九龙江河口区养虾塘沉积物-水界面营养盐交换通量特征

通过对九龙江河口区陆基养虾塘水样和沉积物样品采集分析及结合室内模拟实验,探讨了虾塘在不同养殖阶段沉积物-水界面营养盐通量时间变化特征及其主要影响因素。虾塘沉积物向上覆水体释放NO_x~--N(NO_2~--N和NO_3~--N)、NH_4~+-N和PO_4~(3-)-P能力均呈现随养殖时间推移而降低的特征。沉积物在养殖中期和后期分别呈现对上覆水体NO_x~--N和PO_4~(3-)-P的吸收现象,但总体表现为释放(平均通量分别为(1.87±1.15)、(1.58±0.52)mg m~(-2)h~(-1)和(1.22±0.62)mg m~(-2)h~(-1))。沉积物-水界面溶解无机氮交换以NH_4~+-N为主(沉积物平均释放通量为(46.18±13.82)mg m~(-2)h~(-1))。沉积物间隙水与上覆水间的营养盐浓度差(梯度)及温度对上述交换通量的时间动态特征具有重要调控作用。研究结果表明养殖初期或中期沉积物较高的无机氮(尤其是NO_2~--N和NH_4~+-N)释放是养殖塘水质恶化的一个极具潜力的污染内源,可能会对虾的健康生长产生负面效应,控制沉积物无机氮释放是养虾塘养殖初期和中期重要的日常管理活动之一。     

铜锈环棱螺对藻华水体沉积物-水界面营养盐通量的影响

于2008年在室内小型试验模拟生态系统中进行了为期1个月的铜锈环棱螺生物干扰对底泥耗氧率和上覆水营养盐通量的影响试验,根据铜锈环棱螺放养密度设置了3个处理组和1个对照组。与试验前相比,培养1个月后,所有处理组和对照组的底泥耗氧率均显著下降;各处理组的底泥耗氧率初期高于对照组,后期低于对照组,且密度高的处理组其底泥耗氧率高于密度低的处理组。除12月7日外,对照组沉积物始终向上覆水释放铵氮,且释放量逐渐减小,而各处理组中,除试验初期沉积物向上覆水释放铵氮外,试验中后期均表现为吸收铵氮。除试验初期外,处理组和对照组中亚硝酸盐+硝酸盐通量主要表现为向上覆水中释放,且处理组1与对照组间存在显著差异(P<0.05)。磷酸盐通量主要表现为,试验初期沉积物向上覆水中释放,后期被沉积物吸收。本试验结果表明,短期内铜锈环棱螺的生物干扰增加了底泥耗氧率,但其长期效应可使底泥耗氧率下降,铜锈环棱螺的存在促进了沉积物中的总体硝化速率,加快了沉积物中的N循环。     

亚热带河口养殖塘沉积物有机碳矿化及其影响因子

亚热带河口的养殖塘是温室气体二氧化碳(CO2)的重要排放源,但其沉积物有机碳矿化动力学特征目前尚未厘清.以我国东南沿海亚热带闽江、木兰溪以及九龙江河口区的6个凡纳滨对虾(Penaeus vannamei)养殖塘为研究对象,对沉积物取样,并进行为期60 d的室内厌氧培养,对养殖塘沉积物CO2累积产量曲线利用一阶动力学模型...     

池塘内循环流水养殖模式对养殖塘上覆水-沉积物-间隙水磷时空分布特征及释放通量的影响

为了揭示池塘内循环流水养殖模式(Inner-circulation Pond Aquaculture, IPA)上覆水-沉积物-间隙水不同磷形态时空分布特征,探讨沉积物-水界面磷的释放通量及其主要影响因素,在IPA一条水槽前后端设置6个采样点,共设置4条,同时对常规传统池塘(Usual Pond Aquaculture, UPA)设置5个采样点,采用SMT(磷形态标准测试程序)法测量沉积物中磷的形态组成,对上覆水-沉积物-间隙水磷时空分布特征进行了分析,统计了磷释放通量及主要影响环境因子的关系。结果表明:(1)从整体上, IPA上覆水及间隙水中不同形态磷含量低于UPA,且IPA水体磷空间分布差异较大,水槽后端沉积物向上覆水释放,水槽前端则表现为上覆水向沉积物汇集;(2)在养殖中后期,空间上, IPA水槽后端沉积物不同磷形态随着距离增加逐渐降低,且均低于UPA;时间上,2种模式TP、IP、OP和Fe/Al-P随着养殖的进行而显著增加, Ca-P呈先降低后增加的趋势;(3)UPA基本表现为沉积物对磷的吸收,而IPA磷释放通量时空差异较大,养殖初期,水槽前端表现对磷的吸收,水槽后端10 m内...     

