土壤中水溶性有机质及其对重金属化学与生物行为的影响

土壤水溶性有机质是陆地生态系统和水生生态系统中一种重要的、很活跃的化学组分,已成为环境科学、土壤学和生态学等学科的研究热点．土壤DOM对重金属化学与生物行为有重要影响。但其机理尚不清楚．文中从土壤性质、环境条件、人为因素等方面阐述了土壤DOM产生及影响因素,总结评述了DOM对重金属化学行为和生物有效性的影响,将DOM对重金属的影响机制归纳为络合机制、竞争吸附机制、酸碱缓冲机制．在此基础上,提出了DOM研究存在的问题及其展望．     

城市污泥应用于陆地生态系统研究进展

随着城市化进程加快和人口剧增,城市污泥已成为世界许多城市面临的主要环境问题之一,且不合理的管理可引发严重的环境污染.城市污泥含有大量、微量元素和有机质,可能对土壤及其生产力有利,特别对退化土壤能进行有机修复,并改善土壤理化特性,譬如土壤结构和营养含量.目前,污泥作为一种有机肥料已成为普遍措施.但来自工业及生活污水的污泥常含有重金属、病原物及有毒有机物等,潜在的毒性可能对生态系统构成危险,因此必须经过污泥预处理才可安全施用.评述了近年来国内外污泥应用于陆地生态系统4个方面的主要研究进展:(1)污泥处理与处置方法;(2)污泥应用于农田、草地及森林生态系统;(3)污泥对土壤生态系统的影响,包括污泥对土壤理化性质、土壤酶及微生物的影响;(4)污泥应用的环境效应.提出未来我国污泥处置及利用需要重视的研究领域和方向.     

水溶性有机质对土壤中镉吸附行为的影响

水溶性有机质 (DOM)是陆地生态系统和水生生态系统中的一种很活跃的组分 .本文以赤红壤、水稻土和褐土作为供试土壤 ,研究了来源于稻秆和底泥的DOM对土壤中Cd吸附行为的影响 .DOM对土壤中Cd的吸附行为具有明显的抑制作用 .这种抑制作用与土壤类型和DOM种类有关 .在 3种供试土壤中 ,无论添加稻秆DOM还是底泥DOM ,都会使Cd的最大吸附容量和吸附率明显降低 ,其下降幅度为17 3%～ 93 9%.在添加同一种DOM的前提下 ,DOM对Cd吸附的抑制作用均为 :赤红壤 >水稻土 >褐土 .如果不添加DOM ,则土壤对Cd的最大吸附容量主要取决于土壤固相的吸附特性 ,添加DOM后土壤对Cd的最大吸附容量则主要取决于液相中的DOM .由此推断 ,传统的看法 ,通过施用有机肥来固定土壤中的Cd并达到治理重金属污染土壤的观点值得商榷 .     

陆地生态系统可溶性有机氮研究进展

可溶性有机氮(dissolved organic nitrogen DON)的流动是陆地生态系统氮循环的重要组成部分。本文就陆地生态系统DON的来源、组成、性质;森林生态系统DON的流动、季节动态以及DON在氮循环中的地位等方面作了概括和探讨。今后的陆地生态系统DON的研究应该集中在以下几个方面：确定陆地生态系统中DON的各分室DON的浓度、流量;DON的源与汇问题;量化不同生态系统中DON库的大小和组成;研究DON在氮的矿化、微生物的固持、以及植物吸收等氮循环过程中的地位;对比研究DON与DOC(dissolved organic carbon)的动态差别;探讨DON与植物营养和碳积累的关系等。     

大尺度陆地生态系统状态变化及其资源环境效应的立体化协同联网观测

环境变化和人类活动的双重驱动正在快速地改变地球生态系统状态,呈现出了众多级联的资源环境问题,生态系统的状态变化和时空演变驱动因素以及相应的资源环境效应是大尺度陆地生态系统科学研究的永恒主题.观测和评估生态系统状态变化,发现和理解生态系统响应机制,认知和描述生态系统演变规律,预测和预警生态系统演变趋势,都依赖于大陆及全球...     

