Part?Ⅲ?? ?Report on the Progress of?IGCP 379 “Karst Processes and the Carbon Cycle” in Its Final Year (1999)
? By Yuan Daoxian
1??Summary of Major Past Achievements of the Project
Information about the past achievement of the Projects are available on its website (http://www.karst.edu.cn?),especially the 4 Newsletters, 1996, 1997,??1998 and 1999, which include 403 pages and are all put on the web.
The major past achievements of the Project could be summarized according to the 4 main objectives of the Project.
(1)The carbon cycle in epigenic karst processes
The behaviours of carbon cycle on the interfaces between carbonate rocks, water, soil, vegetation and atmosphere were revealed on the bases of monitoring network distributed at different ecological conditions of the world including arctic Karst (Spitsbergen). This network was set up at the beginning of the Project, and expanded year after year with improved techniques. The carbon cycle in epigenic karst are found related to temperature, rainfall, snowmelt, atmospheric pressure, permafrost or glacier cover, vegetation type and bushfire. Data of carbonate rock denudation rate as basis for estimation of carbon sink in karst processes are accumulated at different parts of the world from year to year. Karst denudation maps are compiled, e.g. Irkutsk region of Russia. Global carbon uptake from atmosphere in karst processes were estimated by different authors with different methods. The results are (1.1-6.08)×108?t of carbon annually.
(2)Deep source CO2?in karst areas
Deep source CO2?are investigated in karst areas of Tethys from China to Spain and Pacific realms including USA, Canada, China and Japan, and also intraplate region, such as mainland China. The origins of deep source CO2?are identified as a mixture from manle or metamorphism of carbonate rock at different ratio, or from oil-gas reservoirs as a result of reduction by hydrocarbon of sulfates mixed in carbonate rock strata. Based on the hydrochemical data of 680 hot springs, a map series for deep source CO2?emission from China's Tibet Autonomous Region and its neighbouring Qinghai, Sichuan and Yunnan provinces was compiled. The annual emission of deep source CO2?from this region is estimated to be 2.68×105?t/a.
(3)Paleoenvironmental reconstruction with karst records
The Project has got wide geographic coverage in this objective with improving techniques and resolution. Important paleoenvironment informations were collected from karst sediments of 25 countries, which are distributed in 6 continents including Europe, Africa, Asia, North America, South America and Oceania. The dating techniques used include uranium series approach, C14, AMS C14, TIMS, TL, fission track, paleomagnetism, Be10, Al26, and Pb210. Paleoenvironment proxies used include paleontology, growth rate of speleothem, trace??elements, stable??isotope, luminescene??microbanding??and??DNA. The resolution of paleoenvironmental???reconstruction??ranges??between??millennial?and seasonal according to the characteristics??of??the karst??sediments??and the techniques used. The??paleoenvironment??informations recovered??from??karst sediments?include not only??paleoclimate , but also paleohydrology??and??paleovegetation.?
(4)Sustainable development of Karstland
The new understanding on the behaviours of carbon cycle, water cycle and element migration in karst dynamic system were used in dealing with many practical problems including karst water exploration; water resources management and pollution of karst water; ecological rehabilitation in rock desertification areas; surface collapse in karst areas; and salt water intrusion in coastal karst.
2??Achievements of the Project this year
2.1 General scientific achievements (including societal benefits)
There are many new achievement in all the three objectives of the Project during its final year. The geographical coverage of its study has been expanded. By careful works on monitoring sites, the behaviours of carbon cycle in Karst Processes are better understood. The time span of Paleoenvironmental reconstruction with karst records are extended to Tertiary and Cretaceous.
