黄土丘陵沟壑区坡面尺度撂荒草地入渗特征影响因素试验研究

为研究黄土丘陵沟壑区多种因素对撂荒草地入渗特征的影响,采用野外自然降雨观测法,研究不同降雨特征（降雨量、平均雨强、降雨历时和最大30 min雨强（I₃₀））、土壤前期含水量、坡长（10 m、20 m、30 m、40 m和50 m）和植被盖度条件下土壤入渗特征差异,通过灰色关联度法判断影响撂荒草地入渗特征的主导因子。结果表明：①入渗量随降雨量、降雨历时和I₃₀增加而增大（R²>0.55,P<0.01）;入渗补给系数随降雨量、I₃₀和平均雨强增大而减小（R²>0.12,P<0.05）;平均入渗率随降雨强度、I₃₀增加而递增（R²>0.53,P<0.01）。②入渗量和平均入渗率随前期含水量增加而减少,入渗补给系数随之增加而增大（R²>0.13,P<0.05）。③入渗量、入渗补给系数和平均入渗率总体随坡长增加而增大（R²>0.56,P<0.01）,但在坡长30 m和40 m之间存在临界坡长。④在入渗效率较高的情况下,植被对土壤入渗的影响并不显著,降雨特征和坡长成为主导因子。     

台风期间波浪和局地风对磨刀门水道盐淡水混合的影响机制

珠江磨刀门水道地处亚热带季风气候区,直面南海,容易受到热带风暴的袭击。选取台风"纳沙",采用SCHISM模型建立磨刀门水道三维水流盐度数值模型,通过数值试验对比,结合势能异常分析法,探究了台风期间波浪和局地风对磨刀门水道混合与层化的影响。结果显示:由于近岸及河道内水深较浅,波高整体较小,波浪对水体层化过程影响不大,对流速分布有一定的调整作用,使其分布更为均匀,并在一定程度上加强水体掺混,利于外海高浓度盐水向河口和海岸扩散。而台风期间强劲的局地风对垂向水体状态以及势能异常变化率各项均有显著作用,影响着盐淡水的层化混合过程。     

大别山北麓高煤级煤的变形——变质类型

对中国东部大别造山带前陆盆地石炭纪含煤岩系的高煤级煤进行了深入研究,划分出3种变形——变质类型。构造——热变质类型煤样采自剪切应变带内,煤镜质组反射率各向异性显著,煤结构参数L_c最大,L_a/L_c和d₀₀₂最小,TEM下存在局部石墨化现象,呈现动力变质特征。岩浆热变质类型煤样受中生代花岗岩侵入体异常高温影响,Ro_max和Ro_bi较大,显微镜下呈非均质结构,L_a/L_c在3类煤中最大。区域变质类型煤的Ro_max最小,但仍远远高于稳定地区相近地质时代煤,反映了造山带旁侧构造——热活动背景下有机质的高演化程度。     

珠江口咸潮入侵分析与经验模型——以磨刀门水道为例

收集了2004-2006年珠江口磨刀门水道咸潮发生时测站(1~7)逐日定时观测的的含氯度、水位与流量数据,分析了各监测站含氯度与水位的日变化与年变化,导出了咸潮演变各过程中,含氯度与径流、潮流、河口地形等的关系式,建立了珠江口地区磨刀门水道咸潮入侵的经验模型。据此,模拟了2006年1月12日的磨刀门地区的咸潮入侵态势,经过和沿途各观测点验证发现与实测数据非常吻合。以含氯度等于250mg/L(饮用水的含氯度最大值)的点作为咸潮入侵的最远点,用简化修改后的盐度模拟模型计算了磨刀门咸潮入侵最大距离,并根据2006年1月12~20日的河口含氯度与最近的上游天河站的径流量实测数据计算出相应的咸潮入侵最大距离。研究表明,在河流枯水期(珠江河口通常是12月至翌年3月),只要获得当天河口的含氯度和上游测站的径流量数据,就能利用此经验模型估算出河流各点的含氯度,作出盐度模拟图,并估算出相应的咸潮入侵最大距离。     