气候变化对陆地生态系统土壤有机碳储量变化的影响

通过研究气候变化对土壤有机碳储藏的影响,对预测未来气候变化下土壤有机碳动态变化与深入理解陆地生态系统变化和气候变化之间的相互作用有着极其重要的意义。本文归纳了土壤类型法、模型模拟法等途径对土壤有机碳储量估算的结果并分析它们各自的不确定性,综述了气候变化对土壤碳贮藏影响机理的研究与相应过程模拟的模型研究进展,并综合分析了当前研究中还存在的问题与不足。     

菌根真菌在陆地生态系统中的作用

对菌根真菌在陆地生态系统中与植物共生、固定土壤中的营养元素及水分、作为动物的食物以及影响植物群落的演替和区系组成以及调节生态系统中的资源配置、维持系统的物种多样性等方面的生态作用进行了讨论。     

臭氧污染与陆地生态系统生产力

空气污染的严重性、普遍性和不断发展的趋势及其对陆地生态系统生产力造成的重大影响已引起科学工作者的高度重视,成为一个急需解决的重要课题。对流层臭氧(O₃)在空气污染现状与未来发展趋势中占据重要角色,该文重点探讨了O₃对陆地生态系统生产力的光合、分配、生长和产量形成等主要过程的影响及其对整个生态系统的长期效应,并评述了相关研究方法进展。主要结论包括:O₃在生产力形成过程中的每个环节中都有着不同程度的负面影响,通过影响光合作用和气孔导度,减少根冠比改变碳分配量,而最终导致粮食生产和森林生物量损失率高达30%;气候变化、CO₂和O₃协同作用对植物影响较为复杂,有促进也有抑制;生态系统模拟已成为研究O₃污染影响陆地生态系统生产力的主要方法之一,在区域评估和未来气候预测方面都具有重要作用。     

全球变化生态学:全球变化与陆地生态系统

工业革命以来,伴随着人类社会的飞速发展,地球系统的物质循环也在不断加速,与此同时,大量的工业污染物和有害废弃物累积于大气、水体、土壤和生物圈中,如氟里昂积存于大气中,有机化合物富集于水生生物体内,化石燃料燃烧释放的污染物和温室气体进入大气、水体、土壤和生物体等。     

大尺度陆地生态系统动态变化与空间变异的过程模型及模拟系统

当代生态系统科学研究更加关注区域生态环境及生态系统状态变化的监测、评估、预测、预警及生态环境可持续管理.在深入理解陆地生态系统的要素、过程、功能、格局及其相互作用机理基础上,发展生态系统定量化描述方法和数值模拟技术,集成构建大陆尺度的多过程耦合-多技术集成-多目标应用的陆地生态系统数值模拟器已成为生态系统与全球变化...     

Composition,Dynamics, and Fate of Leached Dissolved Organic Matter in Terrestrial Ecosystems: Results from a Decomposition Experiment

Fluxes of dissolved organic matter (DOM) are an important vector for the movement of carbon (C) and nutrients both within and between ecosystems. However, although DOM fluxes from throughfall and through litterfall can be large, little is known about the fate of DOM leached from plant canopies, or from the litter layer into the soil horizon. In this study, our objectives were to determine the importance of plant-litter leachate as a vehicle for DOM movement, and to track DOM decomposition [including dissolve organic carbon (DOC) and dissolved organic nitrogen (DON) fractions], as well as DOM chemical and isotopic dynamics, during a long-term laboratory incubation experiment using fresh leaves and litter from several ecosystem types. The water-extractable fraction of organic C was high for all five plant species, as was the biodegradable fraction; in most cases, more than 70% of the initial DOM was decomposed in the first 10 days of the experiment. The chemical composition of the DOM changed as decomposition proceeded, with humic (hydrophobic) fractions becoming relatively more abundant than nonhumic (hydrophilic) fractions over time. However, in spite of proportional changes in humic and nonhumic fractions over time, our data suggest that both fractions are readily decomposed in the absence of physicochemical reactions with soil surfaces. Our data also showed no changes in the ¹³C signature of DOM during decomposition, suggesting that isotopic fractionation during DOM uptake is not a significant process. These results suggest that soil microorganisms preferentially decompose more labile organic molecules in the DOM pool, which also tend to be isotopically heavier than more recalcitrant DOM fractions. We believe that the interaction between DOM decomposition dynamics and soil sorption processes contribute to the ¹³C enrichment of soil organic matter commonly observed with depth in soil profiles. published online 2004     

