西江水体有机碳含量变化及悬浮物碳同位素的意义

以西江马口断面水体为研究对象,讨论其有机碳含量、悬浮物同位素组成(δ¹³C、Δ¹⁴C)与环境之间的关系。西江马口断面有机碳含量呈现季节性变化,其中颗粒有机碳(POC)含量范围介于0.13~4.98mg/L之间,溶解有机碳(DOC)含量范围介于0.98~4.17mg/L之间,DOC/POC比值为1.34,远低于世界多数河流之比值。近年来马口断面悬浮物POCδ¹³C的变化范围介于-21.3‰~-26.1‰之间,随时间出现整体性漂移现象,表明流域生态环境整体改善。POCΔ¹⁴C变化范围介于-132‰~-425‰之间,与取样期间的流域降水过程及土壤的侵蚀相关。     

河水中悬浮颗粒物对重金属的吸附行为

本研究以瓯江河水为对象,研究河水中悬浮颗粒物对重金属（Cu、Zn、Cd、Pb）离子的吸附行为．分别进行了Cu、Zn、Cd、Pb在悬浮颗粒物的吸附速率,解吸速率以及溶解性有机质（DOM）对吸附解吸行为的影响实验．结果表明：河水中悬浮颗粒物对Cu、Zn、Cd、Ph的吸附和解吸速率较快,吸附平衡时间为8h,解吸平衡时间为4h...     

南极南设得兰群岛附近海域表层沉积物中有色溶解有机物的分布特征及来源分析

在南极南设得兰群岛附近海域采集了6个表层沉积物样品,测定了提取液中溶解有机物(DOM)的有机碳含量、紫外-可见吸收光谱和三维荧光光谱,并对有色溶解有机物(CDOM)的分子量信息及各荧光组分的成分和来源进行了分析。结果表明,南设得兰群岛附近海域表层沉积物中DOM提取液的溶解有机碳(DOC)及沉积物有机碳(SOC)的含量呈现由近岸向开阔海域递减的趋势,紫外-可见吸收光谱中的吸收系数(a)也表现出了相似的性质,光谱斜率比(SR)表明近岸沉积物CDOM老化程度较强。通过对三维荧光光谱的分析可知,南设得兰群岛附近海域表层沉积物中的CDOM包含3种荧光组分,即类色氨酸、海洋类腐殖质和陆源类腐殖质,表现出较强的自生源特征,整个研究海域CDOM来源以内源为主,受陆生植物和土壤有机质的外源输入影响较小。通过CDOM各参数的相关性分析发现,沉积物DOM提取液的DOC含量与SOC含量以及吸收系数和腐殖化指数(HIX)等参数相互之间都呈显著正相关,相关系数(r)均在0.88以上,显著性水平P0.01。     

固相萃取—热裂解—气相色谱—串联质谱法测定盐湖卤水中溶解性有机质

以青藏高原地区的大柴旦盐湖湖表卤水为研究对象,采用不同的固相萃取(Solid phase extraction,SPE)材料(HLB,PPL,ENVI-18,ENVI-Carb,XAD8和XAD4)对大柴旦盐湖湖表卤水中DOM进行了分离和富集,初步建立了从高盐体系盐湖卤水中高效分离富集出具有代表性的溶解性有机质(Dissolved organic matter,DOM)的方法,系统的考察了pH,上样体积,柱流速和洗脱溶剂对DOM回收率的影响。结合傅里叶变换红外光谱分析(Fourier transform infrared spectroscopy,FTIR)、热裂解—气相色谱—串联质谱分析(Pyrolysis-gas chromatography-mass spectrometry,Py-GC/MS)进一步对盐湖卤水分离物进行了谱学表征。研究结果表明,盐湖卤水在酸性条件下(pH=2),柱流速为0.5 mL/min时有助于吸附剂对DOM的吸附,而随着上样体积的增加,DOM的回收率逐渐下降,而甲醇是比较理想的洗脱剂。大柴旦盐湖湖表卤水中的DOM主要以芳香类,碳水化合物以及部分脂肪族化合物为主,而含氮类化合物含量较少。     

