Linkage between precipitation isotopes and water vapor sources in the monsoon margin:Evidence from arid areas of Northwest China

The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is usually sensitive to climate change.The water resource management in the monsoon margin should be better planned by understanding the composition of precipitation isotope and its influencing factors.In this study,the precipitation samples were collected at five sampling sites(Baiyin City,Kongtong District,Maqu County,Wudu District,and Yinchuan City)of the monsoon margin in the northwest of China in 2022 to analyze the characteristics of stable hydrogen(δD)and oxygen(δ18O)isotopes.We analyzed the impact of meteorological factors(temperature,precipitation,and relative humidity)on the composition of precipitation isotope at daily level by regression analysis,utilized the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)-based backward trajectory model to simulate the air mass trajectory of precipitation events,and adopted the potential source contribution function(PSCF)and concentration weighted trajectory(CWT)to analyze the water vapor sources.The results showed that compared with the global meteoric water line(GMWL),the slope of the local meteoric water line(LMWL;δD=7.34δ^(18)O-1.16)was lower,indicating the existence of strong regional evaporation in the study area.Temperature significantly contributed toδ18O value,while relative humidity had a significant negative effect onδ18O value.Through the backward trajectory analysis,we found eight primary locations that were responsible for the water vapor sources of precipitation in the study area,of which moisture from the Indian Ocean to South China Sea(ITSC)and the western continental(CW)had the greatest influence on precipitation in the study area.The hydrogen and oxygen isotopes in precipitation are significantly influenced by the sources and transportation paths of air mass.In addition,the results of PSCF and CWT analysis showed that the water vapor source areas were primarily distributed in the south and northwest direction of the study area.

Evaporative enrichment of stable isotopes(δ^(18)O and δD) in lake water and the relation to lake-level change of Lake Qinghai, Northeast Tibetan Plateau of China

Stable isotopic compositions （δ18O and 6D） have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship be- tween the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions （δ18O, 6D and d-excess） in lake water and pre- cipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and 6D in lake water were higher than those in pre- cipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and 6D in lake water and precipitation showed that the local evaporative line （LEL） in lake water （δD=5.88δ18O-2.41） deviated significantly from the local meteoric water line （LMWL）in precipitation （δD=8.26δ18O＋16.91）, indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quanti- fied the Eli ratio （evaporation-to-input ratio） in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios （ranging from 0.29 to 0.36 between 2009 and 2012） clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleo- lake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.

The O and H isotope characteristics of water from major rivers in China

Isotopic compositions of the water sources and evapotranspiration in large rivers of China are not well explored. In this investigation, d18 O and dD values of water from major large rivers of China are integrated to understand the spatial and temporal variations in the isotopes of water and d-excess. River water samples were collected from the channels and tributaries of the Changjiang, Yellow, Songhua and Liao Rivers in China. Water from upstream was generally enriched with light isotopes relative to that from downstream areas. Water from the Songhua River and upper reach of the Changjiang River has relatively negative isotopic values impacted by latitude and altitude effects, respectively. The spatial pattern showed that d18O-H2 O values in rivers mainly ranged from-9 to-7 % in most of China based on roughly mapped contours, and rivers enriched in light isotopes were primarily located in the Tibetan Plateau and northeast China The slopes of linear regression from the Yellow and Liao Rivers suggested that the loss of water by direct evaporation shifted the isotopes of water, especially in some small tributaries. Additionally, there was a narrow range of low d18OH2 O values from the main channel of rivers during the lowflow season relative to the high-flow season due to influence of the monsoon climate. No distinct spatial variation of d-excess values was found in the rivers of China. However, water samples in some rivers with low d-excess values had high d18 O values, indicating that evaporation in the tributaries has led to significant water loss, especially in tributaries of the Yellow and Liao Rivers.

Hydrogen isotopic composition of plant leaf wax in response to soil moisture in an arid ecosystem of the northeast Qinghai-Tibetan Plateau, China

The hydrogen isotopic composition of plant leaf wax（δDwax） is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological factors in determining δDwax values still remains incomplete. To identify the effects of soil moisture and plant physiology on δDwax values in an arid ecosystem, and to explore the implication of these values for paleoclimatic reconstruction, we measured δD values of soil water（δDwater） and δDwax values in surface soils along two distance transects extending from the lakeshore to wetland to dryland around Lake Qinghai and Lake Gahai on the northeast Qinghai-Tibetan Plateau. The results showed that the δDwater values were negatively correlated with soil water content（SWC）（R^2=0.9166）, and ranged from –67‰ to –46‰ with changes in SWC from 6.2% to 42.1% in the arid areas of the Gangcha（GCh） and Gahai（GH） transects. This indicated that evaporative D-enrichment in soil water was sensitive to soil moisture in an arid ecosystem. Although the shift from grasses to shrubs with increasing aridity occurred in the arid area of the GH transect, the δDwax values in surface soils from the arid areas of the two transects still showed a negative correlation with SWC（R^2=0.6835）, which may be due to the controls of primary evaporative D-enrichment in the soil water and additional transpirational D-enrichment in the leaf water on the δDwaxvalues. Our preliminary research suggested that δDwax values can potentially be applied as a paleo-humidity indicator on the northeast Qinghai-Tibetan Plateau.

