放养前后鱼塘沉积物中氮、磷、有机质、色素的变化及环境意义

通过对针塘沉积物中营养盐,有机质及色素在放养前后的测试,对比分析了在人类活动（养殖）的影响下,由于鱼塘水体快速富营养化而引起底质上述指标的变化过程,其中快速沉积环境极有利于沉积色素的保存,具有较好的环境营养状况指示意义,同时有机质,色素和营养盐之间存在着密切的相关关系,这为利用色素方法研究短时间序列环境演变,尤其是在近代人类活动影响下的环境变化提供了一定的依据。     

南四湖现代沉积物中营养元素分布特征

对南四湖不同湖区20个表层沉积物和独山湖湖区沉积岩芯中营养元素进行了分析结果表明表层沉积物中南阳湖总磷最高,独山湖次之;独山湖总有机碳和总氮含量最高,南阳湖次之;而昭阳湖总有机碳、总氮和总磷含量较低.沉积岩芯中137Cs数据表明南四湖独山湖区柱状沉积物上部(0-18 cm)沉积速率为3.5mm/a;总有机碳、总氮和总磷含量主要集中在沉积岩芯0-8 cm内,并呈现一致的垂向分布规律,具有明显的三阶段分布特征,反映了流域社会经济的发展导致营养元素的释放量增加,造成了湖泊现代沉积物中营养元素的积累.碳氮比值处于7.6-11.4之间,有机质的选择性分解不明显,指示沉积物中有机质主要来自无纤维束的陆源植物.监测数据表明济宁市的城市生活污水、工农业废水排放进入南阳湖是南四湖有机质和TP富集的主要来源.     

天然有机质及其在地表环境中的重要性

天然有机质是地表各种环境介质中的重要化学组分,分布广泛.越来越多的研究已经表明:它在地表生态系统的物理、化学和生物过程中都起着十分重要的作用;它与生态系统的各个重要环节密切相关,是生态系统中能量与物质循环的重要途径.因此,天然有机质不仅是生物地球化学、生态学和环境科学等研究领域的重要内容之一,而且也是环境污染的评价、预测和治理研究中的基础理论问题,是目前环境质量、毒理学、环境立法和管理研究共同关注的科学问题.本文主要以陆地地表淡水湖泊与河流水环境为例,对天然有机质的来源、化学结构、循环特征,与养分循环的耦合关系,对有毒金属元素和有机污染物迁移转化和毒性影响机理等几个方面的研究进展进行了简要的总结;针对我国水体富营养化和环境污染等重要环境问题,阐述当前应该采取的研究思路和存在的主要科学内容,并对现代有机环境与生物地球化学学科的研究趋势进行了展望.     

固城湖沉积物中可溶有机质成分及古气候环境意义

通过江苏固城湖ＧＳ１钻孔中可溶有机质成分的全面分析,揭示了可溶有机质中正烷烃,脂肪酸,醇类等生物标志化合物的组成与剖面变化特征,探讨了该湖泊生物输入状况,沉积环境以及沉积物物源的变化。研究表明,固城湖沉积物中有机质以外源高等植物输入为主,湖区１２．２ｋａＢＰ以来古气候总体呈升温趋势,并且暖期对应于湖泊内源藻类,细菌类的繁盛和湖泊生产力的提高。     

有机质对城市污染河道沉积物铵态氮吸附-解吸的影响

采集污染程度不同的城市河道沉积物(通吕运河、濠河和通甲河),在分析H2O2对沉积物有机质和铵态氮影响的基础上,分析沉积物在去除有机质前后铵态氮释放动力学和吸附热力学过程,研究城市污染河道沉积物有机质对铵态氮吸附-解吸的影响.结果表明:单位体积H2O2对有机质去除率随H2O2使用量增多而降低;去除有机质后,沉积物铵态氮含量显著增加,通吕运河、濠河和通甲河铵态氮最大含量分别是有机质去除前的4.16、3.55和2.85倍;沉积物对铵态氮的饱和吸附量随有机质含量减少而下降;沉积物铵态氮释放过程均表现为先快速释放,后减缓至平衡过程;去除有机质后,随着有机质含量的减少,沉积物铵态氮的最大释放量呈增大趋势;沉积物有机质和铵态氮含量是影响沉积物铵态氮释放的主要因素.     

