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1. chinaXiv:201811.00067 [pdf]

腾格里沙漠昂格尔图湖记录的988 AD以来的古气候变化

曹志宏; 安成邦; 尹丽颖
分类: 地球科学 >> 地球化学

文章通过对腾格里沙漠东南部昂格尔图湖岩芯AGE15A的粒度、碳酸盐的百分含量和主要化学元素等多项沉积学气候代用指标及精确定年的综合分析,重建了该区域988 AD以来的古气候变化序列。研究结果表明,988 AD.以来的研究区的气候环境的演化过程与我国西北西风区古气候变化基本一致,呈现“冷湿-暖干”交替变化的特征,但在时间上存在一定的延迟。具体表现为:988~1383 AD,昂格尔图湖由洼地发育成小型湖泊,化学风化作用弱,湖区气候环境整体偏冷湿,期间出现几次暖波动;1383~1560 AD.,研究区处在中世纪暖期,为温暖、干旱的气候特征,此时湖泊扩张,湖中水生植物生长茂盛,呼吸作用增强,致使大量碳酸盐沉淀,最高值达到8.16%;1560~1700 AD.,研究区气候在昂格尔图湖形成之后出现最寒冷的时期,降水增加,气候湿冷,此时段与小冰期最盛期相对应;1700 AD.之后,温度开始上升,气候回暖,在1900 AD.左右达到最甚,此时沉积物中碳酸盐的百分含量也达到最大值,为10.15%,此期间湖泊继续扩张,出现几次气候冷波动。基于我国古代文献重建的历史时期气候变化基本不包括沙漠地区,所以本文利用湖相沉积记录来反演腾格里沙漠昂格尔图湖历史时期的气候环境演变,对中国沙漠研究有着重要参考价值,同时也为中国西北历史时期的气候重建提供科学依据。

提交时间: 2018-11-13 来自合作期刊:《干旱区地理》 点击量357下载量61 评论 0

2. chinaXiv:201807.00030 [pdf]

Toxic metal enrichment characteristics and sources of arid urban surface soil in Yinchuan City, China

ZHANG, Mingxin; LU, Xinwei; SHI, Dongqi; PAN, Huiyun
分类: 地球科学 >> 地球化学

To investigate the environmental quality of the urban surface soil in Yinchuan City, the capital of Ningxia Hui Autonomous Region (Ningxia), China, we sampled surface soil and measured the concentrations of 8 toxic metals (Pb, Cr, Cu, Zn, Co, Bi, Ni and V) using X-ray fluorescence spectrometry. The enrichment characteristics and sources of these toxic metals in the soil were analyzed by the enrichment factor (EF) and multivariate statistical analysis. The results showed that the mean concentrations of these toxic metals in the soil samples were 25.0, 109.1, 16.8, 26.0, 37.2, 2.7, 25.3 and 59.9 mg/kg for Pb, Cr, Cu, Zn, Co, Bi, Ni and V, respectively, which were 1.2, 1.8, 0.8, 0.4, 3.2, 8.7, 0.7 and 0.8 times of the corresponding background values of Ningxia soil, respectively. The variations of Pb, Zn, Co, Bi and Ni concentrations in the surface soil of Yinchuan were larger than those of the other metals. Our results also showed that the toxic metals investigated in the soil had different enrichment levels. Both Co and Bi were significantly enriched, whereas Cr was only moderately enriched in the soil. There was a deficiency or minimal enrichment of the other toxic metals in the soil. Source analysis results based on the concentration, enrichment characteristics and multivariate statistical analysis indicated that Cr, V and Ni originated from a combination of fossil fuel combustion, traffic pollution and natural occurrence. Pb, Cu and Zn were predominantly derived from natural and traffic sources, while Co and Bi primarily originated from construction sources.

提交时间: 2018-07-05 来自合作期刊:《Journal of Arid Land》 点击量1366下载量222 评论 0

3. chinaXiv:201807.00031 [pdf]

Potato absorption and phytoavailability of Cd, Ni, Cu, Zn and Pb in sierozem soils amended with municipal sludge compost

LIU, Zheng; NAN, Zhongren; ZHAO, Chuanyan; YANG, Yang
分类: 地球科学 >> 地球化学

Effects of sludge utilization on the mobility and phytoavailability of heavy metals in soil-plant systems have attracted broad attention in recent years. In this study, we analyzed the effects of municipal sludge compost (MSC) on the solubility and plant uptake of Cd, Ni, Cu, Zn and Pb in a soil-potato system to explore the mobility, potato plant uptake and enrichment of these five heavy metals in sierozem soils amended with MSC through a potato cultivation trial in Lanzhou University of China in 2014. Ridge regression analysis was conducted to investigate the phytoavailability of heavy metals in amended soils. Furthermore, CaCl2, CH3COONH4, CH3COOH, diethylene triamine pentacetic acid (DTPA) and ethylene diamine tetraacetic acid (EDTA) were used to extract the labile fraction of heavy metals from the amended soils. The results show that the MSC could not only improve the fertility but also increase the dissolved organic carbon (DOC) content of sierozem soils. The total concentrations and labile fraction proportions of heavy metals increase with increasing MSC percentage in sierozem soils. In amended soils, Cd has the highest solubility and mobility while Ni has the lowest solubility and mobility among the five heavy metals. The MSC increases the concentrations of heavy metals in the root, stem, peel and tuber of the potato plant, with the concentrations being much higher in the stem and root than in the peel and tuber. Among the five heavy metals, the bioconcentration factor value of Cd is the highest, while that of Ni is the lowest. The complexing agent (DTPA and EDTA) extractable fractions of heavy metals are the highest in terms of phytoavailability. Soil properties (including organic matter, pH and DOC) have important impacts on the phytoavailability of heavy metals. Our results suggest that in soil-potato systems, although the MSC may improve soil fertility, it can also increase the risk of soils exposed to heavy metals.

提交时间: 2018-07-05 来自合作期刊:《Journal of Arid Land》 点击量1372下载量231 评论 0

4. chinaXiv:201710.00017 [pdf]

Low-T Thermo: a new program for arbitrarily combining low-T thermochronological data to model thermal history

丁汝鑫
分类: 地球科学 >> 地质学
分类: 地球科学 >> 地球化学

A robust code, called Low-T Thermo, has been developed to combine low-T thermochronological data arbitrarily to model thermal history. After apatite fission-track age and confined length are decoupled into two completely independent data to inverse thermal history and thermal history inversion using mica Ar-Ar age or bedrock quartz optically stimulated luminescence age are developed, there are eight kinds of low-T thermochronological data used to inverse thermal history including apatite fission-track age, apatite fission-track confined length, zircon fission-track age, apatite (U–Th)/He age, zircon (U–Th)/He age, mica Ar-Ar, bedrock quartz optically stimulated luminescence age and vitrinite reflectance. A total of 247 kinds of combination modes can be used to jointly inverse thermal history in theory (except the eight single methods modelling). These arbitrary combinations are helpful to model thermal history with the “incomplete” low-T thermochronological data set regarded to be unuseful for thermal history modelling and reduce experimental cost. For arbitrary combination of different low-T thermochronological data, each low-T thermochronological method is independent incompletely and the equivalent p-value is used to be the identical evaluation indicator in the inverse process. The usefulness of the code is demonstrated by modelling thermal history of existing low-T thermochronological data in the areas of Dabie Mountain, Ahimanawa Range and Southern Alps.

提交时间: 2017-10-26 点击量2889下载量788 评论 0

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