泥河水库夏季水–气界面甲烷通量日变化研究

为研究东北地区灌溉型水库的甲烷日排放特征,试验采用静态浮箱法于2008年7月测定了泥河水库水–气界面的甲烷通量.结果发现,泥河水库夏季甲烷平均排放通量为13.48 mg/(m2.h);夜间(21:00)甲烷排放最低,日间(5:00和9:00)最高.不同时刻的甲烷通量存在显著差异(P<0.05)2,1:00的甲烷排放通量显著低于5:00和9:00的甲烷通量.泥河水库出水口、库中心和进水口的甲烷通量差异不显著.相关分析表明,甲烷通量与总氮存在显著正相关(P<0.05),与气温、水温、水中总有机碳、水中溶解有机碳、总磷、水深、风速、溶氧等环境因子均未达到显著相关.     

Concentration and flux of bioaerosol and environmental factors

The concentration and flux transportation of bioaerosol are analyzed using the data observed in Nanjing in July 1998. Some results are obtained: (i) the concentration and flux transportation of bioaerosol vary periodically with the cycle of the solar radiation and atmospheric turbulent intensity, (ii) The bioaerosol concentration is affected by both the bioaerosol flux transportation and the environmental factors. The bacterial concentration is obviously affected by the solar radiation while the fungi concentration is significantly affected by temperature.     

Investigation of electron transfer across the ice/liquid interface by scanning electro- chemical microscopy

Charge transfer across a liquid/liquid (L/L) interface is not only related to chemical sensors, drug delivery and phase transfer catalysis, but also significant for mimicking biological membranes[1—3]. The thermodynamics, kinetics and mechanism regarding of this type of heterogeneous transfer process have been intensively investigated in the past three decades. An external potential is usually applied to polarizing the interface in the case of conventional electrochemistry at L/L interfaces.…     

Investigation of electron transfer across the ice/liquid interface by scanning electrochemical microscopy

The study of interfacial electron transfer (ET) reaction between feericinium (Fc^ ) produced in situ in 1,2-dichloroethane (DCE) and ferrocyanide in ice matrix under low temperatures by the scanning electrochemical microscopy (SECM) is reported .Tetrabutylammonium (TBA^ ) is used as the common ion (potential -determining ion )in both phases to control the interfacial potential difference,The potential drop across the liquid/liquid interface can be quantitatively adjusted by changing the ratio of concentrations of TBA^ between beh two phases ,The apparent hetero-gencous rate constants for Fc^ reduction by Fe(CN)6^4- at the interface under different temperatures have been obtained by a best-fit analysis,where the experimental approach curves are fitted to the theoretical simulated curves.A sharp change has been observe for heterogeneous rate constants around the freezing point of the aqueous phase,which reflects the phase transition process.     

Potential oscillations across oil-water interface in the presence of the biological surfactant and amino acids or polypeptides

A lot of potential oscillations across oil-water interface ahve been designed by using various surfactants and biolagical surfactants in the aqueous phase and various amino acids or even polypeptides in the oil phase (nitrobenzene solution). Effects of the reactant’s concentration and the reaction temperature on the oscillating parameters have been studied. The oscillating mechanism has been discussed, and a model to the oscillating mechanism has been proposed which is proved qualitatively reasonable according to the simulation.     

湖泊疏浚对沉积物-水界面溶解氧的环境效应

水体溶解氧含量是水环境质量的重要参数.本研究将室内模拟实验和疏浚工程相结合,探讨了疏浚对沉积物-水界面耗氧能力、微剖面溶解氧分布的环境效应.研究结果显示,疏浚具有降低溶解氧消耗能力的潜在长期效应,但是由于还原性物质的暴露,疏浚后新生表层沉积物短期耗氧能力很强;疏浚没有改变到氧气在沉积物-水界面中的传质深度.结果暗示疏浚可能显著提高重度富营养化湖泊夏季溶解氧含量.     