Groundwater control on the suspended sediment load in the Na Borges River, Mallorca, Spain

Groundwater dominance has important effects on the hydrological and geomorphological characteristics of river systems. Low suspended sediment concentrations and high water clarity are expected because significant inputs of sediment-free spring water dilute the suspended sediment generated by storms. However, in many Mediterranean rivers, groundwater dominance is characterised by seasonal alternations of influent and effluent discharge involving significant variability on the sediment transport regimes. Such areas are often subject to soil and water conservation practices over the centuries that have reduced the sediment contribution from agricultural fields and favour subsurface flow to rivers. Moreover, urbanisation during the twentieth century has changed the catchment hydrology and altered basic river processes due to its ‘flashy’ regime. In this context, we monitored suspended sediment fluxes during a two-year period in the Na Borges River, a lowland agricultural catchment (319 km²) on the island of Mallorca (Balearic Islands). The suspended sediment concentration (SSC) was lower when the base flow index (i.e., relative proportion of baseflow compared to stormflow, BFI) was higher. Therefore, strong seasonal contrasts explain the high SSC coefficient of variation, which is clearly related to dilution effects associated with different groundwater and surface water seasonal interactions. A lack of correlation in the Q-SSC rating curves shows that factors other than discharge control sediment transport. As a result, at the event scale, multiple regressions illustrate that groundwater and surface water interactions are involved in the sedimentary response of flood events. In the winter, the stability of baseflow driven by groundwater contributions and agricultural and urban spills causes hydraulic variables (i.e., maximum discharge) to exert the most important control on events, whereas in the summer, it is necessary to accumulate important volumes of rainfall, creating a minimum of wet conditions in the catchment to activate hydrological pathways and deliver sediment to the drainage network. The BFI is also related to sediment delivery processes, as the loads are higher with lower BFI, corroborating the fact that most sediment movement is caused by stormflow and its related factors. Overall, suspended sediment yields were very low (i.e., < 1 t km^− 2 yr^− 1) at all measuring sites. Such values are the consequence of the limited sediment delivery attributable to soil conservation practices, low surface runoff coefficients and specific geomorphic features of groundwater-dominated rivers, such as low drainage density, low gradient, steep valley walls and flat valley floors.     

在三门峡水库影响下黄河有机碳的输送特征

通在黄河三门峡水文站进行1 a的连续采样分析和调水调沙期间的密集采样分析,揭示了三门峡水库水沙调控对黄河有机碳输送过程的影响。结果表明,在水库调水调沙期间,三门峡站POC含量与TSS含量同步增加,而DOC含量变化趋势不明显;在1 a内,DOC和POC含量均有明显的季节变化。三门峡站POC年通量为124.8万t,其中调水调沙期间POC输送量约占POC年通量的38%,水库敞泄期间（8~9月）的POC输送量约占POC年通量的60%;三门峡站DOC年通量为7.6万t,其中7~9月DOC输送量约占DOC年通量的52%。     

Assessing sedimentation in a temperate dystrophic lake in the NE Atlantic seaboard region

Organic materials deposited in lacustrine environments can be derived from both aquatic and terrestrial ecosystems, and can serve as valuable indicators of catchment and in-lake ecological changes over time. However, spatial and temporal variation in the deposition of these materials within a lake basin will influence the interpretation of these sediment deposits. In this study, materials deposited in suspended sediment traps and basin sediments in Lough Feeagh, a temperate coastal humic lake, show variations in organic matter, total organic carbon and nitrogen loads, algal pigment concentrations and diatom assemblages. Sediment trap samples from three locations along with adjacent surface sediment cores show a clear north–south (inlet to outlet) gradient. C/N ratios reflected a mixture of algal and land-derived organic matter with a major peat influence, and comparisons between sediment trap and surface sediment assemblages revealed pigment and diatom assemblages influenced by lake-basin position and water depth. While some coherency between trap and sediment samples was apparent a more complicated biological response is demonstrated along with reduced water clarity in recent years thus highlighting the implications of increased allochthonous imputs for biological and biogeochemical processes in oligo-humic aquatic systems.     

