Research On The Seasonal Variation Of Trace Elements In Drip Water Of Jiutian Cave In Shandong Penisula And Their Implications For Climate And Environment

Deposition of karst speleothem is the important files which recorded terrestrial climate andenvironment change during the geological history of, especially the stalagmite attracting theancient climate researchers’ attention. With the research of stalagmite reconstruct ancientclimate more advanced, more and more rich alternative indicators, scientists are beginning torealize the environmental implications there may be uncertainty or ambiguity, need to usemodern technology to correction. The cave water is not only the cave sedimentary materialtransmission medium, but also the carrier of climatic indicator, so long-term monitoring incave can help us to understand the characteristics of environment substitute indexes ofthe cave water and should be beneficial in the reconstruction of ancient climate andenvironment.This article chooses the Zibo Yiyuan Jiutian cave in Shandong Peninsula as the Studyobject. From the two aspects of hydrology and water chemistry analyses the changecharacteristics and influencing factors of every indexes in the drip cave of the Jiutian cave.This study begin a year continuous monitoring about Jiutian cave dripping and caveenvironment indicators from January of2012.Monitoring indicators included temperature,humidity, concentration of CO2inside the cave, drip drip speed, cave water conductivity andpH, the ionic concentration of Ca2+、Ba2+、Mg2+、Sr2+and element ratios of Mg/Ca、Sr/Ca、Ba/Ca. At the same time, there is also a long-term dynamic monitoring about theenvironmental indicators, such as temperature and precipitation. This paper studies ontemporal and spatial variation characteristics of these indicators. To investigating the seasonalvariation of cave drip trace elements and its relationship with climate and environment. Theresults show, cave environment indicators and trace element of cave drip water havesignificant seasonal variations. It is mainly affected by the local climate and environmentchanges, especially the changes in temperature and precipitation. Although there is certainresponse relationship between the drip water points of Jiutian cave with climate change in theoutside environment. But the content of trace elements in different drip points and lag time inresponse to rainfall is not identical. This may be caused by the different of karstwater migration path of the cave overlying soil and bedrock fissure in the roof.The cave roofrock thickness and water migration time will also affect the response time of the changes of the environment.The main research results are as follows:(1)The observations during the study period showed that the variation range of temperatureand humidity in Jiutian cave was small during different seasons, but the cave air CO2wasopposite. And there is a certain response relationship with climate change of the outside world.In addition, the cave environment indexes exists certain space differences. Mainly manifestedas increasing of the cave depth gradually increases, this may be due to the distance from thehole. If it is farther to the entrance of the hole that the influence of the external environmentchange is smaller. The changes of the temperature, humidity and CO2concentrations outsidethe Jiutian cave consistented with local temperature and precipitation changes.(2)This paper selected three points are all perennial drip water, there is "piston effect" in theearly rains. Drip rate of3drip water points have certain lag to the local atmospheric rainfall,And the lag time is2-3months. This lag is mainly affected by the thickness of the roof rock,roof characteristics and the size of the matrix seepage of water flowing through the pipe, thelength of the flow path and so on.(3)There are certain characteristics of seasonal variation of cave water pH and conductivityin study period. Among them, the value of pH lower in summer, higher in winter, but theseasonal variation of conductivity is contrast. The study found, there is a response relationshipbetween theirs seasonal variations with change of the outside climate conditions. In addition,the pH value and conductivity of water pools water are different from drip water. Mainly forthe pool water is less than the drip water. This may be due to the pool water after a long-termaccumulation occur sedimentation.(4) Through the analysis of the trace element concentration and ratio of3drop points inJintian cave, Range and mean trace elements and ratio of cave drip water are difference. Thisdifference of trace element concentration is mainly affected by the thickness of overlying soiland roof rock, the migration path of water in the roof bedrock fissure and water-soil-rockinteraction time and so on. Besides the above factors, elements ratio also affected by thechange of trace elements ion concentrations in the drip water.(5)Trace elements ion concentrations of3drip point in Jiutian cave showed seasonalvariation characteristics that the dry season low, the rainy season high. In the early stage ofrainfall, appeared an obvious trend of rising. Combined with the local air temperature, rainfall and other climate environmental data, the seasonal variation of trace elements ionconcentrations in drip water is affected by both the hydro-geological conditions and thelocal climate and environment changes.(6)The study found, the change trend of Mg/Ca ratio and Sr/Ca, Ba/Ca ratio in drip water isnot consistent. Due to the local precipitation affection, Mg/Ca ratio in drip water showed anobvious seasonal variation. But the Sr/Ca, Ba/Ca ratio in the drip water not showed obviousseasonal variation. In addition to the affection of the precipitation, they are also affected bythe interference of other geological and hydrological factors. Therefore, we can see thatMg/Ca ratio in drip water has a better indication to external precipitation. But the indicationof Sr/Ca, Ba/Ca ratio in the drip water is not obvious. They may indicate strong degree ofmicrobial activity in the overlying soil on the cave.