黄土丘陵区上黄试区农业生态经济系统演变阶段划分及其驱动力初探

黄土丘陵区固原上黄试验区近20年(1986-2005)来农业生态经济系统演变过程可划分为三个阶段:第Ⅰ阶段(1986-1999)、第Ⅱ阶段(1999-2002)、第Ⅲ阶段(2002-2005)。在对农业生态经济系统演变三个阶段的特征及互动过程分析的基础上,利用通径分析方法探讨了各个阶段的驱动力。第Ⅰ阶段:提高单产是主要驱动力;第Ⅱ阶段:退耕还林还草是主要驱动力;第Ⅲ阶段:经济利益是主要驱动力。

黄土丘陵区县南沟流域生态恢复的生态经济耦合过程及可持续性分析

生态恢复不但是自然和技术过程,更重要的是经济过程,生态经济耦合是生态恢复成败及能否持续的关键。综合应用经济学、能值和生态足迹分析工具,系统研究了黄土丘陵区县南沟流域生态恢复过程中的生态经济系统演变过程及其特征,旨在探索生态可持续的经济社会发展机制。结果表明,2000～2005年流域产业结构及其多样性显著改善,生产力显著提高并跨越低水平进入高水平发展阶段,农民的生活状况已经由温饱逐步迈向小康水平。基于能值的生态经济耦合分析结果显示2002～2005年流域环境负载率(ELR)下降,持续性指数(ESI)增加。生态足迹结果显示流域2000年和2005年的生态盈余分别为0.03hm2和0.239hm2,新指标万元产值生态足迹(EFprod)分别为53.5hm2/万$和33.6hm2/万$,生态压力指数(EFPI)分别为0.980和0.838,流域处于弱可持续状态。上述结果显示生态恢复提高了流域资源利用和转换效率,环境负载率下降,人类经济活动对生态生产性有效空间的占用减少,可持续性提高。研究结果表明生态恢复是黄土丘陵区实现生态经济良性耦合、协调发展的基本途径。