箱体特征对箱式法观测水-气界面CO2和CH4通量的影响

箱式法是广泛运用于内陆水体CO₂和CH₄通量监测的重要方法,但各研究中使用的箱体特征存在差异,箱体设计缺少统一标准,从而会影响观测结果。为明确箱体透光性、箱体内外气压差以及箱体内气体混合状态对水-气界面CO₂和CH₄通量观测的影响,本研究基于多通道闭路式动态箱观测系统,分别对比明箱和暗箱、箱体是否配备气压平衡阀及风扇对养殖塘水-气界面CO₂和CH₄通量观测的影响。结果表明: 夏季白天观测期间,与可观测CO₂实际通量的明箱相比,当CO₂呈现排放状态时,暗箱高估了90%的CO₂通量;当CO₂呈现吸收状态时,暗箱低估了50%的CO₂通量。暗箱测得的CH₄扩散通量比明箱低40%。箱体内气压是否与外界气压保持平衡对CO₂和CH₄通量影响均不显著。无风扇的箱体观测的CO₂通量代表性较差,在本研究中较有风扇的箱体高20%。无风扇的箱体难以区分不同途径排放的CH₄通量。在运用箱式法观测水-气界面CO₂、CH₄通量时,应使用透明箱体,并在其中安装风扇辅助气体混合。     

全氟辛酸在沉积物-水界面污染及吸附迁移行为研究进展

全氟辛酸(PFOA)是一种重要的全氟化表面活性剂,具有环境持久性、高毒性和生物累积性等特征,成为当前备受关注的新污染物。沉积物是PFOA的重要环境储蓄库,被污染后的沉积物可作为长期污染源造成上覆地表水及周边地下水污染。本文结合近年来国内外研究,对地表水和沉积物中PFOA的来源、污染现状和界面吸附迁移行为进行了综述。结果表明: 地表水体和沉积物中PFOA最主要的污染来源为工业废水排放。全球范围地表水体和沉积物中PFOA污染水平普遍为ng·g^-1和ng·L^-1数量级,且国内部分地区污染形势更为严峻。沉积物组分、水化学条件、有机质及表面活性剂等因素均影响沉积物中PFOA的吸附行为,但目前在吸附主控机制方面仍然存在争议。沉积物中PFOA迁移行为的研究正处于起步阶段,相关报导还较为缺乏,对于迁移机理的认识还很不足,今后需在该方面加大研究力度。     

不同许氏平鮋与栉孔扇贝养殖系统水-气界面CO2通量及其主要影响因子

本试验建立了4组中型实验生态系统,即空白对照系统、许氏平鮋单养系统、栉孔扇贝单养系统和许氏平鮋-栉孔扇贝混养系统,利用静态箱-气相色谱法对各养殖系统水-气界面CO2通量进行观测,并测定养殖水体物理、化学和生物指标.结果表明:试验期间,空白对照系统表现为稳定的对大气CO2的源,平均通量为12.42 mg·m^-2·h^-1.扇贝单养系统在试验前期和中期为CO2的源,后期为CO2的汇,试验期间整体为CO2的源,平均通量为10.95 mg·m^-2·h^-1.许氏平鮋单养系统和许氏平鮋-栉孔扇贝混养系统在试验前期表现为CO2源,实验中后期为CO2的汇,试验期间平均通量分别为-3.53和-10.49 mg·m^-2·h^-1,整体上均为对大气CO2的汇.回归分析结果显示,水体pH是水-气界面CO2通量较好的预测因子,pH=8.25是系统水-气界面碳源/汇功能发生转变的临界值.线性混合模型分析结果显示,水体净初级生产力是影响各系统水-气界面CO2通量的主要因子,表明浮游植物是调控系统水-气界面CO2通量的主要生物内动力.在本试验混养密度条件下的栉孔扇贝能一定程度上促进浮游植物生物量和水体初级生产力,从而增强系统水-气界面CO2的碳汇功能.     

黄河内蒙古段水体氧化亚氮溶存浓度、水-气界面排放通量和沉积物微生物群落结构

【目的】基于全球气候治理背景以及黄河流域在我国生态文明建设中的重要地位,本研究于2023年7月选择黄河内蒙古段流域为对象,测定流域内表层沉积物微生物群落结构与多样性、水体理化性质及水-气界面氧化亚氮(nitrous oxide,N₂O)气体通量。【方法】使用静态箱-气相色谱仪法对黄河内蒙古段水体N₂O溶存浓度、水-气界面N₂O排放通量进行探究,使用高通量测序分析表层沉积物。【结果】结果表明黄河内蒙古段水体N₂O溶存浓度变化范围在0.547 8−0.598 2 mg/m³之间,均值为0.574 1 mg/m³,水-气界面N₂O排放通量(FN₂O)变化范围为−3.645 3−4.392 5 mg/(m²·d),均值为1.086 1 mg/(m²·d),总体表现为大气N₂O的“源”。FN₂O和pH呈极显著正相关、和电位呈显著负相关。表层沉积物中细菌共有7 784个操作分类单元(operational taxonomic unit,OTU),其中变形菌门(Proteobacteriota)以平均35.13%的丰度成为最优势菌群。氨氧化古菌(ammonia-oxidizing archaea,AOA)相关基因丰度较低,检测到116个OTUs,unclassified_d__Unclassified为优势菌属(平均丰度为31.69%)。反硝化细菌共有3 660个OTUs,优势菌属为unclassified_k__norank_d__Bacteria(平均丰度为63.12%)。【结论】由于黄河内蒙古段N₂O相关数据较少,因此本研究结果对填补江河N₂O数据具有积极意义,为进一步了解沉积物微生物群落结构及功能菌在黄河治理中的应用提供参考,有助于黄河的保护和净化计划。     