Dissolved Organic Carbon in Terrestrial Ecosystems: Synthesis and a Model

The movement of dissolved organic carbon (DOC) through soils is an important process for the transport of carbon within ecosystems and the formation of soil organic matter. In some cases, DOC fluxes may also contribute to the carbon balance of terrestrial ecosystems; in most ecosystems, they are an important source of energy, carbon, and nutrient transfers from terrestrial to aquatic ecosystems. Despite their importance for terrestrial and aquatic biogeochemistry, these fluxes are rarely represented in conceptual or numerical models of terrestrial biogeochemistry. In part, this is due to the lack of a comprehensive understanding of the suite of processes that control DOC dynamics in soils. In this article, we synthesize information on the geochemical and biological factors that control DOC fluxes through soils. We focus on conceptual issues and quantitative evaluations of key process rates to present a general numerical model of DOC dynamics. We then test the sensitivity of the model to variation in the controlling parameters to highlight both the significance of DOC fluxes to terrestrial carbon processes and the key uncertainties that require additional experiments and data. Simulation model results indicate the importance of representing both root carbon inputs and soluble carbon fluxes to predict the quantity and distribution of soil carbon in soil layers. For a test case in a temperate forest, DOC contributed 25% of the total soil profile carbon, whereas roots provided the remainder. The analysis also shows that physical factors—most notably, sorption dynamics and hydrology—play the dominant role in regulating DOC losses from terrestrial ecosystems but that interactions between hydrology and microbial–DOC relationships are important in regulating the fluxes of DOC in the litter and surface soil horizons. The model also indicates that DOC fluxes to deeper soil layers can support a large fraction (up to 30%) of microbial activity below 40 cm. Received 14 January 2000; accepted 6 September 2000     

水溶性有机物对黑麦草吸收铜的影响

采用水培试验,研究蚓粪及蚯蚓培养载体牛粪中水溶性有机物(DOM)对不同Cu2+浓度下(0、5、10 mg·L-1)黑麦草吸收Cu2+的影响.结果表明:随着Cu2+浓度的增加,黑麦草地上部、根干质量,以及根系的长度、表面积、体积和根尖数均逐渐下降;DOM显著增加了Cu2+处理下黑麦草地上部及根系生物量,促进了其根系的长度、表面积、体积和根尖数的增长.DOM降低了黑麦草地下部Cu2+浓度,促进了Cu2+从地下部向地上部的运输,显著增加了地上部Cu2+积累量.蚓粪DOM对黑麦草的影响优于牛粪DOM,并且供试高浓度DOM效果优 于低浓度.     

森林生态系统DOM的来源、特性及流动

可溶性有机物质（Dissolved Organic Matter)是森林生态系统主要的可移动碳库及重要的养分库。系统综述了森林生态系统DOM的来源,组成,性质,季节动态;DOM释放与存留机制及影响因素,森林生态系统DOM的流动及干扰对DOM动态影响等,已有研究表明DOM的森林生态系统C、N、P循环,成土作用,污染物迁移等方面起着重要作用。今后森林生态系统DOM的研究应集中于以几方面：（1）确定森林生态系统中DOM源和汇;（2）评价森林水文条件对DOM释放与存留的调节作用;（3）探讨全球气候变化对森林生态系统DOM的影响;（4）可溶性有机氮（Dissolved Organic Nitrogen),可溶性有机磷（Dissolved Organic Phosphorus)动态与可溶性有碳（Dissolved Organic Carbon）动态的差别。     

吉安地区典型景观湖泊浮游植物群落特征及其与水环境因子的关系

2012年8月至2013年7月,对吉安地区将军湖、龙湖、庐陵湖和挹翠湖4个景观湖泊水体浮游植物群落及其主要水环境因子进行了调查,并利用生物多样性指数法(Shannon指数H、Margalef指数D和Pielou指数J)和主成分分析(PCA)法分别对湖泊水质和水环境因子进行了评价。结果表明:4个湖泊共鉴定浮游植物7门82属163种,主要优势种为硅藻或绿藻;浮游植物细胞丰度呈季节性变化,秋夏居高,冬春季偏低,平均丰度变化范围为25.45×10~6~54.04×10~6cells·L~(-1);将军湖、龙湖、庐陵湖和挹翠湖的H值分别为1.26~2.08、1.82~2.61、2.27~2.62和1.10~2.32;D值分别为2.03~3.51、2.36~3.71、2.48~3.93和3.12~3.96;J值分别为0.45~0.69、0.59~0.80、0.67~0.77和0.50~0.84。综合评价结果显示,4个湖泊处于富营养化状态、中等污染水平。而对污染较重的庐陵湖水环境因子PCA分析结果表明,水温(WT)、溶解氧(DO)和总氮(TN)是影响小型封闭景观水体浮游植物群落变化的主要因素。建议对小型封闭景观水体进行必要的治理和生态修复。     

外源水溶性有机物及温度对红壤铜形态的影响

利用模拟培养试验研究了外源水溶性有机物（DOM）添加量和培养温度对红壤中Cu形态的影响. 结果表明: 与不添加DOM比较, 添加不同量的DOM均可提高土壤中交换态Cu的含量、降低铁锰结合态Cu含量; 随着培养时间的延长,不同DOM添加量下土壤交换态Cu含量呈逐渐下降趋势;至试验结束时,DOM添加量为250 mg·L^-1时土壤交换态和碳酸盐结合态Cu含量最高, 添加量为500 mg·L^-1时铁锰结合态Cu含量最高;不同DOM添加量下, 土壤中有机结合态Cu含量较CK增加10.67%～23.66%. 在25 ℃和45 ℃温度条件下, 添加DOM后土壤交换态和铁锰结合态Cu含量均随培养时间的延长呈下降趋势, 但在5 ℃下变化趋势相反; 3种温度下添加DOM后土壤碳酸盐结合态Cu含量有随培养时间延长而增加的趋势. 随着培养温度的升高,土壤有机结合态Cu含量增加, 但在温度较低(5 ℃)时土壤残渣态Cu含量下降.     