黄河内蒙古段异源水沙输移特性

河流悬移质泥沙的输移方式按照水沙来源可以分为水沙同源与水沙异源两大类。黄河内蒙古段水沙来自不同的区域,冲泻质泥沙主要来源于陇西黄土高原区,而径流则主要来自唐乃亥以上的山区,呈现异源特性。通过分析内蒙古河段石嘴山与巴彦高勒水文站1951-2003年的水文数据,发现期间共发生了13次大流量和29次高含沙事件且大流量、高含沙量同时出现现象很少,多呈现大流量、低含沙量,或者小流量、高含沙量的态式。同时,通过改变传统流量-含沙量幂函数公式C_i=aQ^b(C_i为悬移质浓度,Q为流量)的参数项,建立了2种水沙异源情况下流量-含沙量的公式。     

Sources, distribution and composition of the suspended sediments, Kuwait Bay, Northern Arabian Gulf

Qualitative and quantitative assessment of suspended sediment levels and transport pathways in Kuwait's northern territorial waters are described, with special reference to Kuwait Bay. Near-surface water samples were collected from 12 stations, covering the whole of the embayment. Suspended sediment concentrations (SSCs) were derived. Heavy metal concentrations, mineralogical composition and grain size constituents were derived for the suspended sediments retained on the filter papers.The distribution pattern of the suspended sediments indicates the possibility of tidal current activity, dust fallout contribution and to a lesser extent, the effect of the Shatt Al-Arab (especially in northeastern Kuwait Bay). The distribution of various types of sediments and the variations of their textural, compositional and concentrations are controlled largely by the hydrodynamic conditions, nature of sediments.The results demonstrate clearly the potential impact of the Gulf War as manifested by the increase of SSC in 1992, compared to 1989/1990. Such an input may be attributed also to drainage processes from the Iraqi marshes. More studies are required to understand the environmental impacts of the suspended matter and the associated pollutants.     

Flood-borne sediment analysis of the Hoanib River, northwestern Namibia

The suspended sediment contained in six flood events in the Hoanib River catchment during the wet season of 1999/2000 were analysed for volatile (or low molecular weight) fine particulate organic material (FPOM), higher molecular weight FPOM and the total organic carbon (TOC). Samples were evaporated to dryness at 80 °C, then heated in a high temperature oven to 250, 550 and 850 °C. The results show that the amount of sediment carried during the flood events varied between 1.54 and 31.27 g/L, with an average of 14.62 g/L. The amount of suspended sediment in the flood-waters (2.789–616.359×10⁶ kg) was found to be dependent on the timing and duration of the flood event. The largest percentage of organic material was found in the volatile FPOM fraction (5.77±6.26%), with lesser amounts being found in the higher molecular weight FPOM (3.36±0.62%) and TOC (4.93±1.86%) fractions.     

南黄海辐射沙洲邻近海域表层悬浮颗粒物浓度遥感反演

利用2003年春、秋季南黄海辐射沙洲邻近海域水体表观光谱测量与同步水体取样数据,分析该海域不同季节表层水体遥感反射率光谱响应特性。结合常用水色传感器波段光谱响应模拟,建立春、秋季表层水体总悬浮颗粒物浓度(TSM)与悬浮泥沙浓度(SSC)的最适单波段、双波段(波段比值)和3波段统计反演模式。结果表明,不同季节水体上述3类算法的最优波段均不相同,欲寻求适合所有季节水体的统一反演算法,仅能选择次优波段。通过比较,3种不同反演模式中三波段模式更适于反演近岸水体悬浮颗粒物浓度。     