?2.1.1 Carbon cycle in the epigenic karst processes
(1)The investigation on carbon cycle in the dissolution or precipitation of carbonate rocks are expanded from land to seas,?and traced back to glacial - interglacial time (up to 800ka). In Nordic Sea, by weighing foraminiferal tests with two cores covering the past 500ka, carbonate preservation in Glacial period and corrosion in Interglacial are demonstrated clearly. Up to 45% of calcite loss is observed during Interglacial, with the strongest carbonate corrosion occurred in Interglacial stage 11. It is considered that the high plankton productivity during Interglacial, had led to increased downward flow rate of organic material to the sea bottom and, consequently, to more corrosive bottom water enriched with CO2?(J. P Helmke, Germany). The same phenomenon is also observed in Pacific Ocean, e.g., in the core TT013-PC72 (North of New Guinea), which is dated back to 800ka, carbonate contents are high (85%-95%) during Glacial (Kuo-Yen Wei, Taipei, China), but become relatively low during Interglacial period (55%-70%);
(2)Tufa deposits and relevant CO2?outgassing.?In Sierra de la Alfaguara, Granada, Southern Spain, the tufa deposit around a karst spring is considered to be the results of CO2outgassing in addition to common-ion effect (Bartolome Andreo, Manuel Martin-Martin, 1999). Moreover, the authors hold that the deposition was taken place during the warm and wet climatic periods. In Akka Karst, Iwate, Northeastern Honshu Island, Japan, the CO2?degassing which makes tufa deposit is considered to be the results of joint physicochemical and biological Processes (Toru Okamoto et al, 1998). The extensive Norlim tufa deposit near Taung, Northern Cape, South Africa has a total volume of 7.9×106M3. The tufa is very old, as verified by the associated fossils of?Australopithecus africans?which is generally considered to live in the timespan of 2.5-3.2 Ma BP, and the U-series ages of some younger tufa which are 47-114ka, and 256-343ka respectively. It is also suggested that the tufa was depositited during the warmer and wetter climate of?18O stages 5, 9 and 11(B7?field excursion of INQUA 15 conference in South Africa).
(3)New ideas for the carbon cycle in epigenic Karst.?From monitoring data of Akiyoshi-dai karst system, Japan, Youji INOKURA et al (1999) suggest that the limestone??dissolution rate depends not only on the CO2?concentration in soil ( usually the forest soil has a higher CO2?concentration than grassland soil), but more importantly on the openness of the system. When the karst system is more cavernous, the CO2?supply condition will be better, hence the dissolution rate will increase. In the arid region of China, Pan Genxing (1999) estimated that the soil inorganic carbon reservior as pedogenic carbonatess is 60Pg. The annual uptake of carbon by pedogenic carbonates formation is 1.5×106t/a. By the monitoring works at Nonla Karst, Guangxi, China, Jiang Zhongcheng (1999) found that the karst system under dense forest has higher soil CO2?concentration, higher carbonate rock dissolution rate, and more intensive elements migration than that under bush and scarcely scattered trees.
2.1.2 Deep Source CO2?emission.
Some new data are reported in this respect. The CO2?degassing from the Massif Central region in France is estimated to be﹥6000t/km2·yr. Moreover, the methane hydrate which was transformed from methane and accumulated in bedrock during glaciation will change back to methane and emit into atmosphere very rapidly in the deglaciation period( Nils-Axel Morner, 1999). In the Rift Valley of Kenya, notably at Magadi, Mount Kenya,Homa Hills, and Dzombo Hill, deep source CO2?degassing are related to deeply circulating waters near carbonatite centers, with HCO3-?content in excess of 20,000ppm, and?δ13C values of 0~-16.5‰??(Mwakio P Tole, 1999). In China, theδ13C of Taroko Karst spring at Hualien County, eastern part of Taiwan Island was analyzed, and is -12~-3‰?(PDB), which shows a deep source origin (YOSHIMURA, 1999). Moreover, the mantle and limestone- metamorphism mixed Karst spring at Huanglong tufa cascades, Sichuan reported at the early stage of the Project was reexamined by a Sino- Japanese joint team with an automatic continuous PH recorder. The PH value at the outlet of the spring shows limited change between daytime and nighttime, i. e., 6.55 at daytime versus 6.6 in the night, which indicates little photosynthetic or biogenic influence on CO2?outgassing at the outlet. However, at the point 2km?downstream from the spring, the PH value changes remarkably from night to daytime, i.e., the PH value is 7.95-8 from 19:00 o'clock to 10:00 o'clock next morning, and 8.4-8.45 from 10:00 to 19:00. The results show that in addition to inorganic physicochemical processes, the photosynthesis may play a remarkable role in CO2?degassing and the formation of the splendid tufa cascades in Huanglong Ravine.
