华北平原某集约化种植区地下水污染探讨

以华北平原某集约化种植区为典型研究区域,通过对采集的8个地下水样品及11个土壤样品分析,探讨集约化种植区地下水的污染程度,解析其污染影响机制。结果表明:该集约化种植地区土壤中残留物主要为有机氯农药,多环芳烃及邻苯二甲酸酯类有机化合物。地下水中硝酸盐含量显著增加;重金属中以Cr含量最高,但均未超标;地下水并未受到有机氯农药的污染,但仍显示有多氯联苯的输入;半挥发性有机物检出种类较多,其中残留农膜释放的邻苯二甲酸酯类有机化合物浓度最高;地下水已受到较为严重的污染。集约化种植区大量施用化肥、农药和覆盖农膜,污染负荷严重,灌溉频繁且量大,污染质运移驱动力大是地下水污染的根本原因;当地包气带中黏性土厚度不均以及井孔止水不严等因素也成为了地下水受到污染的直接原因。     

江西省鄱阳湖信江决口三角洲沉积特征及模式

利用实地考察、浅钻孔、探槽及卫星影像等方法,对鄱阳湖信江决口三角洲进行了系统研究。该决口三角洲是洪水冲破信江西岸天然堤流入附近的河漫湖泊形成的,其平面形态为鸟足状,总体延伸方向与主河道近垂直。在横切剖面上整个决口三角洲沉积体呈透镜状覆盖在早期的湿地或河漫湖泊沉积之上。鄱阳湖信江决口三角洲可分为3个亚相:决口三角洲平原、决口三角洲前缘和决口前三角洲。决口三角洲平原主要发育决口河道、决口天然堤、废弃决口河道和湿地,其中决口河道又可以进一步划分为决口水道、边滩、汊口滩;决口三角洲前缘主要发育河口坝、支流间湾。河漫湖泊规模小、深度浅、波浪能量弱,对河口坝和决口河道砂体的改造较弱,不易形成连片分布的席状砂;决口前三角洲不发育。决口三角洲沉积受河流作用和河漫湖泊作用的共同控制,其演化可以划分为主河道天然堤生长阶段、决口初期阶段、进积分汊阶段及分汊—废弃阶段4个阶段。     

Availability of coastal groundwater discharge as an alternative water resource in a large-scale reclaimed land,Korea

This study was conducted to identify the availability of coastal groundwater discharge (CGD), subsurface fluids flowing from inland through the coastal area to sea, as an alternative water resource for a large-scale reclaimed land. The behaviors of stable isotopes indicated that groundwater originated from inland precipitation and traveled as CGD along the coast line. Most of the groundwater samples collected from domestic wells installed along the old coast line were considered to be relatively fresh from the correlation analysis among chemical constituents. The average electrical conductivity (EC) values of the samples were identified as averaging 1,125–1,297 μS cm^?1, corresponding to appropriate crop growth. A weathered-rock layer in a small catchment within the reclaimed land was proved to be a main CGD pathway, with electrical resistivity anomalies ranging from 7 to 14 Ω m. Five monitoring wells were placed in this catchment to delineate the occurrence of CGD. Long-term vertical EC profiling results for the monitoring wells indicated that CGD occurs within a depth of 30 m below the ground surface. Annual monitoring data for groundwater level and EC demonstrated that the water quality of CGD was improved by introducing fresh terrestrial groundwater. A remarkable improvement in water quality (EC decrease of 900–1,600 μS cm^?1) of CGD was observed during the saline water pumping test that explains how CGD could be an alternative water resource for the reclaimed land.     