藻源性有机质对高原深水湖泊沉积物矿化作用的激发效应

湖泊营养水平提升,浮游植物快速增殖,大量藻类碎屑沉降到沉积物表面。藻屑作为新生不稳定有机质,对湖泊沉积物有机质(SOM)产生激发效应,影响湖泊沉积物碳循环过程。本文以深水湖泊抚仙湖南湖心沉积物为研究对象,采用优势种水华束丝藻(Aphanizomenon flos-aquae),进行不同浓度藻屑添加(×1倍组、×5倍组和×10倍组)的培养实验。应用碳同位素在线监测仪,探究藻屑添加对于SOM矿化作用的激发效应并预测可能产生的环境效应。结果表明：(1)添加的藻屑对上覆水和间隙水发光性溶解性有机质(CDOM)组成和性质产生影响,前期CDOM中类蛋白组分含量显著增加,但后期CDOM腐殖化程度升高。同时,藻屑的添加使二氧化碳(CO₂)释放量增大,蛋白酶活性和转化酶活性增强;(2)3个不同浓度的藻屑添加组均检测到不同程度激发效应,其中×1倍组和×5倍组对SOM矿化过程前期体现为正激发效应,最大值分别达到(12.18±0.65)和(26.60±9.14)μg/(mL ws),后期两个组别都转为负激发效应;×10倍组则在整个实验过程中均表现为负激发效应;(3)藻屑的添加使得间隙水易...     

富营养化湖泊沉积物有机质矿化过程中碳、氮、磷的迁移特征

采用室内培养的方法,以富营养化湖泊太湖为例,研究了沉积物有机质矿化过程中碳、氮、磷的迁移特征.结果表明,在沉积物中的有机质矿化过程中,碳以溶解性无机碳释放至水中,同时以CH4和CO2形式释放至大气中,培养结束时,CH4和CO2累积排放含量分别为1492.21和498.96 mg/g(dw),其中CH4占气态碳的89.16%(以C质量计);此外,大量的氮、磷营养盐释放至上覆水体,水中总氮、总磷和铵态氮的最高浓度分别是初始浓度的62.16、28.16和139.45倍,而硝态氮浓度在整个培养过程中逐渐下降,培养末期浓度是初期的0.21倍;厌氧条件下,沉积物有机质的矿化,不仅可以生成大量的CH4、CO2气体,还能够促使沉积物中铵态氮和磷的释放;而沉积物有机质矿化释放的碳、氮、磷营养元素又能加剧湖泊富营养化程度,促进湖泊水体的初级生产力,从而增加湖泊沉积物有机质输入.这样的循环方式可能是湖泊富营养化自维持的重要机制之一.     

云南阳宗海表层沉积物有机质组成结构对磷赋存形态特征的影响

利用连续提取分级的方法定量分析阳宗海表层沉积物磷赋存形态,阐明了沉积物C、N、H和O组成及溶解有机质(DOM)紫外-可见光谱特征,探讨沉积物元素组成及DOM组成结构对不同形态磷含量的影响.结果表明:(1)沉积物潜在可移动磷含量在68.67~124.70 mg/kg之间变化,平均占总磷含量的9.81%,表现为BD-PNa OH-nr PNH_4Cl-P;沉积物稳定磷含量在496.73~908.28 mg/kg之间变化,平均占总磷含量的60.86%.(2)沉积物C、N含量和疏水性DOM光谱参数A_(240-400)表现出北部高、南部低的变化趋势,但H/C、O/C和(N+O)/C摩尔比和亲水性DOM光谱参数A_(240-400)变化趋势则与之恰好相反.(3)沉积物NH4Cl-P含量与C、N和H含量之间呈显著正相关,但与H/C、O/C、(N+O)/C摩尔比和亲水性DOM光谱参数E_2/E_3值之间呈显著负相关;NaOH-rP和BD-P+NaOH-rP含量均与O含量及O/H摩尔比呈显著负相关;NaOH-rP、BD-P+NaOH-rP和HCl-P均与疏水性DOM光谱参数A_(240-400)值之间呈显著正相关.因此,天然有机质元素组成及官能团结构是影响沉积物磷赋存形态的重要因素.     

珠江口沉积物溶解性有机质来源及光谱特征的空间变化

作为海陆交互作用的重要区域,河口在海洋碳循环中扮演着重要角色.近年来,溶解性有机质(dissolved organic matter,DOM)在河口区的来源、降解和保存一直是关注的热点.本研究结合三维荧光光谱和紫外可见吸收光谱,对珠江口3个沉积柱(SI、S2、S3站位,盐度依次增加)孔隙水溶解性有机质的空间分布和来源进...     