2.1.3 Paleoenvironmental reconstruction with karst records
(1)Remarkable progress in this direction in the past year?are reported from China, Egypt, Japan, New Zealand, Oman, Poland, Romania, South Africa, UK and USA. In China, TIMS datings for flowstone from the caves with?Homo erectus?fossils of Beijing man and Nanjing man have established, that both Nanjing Man and Peking Man are older than 500ka, i.e., older than previously thought (H. Cheng, 1999). In USA, a vegetation cycle in North America alternated among Forest-Savanna-Prairie-Forest in the past 75ka is established with detailed TIMS and stable isotopic study on four stalagmites taken from Crevice Cave, Southeast Missouri (J. A. Dorale, R.L. Edwards, Science, 1998,Vol.282, P1871-1874). In Egypt, (J Moeyersons, 1999), C14, TL datings and sedimentological study for deposits from 115ka to 6000a BP in Sodmein Cave revealed two wet period (90ka; and 40ka BP), and a dry period(25ka BP to before Holocene). Paleoclimatic signals in speleothem of Oman indicate that the monsoon rainfall, which touches only the Southwest part of the country today, covered most part of Oman in 10.5ka to 6.2ka BP, and 125-117ka BP (5e). Moreover, annual resolution climatic records in speleothem over the past 550years show 92-88, 35, 14, 11, 7.4 and 5.2 years cyclicities in Oman, which are suggested to be related to solar origin or ENSO variation (S J Burns, 1999). In South Africa, paleoenvironment of C3 and C4 vegetation change in the past 6600years are reconstructed with speleothems taken from Ficus Cave, and Cold Air Cave, Northern Province (S Spreckley, 1999). In Romania, a speleothem growth frequency curve for the last 150ka is constructed on the bases of 74 TH/U datings of speleothem taken from 15 caves in northwest of the country (T. Tamas, 1999). It can correlate with results of other paleoclimatic proxies. In the past year, some methodology problems in paleoenvironmental reconstruction with karst sediments were also investigated, e.g., P. Williams (1999) found from New Zealand speleothem that the?δ18O-paleotemperature relation negative over the glacial-interglacial cycles, but positive over most of the Holocene. Peter Rowe (1999) found, by stable isotopic records from fluid inclusions in a speleothem taken from GB cave, Mendip Hills in Southwest Britain, that stalagmite was deposited in isotopic disequilibrium with its dripwater, but he considers the isotopic composition of fluid inclusion water does closely approximate that of their derivative dripwater. In Japan, Akira TANAHARA and Hatsuo TAIRA (1999) use data of excess?210Pb in speleothem derived from airbone?222Rn for dating young straw stalactites less than 100 years old. The 8 straw stalactite samples 10.5-36 cm long were taken from a cave at the southern part of Okinawa Island. The results show that the growth rate of straw stalactites from the same cave are quite different, i. e., from 1.2mm/a to 8.9mm/a.