CMADS降水数据在温带东亚季风气候区水库控制流域适用性——以潮白河、东洋河流域为例

为探究中国气象同化驱动数据集（CMADS）降水数据在温带东亚季风气候区水库控制流域情景下水文模拟中的适用性,选择SWAT （soil and water assessment tool）模型为研究工具,分别以CMADS降水数据与年鉴实测降水数据为模型输入项,以水文站实测月径流资料对模型模拟结果进行参数率定及验证,对潮白河流域有水库、无水库控制情形下水文径流进行模拟,并对东洋河流域有水库控制情形下以CMADS降水数据作为模型输入项进行了水文径流模拟。结果表明：在潮白河流域无水库控制的支流潮河水系,CMADS降水数据和实测降水数据支撑下的模型在率定期R²（决定系数）分别为0.64、0.83,E_NS（纳什系数）分别为0.64、0.83,验证期模型R²分别为0.61、0.83,E_NS分别为0.58、0.60;在潮白河流域有水库控制的支流白河水系,CMADS降水数据和实测降水数据支撑下的模型在率定期R²分别为0.89、0.87,E_NS分别为0.87、0.86,验证期模型R²分别为0.61、0.67,E_NS分别为0.61、0.65;在东洋河有水库控制流域,CMADS降水数据支撑的模型率定期R²=0.84,E_NS=0.78,验证期R²=0.87,E_NS=0.85。说明CMADS降水数据在有水库、无水库控制流域情景下的水文模拟中均具有较好的适用性。因此CMADS降水数据可以用于温带东亚季风气候区水库控制流域水文模型的建立。     

祁连山区雪冰反照率变化及其对冰川物质平衡的影响

雪冰反照率能够改变冰川表面能量收支平衡,是影响冰川消融的重要因素之一。利用祁连山地区冰川面积矢量数据、MODIS逐日积雪反照率、气温和降水以及冰川物质平衡等数据,探讨了祁连山典型冰川区雪冰反照率特征及其对冰川物质平衡的影响。结果表明：祁连山地区冰川多年平均反照率为0.532,冰川区面积大小与其多年平均反照率之间呈显著正相关（R²=0.16,P<0.05,N=91）,即冰川面积缩减1 km²,对应的平均反照率下降0.0025。祁连山老虎沟12号冰川反照率在夏季有明显的海拔效应,且强于其他时段,达到0.047?（100m）^-1。典型冰川年均物质平衡量与冰川表面夏季（6—8月）平均反照率之间存在显著的正相关关系,老虎沟12号冰川和七一冰川决定系数R²分别达到了0.48（P<0.05）和0.66（P <0.05）。冰川表面夏季平均反照率这一指标能够较好地衡量青藏高原北部祁连山地区冰川物质平衡的变化。     

珠江三角洲陆源污染和香港水域排污对伶仃洋的影响

采用河网区非稳态水量数学模型,计算珠江东四口门1985-1995年的入海水量(净泄流量);在此基础上,利用1985-1995年在珠江东四口门每年至少3次(丰、平、枯)的实测水质资料(COD_Mn、BOD₅、无机氮、水溶性磷酸盐、石油类等),计算1985-1995年间每年丰、平、枯三季从东四口门下泄到伶仃洋的污染物总量。利用经率定、验证的伶仃洋近海区二维非稳态水量、水质数学模型对珠江三角洲陆源污染通过东四口门下泄的污染物量、陆源污染物以及香港水域排污对伶仃洋水域的影响进行了研究。     

黄土记录的中亚干旱区东部全新世气候与环境演化

选取位于中亚干旱区东部新疆天山地区的两个典型黄土沉积剖面,通过磁学参数（χ_ARM/SIRM）、亮度（L^*）、有机碳/氮同位素（δ¹³C_org和δ¹⁵N）等记录,对研究区内全新世以来的气候环境进行重建。结果表明：早全新世,χ_ARM/SIRM、L^*指示黄土成壤较弱、有机质含量低,δ¹³C_org记录表明区域降水较少,共同反映该时期地表植被覆盖低、相对干旱的气候环境;中晚全新世,χ_ARM/SIRM、L^*和δ¹³C_org记录的湿度逐渐增加,黄土δ¹⁵N偏正变化,指示地表生态系统生产力增强、植被覆盖增加,表明该区域气候适宜期发生在中晚全新世。中亚干旱区东部全新世以来的气候环境特征,与北半球高纬度冰盖、太阳辐射强度的变化密切相关。     