热带西太平洋次表层水和中层水分布特征及其年代变化

热带西太平洋是一个流系和水团分布十分复杂的海域。热带西太平洋是一个在别处形成的几种水团的交汇区。许多起源于中、高纬度海域的次表层和中层水团，由不同流系带入和带出这个海域。热带西太平洋水团分布及其变化，与各种时间尺度的大尺度海洋环流和全球水循环变化密切联系，所在位势密度层次越深，所关联的气候变化时间尺度越长。因此，研究该海域次表层水和中层水的分布、扩散及其变化特征，对大洋环流动力学和气候变化研究有重要意义。本文利用中国ARGO资料中心提供的ARGO延时处理资料和美国NODC提供的WOD01中的高分辨率CTD资料，运用盐度极值法确定水团的核心，通过水团核心位置的分布及变化反映热带西太平洋次表层水和中层水的分布及其起源和归宿问题，试图获得较以往更加准确的NPIW和AAIW以及NPTW和SPTW的向南及向北扩散的特征，以及ITF在不同层次上的水源。对新发现的西太平洋热带水（WPTW）和西太平洋热带中层水（WPTIW）的水团性质、分布特征，成因和起源进行了比较系统的分析。在此基础上，分析上述次表层水和中层水20世纪八九十年代以来的年代变化特征。主要结果如下：（1）SPTW在137°E以西跨越赤道后，仍在很大程度上保持原有盐度，向西北和东北方向发展。SPTW在131°E以东几乎没有越过5°N，但在131°E以西可局部影响到6°N，棉兰老冷涡和哈马黑拉暖涡的涡混合输运在这一局部过程中可能起主要作用。NPTW主要位于10°N－20°N之间，在NEC输送下从东向西一直延伸到菲律宾沿岸，分成向北和向南两个分支，南分支在130°E以西沿棉兰老沿岸向南扩散大约到2°N，部分向西进入苏拉威西海，部分与SPTW相遇后有向东扩散的趋势。（2）AAIW几乎齐头并进地向北扩散到12°N－13°N，在125°E附近向北可以到达13°N左右。NPIW的主体分布在10°N以北、122°E以东，呈东北向西南的扩散趋势，在132°E以西至棉兰老沿岸之间可以到达4°N附近。（3）在已知的NPTW与SPTW之间，发现一个以往从未被报道过的次表层水，称之为WPTW。WPTW存在于3°N－12°N之间，核心盐度低于34.8psu，位势密度约在23.7 －24.7 之间。WPTW源于东太平洋20-25°N附近，由NEC南翼携带向西到达西边界后，部分经MC向南，经NECC向东折回，被局限在NEC与NECC之间的狭长水域。（4）2°N－10°N之间、从170°W到西边界分布着一片盐度比较均匀、呈现垂向盐度极小值特征的中层水。该水体位势密度约为26.0 －26.6 、位于AAIW之上、NPIW以南，核心盐度与AAIW相仿、但高于NPIW，在以往研究中未给予重视。从流场配置来看，这个被本文称为WPTIW的水体恰好处在NEC-NECC-SEC之间的强剪切区，在其北侧的是NPIW与同样起源于东北太平洋的浅的盐度极小值（SSM）之间的混合水，在其南侧相应层次上则是AAIW与SPTW之间的过渡水，两者之间被剪切流充分混合，形成盐度相对均匀的WPTIW。因此，WPTIW是热带西太平洋局地混合和再循环的产物。（5）在20世纪八九十年代和2000年以后这两个时期，本文所关注的次表层水和中层水在热带西太平洋扩散和在西边界附近交织在一起的总体态势基本一致。两个时期相比较，SPTW向西扩散程度变化不大，向北扩散程度有所加大，由前一时期的5°N，进一步扩散到6°N－7°N。NPTW在西边界附近的向南扩散程度有所削弱，在2002－2005年间只向南扩散到4°N，并且被SPTW阻挡于128°E以西，而前一个时期则可向南扩散到2°N，并且在2°N－4°N之间转向东跨过130°E。AAIW在西边界附近向北扩散程度有所加大，在2002－2005年到13°N附近，而前一个时期只到达11°N。NPIW在西边界附近的向南扩散程度有所削弱。（6）ITF的次表层水源基本上可以确定主要来自北太平洋，中层水源既有北太平洋，也有南太平洋。其中北太平洋次表层水和中层水经苏拉威西海、望加锡海峡到达弗罗勒斯海，层次越深趋势越明显。南太平洋次表层水没有进入印度尼西亚海域，AAIW则明显是经哈马黑拉海峡和马鲁古海峡到班达海。在各层次上，南海次表层水和中层水通过苏禄海进入ITF的可能性不大。