(2)Karst records of Paleoenvironmental change in the past 3.5 Ma in South Africa.The informations about karst formation and paleoenvironmental change we got from the excursions in South Africa are quite different from those ever made in the previous excursions of IGCP 379 or IGCP 299. They are characterized as follows: (1) All the caves were developed in Pre-Cambrian dolomite deposited in warm shallow sea, dated back to over 2.5 billion years; (2) The time of cave formation are also very old, and considered to be at Tertiary time (20-30 Ma BP). From some big underground passages, and remarkable speleothem, especially flowstones, we can see the area had experienced periods of intensive karstification, besides, modern karst processes is also ongoing under annual precipitation of 500mm/yr, as evidenced by tiny karren on the surface; (3)The unique feature of the cave fillings is the alternate deposition of thick flowstone and breccia. They could be a good paleoclimatic proxies, because the former is a product of humid warm stage, whereas the latter, composed of pieces of angular dolomites and cherts is a product of drier stage. However, flowstone in all the caves in North Province, South Africa are seriously damaged because it has been mined for lime-making for many years. Flowstone in the area is even given a local name of?“limestone”?from that practice, in contrast with the Pre-Cambrian dolomite which is not good for lime-making;(4)The breccia which dated back to 3.5Ma through 1.5 Ma is very important for paleoanthropological study in the world. It is very fossiliferous. In some places, e.g., the Gladysvale Cave, vertebrate bone fossils make about 30%-50% of the rock. Fossils of?Australopithecus?were found in all the caves visited in the excursions, including the Sterkfontein Cave, where the very first adult?Australopithecus africanus?was found by Dr. Robert Broom in 1936. Accordingly, the highlight of the excursion is to see the evidences of the early development of the family of Man(the?hominids) in a time span of 2 million years(3.5 Ma to 1.5 Ma BP), and the relationship between environmental changes and the development of Man;(5) The dating techniques for karst sediments in South Africa caves are also different from other studies in IGCP 379, because they are much older. For instance, the Members 2 flowstone in Sterkfontein cave was dated back to 3.3 million years by paleomagnetic approach. The flowstone and breccia in Gladysvale cave were dated back to 1538Ka-440Ka by ESR(Electron Spin Resonance) method. Moreover, the concentration of some trace elements in cave deposits which is related to surface denudation events is also used for a relative dating. For example, by comparing the Vanadium concentration in the deposits of Kromdraai cave with those of the Sterkfontein cave, which is supposed to be moved from the Black Reef quartzite exposed near the caves, the ages of the sediment in Kromdraai cave are estimated.
(3)Karst records of Paleoenvironmental change in Japan since Cretaceous.?Akihiro KANO (1999) made stable isotopic analyses for the Cretaceous laminated speleothem taken from a cave in Okayama, Southwest of Honshu Island, Janan. The results indicate that the Cretaceous rainwater had much lowerδ18O than the present-day rainfall in Okayama Prefecture. He explained the phenomena as coming from the Cretaceous Paleographysical setting of Japan Islands, namely, higher latitude, or far from the coast than present. The 40km??long in north-south, 3-4km wide Akka Karst of Iwate Prefecture, NE of Honshu Island is located at 60-100km east of Towada, Iwate, and Akitakoma Volcanos. By geomorphological analyses and dating of 7 tephra samples around Akka Karst which range between 40 ka BP and 915 AD, Toru Okamota (1999) reconstructed the course of periglacial processes, such as solifluction and frost shattering in the Cold Phase of Last Glaciation, and soil creep, soil erosion in Holocene when the climate become more temperate and humid. Atsushi Fujii (1999) made estimation of precipitation in the late Edo Period (1850s) based on the periodicity of an ebb and flow spring, the "Ippai-Mizu" spring in Hiroshima, South-west Honshu Island. The basic hypothesis is that the less the precipitation, the longer the periodicity. According to historical literature, its periodicity was 100-240 minutes in the middle 1800s, 20-80 minutes in the early Showa period (1930s-1940s), and stopped ebb-flow phenomena after a heavy rainfall on July, 1972. A hydrologic simulation model was established based on the hydrograph measured on Aug. 22, 1942. According to simulation FUJII suggested that the precipitation in the middle 1800s in the study area may have been limited to a small quantity, namely 92-96% inflow of water into the system compared with that of early middle 1900s. The result is supported by historical records of drought and dendroclimatologic data.
2.1.4 Societal benefits
(1)Sustainable development in karst regions.?In the Bratislava symposium, results of many works on karst water quality, karst hydrogeological investigation, mapping and the vulnerability and protection of karst environment were presented.The works cover 10 countries including Austria, Croatia, Italy, Poland, Portugal, Slovakia, Spain, Turkey, USA and Zambia. For instance, Cristina and B Andreo reported the hydrodynamic and hydrochemical behaviors of a 170km2?Yunquera- Nieves unit, west of Malaga, Spain on the bases of one year monitoring (1996-1997). I Vadillo Perez reported the effect of La Mina Landfill, north of Marbella, Spain on karst aquifer, and found that the saturation indices of calcite, aragonite and dolomite could be indicators of such effects, because the Landfill can produce great amount of CO2, which intensifies carbonate rock dissolution.
