Validating a dust production model by field experiment in Mu Us Desert, China

It is essential for validation and improvement of a dust production model to perform field observations on dust emissions. The dust production model (DPM model) consists of two physically explicit sub-models, namely saltation model [1, 2] (eq. (1)) and sandblasting model [3] (eqs. (2) and (3)). Fh is saltation flux, E is fraction of erodible surface, C is a dimensional constant, ρa is air density, g is gravitational acceleration, U* is the wind friction velocity, Ut*(Dp) is threshold frict…     

石油污染对土壤渗透性的影响研究

 选择砂土和壤土2种土壤及柴油和原油2种油品类型,通过室内渗透试验研究了不同污染程度的油污土壤的渗透性能。试验结果表明,柴油污染清洁砂土后,可使砂土渗透系数降低64%左右;原油含量大于2%时,砂土的渗透系数降低了一个数量级;8%含油率的柴油污染壤土的渗透系数比清洁壤土降低了97%左右;壤土中原油含量为8%时,其渗透系数为5×10^-7cm/s左右,比同一干密度（1.57g/cm³）清洁壤土的渗透系数降低了两个数量级,含油量增大,其渗透性能更差。无论对于砂土还是壤土,原油引起的渗透系数的降低比柴油显著,主要是因为原油的粘滞系数大大高于柴油的粘滞系数。     

Estimation of soil respiration in a paddy ecosystem in the subtropical resion of China

Water vapor, energy exchange, and CO2 flux were measured continuously from 2003 to 2005 using the eddy covariance technique in a paddy ecosystem in the subtropical region of China. The CO2 fluxes at nighttime during fallow periods （from middle October to late April） were used to analyze the dynamics of soil respiration and its relationship with soil temperature, and to simulate the annual dynamics of soil respiration in paddy ecosystems. The variation of soil respiration showed a clear seasonal pattern. The soil respiration rates at night during the fallow periods were 52--398 mg· m^-2· h^-1, and exponentially correlated （P〈0.001） with soil temperatures at different depths of soil （5, 10, and 20 cm）, particularly the temperature measured at a depth of 5 cm. Based on the simulated exponential equations developed, annual average soil respiration rates and total soil respiration of paddy soil in the subtropical region of China were estimated to be 178.5--259.9 mg· m^-2· h^-1 and 1.56--2.28 kg· m^-2· a^-1, respectively. The simulation equations can be applied to evaluating soil respiration in paddy ecosystems during the rice-growing season.     

Fluxes of carbon dioxide and methane from swamp and impact factors in Sanjiang Plain,China

Incomplete decomposition of organic matter results in the accumulation of the carbon and other nutriments in wetlands. The wetland ecosystem gains a large amount of carbon from atmosphere CO2 by photosynthesis, and it loses much of which back into the atmosphere as CO2 and CH4 emission through the decomposition and respiration. Climate change, such as global warming and reduction of precipitation could drive the wetlands from carbon sink to source[1,2]. Wetland plays an important role in car…     

防城湾自然环境与沉积物组成分析

讨论防城湾水动力条件，地貌特征及沉积物组成。其中，水下动力地貌有６种类型：潮间浅滩，潮流冲刷深槽，水下拦六沙坝，水下沙嘴，水下岸坡，海底平原。表层沉积物类型有６种；砂砾，粗砂，粗中砂，中细砂，细砂，粉砂质粘土。沉积物中重矿物组合为钛铁矿－锆石－电气石。     

Analysis of carbon isotopes in airborne carbonate and implications for aeolian sources

Methods were developed to determine the mass ratios of carbon isotopes in trace amounts of aerosol carbonate. A Finnigan MAT 252 mass spectrometer fitted with an on-line Kiel device was to determine the ^13C/^12C ratio in CO2 produced from the carbonate. A study using these methods was conducted to characterize the carbonate carbon isotopes in aerosol samples collected in Xi‘an on dusty and normal days during March and April 2002. Results of the study demonstrate that insights into the origin of the dust can be deduced from its isotopic composition. That is, the δ^13C ofcarbonate for dust storm samples ranged from -1.4‰ to -4.2‰, and this is consistent with sandy materials in dust source regions upwind. In contrast, for non-dusty days δ^13C ranged from -7.5% to -9.3‰, which is more similar to fine particles emitted from local surface soils. Comparisons of dust storm aerosols with surface soils from source regions and with aerosol samples collected downwind indicate that the δ^13C values did not change appreciably during longrange transport. Therefore, carbon isotopes have the potential for distinguishing among source materials, and this approach provides a powerful new tool for identifying dust provenance.     

