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1.
ＩＳＯＴＯＰＩＣＥＶＩＤＥＮＣＥＦＯＲＨＯＬＯＣＥＮＥＣＬＩＭＡＴＩＣＣＨＡＮＧＥＳＩＮＢＯＳＴＥＮＬＡＫＥ,ＳＯＵＴＨＥＲＮＸＩＮＪＩＡＮＧ,ＣＨＩＮＡＺｈｏｎｇＷｅｉ（钟巍）ＸｉｏｎｇＨｅｉｇａｎｇ（熊黑钢）ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏｇｒａｐ...  相似文献   

2.
Ｉｔｉｓｏｎｅｏｆｔｈｅｆｒｏｎｔｉｅｒｆｏｃｕｓｅｓｉｎｔｈｅｆｉｅｌｄｏｆｇｌｏｂｌｅｅｎｖｉｒｏｎｍｅｎｔａｌｃｈａｎｇｅｓｔｏｅｘｔｒａｃｔｑｕａｎｔｉｔａｔｉｖｅｌｙｐａｓｔｃｌｉｍａｔｉｃｓｉｇｎａｌｓｆｒｏｍｌａｋｅｓｅｄｉｍｅｎｔｒｅｃｏｒｄｓ．Ｉｎｔｈｅｒｅ-ｃｅｎｔｄｅｃａｄｃｉｏｕｓｙｅａｒｓａｓｅｒｉｅｓｏｆａｃｈｉｅｖｅｍｅｎｔｓｏｎｒｅ-ｂｕｉｌｄｉｎｇｔｈｅｓｅｑｕｅｎｃｅｓｏｆｃｌｉｍａｔｉｃａｎｄｅｎｖｉｒｏｎｍｅｎｔａｌｅｖｏｌｕｔｉｏｎｓａｔｖａｒｉｏｕｓｓ…  相似文献   

3.
1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, …  相似文献   

4.
Traditionally, the mid-Holocene in most parts of China was thought to be warmer with higher precipitation, resulting from a strong Asian summer monsoon. However, some recent researches have proposed a mid-Holocene drought interval of millennial-scale in East Asian monsoon margin areas. Thus whether mid-Holocene was dry or humid remains an open issue. Here, Zhuyeze palaeolake, the terminal lake of the Shiyang River Drainage lying in Asian monsoon marginal areas, was selected for reconstructing the details of climate variations during the Holocene, especially mid-Holocene, on the basis of a sedimentological analysis. Qingtu Lake (QTL) section of 6.92m depth was taken from Zhuyeze palaeolake. Multi-proxy analysis of QTL section, including grain size, carbonate, TOC, C/N and δ13C of organic matter, was used to document regional climatic changes during 9-3 cal ka B.P. The record shows a major environmental change at 9.0-7.8 cal ka B.P., attributed to a climate trend towards warmth and humidity. This event was followed by a typical regional drought event which occurred during 7.8-7.5 cal ka B.P. And a warm and humid climate prevailed from 7.5 to 5.0 cal ka B.P., attributed to the warm/humid Holocene Optimum in this region. After that, the climate gradually became drier. Moreover, comparison of the climate record from this paper with the summer insolation at 30°N indicates that the climate pattern reflecting the Asian monsoon changes was caused by insolation change.  相似文献   

5.
The hole RM, the deepest one fully obtained core in the Qinghai-Xizang Plateau, situated in the depositional center of the Zoige Basin (33°57′N; 102° 21′E) in the northeastern Qinghai-Xizang Plateau with a depth of 310.46 m. From 14C dating and paleomagnetic stratigraphic study, the core RM can date back to 900 ka B.P.. In this paper we analyzed the compositions of δ18O and δ13C in various carbonates can date (snail, obstrode, chemical carbonate) in core RM and discussed preferably the paleoclimatic record by the proxies of δ18O and δ13C of chemical carbonate (authicarbonate) from core RM in the past 140 ka. The results showed that the values of δ18O in various carbonates are generally identical, and the values of δ13C in it are inconsistent, while there exist better relativity. The studies also demonstrated that there was a negative correlation between δ18O and δ13C of authicarbonate in core RM in the past 140 ka, showing that the changes of δ18O values were mainly relative to the water temperature. According to above, the climatic evolutionary sequence were rebuilt in the past 140 ka in the region.  相似文献   

6.
The paper analyzes the relation between δ18O and temperature and precipitation in different regions of the world on the basis of the data from the global observational network set by the International Atomic Energy Agency (I-AEA) and the World Meteorological Organization (WMO). The results show that there is the marked positive correlation between δ18O and temperature in the mid-high latitude continent regions, and the marked negative correlation between δ18O and precipitation in the mid-low-latitude ocean and coast stations.  相似文献   