鄂尔多斯盆地西缘中奥陶统地球化学特征及古环境意义

鄂尔多斯盆地西缘位于中国东西部构造接合区,其奥陶纪末期构造体制的改变引起了广泛关注。选取老石旦剖面中奥陶统碳酸盐岩作为研究对象,通过地球化学分析,恢复其古环境特征并探索盆地西缘中奥陶世构造体制改变在沉积学与地球化学方面的响应。结果显示:(1)三道坎组和桌子山组碳酸盐岩δ¹⁸O为-5.2‰~-8.9‰,平均值为-7.0‰;δ¹³C为1.3‰~-1.8‰,平均值为-0.1‰。δ¹⁸O自下而上不断增加,并在顶部出现小幅降低。δ¹³C与δ¹⁸O变化趋势相似。(2)古环境特征表现为从三道坎组到桌子山组,水温经历了初期震荡,从32.7 ℃缓慢降至15.7 ℃。古盐度Z值呈不断增加的趋势,反映出该沉积期水体加深、盐度不断升高。(3)主量、微量元素指标反映出研究区中奥陶世沉积水体不断加深,从三道坎组到桌子山组陆源碎屑物质含量逐渐降低,指示沉积环境由局限台地向开阔台地转变。结合研究区中奥陶统构造背景,认为中奥陶世鄂尔多斯盆地西缘已经处于前陆盆地的构造体制下,逐渐受到阿拉善地块和华北板块碰撞造山影响,盆地呈现西北高、东南低的古地貌特征,从而导致蒸发浓缩的富钾卤水向东南部汇聚;因此,陕北盐盆东南部次级凹陷是海相钾盐矿床的重点勘探靶区。     

大兴安岭北段宝兴沟金矿床成矿流体特征及矿床成因

宝兴沟金矿床是大兴安岭北部上黑龙江成矿带内大型金矿床之一,矿体主要产于下侏罗统二十二站组砂岩与早白垩世石英闪长岩、闪长玢岩内外接触带内,其热液成矿作用可划分为：黄铁矿±毒砂-石英（Ⅰ）、多金属硫化物-石英（Ⅱ）及少硫化物-碳酸盐（Ⅲ）3个阶段。流体包裹体岩相学研究表明：Ⅰ阶段矿石主要发育气液两相（LV）、少量含CO₂三相包裹体（H_CO2）及富气相包裹体（FV）;Ⅱ阶段矿石中主要发育LV及少量H_CO2包裹体;Ⅲ阶段矿石中只发育LV包裹体。测温结果显示：Ⅰ、Ⅱ阶段包裹体总体均一温度峰值集中于225.00~300.00℃,盐度（w（NaCl））为2.00%~10.00%;Ⅲ阶段均一温度峰值集中于175.00~225.00℃,盐度为4.00%~8.00%;成矿流体为简单的含CO₂中低温、低盐度的NaCl-H₂O热液体系,总体具有从成矿早期到晚期均一温度、盐度逐渐降低的特征。氢、氧同位素分析结果显示,Ⅰ、Ⅱ阶段成矿流体δD_SMOW为-131.00‰~-108.00‰、δ¹⁸O_SMOW为1.00‰~4.00‰,Ⅲ阶段δD_SMOW为-108.00‰、δ¹⁸O_SMOW为-1.89‰,表明早期以岩浆水为主,晚期逐渐演化为与大气降水混合热液。矿石中黄铁矿（毒砂）δ³⁴S_V-CDT为1.50‰~4.20‰,显示其物质来源以深源岩浆为主。综合分析认为,区内金成矿作用与早白垩世（石英）闪长岩、闪长玢岩侵入活动有直接关系,矿床属中低温岩浆热液成因类型。     

Application of empirical and semi-analytical algorithms to MERIS data for estimating chlorophyll a in Case 2 waters of Lake Erie