表土粒度特征对风蚀荒漠化的响应

 为了阐明风蚀对表土粒度特征的影响,采用时空替代法选择毛乌素沙地5 种不同利用类型的土地（草地、新垦耕地、7~8 年耕地、>20 年耕地、沙丘）,以其表层土壤（0~1、1~2、2~3、3~4、4~5 cm）为研究对象,通过野外实地采样和室内实验相结合的方法进行土壤机械组成与土壤颗粒分形分析。结果表明：1）5 个样地表层土壤机械组成均以细沙质量分数最高,为62.52%~80.40%,粗沙质量分数最低,仅为0.16%~0.43%,不同粒级土壤颗粒的质量分数高低排序为：细沙>中沙>极细沙+粉沙>粗沙,说明研究区土壤基质组成以细沙为主,沙物质分选好;2）5 个样地不同采样深度上的粗沙和中沙质量分数从大到小为0~1 cm>1~2 cm>2~3 cm>3~4 cm>4~5 cm;细沙质量分数各层次之间差异不显著（P=0.4558）,以0~1 cm 层的质量分数最低;极细沙+粉沙的质量分数0~1 cm和1~2 cm层显著低于其他3层（P=0.0126）,表明从草地到沙丘的演化是一个主要以极细沙+粉沙质量分数减少的风蚀荒漠化过程;3）土壤颗粒分形维数与极细沙+粉沙的质量分数呈极显著正相关关系,D=0.3661lnx+1.3409（P<0.0001）。5个样地的土壤颗粒分形维数存在极显著差异（P<0.0001）,从大到小依次为：草地（2.579）、新垦耕地（2.479）、7~8年耕地（2.361）、>20年耕地（2.100）、沙丘（1.716）。因此认为土壤颗粒分形维数可替代土壤机械组成来表征土地风蚀荒漠化的程度。     

天童常绿阔叶林次生演替过程中细根的生物量动态

应用土钻法对天童常绿阔叶林次生演替过程中细根的生物量进行了调查,结果显示：细根生物量随演替进程变化显著（P<0.05）,在演替前期的灌丛阶段达最高(3.286 t·hm^-2),在演替中期马尾松和马尾松+木荷群落降低(1.066 t·hm^-2和1.531 t·hm^-2),到演替后期的木荷群落和栲树群落再次升高(2.715 t·hm^-2和3.181 t·hm^-2).各演替阶段活细根和死细根生物量的季节变化显著（P<0.01）.各群落的活细根生物量在7月达最高,而在11月最低;死细根生物量,各群落皆于11月最小,而在演替早期两群落和马尾松+木荷群落4月最大而其它群落7月最大.各演替阶段细根生物量随着土层深度增加而下降明显,细根生物量80％左右分布在20 cm以上土层.     

非饱和砂土有效应力增量的试验研究

为了解土层有效应力增量对地基沉降的贡献程度,进行了非饱和砂土在不同轴向荷载和围压作用下的饱和试验、静载试验和莫尔-库伦应力分析,得到了砾砂土和圆砾土在饱和状态下的天然重度、黏聚力及内摩擦角等主要物理力学指标,利用这些指标计算得到有效应力增量值及其沉降贡献量.试验结果表明:与砾砂相比较,圆砾土的饱和度更易达到100%,其饱和重度较砾砂大,孔隙率和含水量却较砾砂小.对于饱和砂土,由有效应力法计算出来的主应力值大于由总应力法计算出来的主应力值,所得内摩擦角和黏聚力比用总应力法得出的结果更加合理.另外,有效应力增量对基底沉降的贡献不可忽略.     

从晚更新世以来我国沙漠的变迁看干旱区沙漠化问题

通过野外调查研究,作者提出我国东部干旱地区的沙漠早在有史记载以前的第四纪地质时期就已存在.晚更新世以来沙漠几经流沙(?)半固定、固定沙丘一系列正、逆变迁过程.人类历史时期以来出现的沙漠化,只是沙漠长期演变过程最近经历的一个发展阶段;沙漠化是自然因素和人为因素共同作用的结果,且总的看来,自然因素是第一位的.在全国干旱—半干旱区范围内沙漠的变迁和沙漠化的形成,在时间上是可以对比的,基本上是同步的.     