7.
Spectrometry of ~(238)U, ~(234)U, ~(230)Th and, ~(232)Th in three Okinawa Trough cores showed that, based on the~(230)Th/~(232)Th activity ratio, the sedimentation rates were about 2.5 cm/ka, 2.8 cm/ka and 8.5 cm/ka respectivelyduring the Holocene and about 20.1 cm/ka, 12.29 cm/ka, 8.8 cm/ka and 12.6 cm/ka respectively during theWurm glacial. To examine the past global climatic and oceanographic changes, the stable oxygen isotopesδ~(18)O and CaCO_3 were measured. The Th content and Th/U ratio showed that variations of terrigenous materialinput from the continental shelf were associated with glacial and interglacial changes and sea level  相似文献   

8.
Fine-grained disseminated carbonate was found in Holocene sediments in a core taken from the northern basin of Lake Baikal. The core had two distinct facies. a terrigenous blue-clay overlain by a diatomaceous silt. Oxygen and carbon stable isotope analyses, combined with SEM , X-ray diffraction and .palynology, show that the carbonate in the blue-clay layer is pedogenic in origin, rather than biogenic or authigenic . The S C values in the blue clay suggest that the carbonate is derived from a single source , while the carbonate in the diatom-rich layer might be transported by winds from different sources. On the assumption that the carbonate was formed during the post-glacial age and was transported primarily by river runoff, the 18O isotopic values suggest that the annual temperature in the northern Baikal drainage area was about 3℃ warmer during the middle Holocene (8500-7000 a, B. P.) than during the early Holocene (11 000-8 500a, B.P.) when the blue clay was being deposited . This interpretation is  相似文献   

9.
The toxic effects of benzo[α]pyrene (B[α]P) at different concentrations (0.1, 0.5, 1, 2.5 and 7.5 μgL−1) on scallop (Chlamy farreri) immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity (P<0.05), while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL−1 B[α]P decreased significantly (P<0.05). Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]P. Bacteriolytic activity in 0.1μgL−1 B[α]P treatment group and antibacterial activity in 0.1 μgL−1 and 0.5 μgL- B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group (P<0.05), except for antibacterial activity in 0.1 μgL−1 B[α]P treatment group (P>0.05). Thus, B[α] has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms.  相似文献   

10.
Depositing ages of sediment in Core Ck6 of Qarhan Lake were dertermined by14C,230Th and geomagnetic polarity methods. Results of analyses of stable isotopes composition in carbonate and organic matter were used to set up a model of fluctuating paleoclimate (since 750 ka B. P.) consisting of 11 warm and humid stages and 10 dry and cold stages.  相似文献   

11.
Information on the palaeoenvironment from Late Pleistocene to Holocene in northwestern Yannan Plateau has been deduced from a study of a 28.81m-long core taken from Napahai Lake.The results from Relative Brightness In-dex(RBI) as well as those from the lithological analyses of bulk sediments,total organic carbon and granulometric analy-ses have been used to reconstruct the environmental and climatic evolution of the area.The ages were provided by three ^14C datings.The record suggested a climate fluctuation between warm-dry and cool-wet from ca.57 to 32ka B.P.which led a shallowing and swamping of the lake.The water level again increased quickly at ca.32ka B.P.,reached itˊs peak during LGM(Last Glacial Maximum,ca.18-20kaB.P.)and remained relative high until ca.15kaB.P.The high wa-ter level at LGM is attributed to cold-wet conditions.The area experienced an abrupt and unstable climatic changes dur-ing the transition period form 15 to 10ka B.P.with a dominated littoral environment.Awarm-dry climate led to the contrac-tion of the lake during the Holocene and reed-swamps became dominant..After a minor wet-cool pulse during the Late Holocene,the modern climate became to be established.  相似文献   

12.
Analysis of 13 spore-pollen assemblage zones reflecting environmental changes since the later middle Pleistocene showed the seccession of paleovegetation and the paleogeographic changes in the Bohai Basin and circumjacent area. Paleoclimatic variations here can obviously be divided into 5 cold and 5 warm periods: 2 cold and 1 warm periods in 200,000–100,000 a B.P.(late middle Pleistocene) 3 cold and 3 warm periods in 100,000–12,000 a B.P.(late Pleistocene), and 1 warm period since 12,000 a B.P. Late Pleistocene climate tended to become colder and colder. The coldest period was in the later stage of late Pleistocene, when the study area was a periglacial zone. The mean annual temperature then was about 10°C lower than it is now. In the middle stage of late Pleistocene, climate became warm; the mean annual temperature then was about 3–4°C higher than it is now. By applying principles of climatic stratigraphy, the authors deduced through sporo-pollen analysis, that the boundary between middle and late Pleistocene should be at 178–181 m, and that between Pleistocene and Holocene should be at 12.8 m. The results of climatic stratigraphy are consistent with those of magnetic stratigraphy. This paper was published in Chinese inOceanologica et Limnologia Sinica.18 (3): 253–266, 1987.  相似文献   