(2)The project has been continuously involved in Global Change Study.?Many of the new findings of the Project including carbon uptake by karst processes and karst proxies of paleoclimatic change will be used in the synthetic work at the IGBP's final stage.
(3)Some results of the Project are used in practical purposes.?For instance, the findings of deep karst related to oil field CO2?are used in exploring deep karst water in NW China's arid region. In the rehabilitation of karst rock desertification areas of South China, the findings of element migration in a karst dynamic system are used to guide the plantation of some medical herbs on limestone slope, thus to help local people overcome poverty.
2.2 List of meetings with approximate attendance and number of countries
(1)Meeting at the INQUA 15 Conference "the Environmental Background to Hominid Evolution in Africa", Durban, South Africa, August 3-11, 1999. 55 IGCP 379 members from 18 countries took part in the meeting. 47 papers of IGCP 379 relevance were presented in the sessions S10.1, P16 and P38 of the conference. 20 people participated in the B4excursion to visit 6 caves in Northern Province. The caves are developed in pre-Cambrian dolomite with many?hominid, especially?Australopithecus?fossils in Plio-Pleistocene deposits. South Africa colleagues show their achievements on paleoenvironmental reconstruction with karst records provided by hominid fossils and speleothems.
(2)Meeting at the 29th?congress of the International Association of Hydrogeologists (IAH) "Hydrogeology and Land Use Management", Bratislava, Slovakia, Sept. 6-10, 1999. 22 IGCP 379 members from 10 countries participated in the meeting. 19 papers of IGCP 379 relevance were presented. In the post conference excursion, some sites of karst water management and recent travertine deposition as results of deep source CO2?degassing were visited.
2.3 List of most important Publications (including maps)
1. CO2?source-sink in karst processes in karst areas of China, Episodes, 1999,Vol. 22, No.1 P33-35,Jiang Zhongcheng, Yuan Daoxian.
2.Hydrochemistry of spring water associated with travertines, Example of the Sierra de la Alfaquara(Granada, Southern Spain).Earth and Planetary Sciences, 1999, 328, 745-750, Bartolome Andreo & Manuel Martin-Martin.
3.The Japanese Group of IGCP 379 contribute 9 papers published in Japan Contribution to the IGCP, Karst Processes and the Carbon Cycle-IGCP 379, January, 1999, IGCP National Committee of Japan, 73pages.
4.A late Holocene climate record from a stalagmite, Cold Air Cave, Northern Province, South Africa, Paleogeography, Paleoclimatology, Paleoecology, 150(1999), 269-277, P Repinski , K Holmgren et al.
5.Climate and Vegetation History of the Midcontinent from 75Ka to 25 Ka: A Speleothem Record from Crevice Cave, Missouri, USA, Science, Vol. 282, p 1871-1874, December, 1998, J A Dorale, R L Edwards et al.
6.Tufa deposits in the Akka Karst, Northeastern Japan, Journal of the Speleological Society of Japan, Vol.23, Dec. 1998, P17-27, Toru OKAMOTO, Tada-aki YANAGISAWA, and Kazuhisa YOSHIMURA.
7.A 3000-year high-resolution stalagmite-based record of paleoclimate for northeastern South Africa.The Holocene 9,3 (1999) PP. 295-309, K. Holmgren, W. Karlen, S.E. Lauritzen et al.
8.Late Quaternary Palaeoclimates at Nelson Bay cave, based on stable carbon and nitrogen isotope ratios from Ungulate teeth: a re-assessment, South Africa Journal of Science Vol.94, Sept. 1998, P442-443, Francis Thackeray.
9.Karst hydrology: recent developments and open questions. In Hydrogeology and Engineering Geology of Sinkholes and Karst, editors: Beck, Pettit and Herring, P.3-21, 1999 Balkema, Rotterdam, William B. White.