Controlling factors of the δ 11B-pH proxy and its research direction

Significant boron isotope fractionation occurs in nature (?70 ‰ to +75 ‰) due to the high geochemical reactivity of boron and the large relative mass difference between ¹⁰B and ¹¹B. Since the 1990s, reconstruction of ancient seawater pH using the isotopic composition of boron in bio-carbonates (δ ¹¹B_carb), and then calculation of the past pCO₂ have become important issues for the international isotope geochemistry community, and are called the δ ¹¹B-pH proxy. Although many achievements have been made by this proxy, various aspects of boron systematics require rigorous evaluation. Based on the previous researches, mechanism of boron isotope fractionation, variation of boron isotope (δ ¹¹B) in nature (especially in bio-carbonates) and controlling factors of the δ ¹¹B-pH proxy, such as the dissociation constant of B(OH)₃ in seawater (pK_a), the δ ¹¹B of seawater (δ ¹¹B_SW), the boron isotopic fractionation factor between B(OH) ₄ ^? and B(OH)₃ (α _4–3), and the incorporated species of boron into bio-carbonates, are reviewed in detail and the research directions of this proxy are proposed. Generally, the controversy about pK_a, δ ¹¹B_sw, and α _4–3 is relatively less, but whether boron incorporated into bio-carbonates only in the form of B(OH) ₄ ^? remains doubtful. In the future, it is required that the physicochemical processes that control boron incorporation into carbonates be rigorously characterized and that the related chemical and isotopic fractionation be quantified. It is also necessary and important to establish a “best-fit empirically equation” between δ ¹¹B_carb and pH of seawater based on the precipitation experiments of inorganic or culture experiments of corals or foraminifera. In addition, extended application of the δ ¹¹B-pH proxy to the earlier part of the Phanerozoic relying on the Brachiopods is worthy of studying. Like other geochemical indicators, there are limiting factors of δ ¹¹B; however, it remains a very powerful tool in the reconstruction of past seawater pH at present.     

Response of vegetation pattern to different landform and water-table depth in Hailiutu River basin,Northwestern China

The spatial distribution of vegetation pattern and vegetation cover fraction (VCF) was quantified with remote sensing data in the Hailiutu River basin, a semiarid area in North China. The moderate resolution imaging spectroradiometer normalized different vegetation index (NDVI) values for 4 years from 2008 to 2011 and field observation data were used to assess the impact of climate factors, landform and depth to water table on vegetation distribution at large scale. In the VCF map, 74 % of the study area is covered with low and low–medium density vegetation, 24 % of the catchment is occupied by medium–high and high-density vegetation, and 2 % of area is bare soil. The relationship between NDVI and climate factors indicated that NDVI is correlated with relative humidity and precipitation. In the river catchment, NDVI increases gradually from landform of sand dune, eolian sand soil to river valley; 92.4 % of low NDVI from 0.15 to 0.3 is mostly distributed in sand dunes and the vegetation type is shrubs. Crops, shrubs and some dry willows dominate in eolian sand soil and 82.5 % of the NDVI varies between 0.2 and 0.35. In the river valley, 70.4 % of NDVI ranges between 0.25 and 0.4, and grass, dry willow and some crops are the main plants. Shrubs development of Korshinsk peashrub and Salix psammophila are dependent on groundwater by analyzing NDVI response to groundwater depth. However, NDVI of Artemisia desertorum had little sensitivity to groundwater.     

姬塬地区长8油层组层序地层格架内成岩相展布特征

通过岩心观察并充分利用普通薄片、铸体薄片、阴极发光、X-衍射和扫描电镜等资料,对姬塬地区长8油层组储层的成岩作用、成岩矿物、成岩阶段和成岩演化序列特征等进行了研究。根据成岩作用类型及强度、成岩矿物等将储层划分为绿泥石衬边弱溶蚀、不稳定组分溶蚀、压实致密、高岭石充填和碳酸盐胶结5种成岩相。并通过岩心薄片资料刻度测井归纳出不同成岩相在GR、AC等测井曲线及其组合上的响应特征,由此实现各单井储层成岩相的连续划分。对长8油层组层序界面和基准面旋回与成岩相展布的关系进行了研究,结果表明层序界面附近不稳定组分溶蚀相及高岭石充填相较为发育,且各井之间对比性良好,同时层序界面也控制了碳酸盐胶结;中期基准面旋回的最大湖泛面处均发育井间可对比的压实致密相,长82中期基准面下降半旋回砂体一方面易于遭受溶蚀产生次生孔,另一方面由于受沉积驻留和碎屑组分影响导致压实强度较弱,因此物性总体比长81砂体好。     

Geochemical features and origin of natural gas in heavy oil area of the Western Slope,Songliao Basin,China