13.
A laboratory experiment was conducted to assess the bioaccumulation of Pb2+ and its effects on growth, morphology and pigment contents of Spirulina (Arthrospira) platensis. The specimen cultured in Zarrouk liquid medium was treated with various initial metal concentrations (0, 5, 10, 30, 50 and 100 μg mL−1). The growth of S. platensis was adversely affected by Pb2+ at high concentrations (30, 50 and 100 μg mL−1). However, at low concentrations (5 μg mL−1), Pb2+ could stimulate its growth slightly. The pigment contents (chlorophyll α and β carotene) were decreased in a dose-dependent manner. The highest reductions (67% and 53% respectively in chlorophyll α and β carotene) were observed in 100 μg mL−1 treatment group. The LC50 (96 h) of Pb2+ was measured as 75.34 μg mL−1. Apart from a few cases of filament breakages at elevated concentrations (50 and 100 μg mL−1), morphological abnormalities are not specific. Metal bioaccumulation increased with Pb2+ concentrations, but decreased with exposure time. The maximum accumulated amount was 188 mg g−1 dry weight. The bioconcentration factor (BCF) reached to a peak at day 2, followed by a gradual reduction for all the exposure concentrations. S. platensis is able to tolerate considerably high Pb2+ concentrations. Consequently it can be used as a potential species to remove heavy metal from contaminated waters.  相似文献   

14.
Acute toxicities of potassium permanganate, formalin, and Lugol’s iodine solution to a commonly occurred marine ciliate Pleuronema coronatum (Ciliophora, Scuticociliatida) were measured. Linear regression analysis of the results highlighted the close relationships between doses of the medicines and mortalities of the organisms, thus providing a capability to predict toxicity effects from the dose. Toxic effects of the medicines on the ciliates were described in the present paper, and the median lethal concentrations (LC50 values) were given. Results of measurements indicated that 2 h-LC50 and 12 h-LC50 values of formalin on P. coronatum were 59.00×10−6 and 43.57×10−6, while those of Lugol’s solutions were 90.13 and 67.84×10−6 respectively. The tolerance of P. coronatum to formalin is apparently lower than that to Lugol’s iodine solution and potassium permanganate is a suitable medicine to kill ciliates in short time.  相似文献   

15.
The effects of environmental Na+/K+ ratio on the gill ion-transport enzyme activity, plasma osmolality and growth of Cynoglossus semilaevis juveniles were investigated. The results showed that, plasma osmolality was similar among flounder adapted to different Na+/K+ ratios of saline groundwaters (P>0.05), while the growth, gill Na+, K+-ATPase and HCO3 −-ATPase activities were affected by Na+/K+ ratio significantly (P<0.05). The gill Na+, K+-ATPase activity reached its maximum on day 3, then decreased gradually from day 3 to day 9 and remained constant from day 9 to day 15. The peak values of gill Na+, K+-ATPase activity were detected on day 3 for all Na+/K+ ratios of saline groundwaters, then the enzyme activities descended, and on day 9 the enzyme activities achieved steady state, and the gill HCO3 −-ATPase activity increased rapidly and achieved steady state after one day. During steady state, the gill Na+, K+-ATPase and HCO3 −-ATPase activity of Na+/K+ ratios 20 and 40 treatments were significantly higher than those in the control group (Na+/K+ ratio 27.5), while there were no significant differences between the Na+/K+ ratio 30 treatment and the control group; the gill Na+, K+-ATPase activity of Na+/K+ ratio 20 and 40 treatments were significantly higher than that for ratio 30 treatment, but there were no significant differences of gill HCO3 −-ATPase activity among these treatments. At the end of the 15-day experiment, the weight gain (%) and specific growth rate (SGR) of flounders maintained in seawater were significantly higher than those in groundwaters; significant differences also occurred among the treatments; Na+/K+ ratio 30 treatment had the highest values (33.7% and 1.94 respectively), which were significantly higher than those under Na+/K+ ratios 20 and 40 treatments. Therefore, for the saline groundwater used in this experiment, it is suggested that the Na+/K+ ratio be adjusted to approximately 30, i.e., as close to that of natural seawater as possible in the culture of flounder.  相似文献   