长江口潮滩有机质稳定碳同位素时空分布与来源分析

通过测定长江口潮滩悬浮颗粒有机质和表层沉积有机质在枯水季节 (2006年2月 )和洪水季节 (2006年8月 )的稳定碳同位素值,对有机质潜在来源及局部岸段改造作用进行了分析。结果显示,悬浮颗粒有机质稳定碳同位素值在2月明显低于8月,变化范围分别在-25.8‰~-23.4‰和-25.1‰~-22.9‰,主要是受径流量枯洪季变化和浮游生物生长季节变化两种因素的叠加作用。表层沉积有机质2月和8月的稳定碳同位素分别为-25.0‰~-20.4‰和-24.7‰~-19.5‰,季节变化不明显,主要来自悬浮颗粒物的沉降。除受大背景环境因素影响,局部环境对潮滩有机质也有一定的改造作用,污水、支流河水的输入对悬浮颗粒有机质碳同位素有一定的影响,埋藏的潮滩植物和底栖微藻则对沉积有机质有部分贡献。     

长江河口悬浮泥沙的混合过程

根据准同步观测的悬浮泥沙及表层沉积物粒度、流速、含沙量资料, 分析了长江口及临近海域悬浮泥沙在河口的混合过程。长江河口-陆架系统悬浮泥沙中值粒径呈现“细-粗-细”的变化规律, 河口上段悬浮泥沙中值粒径为8.9 μm, 拦门沙海域为10.5 μm, 陆架区为4.5 μm, 北支为9.9 μm, 杭州湾口为5.6 μm, 泥沙类型为粘土质粉砂。河口上段和陆架区悬浮泥沙与表层沉积物的垂向混合作用较弱, 拦门沙区域二者发生强烈的混合和交换, 悬浮泥沙在由长江河口向陆架系统输移过程中仅有表层泥沙保留了流域输入的泥沙粒度特征。长江口悬浮泥沙中值粒径与含沙量呈良好的正相关关系, 水流的剪切作用是引起拦门沙海域泥沙再悬浮、近底高含沙量和悬浮泥沙粒径增加的主要原因, 悬浮泥沙粒径和含沙量的增加主要由粉砂组分的增加引起。2007 年长江河口区范围内悬浮泥沙中值粒径比2003 年普遍减小11％, 含沙量比2003 年减小22%, 河口上段含沙量对流域来沙减少的响应最为敏感, 而拦门沙区的泥沙粒径对流域来沙减少的响应最敏感。在长江流域来沙量减少的背景下, 河口拦门沙区域仍能维持较高的含沙量, 主要缘于河口系统内部的供沙     

北部湾北部滨海湿地水体和表层沉积物中营养元素分布与污染评价

2009年4～5月,对北部湾北部滨海湿地水体和表层沉积物进行了取样调查,研究水体中营养盐和表层沉积物中碳、氮和磷元素含量、分布及其影响因素,并在此基础上评价了滨海湿地水体富营养化水平和表层沉积物的污染状况.研究区水体中的溶解无机氮(dissolved inorganic nitrogen,DIN)、活性磷酸盐PO43-—P和化学需氧量(CODMn)平均含量分别为(211.84±37.44) μg/L、(11.01±12.11) μg/L和(0.92±0.32) mg/L;表层沉积物中总氮(TN)、总磷(TP)和总有机碳(TOC)的平均含量分别为(373±355) μg/g、(232.28±157.34) μg/g和(0.45±0.46)％.北部湾北部滨海湿地水体中的DIN含量和PO43-—P含量在茅尾海和廉州湾东部西场海区都很高,且水体富营养化比较严重,大规模的海水养殖可能是造成该现象的主要原因.研究区水体中CODMn含量空间分布呈近岸高、远岸低的特征.研究区铁山港顶部、南流江口、大风江口、钦江和茅岭江口较细的表层沉积物中的TN、TP和TOC含量较高.研究区表层沉积物的TOC/TN值分布表明,钦江口、钦州港区、防城港、企沙港区和珍珠湾东北部的沉积物有机质含量受到了强烈的陆源影响.根据加拿大安大略省环境质量评价标准,除了钦州湾顶部的龙门港区、大风江口中部和铁山港顶部西北角一小部分区域的表层沉积物中的TOC、TN和TP含量分别略高于1％、550μg/g和600μg/g,已被明显污染,而处于最低级别或严重危害级别,会对部分底栖生物产生影响外,其他绝大部分区域都属安全级别,为清洁或部分已被轻微污染.     