Mercury release flux and its influencing factors at the air-water interface in paddy field in Chongqing, China

The exchange of mercury(Hg) across the air-water interface is an important part of Hg biogeochemical cycle.Mercury fluxes across the air-water interface in paddy fields were measured by a Dynamic Flux Chamber(DFC) coupled with a Lumex multifunctional mercury analyzer RA-915+ at two sites(Chengjiang(CJ) and Caoshang(CS)) in Beibei,Chongqing,China in 2008.The results showed that mercury emission followed a power-law relationship with solar radiation and air temperature,and it increased exponentially with water temperature at both sites.Mercury emission was mainly influenced by the solubility of gaseous elemental Hg,photo-thermal effect,electron activity(Eh) and air Hg concentrations.Solar radiation made the greatest direct contribution to mercury emission during the daytime(0.80),with an 83.60% contribution,whereas at nighttime the water temperature(0.72) contributed to 71.65% of emissions.The temperature gradient between water and air might also influenced mercury emission across the air/water interface at nighttime.These findings suggest that paddy fields could act as a significant source of atmospheric mercury,and it can contribute significantly to the atmospheric mercury in a local region.     

Complex investigation of a soil microcatena across gilgai microrelief to reconstruct environmental changes.

This paper outlines a detailed study to obtain data on the age and paleoenvironment of Vertisols in order to reconstruct the history of the landscape and soils of the North Caucasus region of south Russia. Data are from a sequence of three Vertisol pedons - the depression, the microslope, and the mound of a gilgai complex. Soils are formed on Neogene marine clays under steppe vegetation. Rradiocarbon, stable isotope, botanical and biolith data reveal the paleoecology of the region during the Holocene up to the present. The environment included a drier period indicated by humus, a warmer and wetter period indicated by carbonate nodules, and a more humid and cool period indicated by forest grass species and Comarum Pallustre. Microrelief gilgai aids for the environmental reconstructing. The soil profile in the depression supplies the most complete information. Nevertheless, it is necessary to study the whole gilgai complex to obtain full and reliable data for the environmental changes.This approach is expected to be useful for environmental reconstruction of other soils with microrelief.     

北亚热带次生栎林碳通量及其影响因子研究

以位于江苏句容下蜀的长江三角洲森林生态站栎林为研究对象,采用涡度相关技术进行长期CO2通量观测,得到2007年12月至2008年11月间栎林净碳交换（NEE）的日变化过程：栎林从7:00左右开始吸收CO2, 10:00至14:00期间,对CO2的吸收一直维持在较大量,到17:30左右转化为碳排放。对于栎林NEE与光合有效辐射（PAR）及气温的响应关系分析表明：当光合有效辐射大于5 μmol/(m2·s)时,在不同季节NEE与PAR相关关系不同,NEE的月平均值与冠层月平均温度呈直线相关。     

长通道内烟气层水平蔓延阶段的质量卷吸速率实验研究

根据卷吸机理不同,可将通道内烟气蔓延过程分为四个不同阶段.通过模拟尺寸实验,测量了烟气层温度、厚度以及典型截面处的烟气流动速度,确定了不同蔓延阶段的起止位置,并重点计算了火羽流撞击顶棚后的径向蔓延阶段以及随后向一维水平蔓延的过渡阶段烟气层分界面处的质量卷吸速率.通过对实验结果的分析,给出了这两个阶段烟气层卷吸速率的经验关系式.     

滇池水-沉积物界面氮分布特点及其对控制蓝藻水华的意义

 造成水体富营养化的污染源可以分为外源和内源,当湖泊的外源得到控制以后,内源营养盐的释放仍然可以发生富营养化,甚至爆发藻类水华.研究营养物质在水-沉积物界面的地球化学行为,对于控制水体富营养化和水华爆发具有重要意义.以滇池为研究对象,测定了间隙水和上覆水中总氮(TN)、氨态氮(NH₄⁺-N)、硝态氮(NO₃^--N)和有机氮(ON)的质量浓度.结果表明:①无论在草海还是外海,间隙水中TN,NH₄⁺-N及ON质量浓度均高于上覆水,说明底泥中的氮元素有向水体中扩散的趋势;②草海上覆水及间隙水中TN,NH₄⁺-N和NO₃^--N质量浓度均高于外海,其受污染的程度比外海高.研究揭示了滇池底泥中氮分布区域和垂直变化特征,阐明了内源氮负荷在湖泊富营养化中所起的作用.     

