book, Friends of Karst-IGCP 379, p34, Western Kentucky University, by M.Hoyos et al
7. Age of sediments in the Mammoth Cave System, 1998, abstract book, Friends of Karst-IGCP 379, p.4 WKU, by D Granger et al
8. Hydrogeology of isolated karst plateau: An example from Hirao-Dai karst, Japan, 1998, abstract book, Friends of Karst-IGCP 379, p.11, WKU, by Kensaku Urata
9. A study of several karst phenomena in Croatia, 1998, abstract book, Friends of Karst-IGCP 379, p.12, WKU, by Nada Horvatincic et al
10. .Snowmelt-initiated CO₂ cycle in a Dry-summer subalpine landscape, Marble Mts, California, 1998, abstract book, Friends of Karst-IGCP 379, p.13, WKU, by J D Davis et al
11. .Contribution of CO₂ to processes of chemical denudation of carbonate rocks in Spitsbergen, 1998, abstract book, Friends of Karst-IGCP 379, p.14, WKU, by W E Krawczyk et al
12. .Anthropogenic influence on global and regional carbon cycles recorded in the d ¹³C of speleothem, 1998, abstract book, Friends of Karst-IGCP 379, p.15, WKU, Hongchun Li et al
13. .Carbonate Deposition, Karst Dissolution, and Carbon Dioxide flux in the Quaternary, 1998, abstract book, Friends of Karst-IGCP 379, p.18, WKU, by John Mylroie
14. .Carbon dioxide fluxes in Karst drainage basins calculated from spring water chemistry, 1998, abstract book, Friends of Karst-IGCP 379, p.22, WKU, by W.B.White
15. .Short-term decline in soil CO₂ concentrations caused by burning of secondary vegetation in the karst of Belize, 1998, abstract book, Friends of Karst-IGCP 379, p.35, WKU, by M.Day
16. .Isotopic stratigraphy of a Last Interglacial stalagmite from NW Romania: correlation with the deep-sea record and Northern-latitude speleothem, 1998, abstract book, Friends of Karst-IGCP 379, p.36, WKU, by S-E Lauritzen, B.P.Onac
17. .Map series of deep source CO₂ emission from China’s Tibet Autonomous Region and its neighbouring Qinghai, Sichuan, and Yunnan Provinces, scale 1:10,000,000, 1998, by Yang Lizheng, Chengdu Institute of Technology
18. .Paleoenvironmental change in Java Island and its surrounding areas, Journal of Quaternary Science, 1997, 12(5) 435-442, by Kazuko Urushibara-Yoshino et al
19. .Solution ratio of limestone Tablets and CO₂ contents in soils of Minamidaito Island, 1997, Kamazawa Geography, No.33, 33-47, by Kazuko Urushibara-Yoshino et al
20. .Contribution of carbonate rock weathering to the atmospheric CO₂ sink, 1998, Proceedings Volume of 28^th IAH conference pp.187-193, American Institute of Hydrology, by Liu Zaihua et al
21. .An example of bacteriological contamination of a captured karst spring, 1998, proceedings volume of 28^th IAH conference, p.173-177, American Institute of Hydrology, by Z Stevanovic et al
22. .Hydrogeophysical exploration of aquifer vulnerability to pollution-A case study, 1998, proceedings volume of 28^th IAH conference, p.373-377, American Institute of Hydrology, by S Komatina
23. .The Spanish IGCP 379 Group will contribute 6 papers, to be published in International Journals
24. .A dedicated theme volume of selected papers from the Project will be compiled to be published in Environmental Geology
25. .IGCP 379 Newsletter 1998, 102 pages, Editors: Zhang Cheng, Xie Yunqiu, The Institute of Karst Geology, Guilin, distributed to all participants during the meetings this year
26. .The Project’s Web Page was improved remarkably and includes many new informations (http://www.gxnu.edu.cn/KDL/IGCP379)
    

(1)The Project has close link with IGCP 404 "The terrestrial carbon cycle in the past 125ka" from the very beginning. Besides attending some of the meetings each other, informations have been exchanged regularly. A joint meeting is scheduled to take place in Durban, S. Africa.

(2)Under the initiation of Dr. E Derbyshire, we are working together with IGCP 404, IGCP 386 "Response of the Ocean/Atmosphere System to Past Global Change", IGCP 396 "Continental Shelves in the Quaternary", IGCP 413 "Understanding Future Dryland Changes from Past Dynamics" for the formation of a ICSU-UNESCO supported "Super-Project", which is presumably named as "Climate change, environmental response and the Earth’s carbon cycle".

(3)INQUA Commission on Carbon. The scientific exchanges with the Commission are as usual, more intimate discussion is planning this year at the 15^th INQUA in Durban.

(4)Internation Karst-related Academic Organizations: Karst Commission of IAH; Karst Commission of IGU; and the International Union of Speleology. Members of the organizations have taken active part in the Project by attending meetings and excursions, contributing papers for the Project’s publication, including the newly published book "Global Karst Correlation". The leaders of those organizations have all took part at the Project’s meeting this year.

(1)Joint IGCP 379 and IGCP 404 meeting in Durban, S. Africa, August 3-11, 1999. It will coordinate the works of the two IGCP projects, and in conjunction with the 15^th INQUA Conference. Field sites of specific interest to the objectives of the Project will be visited.

(2)IGCP 379 meeting in Bratislava, Slovakia, Sept 6-10, 1999 in conjunction with the 29^th Congress of IAH. Some sites of Slovakia contributed to the Project, such as the 126km² Muranska Planina karst plateau developed in Triassic limestone will be visited.

During the Project’s meetings in 1998, a suggestion for successor project was discussed, which is preliminarily named as "World Correlation on Karst Ecosystem". From the works of IGCP 299 "geology, climate, hydrology and karst formation" (1990-1994), and IGCP 379 "karst processes and the carbon cycle" (1995-1999), it is recognized that the karst ecosystem is fragile, and characterized by calciphile, petrophile and xerophile as a result of karst hydrological system and Ca-Mg rich geochemical background. However, its impact on human life is quite different in different karst regions with varied ecological features. World comparison on karst ecosystems will enlighten knowledge on the mechanism of how different karst ecosystems coming into being, and thus benefit more reasonable treatment of ecological problems and sustainable development in karst. It will be in keeping with the guideline of IGCP " Geosciences in the Service of Society".

The suggestion got written support of 19 scientists from 14 countries.

(1)Number of participants included in the Project’s email list increased to 95. They are from 30 countries. The facility provides fast communication for the Project. The Home Page of the Project has been improved remarkably and got more visitors.

(3)Since 1996 we have established tie with the Friends of Karst, an informal scientific organization of USA. Joint meetings were organized in 1996 (Norway) and last year (Bowling Green,1998). It turns out to be very helpful for the running of the Project.

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