The Western Slope of the Songliao Basin is rich in heavy oil resources (>70 × 10⁸ bbl), around which there are shallow gas reservoirs (∼1.0 × 10¹² m³). The gas is dominated by methane with a dryness over 0.99, and the non-hydrocarbon component being overwelmingly nitrogen. Carbon isotope composition of methane and its homologs is depleted in ¹³C, with δ¹³C₁ values being in the range of −55‰ to −75‰, δ¹³C₂ being in the range of −40‰ to −53‰ and δ¹³C₃ being in the range of −30‰ to −42‰, respectively. These values differ significantly from those solution gases source in the Daqing oilfield. This study concludes that heavy oils along the Western Slope were derived from mature source rocks in the Qijia-Gulong Depression, that were biodegraded. The low reservoir temperature (30–50 °C) and low salinity of formation water with neutral to alkaline pH (NaHCO₃) appeared ideal for microbial activity and thus biodegradation. Natural gas along the Western Slope appears mainly to have originated from biodegradation and the formation of heavy oil. This origin is suggested by the heavy δ¹³C of CO₂ (−18.78‰ to 0.95‰) which suggests that the methane was produced via fermentation as the terminal decomposition stage of the oil.     

Spatiotemporal variation of meteorological droughts based on the daily comprehensive drought index in the Haihe River basin,China

Meteorological droughts can affect large areas and may have serious environmental, social and economic impacts. These impacts depend on the severity, duration, and spatial extent of the precipitation deficit and the socioeconomic vulnerability of the affected regions. This paper examines the spatiotemporal variation of meteorological droughts in the Haihe River basin. Meteorological droughts events were diagnosed using daily meteorological data from 44 stations by calculating a comprehensive drought index (CI) for the period 1961–2011. Based on the daily CI values of each station over the past 50 years, the drought processes at each station were confirmed, and the severity, duration and frequency of each meteorological drought event were computed and analyzed. The results suggest the following conclusions: (1) the use of the CI index can effectively trace the development of drought and can also identify the duration and severity of each drought event; (2) the average drought duration was 57–85 days in each region of the Haihe River basin, and the region with the highest average values of drought duration and drought severity was Bohai Bay; (3) drought occurred more than 48 times over the study period, which is more than 0.95 times per year over the 50 years studied. The average frequencies of non-drought days, severe drought days and extreme drought days over the study period were 51.2, 3.2 and 0.4 %, respectively. Severe drought events mainly occurred in the south branch of the Hai River, and extreme drought events mainly occurred in the Shandong Peninsula and Bohai Bay; (4) the annual precipitation and potential evapotranspiration of the Haihe River basin show decreasing trends over the past 50 years. The frequency of severe drought and extreme drought events has increased in the past 20 years than during the period 1961–1990. The results of this study may serve as a reference point for decision regarding basin water resources management, ecological recovery and drought hazard vulnerability analysis.

     

招平断裂带中段断裂成矿有利度分析

招平断裂带是我国著名的金矿成矿带。断裂的空间展布形态特征对寻找断裂构造控矿型金矿床具有重要作用。通过断裂的遥感解译,研究了招平断裂带主断裂的走向、主断裂地表破碎带宽度以及主断裂起伏程度等成矿有利度指标,构建了基于断裂距离场的成矿有利度分析模型,并圈定研究区域成矿远景区11处,为区域地质、物化探等勘查工作提供了指导性意见。     

基于交通大数据的广东省高速公路碳排放计量模型与空间格局

以广东省为例,基于高速公路联网收费系统的路段车流数据,建立包含I~IV类客车和I~VI类货车在内的全样本、高精度碳排放计量模型,并采用地理空间分析法探索广东省高速公路碳排放空间差异性。结论主要有：1）广东省高速公路碳排放主要来自于货车,货车碳排放占碳排放总量的57.1%;客车占42.9%。其中,中小型机动车,如I类客车（即小汽车）、I类和III类货车等是高速公路主要碳排放源。2）在高速公路网络中,碳排放高值路段具有集中于国家级高速公路、邻近经济发达和人口密集区、邻近机场和港口等空间特征。客车碳排放高值路段主要集中在珠三角区域,沿广州市向外呈放射状分布;货车碳排放高值路段主要分布在国家级高速公路,且货车载货量越小,碳排放空间分布越集中。3）广东省高速公路碳排放较高的地市多集中在珠三角城市群,广州市城市首位效应突出。县区尺度下,高速公路碳排放的空间非均衡特征显著,碳排放较高的县区多为广州市和佛山市下属县区。