Leaf litter age,chemical quality,and photodegradation control the fate of leachate dissolved organic matter in a dryland river

We used biodegradable dissolved organic carbon (BDOC) incubations, specific ultraviolet absorbance (SUVA_254, indicator of aromatic carbon content) and laboratory experiments to determine the bioavailability and chemical composition of dissolved organic matter (DOM) leached from fresh leaves and litter aged on a seasonally dry floodplain for 2, 4, and 6 months. Our objective was to elucidate how litter age and solar radiation affect the bacterial utilization of DOM released from floodplain leaf litter when inundated. Leachate percent BDOC ranged from 22 to 47% for three different leaf species and significantly decreased (p < 0.05) with increasing litter age. However, total BDOC (mg C L⁻¹) was unrelated to litter age. Bacterial utilization of DOM leachate collected from litter aged on the floodplain for four and six months significantly increased following 48 h of irradiation for all species but there was no difference for leachate from fresh and two month old litter. The photo-mediated increase in percent BDOC was concomitant with a decrease in aromatic carbon content, as SUVA₂₅₄ values decreased on average 9 ± 6% for light exposure experiments. Our findings demonstrate that sunlight moderates the degradation of plant litter in the terrestrial environment through the photo-mediated shift in DOM composition and its bioavailability in streams.     

Role of landscape parameters in riverine run-off,and sediment and organic matter yield on Disko Island,West Greenland

Measurements of discharge and suspended sediment and organic matter yield from nine different drainage basins on the island Disko in central West Greenland were carried out in the period 19–30 July 1997. A series of landscape properties (glacier cover, altitude, slope, aspect and vegetation cover) were measured for each drainage basin from a digital elevation model and a satellite image. Principal Component Analysis and regression statistics have been used to examine which landscape parameters dominate the measured discharges and yields. It is concluded that differences in suspended sediment and organic matter yield between the drainage basins can be explained by the measured morphometric properties while differences in water run-off can not. Glacier cover percentage and percent area above 800 m a.s.l. were the most important parameters influencing suspended sediment and organic matter yield in the drainage basins on Disko during the study period.     

湘东丘陵区4种林地深层土壤溶解性有机碳的数量和光谱特征

选取湘东丘陵4种典型母质发育的林地土壤,挖掘土壤剖面并分层采集土壤样品至母质层/母岩,研究深层土壤有机碳（SOC）和溶解性有机碳（DOC）的数量和分布规律,采用紫外-可见光谱技术分析深层土壤DOC的宏观化学结构特征。结果表明,土壤DOC含量（2.33~185.26 mg·kg^-1）在板岩红壤和酸性紫色土剖面上某些深层土层出现升高现象。DOC/SOC除第四纪红土红壤在浅层表土最高（1.5%）外,其他3种土壤均在60~80 cm深层土层达到最高峰值（1.0%~2.5%）。SOC数量是控制不同母质土壤DOC数量的重要因素。但光谱分析显示,随着土壤剖面的加深,DOC的宏观化学组成、结构趋于复杂,化学稳定性升高。尽管一些深层土层中DOC/SOC升高,但其DOC化学结构更为复杂,评价深层土壤SOC和DOC稳定性还应考虑其化学结构特性。     