Lake Erie is biologically the most active lake among the Great Lakes of North America, experiencing seasonal harmful algal blooms (HABs). The early detection of HABs in the Western Basin of Lake Erie (WBLE) requires a more efficient and accurate monitoring tool. Remote sensing is an efficient tool with high spatial and temporal coverage that can allow accurate and timely detection of the HABs. The WBLE is heavily influenced by the surrounding terrestrial ecosystem via rivers such as the Sandusky River and the Maumee River. As a result, the optical properties of the WBLE are influenced by multiple color producing agents (CPAs) such as phytoplankton, colored dissolved organic matter (CDOM), organic detritus, and terrigenous inorganic particles. The diversity of the CPAs and their non-linear interactions makes these waters optically complex, and the task of optical remote sensing for retrieving estimates of CPAs more challenging. Chlorophyll a, which is the primary light harvesting pigment in all phytoplankton, is used as a proxy for algal biomass. In this study, several published remote sensing algorithms and band ratio models were applied to the reflectance data from the full resolution MERIS sensor to remotely estimate chlorophyll a concentrations in the WBLE. Efficiency of the sensor and the algorithms performance were tested through a least squares regression and residual analysis. The results indicate that, among the suite of existing bio-optical models, the Simis semi-analytical algorithm provided the best model results for measures of algal biomass in the optically complex WBLE with R ² of 0.65, RMSE 0.85 μg/l, (n = 71, P < 0.05). The superior results of this model in detecting chlorophyll a are attributed to several factors including optimizing spectral regions that are less sensitive to CDOM and the incorporation of correction factors such as absorption effects due to pure water (a _w), backscatter (b _b) from suspended matter and interference due to phycocyanin (δ), a major accessory pigment in the WBLE.     

A simple empirical optical model for simulating light attenuation variability in a partially mixed estuary

Representation of the subsurface light field is a crucial component of pelagic ecosystem and water quality models. Modeling the light field in estuaries is a particularly complicated problem due to the significant influence of high concentrations of dissolved and particulate matter that are derived from both terrestrial and estuarine sources. The goal of this study was to develop a relatively simple but effective way to model light attenuation variability in a turbuid estuary (Chesapeake Bay, United States) in a coupled physical-biological model. We adopted a simple, nonspectral empirical approach. Surface water quality data (salinity was used as a proxy of chromophoric dissolved organic matter [CDOM]) and light measurements from the Chesapeake Bay Program were used to determine the absorption coefficients in a linear attenuation model using regression methods. This model predicts K_c (specific attenuation due to phytoplankton/chlorophylla [chla]), K_t (specific attenuation due to total suspended solids), and K_s (a function of specific attenuation coefficients of CDOM in relation to salinity). The Bay-wide fitted relation between the light attenuation coefficient and water quality concentrations gives generally good estimates of total light attenuation, K_d. The direct inclusion of salinity in the relationship has one disadvantage: it can yield negative values for K_d at high salinities. We developed two separate models for two different salinity regimes. This approach, in addition to solving the negative K_d problem, also accounts for some changes in specific light absorption by chla, seston (nonphytoplankton particulate matter), and CDOM that apparently occur in different salinity regimes in Chesapeake Bay. The resulting model predicts the statistical characteristics (i.e., the mean and variance) of K_d quite accurately in most regions of Chesapeake Bay. We also discuss in this paper the feasibility and caveats of using K_d converted from Secchi depth in the empirical method.     

Estimation of colored dissolved organic matter and salinity fields in case 2 waters using SeaWiFS: Examples from Florida Bay and Florida Shelf

Estimates of water quality variables such as chlorophylla concentration (Chl), colored dissolved organic matter (CDOM), or salinity from satellite sensors are of great interest to resource managers monitoring coastal regions such as the Florida Bay and the Florida Shelf. However, accurate estimates of these variables using standard ocean color algorithms have been difficult due to the complex nature of the light field in these environments. In this study, we process SeaWiFS satellite data using two recently developed algorithms; one for atmospheric correction and the other a semianalytic bio-optical algorithm and compare the results with standard SeaWiFS algorithms. Overall, the two algorithms produced more realistic estimates of Chl and CDOM distributions in Florida Shelf and Bay waters. Estimates of surface salinity were obtained from the CDOM absorption field assuming a conservative mixing behavior of these waters. A comparison of SeaWiFS-derived Chl and CDOM absorption with field measurements in the Florida Bay indicated that although well correlated, CDOM was underestimated, while Chl was overestimated. Bottom reflectance appeared to affect these estimates at the shallow central Bay stations during the winter. These results demonstrate the need for new bio-optical algorithms or tuning of the parameters used in the bio-optical algorithm for local conditions encountered in the Bay.     