Investigation of isotope effects of dynamic properties for H(D) + OF reactions by the quasi-classical trajectory method

Quasi-classical trajectory （QCT） calculations are employed to study the dynamic properties for H（D）＋OF reactions on the adiabatic potential energy surface （PES） of the 1^3A″ triplet state. Obvious differences between the reaction probabilities for J=0, integral cross sections for J≠0, branch ratios of the product and internuclear distances as well as product rotational alignments between the title reactions axe found. These differences are attributed mainly to the different reduced masses of the reactants and the different zero-point energies （ZPEs） of the transition state.

超声血流参数、D-二聚体手术前后变化及复合模型在创伤骨折患者下肢DVT预警中的应用价值

目的探究超声血流参数[收缩期峰值血流速度(Vs)、舒张末期血流速度(Vd)、阻力指数(RI)]、D-二聚体手术前后变化及复合模型在创伤骨折患者下肢深静脉血栓形成(DVT)预警中的应用价值。方法选取2021年7月—2023年7月收治的创伤骨折200例,根据术后是否发生下肢DVT分为发生组25例与未发生组175例。收集2组基线资料及手术前后Vs、Vd、RI、D-二聚体数据,根据创伤骨折患者术后下肢DVT发生影响因素构建预测复合模型,评估Vs、Vd、RI、D-二聚体手术前后差值联合及复合模型对创伤骨折患者术后下肢DVT发生的预测价值。绘制决策曲线分析(DCA),分析超声血流参数、D-二聚体与复合模型预测创伤骨折患者术后下肢DVT发生的获益情况。结果发生组手术时间长于未发生组,术中使用止血带比例高于未发生组(P<0.01);发生组术后3 d Vs、Vd低于未发生组,RI、D-二聚体高于未发生组(P<0.01);发生组Vs、Vd、RI及D-二聚体手术前后差值均大于未发生组(P<0.01);多因素Logistic回归分析显示,手术时间、术中使用止血带及Vs、Vd、RI、D-二聚体手术前后差值为创伤骨折患者术后下肢DVT发生的独立危险因素(P<0.01);以Vs、Vd、RI、D-二聚体手术前后差值联合预测下肢DVT的曲线下面积(AUC)为0.882(95%CI:0.829,0.923),敏感度、特异度均为0.88。构建下肢DVT预测模型,其AUC为0.920(95%CI:0.873,0.954);DCA显示,复合模型在阈值概率为0.10~0.90时具有更高的临床价值。结论手术时间、术中使用止血带及Vs、Vd、RI、D-二聚体手术前后差值为创伤骨折患者术后下肢DVT发生的独立危险因素;与Vs、Vd、RI、D-二聚体手术前后差值相比,多指标联合建立的复合模型在创伤骨折术后下肢DVT早期预警中应用价值更高。

The Deconvolution Method for Obtaining Correspondence in Data-Independent Acquisition Mass Spectrometry Data

Although data-independent acquisition (DIA) shows powerful potential in achieving comprehensive peptide information acquisition, the difficulty in determining the precursor m/z and distinguishing fragment ions has posed challenges in DIA data analysis. To address this challenge, a common approach is to recover the correspondence between precursor ions and fragment ions, followed by peptide identification using traditional data-dependent acquisition (DDA) database searching. In this study, we propose a cosine similarity-based deconvolution method that rapidly establishes the correspondence between chromatographic profiles of precursor ions and fragment ions through matrix calculations. Experimental results demonstrate that our method, referred to as CosDIA, yields a peptide identification count close to that of DIA-umpire. However, compared to DIA-umpire, we can establish the correspondence between original MS/MS spectra and pseudo-MS/MS spectra. Furthermore, compared to the CorrDIA method, our approach achieves higher efficiency in terms of time, reducing the time cost of the analysis process. These results highlight the potential advantages of the CosDIA method in DIA data analysis, providing a powerful tool and method for large-scale proteomics research.