水溶性有机质对土壤吸附菲的影响

研究了来源于稻草腐熟物的外源水溶性有机质(DOM)和土壤本身固有的内源DOM对有机碳含量不同的3种土壤吸附菲的影响.结果表明,不同处理土壤对菲的吸附曲线均为线性,其吸附系数(K_d)与土壤有机碳含量(f_oc)正相关.去除内源DOM后,黄棕壤、红粘田和黑土吸附菲的K_d值增加了7.08%～21.4%,增加量(ΔK_d)和增加幅度与f_oc正相关,表明土壤中存在的内源DOM抑制土壤对菲的吸附.而外源DOM对土壤吸附菲的影响与其浓度密切相关.在供试浓度范围(0～106 mg DOC·L^-1)内,红粘田吸附菲的K_d值随加入外源DOM浓度的提高先增大后减小.外源DOM浓度为28 mg DOC·L^-1时,红粘田吸附菲的K_d值增加了19.5%;而当外源DOM浓度≥52 mg DOC·L^-1时,则明显抑制菲的吸附.内源和外源DOM对土壤吸附菲的影响,主要与DOM和菲在溶液中的结合作用、在土壤中的累积吸附效应等有关.     

华南典型树种凋落叶的野外分解和溶解性有机质溶出动态

选用华南亚热带地区常见阔叶树种木荷和针叶树种湿地松的新近凋落叶,在野外分解0、30、60、90、150、210、240、365 d,分析溶出的溶解性有机质(DOM)浓度、组成和性质的变化,以及对土壤可溶性有机碳(DOC)的影响.结果表明: 随着分解的进行,尽管木荷叶片的DOM浓度高于松针,但是2种凋落叶DOM浓度、性质和物质组成变化规律一致;2种凋落叶的DOM浓度均呈下降趋势,芳香化程度和分子量增大,富里酸、腐殖酸类物质逐渐增多,可降解的简单芳烃蛋白(如酪氨酸)逐渐减少.在分解初期,DOM主要由亲水中性和酸性部分组成,易分解、易迁移,对表层土壤DOC影响不显著;在分解后期,DOM主要为腐殖酸和富里酸类物质,吸附性强,表层土壤DOC浓度显著下降.     

Modeled Effects of Dissolved Organic Carbon and Solar Spectra on Photobleaching in Lake Ecosystems

Dissolved organic matter (DOM) contains molecules that absorb light at various wavelengths. This chromophoric DOM (CDOM) influences the transmission of both visible and ultraviolet energy through water. The absorption of light by CDOM often causes structural changes that reduce its capacity to further absorb light, a process termed ‘photobleaching‘. A model was designed to assess photobleaching through the entire water column of lake ecosystems. The model uses lake morphometry and dissolved organic carbon (DOC) concentration in conjunction with a defined solar spectrum and experimentally measured photobleaching rates to compute the total water columm photobleaching. The model was initially applied to a theoretical ‘average‘ lake using solar spectra for both the north (N) and south (S) temperate western hemispheres and variable DOC from 0.3 to 30 mg L⁻¹. The consequences of varying waveband-specific photobleaching coefficients and lake morphometry were explored in a second set of simulations. Finally, the model was also applied to four temperate northern lakes for which we had prior measurements of CDOM photobleaching rates. The model demonstrates that all three wavebands of solar radiation (UVB, UVA, and PAR) contribute significantly to total water column photobleaching, with UVA being most important. The relative contributions of the three wavebands were invariant for DOC more than 3 mg L⁻¹. Total water column photobleaching at 440 nm was three to five times faster under the UV-enriched solar spectrum of the southern hemisphere. Increasing the lake’s mean depth (from 0.37 to 9.39 m) resulted in five- or 15-fold slower rates of total water column photobleaching for DOC concentrations of 1 or 10 mg L⁻¹, respectively. Varying the waveband-specific photobleaching coefficients by 10-fold resulted in a similar change in total water column photobleaching rates. Applying the model to four specific lakes revealed that photobleaching for the entire water column would reduce CDOM light absorption by 50% in 18–44 days under summer conditions. Received 17 November 1998; accepted 27 June 2000.