太阳辐射对热层和电离层变化性的影响

Solar ultraviolet (UV) radiation at wavelengths less than 400 nm is an important source of energy for aeronomic processes throughout the solar system. Solar UV photons are absorbed in planetary atmospheres, as well as throughout the heliosphere, via photodissociation of molecules, photoionization of molecules and atoms, and photoexcitation toexcitation including resonance scattering. In this paper, the solar irradiances data measured by TIMED SEE, as well as the solar proxies such as F10.7 and Mg II, thermosphere neutral density of CHAMP measurements and topside ionospheric plasmas densities from DMSP, are used to analyze solar irradiance effects on the variabilities of the thermosphere and the ionosphere. First, thermosphere densities near 410 km altitude are analyzed for solar irradiance variability effects during the period 2002-2004. Correlations between the densities and the solar irradiances for different spectral lines and wavelength ranges reveal significantly different characteristics. The density correlates remarkably well with all the selected solar irradiances except the lower chromospheric O I (130.4 nm) emission. Among the chosen solar proxies, the Mg II core-to-wing ratio index, EUV (30-120 nm) and F10.7 show the highest correlations with the density for short-term (< ~27 days) variations. For both long- (> ~27 days) and short-term variations, linear correlation coefficients exhibit a decreasing trend from low latitudes towards high latitudes. The density variability can be effectively modeled (capturing 71% of the variance) using multiple solar irradiance indices, including F10.7, SEUV (the EUV 30-120 nm index), and SFUV (the FUV 120-193 nm index), in which a lag time of 1 day was used for both F10.7 and SEUV, and 5 days for SFUV. In our regression formulation SEUV has the largest contribution to the density variation (40%), with the F10.7 having the next largest contribution (32%) and SFUV accounting for the rest (28%). Furthermore, a pronounced period of about 27.2 days (mean period of the Sun's rotation) is present in both density and solar irradiance data of 2003 and 2004, and a pronounced period of about 54.4 days (doubled period of the solar rotation) is also revealed in 2004. However, soft X-ray and FUV irradiances did not present a pronounced 54.4 day period in 2004, in spite of their high correlation with the densities. The Ap index also shows 54-day periodicities in 2004, and magnetic activity, together with solar irradiance, affects the 54-day variation in density significantly. In addition, NRLMSISE00, DTM-2000 and JB2006 model predictions are compared with density measurements from CHAMP to assess their accuracy, and the results show that these models underestimate the response of the thermosphere to variations induced by solar rotation. Next, the equatorial topside ionospheric plasmas densities Ni are analyzed for solar irradiance variability effects during the period 2002-2005. Linear correlations between Ni and the solar irradiances for different wavelength ranges reveal significantly different characteristics. XUV (0-35 nm) and EUV (115-130 nm) show higher correlation with Ni for the long-term variations, whereas EUV (35-115 nm) show higher correlation for the short-term variations. Moreover, partial correlation analysis shows that the long-term variations of Ni are affected by both XUV (0-35 nm) and EUV (35-115 nm), whereas XUV (0-35 nm) play a more important role; the short-term variations of Ni are mostly affected by EUV (35-115 nm). Furthermore, a pronounced period of about 27 days is present in both Ni and solar irradiance data of 2003 and 2004, and a pronounced period of about 54 days is also revealed in 2004. Finally, prompted by previous studies that have suggested solar EUV radiation as a means of driving the semiannual variation, we investigate the intra-annual variation in thermosphere neutral density near 400 km during 2002-2005. The intra-annual variation, commonly referred to as the ‘semiannual variation’, is characterized by significant latitude structure, hemispheric asymmetries, and inter-annual variability. The magnitude of the maximum yearly difference, from the yearly minimum to the yearly maximum, varies by as much as 60% from year to year, and the phases of the minima and maxima also change by 20-40 days from year to year. Each annual harmonic of the intra-annual variation, namely, annual, semiannual, ter-annual and quatra-annual, exhibits a decreasing trend from 2002 through 2005 that is correlated with the decline in solar activity. In addition, some variations in these harmonics are correlated with geomagnetic activity, as represented by the daily mean value of Kp. Recent empirical models of the thermosphere are found to be deficient in capturing most of the latitude dependencies discovered in our data. In addition, the solar flux and geomagnetic activity proxies that we have employed do not capture some latitude and inter-annual variations detected in our data. It is possible that these variations are partly due to other effects, such as seasonal-latitudinal variations in turbopause altitude (and hence O/N2 composition) and ionosphere coupling processes that remain to be discovered in the context of influencing the intra-annual variations depicted here. Our results provide a new dataset to challenge and validate thermosphere-ionosphere general circulation models that seek to delineate the thermosphere intra-annual variation and to understand the various competing mechanisms that may contribute to its existence and variability. We furthermore suggest that the term “intra-annual” variation be adopted to describe the variability in thermosphere and ionosphere parameters that is well-captured through a superposition of annual, semiannual, ter-annual, and quatra-annual harmonic terms, and that “semiannual’ be used strictly in reference to a pure 6-monthly sinusoidal variation. Moreover, we propose the term “intra-seasonal” to refer to those shorter-term variations that arise as residuals from the above Fourier representation.