夏季丰水期河流输入对太湖有色可溶性有机物的贡献

结合2008年夏季丰水期对太湖上游直湖港、大浦河、长兜港3条河流有色可溶性有机物(CDOM)吸收和三维荧光的测定分析,探讨了夏季丰水期时河流输入对太湖中CDOM的贡献.3条河流中直湖港CDOM浓度最高,大浦河次之,长兜港最低,反映了太湖北部外源河流污染物输入大于西南部.3条河流内CDOM吸收α(355)的均值为(4.7...     

Studies on the reflectance spectral features of saline soil along the middle reaches of Tarim River: a case study in Xinjiang Autonomous Region, China

There has been growing interest in the use of reflectance spectroscopy as a rapid and inexpensive tool for soil characterization. In this study, 53 soil samples were collected from the oasis in the Weigan and Kuqa River delta along the middle reaches of Tarim River to investigate the level of soil chemical components in relation to soil spectral. An approach combining spectral technology and multi-variant statistical analysis was used to determine the reflectance spectral features of saline soil. The spectral data was first pretreated to remove noises and absorption bands from water, which eliminated influence from instrument errors and other external background factors. Several spectral absorption features were calculated for several saline soil samples to confirm that soil at the same salinity level had similar absorption spectral properties. Secondly, a correlation relationship between reflectance spectra and salinity factors was estimated by bivariate correlation method. Fourteen salinity factors including eight major ions and soil electrical conductivity (EC), soil salt content (SSC), pH, and total dissolved solid (TDS) in the saline soil were evaluated. Datasets of the salinity factors that correlated significantly with field data measurements of reflectance rate and the corresponding spectrum data were used to construct quantitative regression models. According to the multiple linear regression analysis, SSC, SO₄ ^2?, TDS, and EC had a correlation coefficient at 0.746, 0.908, 0.798, and 0.933 with the raw spectral data, respectively, which confirmed strong correlation between salinity factors and soil reflectance spectrum. Findings from this study will have significant impact on characterization of spectral features of saline soil in oasis in arid land.     

In-situ reflectance spectroscopy – analysing techniques for high-resolution pigment logging in sediment cores

The temporal resolution of marine proxy data is limited by analytically required sample size. We present in-situ reflectance spectroscopy techniques (usually applied in remote sensing) to analyse the organic fraction of marine and terrestrial sediment. From absorption band depths, photosynthesis pigment variations are derived for sediments from the upwelling region off Peru, where productivity is related to the annual variability of El Niño strength. Quantitative estimations of diagenetic photosynthesis pigments derived from absorption band analysis in reflectance spectra are highly correlated to organic carbon content. The ratio of pigment fractions is related to chlorine concentration and reflects organic matter preservation and deep-water ventilation changes. The import of terrigenous mineroclastics (TM) by local rivers is semi-quantitatively documented in the spectrum continuum. TM is inversely varying with organic matter preservation and chlorine concentration.     

Modeling the transport and distribution of lead in tidal Keelung River estuary

A vertical, two-dimensional heavy metal (lead) transport model incorporated into the hydrodynamic, salt, and sediment transport modules was developed to simulate the lead concentration in the tidal Keelung River estuary of northern Taiwan. We validated the developed model with measured data, including longitudinal velocity, salinity, suspended sediment, and heavy metal (lead) concentration, obtained in 1998. An exponential relationship relating the salinity and suspended-sediment concentrations was established to calculate the partition coefficient of lead in the estuary. The simulated results of dissolved, particulate, and total lead concentrations agreed well with the measured data. A model sensitivity analysis indicated that the partition coefficient plays an important role in the distribution of dissolved and particulate lead concentrations along the tidal Keelung River estuary.     