泥质沉积物和泥岩中有机质的赋存形式与富集机制

运用多学科的、系统的分析方法, 研究泥质沉积物和泥岩中有机质赋存形式与富集机制的差异性. 黏土粒级的有机碳和氯仿沥青A含量明显高于其他粒级, 说明黏土矿物对富集有机质具重要作用; 其中氯仿沥青A含量增加尤为显著, 表明黏土矿物富集的主要是可溶有机质. 热重(TG)和差热分析(DTA)结果显示, 有机质富集和赋存形式具明显的多样性, 除在黏土粒级中主要富集可溶有机质外, 在其他粒级中见大量的生物碎屑和无定形有机质的存在, 在DTA曲线上表现为多个放热峰的出现. 泥岩样经不同方法预处理后, 进行X射线衍射(XRD)和DTA分析. 在XRD曲线上黏土矿物层间距随温度变化, DTA曲线上的有机质放热峰也随温度变化. 在350℃附近黏土矿物层间距与有机质放热峰的变化具有一致性, 且极其稳定, 这是有机质进入黏土矿物层间形成有机黏土复合体的显著特征. 由此可见, 有机质与黏土矿物结合并不完全是简单的表面吸附, 部分有机质进入到黏土矿物的层间, 形成非常稳定的有机质黏土复合体. 有机质在沉积物和泥岩中的保存形式和富集机制的研究对于深入理解全球碳循环过程和通量, 以及评价有机质的生烃过程具有重要意义.     

Characterization of Organic Contaminants in New York/New Jersey Harbor Sediments Using FTIR‐ATR and Synchrotron FTIR

Dredging and remediation of contaminated Harbor sediments requires characterization of organic pollutants. In this paper, we apply a combination of Fourier transform IR attenuated total reflectance (FTIR‐ATR) and synchrotron FTIR techniques to the investigation of sediments and related materials from New York/New Jersey Harbor and other locations. The FTIR techniques give information on the functional groups of the compounds found in the sediments and make possible measurements with a spatial resolution of about 0.015 mm. Comparisons of natural organic materials namely, river and groundwater humic substances, recent marine and lacustrine sediments, and ancient sedimentary kerogen show that contaminated NY/NJ Harbor sediments display a strong and distinct absorption in their IR spectra at 2850–2950 cm^?1 identified as a C? H stretching band, indicative of the presence of anthropogenic hydrocarbons. We suggest that the presence of this band could be used for rapid screening for the presence of contaminant organic compounds in sediments encountered in dredging operations and/or as an indicator for the efficacy of sediment decontamination technologies used for treatment of dredged material.     

湖泊沉积有机碳同位素与环境变化的研究进展

湖泊沉积有机质稳定碳同位素（δ^13Corg)在区域气候与环境变化方面的应用近年来发展迅速,成果令人瞩目,保存在各类湖泊岩芯中的δ^13Corg记录揭示了晚更新世以来大气CO2浓度的变化、湖泊水位波动、湖区生态与植被的变迁以及气温变化等重要环境信息,由于造成δ^13Corg值变化的影响因素较多,确定个湖与环境变化有关的主导因素时常有赖于其它证据的帮助,诸如地球化学、古湖沼学、孢粉学、分子同位素地层学等等,前人通过研究来自不同类型湖泊、具不同曲线形态特征的δ^13Corg记录,提出了多种环境解释模型,本文对此作了归纳和评述。鉴别和澄清湖泊沉积有机质的源物质以及有机物源随环境变化而发生过的变化,是研究δ^13Corg记录环境意义至关重要的基础性工作,由于有机质含量、碳氮比值、氢指数、生物残留物鉴别等常能提供有关有关湖泊有机质来源、产率、成岩作用等方面的有用信息,这方面的研究结果应该尽可能一并提供,以利于恰当地应用现有的环境解释模型,或者建立个湖新模型,单体生物标志化合物鉴别通常也能为区分湖积有机质中陆生、水生、细菌生等不同碳的来源提供有用信息,特定化合物同位素分析技术近年来成功地应用于建立单体生物标志化合物碳同位素地层学,为湖积有机碳同位素在生态环境演变研究方面的应用提供了思路,我国许多湖泊的湖底沉积岩芯尚未钻取,那些对过去全球变化研究有价值的δ^13Corg记录有待我们去获取和研究。     

陕西红碱淖近百年来环境变化的湖泊沉积记录

本文通过岩性、粒度、磁化率、有机碳、化学元素的多指标综合分析,对陕西红碱淖近百年以来的环境演化进行了探讨。红碱淖于1927年后开始成湖,以较低的磁化率值、低湖泊生产力和较高的Fe/Mn比值为特征;1952-1960年,为短暂湖泊快速扩张时期,在沉积物中表现为粘粒含量一度下降、各元素浓度明显被稀释;自1960年以来,岩性和指标特征反映了该湖演化为稳定的深湖环境。湖泊的形成和扩张与区域降水量的增加有关,而50年代后期以来湖面的迅速扩大同时得益于人类滩地疏导导致的入湖水量增加。人类活动也引起了近40年来湖泊生产力的提高和沉积物-水界面氧系统的变化。此外,钻孔粒度特征较好地分辨出20世纪30年代末至40年代3次强沙尘暴事件。     