洗煤废水对环境的影响

煤作为重要的能源物质,在提供能量的同时,也对生态系统产生巨大的负面效应,尤其在产煤过程中产生的酸性洗煤废水对矿区周边生态环境造成严重破坏.如:波兰奥得河和维斯瓦河的上游因受酸性煤矿废水污染的影响,重金属及氯化物含量超标,大约50%的上游河段未达到水质Ⅲ级标准(Rybicka,1996);美国俄亥俄州霍金河流域受酸性煤矿废水季节性变化的影响,河流生态系统也随之发生改变(Rob-ert等,2001);我国山西省大同市口泉煤矿直接排放的洗煤废水导致附近河流下游断面水质为Ⅴ级,且SO42-、氨氮、Hg、COD和氟化物等超标率很高(时红,2002).……　煤炭作为重要的能源物质,在提供能量的同时,也对生态系统产生巨大的负面效应,尤其在产煤过程中产生的酸性洗煤废水对矿区周边生态环境造成严重破坏.如:波兰奥得河和维斯瓦河的上游因受酸性煤矿废水污染的影响,重金属及氯化物含量超标,大约50%的上游河段未达到水质Ⅲ级标准(Rybicka,1996);美国俄亥俄州霍金河流域受酸性煤矿废水季节性变化的影响,河流生态系统也随之发生改变(Rob-ert等,2001);我国山西省大同市口泉煤矿直接排放的洗煤废水导致附近河流下游断面水质为Ⅴ级,且SO42-、氨氮、Hg、COD和氟化物等超标率很高(时红,2002).

岩溶水对不同环境的响应以及其与大气CO2源汇的关系－基于热力学的研究

碳酸盐岩是最大的无机碳库。这一无机碳库对全球变化的响应是目前科学界关心的一个重要问题。岩溶水是对外界气候和环境最敏感的介质。因此，认识不同环境条件下岩溶水体系对大气CO2源汇的贡献是认识碳酸盐岩无机碳库对全球变化响应的基础。 前人基于平衡常数热力学途径对岩溶水体系有一定的研究。本研究从热力学另一途径即吉布斯自由能原理出发，建立岩溶水体系（以方解石为例）的化学平衡式，采用Mathematic数学软件建立了岩溶水体系各组分的多参数方程，对其进行计算处理，本文主要对以下4个方面的内容进行了研究。 1. 对两种热力学途径计算值进行方差显著性分析，结果显示：基于吉布斯自由能途径的热力学方法是研究岩溶水SIc、pco2的有效方法，且其比平衡常数热力学途径的已有程序应用性更普遍，可应用于任一岩溶水体系的研究。 2. 研究了岩溶水对环境变化的响应。结果显示，岩溶水温度（T）、压强（p）、离子强度（I）、pH值的变化以及离子对存在与否等分别对岩溶水体系组分有重要的影响。其中，pH值对岩溶水体系组分的影响最大。 3. 对世界范围内不同岩溶地区140组实例岩溶水（河水、溪水等）进行研究，根据岩溶水体系SIc计算值，判定在所处环境条件下岩溶水体系与大气CO2源汇的潜在关系。结果显示，（1）河水、溪水、湖水等岩溶水在所处环境条件下释放CO2，因而是大气CO2的潜在源。（2）地下水在所处环境条件下是大气CO2潜在的汇。（3）泉水在所处环境条件下一部分是大气CO2潜在的源，另外一部分则是大气CO2潜在的汇。 4．对1993年、2002 ~ 2005年每年6月份红枫湖水SIc进行了计算并分析其变化趋势，结论如下：（1）据1993年以及近几年（2002 ~ 2005）监测的pH值，红枫湖水的pH值呈逐渐下降的大趋势。（2）红枫湖水1993年、2002 ~ 2005年每年6月份SIc呈下降的大趋势。这与对应年份红枫湖水pH值变化一致。红枫湖水SIc从1993年6月份的正值转变成2005年6月份的负值。这表明红枫湖水由发生方解石的沉积向发生方解石的溶解转变。 　　我们的研究表明，从吉布斯自由能途径热力学方法出发，不仅可以从理论上讨论岩溶水体系对岩溶环境差异的响应，而且也可应用于实例研究。特别是研究近年来西南地区酸雨对岩溶水体系的影响。因此，吉布斯自由能途径是一较好的方法。