Spatial and temporal variation of organic carbon in the northern South China Sea revealed by sedimentary records

Three sediment cores were taken from the Pearl River estuary and adjacent northern South China Sea (SCS). These sediment cores span the time interval 1900–2000 AD. The stratigraphy of the concentration, the ratio of total organic carbon (TOC) to total nitrogen (TN) and stable isotope (δ¹³C_org) of organic carbon (OC) from three high-resolution sediment cores were analyzed. The stratigraphic profiles of OC concentration, TOC/TN ratios and δ¹³C_org for the near past 100 yrs indicate that terrestrial organic matter decreases from 68.3% to 27.4% of the TOC in the Pearl River estuary, while Dapeng Bay (offshore east of Hong Kong) apparently had throughout little terrestrial organic matter input. The highest deposited OC occurs at the Humen River mouth and the OC concentrations are higher in the outer estuary than in the inner shelf of the northern SCS. The deposited OC at the River mouth increased with time, which could be caused by the high precipitation of land-derived organic matter and the high input of terrestrial organic matter, which is likely related to the rapid urbanization and industrial development in the Pearl River Delta since the 1970s. The OC concentrations did not exhibit an obvious increase with time in most areas of the Pear River estuary and adjacent inner shelf of the SCS, but the algal-derived OC concentration inferred from the δ¹³C_org values increased with time especially from 1980 to 2000 in the outer Pearl River estuary and Dapeng Bay. This increase is presumably caused by enhanced primary marine productivity supported by higher anthropogenic nutrient inputs.     

Temporal and Spatial Distribution Characteristics of Colored Dissolved Organic Matter in Coastal Waters of Jiangsu Province

Colored Dissolved Organic Matter (CDOM) is one of important ocean color factors. In the background of “Jiangsu Coastal Development”, it is important to monitor the water quality and pollution status of coastal waters by analyzing its spatial and temporal distribution characteristics with remote sensing data. This paper was based on the high temporal resolution of Geostationary Ocean Color Imager (GOCI) image downloaded from Korea Ocean Satellite Center. The temporal-spatial distribution of CDOM in Jiangsu coastal waters was analyzed on daily, weekly and monthly time scales from April, 2011 to May, 2016. CDOM in Jiangsu coastal waters are mainly terrigenous, and higher inshore than that of offshore. The monthly average concentration of CDOM in the western coast of the South Yellow Sea was 0.167~0.201 m^-1, and those of central and southern regions were 0.086~0.187m^-1. The maximum values were outside the maximum turbidity zone of the Yangtze River Estuary, which was 0.180~0.206 m^-1 (absorption coefficient at 440 nm). The diurnal variation of CDOM in near shore waters was found to coincide with the change of tide, which decreased at first and then increased in the sea area. By fitting the monthly mean using cosine function, significantly cyclical variation of mean CDOM was found in the South Yellow Sea. The central region of the South Yellow Sea waters fitting coefficient was 0.823. Affected by the Yellow Sea cold water mass, the sub-regions of the South Yellow Sea changed seasonally, whose CDOM concentration in winter and spring was higher than that in summer and autumn. Because of Changjiang Diluted Water and other water masses, seasonal variation of the Yangtze River Estuary was contrary to that of the South Yellow Sea. On monthly scale, CDOM concentration was positively correlated with total suspended matter, with correlation coefficient r being 0.72. The trend of the central and southern region was more significant.     

Wind-Driven Dissolved Organic Matter Dynamics in a Chesapeake Bay Tidal Marsh-Estuary System

Controls on organic matter cycling across the tidal wetland-estuary interface have proved elusive, but high-resolution observations coupled with process-based modeling can be a powerful methodology to address shortcomings in either methodology alone. In this study, detailed observations and three-dimensional hydrodynamic modeling are used to examine biogeochemical exchanges in the marsh-estuary system of the Rhode River, MD, USA. Analysis of observations near the marsh in 2015 reveals a strong relationship between marsh creek salinity and dissolved organic matter fluorescence (fDOM), with wind velocity indirectly driving large amplitude variation of both salinity and fDOM at certain times of the year. Three-dimensional model results from the Finite Volume Community Ocean Model implemented for the wetland system with a new marsh grass drag module are consistent with observations, simulating sub-tidal variability of marsh creek salinity. The model results exhibit an interaction between wind-driven variation in surface elevation and flow velocity at the marsh creek, with northerly winds driving increased freshwater signal and discharge out of the modeled wetland during precipitation events. Wind setup of a water surface elevation gradient axially along the estuary drives the modeled local sub-tidal flow and thus salinity variability. On sub-tidal time scales (>36 h, <1 week), wind is important in mediating dissolved organic matter releases from the Kirkpatrick Marsh into the Rhode River.