南四湖表层底泥重金属污染及其风险性评价

通过对南四湖表层底泥中的重金属元素浓度分析,揭示出南四湖不同湖区重金属污染物空间分布特征.利用潜在生态风险指数(RI)和地质积累指数(Igeo)两种指标相结合的方法对表层底泥中重金属污染程度进行评价.结果表明,南四湖上级湖的重金属污染主要以汞为主,并依据潜在生态风险指数将南四湖上级湖分为三个生态风险功能区: 昭阳湖轻污染区;独山湖中等污染区和南阳湖重污染区.     

Pesticide and Herbicide Residues in Sediments and Seagrasses from the Great Barrier Reef World Heritage Area and Queensland Coast

Pesticides and herbicides including organochlorine compounds have had extensive current and past application by Queensland's intensive coastal agriculture industry as well as for a wide range of domestic, public health and agricultural purposes in urban areas. The persistent nature of these types of compounds together with possible continued illegal use of banned organochlorine compounds raises the potential for continued long-term chronic exposure to plants and animals of the Great Barrier Reef. Sediment and seagrass samples were collected from 16 intertidal and 25 subtidal sampling sites between Torres Strait and Townsville, near Mackay and Gladstone, and in Hervey and Moreton Bays in 1997 and 1998 and analysed for pesticide and herbicide residues. Low levels of atrazine (0.1–0.3 μg kg⁻¹), diuron (0.2–10.1 μg kg⁻¹), lindane (0.08–0.19 μg kg⁻¹), dieldrin (0.05–0.37 μg kg⁻¹), DDT (0.05–0.26 μg kg⁻¹), and DDE (0.05–0.26 μg kg⁻¹) were detected in sediments and/or seagrasses. Contaminants were mainly detected in samples collected along the high rainfall, tropical coast between Townsville and Port Douglas and in Moreton Bay. Of the contaminants detected, the herbicide diuron is of most concern as the concentrations detected have some potential to impact local seagrass communities.     

Alkaline Degradation of Dissolved Organic Matter

The degradation of dissolved organic matter (DOM) was studied in alkaline solution. The products were characterised using UV/vis spectroscopy, size‐exclusion chromatography (SEC), and by the analysis of low‐molecular‐weight organic acids (LMWOA). The degradation experiments were performed with water from a brown water lake or its isolated fulvic acid fraction and sodium hydroxide at different reaction times and temperatures. Depending on the wavelength and the reaction time, the UV/vis absorbance between 230 nm and 600 nm increased or decreased. The behaviour of model compounds during reactions in alkaline media was compared to the UV/vis spectroscopic behaviour of DOM. The release of LMWOA was described by kinetic data and compared to the data of model reactions. Evidence was given for the carboxylic esters playing a significant role in the release of LMWOA only during the beginning of the alkaline degradation. The results gained by SEC with on‐line UV and DOC detection showed that the average size of DOM was decreasing, and that a major part of the degradation products consisted of low‐molecular‐weight mono‐ and dicarboxylic acids.     

A Review Of Environmental Applications Of Quasi-Stationary Electromagnetic Techniques

Electromagnetic (EM) techniques are the most commonly used geophysical methods in mineral exploration. However, the use of EM measurements for environmental and engineering applications like the detection of contaminant plumes or the exploration of waste sites is relatively new.The reason for the success of the application of EM methods to environmental problems lies in the variation of conductivity caused by different geometry of pore fluids and clay contents in rocks, and by the presence of organic and inorganic contaminants.Many EM methods/instruments used for mapping near surface geology exist and nowadays they play a central role in environmental geophysics. In general, these methods can be classified in two blocks: EM methods using a plane wave source of excitation and EM methods using a controlled source like a magnetic dipole or a loop source. The Very Low Frequency (VLF, VLF-R) and Radiomagnetotelluric (RMT) methods are chosen as representative methods for plane wave techniques, while horizontal loop EM methods operating in low induction numbers (EM31, EM34) and Transient Electromagnetic methods (TEM) are chosen as representatives of magnetic dipole or loop source techniques. Basic principles, advantages and disadvantages of each technique as well as their connection to specific environmental problems will be discussed.Different successful applications of these methods are reported in the literature. However, this review will focus on three major subjects: waste site exploration, detection of contaminated earth layers, and groundwater exploration. Case histories are presented illustrating the suitability of EM methods for solving such problems.