新疆三工河流域土壤水δD和δ^(18)O特征及其补给来源

采用环境同位素示踪技术研究旱区不同土地利用类型下的土壤水来源与运移机理,通过以新疆三工河流域为研究区,对三工河流域四个土壤剖面分层采集了不同土地利用类型的土壤水,测定了其稳定同位素(δD、δ^(18)O)的含量,分析了非饱和带土壤水稳定同位素沿土壤剖面的垂向变化规律。结果表明:区内非饱和带中的土壤水在入渗的同时经历了明显的混合作用,荒地土壤水比耕地受蒸发作用影响更强烈,荒地蒸发影响深度为1.2~1.6 m,耕地蒸发影响深度为0.8~1.2m;荒地与耕地土壤水中氢氧同位素在垂向上呈现旋回变化,每个旋回经历了一次新水入渗补给的过程,即新水入渗与土壤老水混合-土壤水氢氧同位素逐渐变小直到贫化极值-地表入渗补给结束,土壤水向下运移并逐渐与土壤老水混合同时受蒸发作用-同位素逐渐富集直到土壤老水本底值;耕地土壤剖面补给水δD值为-112.93‰^-102.58‰,荒地土壤剖面补给水δD值为-111.07‰^-94.44‰,比地下水、地表水同位素值更贫化,可见土壤水中的补给水主要来源于大气降水;灌溉水入渗地表后,在强烈的蒸发作用下,很难向非饱和带深部运移对地下水补给,节水灌溉方式改变了绿洲内土壤水入渗补给机制。研究结论为进一步厘定绿洲内垂向补给量,准确评价三工河流域水资源量提供重要依据。

黑河下游不同林龄胡杨水分来源的D、^(18)O同位素示踪

对黑河下游不同林龄胡杨木质部水及其不同潜在水源稳定同位素组成(δD、δ18O)的测定分析,探讨不同潜在水源对胡杨的贡献。结果表明:(1)不同林龄胡杨木质部δ18O差异显著,胡杨幼苗、成熟木、过熟木的δ18O值分别为-5.368 14‰、-6.032 75‰和-6.924 18‰;(2)不同林龄胡杨所利用的水分来源不同,胡杨幼苗主要利用30~50 cm的土壤水,利用率在70%左右,对地下水的利用仅为6%;成熟木主要利用200~220 cm的土壤水及地下水,对地下水的利用最多达85%;胡杨过熟木主要利用100~260 cm的土壤水及地下水,深度范围较幼苗和成熟木都广,对地下水的利用较高,最多达96%,胡杨成熟木和过熟木主要利用的是地下水。

川东北宋家洞高分辨率石笋δ^(13)C记录与D/O事件5-1

基于川东北宋家洞石笋SJ1的399个稳定碳同位素组成(δ13C)数据建立了末次冰期中晚期(14~43 ka)高分辨率δ13C时间序列。SJ1的δ13C变化与已发表的该石笋稳定氧同位素组成(δ18O)变化趋势非常一致,清晰地记录了该地区植被对D/O事件5-10的敏感响应。东亚夏季风气候控制的地表植被(包括C3和C4植被比例C3/C4变化和植被密度变化)和土壤微生物活动变化可能是影响SJ1的δ13C变化的主要因素。在这些D/O事件发生时δ13C变轻,指示了C3/C4植被比例上升和植被密度增加。此外,受降水控制的岩溶地下水流速影响的水-岩相互作用,石笋表面滴水时间间隔、洞穴空气的CO2分压和洞穴通风效应等因素影响的CO2脱气作用和先期碳酸盐沉积也可能对SJ1的δ13C变化产生了影响。

应用D、^(18)O同位素峰值位移法求解大气降水入渗补给量

采用D、18O同位素峰值位移法求出研究区大气降水入渗补给量。通过野外地中渗透计法和降水入渗系数法对同位素法计算结果检验,发现D、18O同位素法计算结果具有较高精度,同时验证了在研究区用D、18O同位素方法求大气降水入渗补给量是可行和可靠的。用该方法求解大气降水入渗补给量具有方便快捷、经济省时的优点,在湿润、半湿润地区大气降水补给研究方面,具有很大的应用潜力和重要的应用价值。

谱图准确度在高分辨飞行时间质谱分析硝铵类有机炸药RDX中的应用

应用实时直接分析-高分辨飞行时间质谱(DART-HR-TOFMS)对硝胺类有机炸药黑索金(RDX)及其爆炸残留物进行精确质量质谱分析,借助MassWorks质谱解析软件对质谱数据进行了噪音过滤及峰形校正处理,获得了炸药准确的同位素分布模式,然后通过实际同位素分布模式的校正峰形与理论峰形匹配的谱图准确度对待选的分子式进行排序,实现了RDX的准确识别和鉴定。

D-二聚体在评估下肢深静脉血栓形成溶栓效果中的价值

目的:观察下肢深静脉血栓形成(DVT)患者在溶栓过程中D-二聚体(DD)的达峰速度,探讨DD的达峰速度与溶栓效果的关系。方法:41例DVT患者分为系统溶栓组和导管接触性溶栓组,观察两组患者的DD峰值、达峰速度及疗效,采用Pearson法分析DD达峰速度与血栓溶栓率及下肢消肿率的相关性。结果:两组都在溶栓治疗后的第2天DD达峰值,但导管接触性溶栓组DD峰值及达峰速度明显高于系统溶栓组,导管接触性溶栓组溶栓治疗显效率亦高于系统溶栓组(P<0.01);相关性分析显示,DD的达峰速度分别与静脉通畅、大小腿消肿率呈正相关(r=0.912、0.85、0.86,P<0.01)。结论:可通过监测DD的达峰速度简单评估溶栓效果,导管接触性溶栓临床疗效优于系统溶栓。