10.Human influence on the karst water of the Nerja Cave, Malaga, Southern Spain. In "Karst Hydrogeology and Human Activities, Impacts, Consequences and Implicatin", Editors: David Drew and Heinz Hotzl. International Contributions to Hydrogeology Vol.20, 1998, PP.178-183, A.A. Balkema, the Netherlands, Francisco Carraso-Cantos, Bartolome Andreo- Navarro et al.
11.Variation in the groundwater calcocarbonic system parameters by the infiltration of La Mina landfill leachate, Geogaceta, 25, 1999, PP. 199-201, I. Vadillo Perez, F. Carrasco Cantos, B. Andreo Navarro et al.
12.Hydrogeologocal research on carbonate aquifers of a UNESCO Biosphere Reserve ( Sierra de las Nieves, Malaga, S. Spain). In Proceedings of the XXIX Congress of International Association of Hydrogeologist, Bratislava, Slovakia, Sept. 6-10, 1999, PP. 203-208, Cristina Linan, Bartolome Andreo, Francisco Carrasco.
13.Relationship between water-holding of carbonate rock and?Saxicolous?algae, lichen and moss and its ecological significance, Geochimica Vol. 28, No. 3, 1999, PP. 248-256, Cao Jianhua, Yuan Daoxian.
14.Pedogenic Carbonates in aridic soils of China and the significance in terrestrial carbon transfer, Journal of Nanjing Agricultural University, 1999, 22 (1) : 51-57, Pan Genxing.
15.Element migration of karst dynamic system, Acta Geographica Sinica, Vol. 54, No.5, Sept. 1999, PP. 438-444, Jiang Zhongcheng.
16.47 papers of IGCP 379 relevance included in the Abstract Book of the INQUA 15 Congress, August 3-11,1999, Durban, South Africa.
17. 19 papers of IGCP 379 relevance included in the proceedings of the 29th?Congress of IAH, Hydrogeology and Land Use Management, September 6-10, 1999, Bratislava, Slovakia.
18.4 papers contributed to IGCP 379 included in the Proceedings of the Geology Symposium Nerja Cave, June 17-20,1999, Malaga, Spain.
19.IGCP 379 Newsletter 1999, 88 pages, Eds: He Shiyi, Li Bin, Shi Shiping, Karst Dynamics Laboratory, Guilin, Distributed to all participants during the meetings.
20.The Project’s web page gets new improvement. All the 9 Newsletters of IGCP 299 and 379(1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998, 1999) totaling 922 pages are available on the web?(http://www.karst.edu.cn?)
21.The final product of IGCP 379, A book entitled?“Karst Processes and the Carbon Cycle”is being prepared.
2.4 Activities involving other IGCP Projects or the IUGS
(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. We had a joint meeting in Durban, S. Africa, August, 1999.
(2) 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??“CO-IGCP 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. The Project members took part in the Commission's meeting during the 15th?INQUA in Durban, S. A. The achievements of IGCP 379 were introduced to members of the Commission along with its latest Newsletter at the meeting.
(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.
3???Attach other informations considered relevant
(1)The Project's email list gets 101 participants from 30 countries. The Home Page of the Project has been improved remarkably and got more visitors this year (8511). This facility has not only provided fast communication for the Project, but also attracted more people involved in it.
(2)The connections with relevant international projects or organizations, such as IGBP, IHP, and CDIAC (carbon dioxide information analysis center, DOE ) are continued to develop. Dr. Frank Oldfield, the official representative of IGBP was at Durban S.A. to attend our joint meeting with IGCP 404. Dr. Alice Aureli of IHP was at the IGCP 379 meeting in Bratislava. We have received the latest issue of CDIAC Communications ( No.26, Sept, 1999).
(3)The cooperation with Friends of Karst, an informal scientific organization of USA has been helpful for the smooth running of the Project. Following our joint meeting in 1996 (Norway), and 1998 (Bowling Green), another joint meeting is being prepared in Romania, July, 2000.