Magnitude and frequency of landsliding in a large New Zealand catchment

Knowledge of long-term average rates of erosion is necessary if factors affecting sediment yields from catchments are to be understood. Without such information, it is not possible to assess the potential influence of extreme storms, and, therefore, to evaluate the relative importance of various components of a sediment budget. A study of the sediment budget for the Waipaoa catchment, North Island, New Zealand, included evaluation of long-term rates of landsliding for six landslide-prone land systems in the catchment. The number of landslides per unit area generated by each of several storms was counted on sequential aerial photographs and correlated with the magnitude of the corresponding storm. The resulting relationships were combined with magnitude–frequency relationships derived for storms from 70- to 100-year rainfall records in the area to estimate a long-term magnitude–frequency relationship for landsliding for each land system. The long-term average values of the areal landslide frequency (number of slides per unit area per unit time) were then calculated from these relationships. The volumes of a sample of landslide scars were measured in the field, and the proportion of slides that deliver sediment to channels was determined from aerial photographs. These measurements then allowed calculation of the long-term average rate of sediment production to streams from landslides for different land systems and types of vegetation. Results suggest that shallow landslides currently contribute about 15±5% of the suspended sediment load in the Waipaoa River above the Kanakanaia gauging station, and that 75% of the sediment production from the landslides occurs during storms with recurrence intervals of less than 27 years. Reforestation of 6.3% (93 km²) of the slide-prone lands in the catchment between 1990 and 1995 resulted in a calculated decrease in slide-derived sediment of 10%. Calculations suggest that reforestation of an additional 3% (66 km²) of the catchment in areas with the most sensitive combinations of land system and storm regime could decrease the total sediment inputs from landsliding by about 20%.     

WHY MONITOR CARBON IN HIGH‐ALPINE STREAMS?

In this short communication, we report on dissolved organic and inorganic carbon concentrations from a summer stream monitoring campaign at the main hydrological catchment of the Tarfala Research Station in northern Sweden. Further, we place these unique high‐alpine observations in the context of a relevant subset of Sweden's national monitoring programme. Our analysis shows that while the monitoring programme (at least for total organic carbon) may have relatively good representativeness across a range of forest coverages, alpine/tundra environments are potentially underrepresented. As for dissolved inorganic carbon, there is currently no national monitoring in Sweden. Since the selection of stream water monitoring locations and monitored constituents at the national scale can be motivated by any number of goals (or limitations), monitoring at the Tarfala Research Station along with other research catchment sites across Fennoscandia becomes increasingly important and can offer potential complementary data necessary for improving process understanding. Research catchment sites (typically not included in national monitoring programmes) can help cover small‐scale landscape features and thus complement national monitoring thereby improving the ability to capture hot spots and hot moments of biogeochemical export. This provides a valuable baseline of current conditions in high‐alpine environments against which to gauge future changes in response to potential climatic and land cover shifts.     

黄河下游主槽断面形态对水沙变化响应过程的模拟

准确把握环境变化下前期水沙条件对当前河床形态调整的影响,建立非平衡态河床形态调整的模拟方法,对深化河床非平衡调整过程的认识至关重要。基于黄河下游花园口—利津河段1965—2015年的水沙和沿程82个大断面数据,首先统计分析了不同河段主槽断面形态参数（面积、河宽、水深和河相系数）的调整过程及其对水沙变化的响应规律;进而以水沙因子作为主槽断面形态调整的主控因素,采用滞后响应模型的多步递推模式,建立了其对前期水沙条件变化的滞后响应模型。结果表明,各河段面积、河宽和水深经历了减小—增加—减小—增加的变化过程,并且其与4 a滑动平均流量和含沙量之间分别呈正相关和负相关;而河相系数孙口以上段整体减小,孙口以下段呈增加—减小—增加—减小的变化过程,除花高段1965—1999年外,其与流量呈负相关,与含沙量呈正相关。滞后响应模型在黄河下游主槽断面形态对前期水沙条件响应过程的应用表明,各参数模型计算值与实测值符合程度均较高,模型能够很好地模拟主槽断面形态对水沙变化的响应调整过程,模型计算结果显示主槽断面形态调整受当年在内的前8 a水沙条件的累积影响,当年和前7 a水沙条件对当前断面形态的影响权重分别约为30%和70%。本文模型有助于深化前期水沙条件对当前河床形态调整影响机理的认识,并为未来不同水沙情形下主槽断面形态的预测提供了有效计算方法。