饲料中添加虾青素对斑节对虾生长和免疫指标的影响

 虾青素以不同质量分数(0,10,20,40,80,160 mg·kg^-1)添加到斑节对虾 Penaeus monodon 的饲料中投喂30 d,研究虾青素对斑节对虾［初始体质量（1.32±0.03 ）g］生长、存活和免疫指标的影响。结果显示：虾青素可提高斑节对虾的存活率,但无明显规律性;而增质量率和特定生长率,实验组和对照组间差异显著(P<0.05);就终末均质量而言,实验组与对照组差异显著(P<0.05),但实验组之间无显著差异(P>0.05);虾青素可提高斑节对虾酚氧化酶（PO）的活力,除10 mg·kg^-1和20 mg·kg^-1 组外,其余实验组与对照组差异显著(p<0.05),但对碱性磷酸酶(ALP)、过氧化物酶(POD)、超氧化物岐化酶(SOD)的活力无显著影响。以增重率、特定生长率和酚氧化酶（PO）活力为参考指标,虾青素适宜添加量为40～80 mg·kg^-1。     

Degradation of organic matter in the sediments of Hongfeng Reservoir

In this work, the distribution of organic carbon, DNA and lipids in the sediments of Hongfeng Reservoir were described in addition to SO4^2- profile in pore water. The contents of organic carbon in the sediments range from 23.3 to 76.8 mg·g^-1, with the peak value appearing at the depth of 8 cm bellow the sediments water interface （SWI）, and tend to decrease gradually with sedimentation depth. The concentrations of SO4^2- decreased from 40.50 mg·L^-1 to 12.00 mg·L^-1 at SWI in top 4 cm sediment, and was kept at 12.0 mg·L^-1 bellow that depth. Newly produced organic carbon can be conserved as long as 14 years in the sediments. The contents of DNA were relatively high in top 9 cm surface sediments, as revealed by agarose gel images, close to those of organic carbon and sulphate reduction index （SRI）. This study shows that bacteria played an important role in organic matter degradation; SO4^2- is the primary electron acceptor under anaerobic condition in this reservoir; DNA in the lake sediments can provide important information for the study of cycling of nutrient elements in the lake.     

不同固沙植物材料对土壤生物活性的影响

在科尔沁地区采集小叶锦鸡儿、樟子松、山竹岩黄芪和差巴嘎蒿这4种22年生固沙群落的土壤样品,对土壤有机C,全N,微生物生物量和主要酶的活性进行了对比研究.土壤按3层取样0~10,10~20,20~30cm.结果表明,4种固沙植物均能明显改善土壤C,N水平,提高微生物生物量,改善土壤酶的活性.尤其是对土壤表层0~10cm的改良效果更加明显.4种材料中,小叶锦鸡儿对土壤生物活性的影响最大,其群落土壤中微生物C,N含量、土壤脲酶、磷酸单酯酶、蛋白酶、脱氢酶的活性均明显高于其他几种植物群落,表现出强大的改善沙土环境的能力,可作为优良的固沙植物材料在当地大面积推广应用.     

Source of a floating dust episode over the Qingdao region and dust throughput to the ocean

A floating dust weather happened on March 11–12, 1995 over the Qingdao region. Its source’s and throughput to the ocean were studied. The result indicated that the floating dust was caused by the dust storm that started in northwestern China and developed in northern China. 21 × 10⁶t fine soil particles were carried to the ocean during the episode.     