16.
This study on dynamic changes of culture color,astaxanthin and chlorophylls,inorganic N including N-NO3^-,N-NO2^- and N-NH4^ in batch culture of Haematococcus pluvialis exposed to different additive nitrate concentration showed(1)ast/chl ratio was over 0.8 for brown and red algae,but was usually less than 0.5 for green and yellow algae;(2)N-NO3^-,in general,was unstable and decreased,except for a small unexpected increase in nitrate enriched treatment groups;(3)measurable amounts of N-NO2^- and N-NH4^ were observed respectively with three change modes although no extemal nitrite and ammonia were added into the culture;(4)a non-linear correlation between ast/chl ratio(or color)changes and the levels of N-NO3^-,N-NO2^-,N-NH4^ in H.pluvialis culture;(5)up and down variation of the ast/chl ratio occurred simultaneously with a perceptible color change from yellow to brown(or red)when N-NO3^-,N-NO2^- and N-NH4^ fluctuated around 30,5,5μmol/L respectively;(6)existence of three dynamic modes of N-NO3^-,N-NO2^- and N-NH4^ changes,obviously associated with initial extemal nitrate;(7)the key level of total inorganic N concentration regulating the above physiological changes during indoor cultivation was about 50 μmol/L;and(8)0.5-10mmol/L of nitrate was theoretically conducive to cell growth in batch culture.  相似文献   

17.
ＩＮＴＲＯＤＵＣＴＩＯＮＱｕａｎｔｉｔａｔｉｖｅｅｘｔｒａｃｔｉｏｎｏｆｐａｓｔｃｌｉｍａｔｉｃｅｎｖｉｒｏｎｍｅｎｔｉｎｆｏｒｍａｔｉｏｎｉｓａｎｅｗｆｏｃｕｓｏｆａｔｔｅｎｔｉｏｎｉｎｔｈｅｆｉｅｌｄｏｆｇｌｏｂａｌｅｎｖｉｒｏｎｍｅｎｔａｌｃｈａｎｇｅｓ.Ｉｎｔｈｅｒｅｃｅｎｔ 1 0ｙｅａｒｓ,ａｓｅｒｉｅｓｏｆａｃｈｉｅｖｅｍｅｎｔｓｉｎｒｅ ｂｕｉｌｄｉｎｇｔｈｅｓｅｑｕｅｎｃｅｓｏｆｃｌｉｍａｔｉｃａｎｄｅｎｖｉｒｏｎｍｅｎｔａｌｅｖｏｌｕｔｉｏｎｓｉｎｖａｒｉｏｕｓｓｃａｌｅｓｈａｖｅ…  相似文献   

18.
Based on the archaeological rice cultivation with the14C dating of about 4000–5000 a B.P. the author holds that the plain at the lower reaches of the Changjiang (Yangtze) River is one origin of rice cultivation in Asia and the other is Allahabad of India. The propagation of ancient rice cultivation in China can be divided into three stages, namely 4000–3000, 2635–2420 and about 1000 a B.P. It is inferred that there were two ways for propagating rice cultivation from China to Japan. One was from lower reaches of Changjiang River to Kyushu by sea way and the other was from Shandong Peninsula to southern Korea and then to Kyushu. The age of propagating rice cultivation into Vietnam from South China is about 1000 a B.P. Being influenced by climatic changes since about 5000 a B.P. the propagation of rice cultivation was stagnated for two times at least, for example, the three warm climatic stages and the two cold stages were quite in correspondence with the propagation and stagnation stages of rice cultivation, respectively, in China. During the ancient times the development of paddy rice was directive related to the fluctuation of sea level which is in keeping with the climatic changes.  相似文献   

19.
A 6.2 m thick core of Gucheng Lake sediment provided a 3600 years record of climate change. The contents of the TOC in the core changed from 2.63% to 8.48%, and the δ13C values of organic matter were from −21.54% to −27.3%. The TOC/TN ratios indicated that the organic materials in sediments were from lake plankton and land-derived plants. The 2.9–22 m core interval with high TOC/TN ratios, low δ13C values and low contents of TOC indicated a cold climate stage. The 6.2–5.5 m and 0.4–0.1 m intervals were characterized by low TOC/TN ratios, high δ13C values and high contents of TOC, and reflected temperate climate stages. Project 49372129 supported by NSFC.  相似文献   

20.
An April 1996 to March 1997 comparative study on the abundance and secondary production ofBranchiura sowerbyi Beddard, 1892 in two typical shallow lakes showed that in Houhu, an algae-dominated lake, the worm density (68 ind·m−2) peaked in July, biomass (1.930 g·m−2) peaked in June, while in Biandantang, a macrophyte-dominated lake, standing stock (density: 60 ind·m−2; biomass: 1.019 g·m−2 in wet weight) peaked in December. Secondary production of the animal in Houhu Lake was 3.413 g wet wt m−2 a−1, a little more than that (2.675 g wet wt m−2 a−1) in Biandantang Lake. Their turnover rates (P/B ratios) were 4.0 and 5.0, respectively. Project (39600019 and 39430101) supported by NSFC.  相似文献   

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