Variable diffusion boundary layer and diffusion flux at sediment-water interface in response to dynamic forcing over an intertidal mudflat

The diffusion boundary layer (DBL) significantly limits the exchange between sediment and overlying water and therefore becomes a bottleneck of diffusive vertical flux at the sediment-water interface (SWI). Variable DBL thickness and diffusion flux in response to dynamic forcing may influence replenishment of nutrients and secondary pollution in coastal waters. In situ measurements of velocity in the bottom boundary layer (BBL) and oxygen concentration in the DBL were made over an intertidal mudflat, using an acoustic Doppler current and mini profiler. A linear distributed zone in the oxygen profile, the profile slope discontinuity and variance of concentration can be used to derive accurate DBL thickness. Diffusion fluxes calculated from the water column and sediment are identical, and their bias is less than 6%. A numerical model PROFILE is used to simulate the in situ dissolved oxygen profile, and layered dissolved oxygen consumption rates in the sediment are calculated. The DBL thickness (0.10-0.35 mm) and diffusion flux (15.4-53.6 mmol m 2 d 1) vary with a factor of 3.5 during a tidal period. Over an intertidal mudflat, DBL thickness is controlled by flow speed U in the BBL, according to δDBL=1686.1DU 1+0.1 (D is the molecular diffusion coefficient). That is, the DBL thickness δDBL increases with decreasing flow speed U. Changes of diffusion flux at the SWI are caused by variations in the water above the sediment and the turbulent mixing intensity. The diffusion flux is positively related to the turbulent dissipation rate, friction velocity and turbulent energy. Under the influence of dynamics in the BBL, DBL thickness and flux vary significantly.     

Mechanisms of sodium and potassium ions transfer facilitated by dibenzo-15-crown-5 across the water /1,2-dichloroethane interface using micropipettes

The transfer of sodium and potassium ions facilitated by dibenzo-15-crown-5 (DB15C5) has been studied at the micro-water/1,2-dichloroethane (water/DCE) interface supported at the tip of a micropipette. Cyclic voltammetric measurements were performed in two limiting conditions: the bulk concentration of Na+ or K+ in the aqueous phase is much higher than that of DB15C5 in the organic phase (DB15C5 diffusion controlled process) and the reverse condition (metal ion diffusion controlled process). The mechanisms of the facilitated Na+ transfer by DB15C5 are both transfer by interfacial complexation (TIC) with 1∶1 stoichiometry under these two conditions, and the corresponding association constants were determined at log β1 = 8.97 ( 0.05 or log β1 = 8.63 ( 0.03. However, the transfers of K+ facilitated by DB15C5 show different behavior. In the former case it is a TIC process and its stoichiometry is 1∶2, whereas in the latter case two peaks during the forward scan were observed, the first of which was confirmed as the formation of K+(DB15C5)2 at the interface by a TIC mechanism, while the second one may be another TIC process with 1∶1 stoichiometry in the more positive potential. The relevant association constants calculated for the complexed ion, K+(DB15C5)2, in the organic phase in two cases, logβ2, are 13.64 ( 0.03 and 11.34 ( 0.24, respectively.     

Study of ionizable drugs transfer across the water/1,2-dichloroethane interface with phase volume ratio equal to unity using a three-electrode system

In the past few decades, much attention has been paid to the experimental and theoretical investigations of electrochemical processes at the interface between two immiscible electrolyte solutions (ITIES). This is mainly due to the potential applications these systems have been found in chemistry and biology, such as phase-transfer catalysis, analysis with chemical sensors, drug lipophilic-ity and its consequences to drug delivery, and mimicking biological membranes[1,2]. Compared with the m…