高浓度拜耳精液制取砂状氧化铝的最佳条件研究

为提高我国某氧化铝厂生产砂状 Al_2O_3的分解率(～30%)和产品强度(磨损指数～30%),同时结合我国引进法国的强化高压溶出新工艺,我们对浓度为153.7g/1Na_2O_K,α_k=1.55,12g/1Na_2O_c 的铝酸钠溶液制取砂状 Al_2O_3进行了试验研究。找到了细晶种附聚和粗晶种粘结长大两段分解的最佳工艺条件。附聚效率达到90%以上,分解率达到46%,磨损指数为8%的实验室研究成果。初步弄清楚了高强度砂状 Al_2O_3形成的机理及其影响的主要因素。     

盐酸环丙沙星在不同模拟水体中的降解与残留

 通过反相高效液相色谱法研究在不同模拟水体中,溶液质量浓度、pH对盐酸环丙沙星（CPFX）在水和底泥中含量变化的影响,分析其在模拟水体中降解和残留规律。研究结果表明：在1、5、10 mg·L^-1三个CPFX溶液质量浓度中,光降解度最高的溶液质量浓度为1 mg·L^-1,自然光照下,72 h后盐酸环丙沙星在有底泥和无底泥的水体中残留率分别为19 %和20 %,光降解率与初始质量浓度成反比。在pH分别为3、5、9、11条件下,pH=9的微碱性环境下最易光降解,而当pH=3时其光稳定性最佳,48 h后水体残留率分别为22.6 %和95.7 %。盐酸环丙沙星进入模拟水生态系统后,水体中CPFX质量浓度迅速下降,45 d后检测不到它的存在;底泥中CPFX质量分数迅速上升,之后缓慢下降,45 d后底泥中仍有一定残留量,达到93.86 μg·kg^-1。     

Radiative forcing due to dust aerosol over east Asia-north Pacific region during spring, 2001

Atmosphericaerosolsinfluencetheradiationbudgetoftheatmosphere-terrestrialsystem,andthereforeinflu-encetheclimate.Dustaerosolisconsideredtobeacriticalfactortoclimateforcingamongotherkindsofaerosols,whichaccountsfor30percentofaerosolloadingandop-ticaldepth[1].Therearelargeuncertaintiesinthequantita-tiveassessmentsoftheradiativeeffectofdustatthepre-sentday,involvingvariousfactors:refractiveindices,par-ticlesizedistribution,atmosphericaerosolloading,parti-cleshape,etc.[2].Dustaerosolgenerallyorigi…     

上覆粗砂层河床群桩基础冲刷特性试验

采用波流水槽试验,针对上覆粗砂层双层砂土进行局部冲刷机理研究,并与中国和美国规范的局部冲刷深度计算方法对比分析.试验研究表明:由于上覆粗砂层的存在,冲刷前期进展缓慢,后期主要为细砂层冲刷,发展较快;而上覆粗砂层对下卧细砂层冲刷起到抑制作用,粗砂层越厚,抑制效果越明显;中美规范对于上粗下细双层砂土局部冲刷深度计算结果偏大,应进行适当折减,以更为合理地反映粗砂层对细砂层冲刷的影响.     

东海浪岗山岛屿黄土的粒度组成及风尘特征

通过对东海浪岗山岛屿黄土的系统采样和粒度测试分析，并与其他地方黄土充分对比，讨论了浪岗山第四纪风尘沉积的粒度特征.浪岗山黄土剖面粒度垂向变化不大.小于5 μm颗粒平均含量为24.9%.10~50 μm粒组富集，分布均匀，符合黄土的风成特性.但粗颗粒（>50 μm）含量均超过10%，高于西部黄土的粗颗粒含量.显示该剖面除了接受来自西北内陆的远源风尘物质外，还接受来自沉积区附近的“近源”风尘物质.     

生物曝气技术修复地下水中的苯和二甲苯实验研究

 结合东北某石油污染场地的水文地质特征,通过影响因素试验探讨了不同环境因子对微生物生长及降解地下水中苯和二甲苯效果的影响作用。同时,通过土柱实验,分析了微生物在不同砂土介质中的迁移规律和降解地下水中苯和二甲苯的效果。结果表明,微生物降解苯和二甲苯的最佳条件为,培养基温度20℃、pH值7.0、添加氮磷和溶解氧(DO)5.21mg/L。微生物在砾砂、粗砂和中砂中的迁移速度随着介质平均粒径和孔隙度的增大而加快。在同一种介质中,微生物穿透前20cm所需时间大于穿透后20cm所需时间,在不同介质间,微生物穿透40cm所需时间均为:砾砂<粗砂<中砂。总的来说,随着介质平均粒径的变小,苯和二甲苯的去除率增加。在中砂介质中,苯和二甲苯的去除率达到40%以上。