儿童青少年时期钙和维生素D营养状况对成年后骨骼健康的影响

包括钙和维生素D在内的膳食因素是影响峰值骨量的重要环境因素,增加生长发育期的峰值骨量是延缓成年后发生骨质疏松症的重要措施。本文综述儿童青少年时期的膳食因素对峰值骨量及成年后骨骼健康的影响。

雷暴云准静电场对夜间电离层D区的影响

利用一个自洽的准静电场 (QE)模型 ,计算了雷暴云电荷突然对地放电后QE场大小在 0～ 90km高度上的分布 .对 2 0 0C的正电荷对地放电后的计算表明 ,在放电 1ms后 ,在 6 5～ 78km的区域内 ,QE场大于大气的雪崩电场 ,而 0 .5s后 ,该电场迅速衰减到很低的水平 .在电离层高度上 ,由于电子的热化时标和电离时标极短 ,在QE场的作用下 ,夜间局部低电离层会有比较大的响应 .对Boltzmann方程数值求解的结果表明 ,在某些高度上 ,电子分布函数有明显的高能尾巴 ;在 6 3～ 83km的高度上 ,电子平均能量为 3eV <ε <6eV ;计算的电子数密度的峰值扰动表明 ,在 6 5～ 78km的高度上 ,电子的数密度增加 ,最大的电离峰值约在 74km处 ,大约增加了 3个数量级 ,比电磁脉冲(EMP)的电离效果大得多 .

钚γ能谱专用分析软件 WSGCDPS

介绍了自行开发的钚γ能谱分析专用软件ＷＳＧＣＤＰＳ的特点及其分析结果的准确度和精确度。标样分析结果在误差范围内与质谱法所给的结果相符。分析精度处在美国Ｃ１０３０－９５标准文件的要求范围内。

用脉冲D_2反应研究CeO_2在Co-CeO_2/SiO_2费托合成催化剂中的促进作用机理

采用脉冲D2反应研究了CeO2在Co-CeO2/SiO2费托合成催化剂中的作用机理.通过比较在Co-CeO2/SiO2和Co/SiO2催化剂上的脉冲D2反应实验结果发现,CeO2可以提高载体表面Si-OH的H-D同位素交换活性和Si-OH中H参与CO加氢反应的活性;CeO2不仅增加了催化剂表面活性碳物种的总量,而且活性碳物种以链增长单体-CH2-为主,因而有利于增加费托合成反应速率和链增长几率;CeO2的加入明显提高了催化剂表面碳原子的加氢反应速率,从而减少了碳沉积.

γ射线峰形描述技术 CDPS

以钚的γ射线谱为例，介绍自行提出的γ射线峰形描述方法ＣＤＰＳ（ＣｈａｎｇｅａｂｌｅＤｉｇｉｔａｌＰｅａｋＳｈａｐｅ）。对分别用ＣＤＰＳ峰形描述技术和高斯峰形函数得到的２４０Ｐｕ丰度分析的结果作了比较。

AD7705在万能试验机数据采集中的应用

针对目前低档液压式万能试验机存在的问题,结合试验站的实际情况,设计采用计算机集中管理分散控制模式的技术改造方案。该方案使低档液压万能试验机实现了试验数据采集及控制的自动化,实践证明该系统的测量精度达到±0.5%FS,完全满足国家对试验机检定的技术标准(测量精度±1%FS)要求。结合AD7705在万能试验机数据采集中的应用,详细介绍了AD7705与MCS-51系列单片机的硬件接口设计和软件设计中应注意的问题,给出单片机对AD7705实现读、写操作的源程序。本测控系统采用集散控制技术,充分利用系统的硬件资源;数据采集采用双通道A/D转换器AD7705,简化了常规的信号调理环节,提高了系统的可靠性。

PCVD低水峰光纤的制备与性能

介绍了PCVD低水峰光纤生产工艺和其材料组成、结构及性能,在生产普通单模光纤的基础上,通过优化PCVD工艺,成功抑制了普通单模光纤在1383nm由于羟基(OH)吸收造成的水峰损耗。光纤中功能梯度的芯层和光学包层、高纯均匀的机械包层和性能优越的双层涂覆层,使PCVD低水峰光纤各项性能指标全面达到或优于最严格的ITU-TG.652.C/D和IEC60793-2-50B.1.3光纤标准要求。