城市化地区典型水体的N2O排放通量特征——以南京市为例

内陆淡水水体是大气中N₂O的重要排放源,然而目前对于内陆典型城市水体N₂O排放通量的监测数据依然匮乏,典型城市水体的N₂O排放特征及驱动因素尚不清楚。本研究选取了南京市江北新区的典型水体,包括湖库、河流、养殖池塘和景观池塘,在2020年5月-2021年4月利用漂浮箱法连续监测了不同水体类型的水-气界面N₂O排放特征,并通过测定水环境特征,探究驱动水体N₂O排放通量的关键因素。研究结果表明,典型城市水体整体均表现为N₂O排放源,河流和养殖池塘的日平均排放通量最大,分别为（503±1236）μg m^-2 d^-1和（508±797）μg m^-2 d^-1,其次为景观池塘（（179±989）μg m^-2 d^-1）,而湖库的N₂O排放通量最小,仅表现为微弱的N₂O排放源（（54±212）μg m^-2 d^-1）。水体的N₂O排放呈现季节性差异,河流和养殖池塘夏季的N₂O排放通量显著高于其他季节（P<0.01）。水体全年N₂O排放数据与水体温度和溶解氧含量（DO）呈显著相关。而在温度较高的5月份-9月份（>20℃）,氮输入成为影响N₂O排放通量的关键因素（P<0.01）,因此控制城市水体的氮输入尤其是在水温较高的夏季是减少N₂O排放的有利措施。此外,由于水文化学条件差异等因素,小型封闭水体包括养殖池塘和景观池塘的N₂O排放通量差异较大,未来应加强监测不同水体的水文化学特征和N₂O的时空排放特征,探讨影响小型封闭水体水-气界面N₂O排放通量的具体驱动因素。此研究为城市区域N₂O排放的精准核算提供了数据支撑,为N₂O排放模型的修正提供了科学依据。     

鄱阳湖秋季水-气界面CH4排放通量的区域差异及影响因素

有限的观测点以及空间的异质性已经成为准确估算湖泊水-气界面CH4通量的挑战。鄱阳湖是我国最大的淡水湖,为了解秋季湖区水-气界面的CH4排放通量,2010年10月利用密闭静态箱-气象色谱法对星子、都昌、南矶山和吴城4个湖区水-气界面CH4排放通量及气象、底泥、水体等因素进行了测定。研究表明,都昌湖区CH4排放通量平均值为0.26mg·m-2·h-1,显著高于星子(0.15mg·m-2·h-1)、吴城(0.13mg·m-2·h-1)和南矶山(0.10mg·m-2·h-1)湖区。鄱阳湖水-气界面秋季CH4排放通量平均为0.17mg·m-2·h-1,变异系数为58.6%。相关分析表明,风速显著影响CH4排放通量(P<0.01)。在排除风速>5m·s-1的数据后,底泥有机碳以及水体铵态氮含量与CH4排放通量显著相关,而水体DOC含量与CH4排放通量呈显著负相关(P<0.05)。对鄱阳湖CH4排放量的精确估算,依赖于较广区域和较长时间的观测。     

Enrichissement expérimental d'eaux printanières de claires à huîtres en baie de Bourgneuf (Vendée,France): augmentation de la biomasse et utilisation des éléments nutritifs par les algues unicellulaires

Oyster-pond sea-waters with natural populations were experimentally enriched to determine the nutrient limiting algal growth and the resulting effect on species composition. Results show that nitrogen is the limiting factor of growth-potential. N-NO₃ alone is exhausted, while other ion concentrations remain always measurable. Addition of N-NO₃ is needed to increase algal biomass. Favoured species differ when nitrogen is added alone or added with phosphorus.

     

森林生态系统可溶性碳和颗粒碳通量

可溶性碳(Dissolved carbon,DC)和颗粒碳(particulate carbon,PC)通量作为森林生态系统碳收支的重要组分,在森林固碳功能的评价和模型预测中具有重要意义,但常因认识不足、测定困难等而在森林碳汇研究中被忽略。综述了森林生态系统DC和PC的组成、作用、相关生态过程及其影响因子,并展望了该领域应该优先考虑的研究问题。森林生态系统DC和PC主要包括可溶性有机碳、可溶性无机碳和颗粒有机碳,主要来源于生态系统的净初级生产量。DC和PC是森林土壤的活性碳库,主要以大气沉降、穿透雨和凋落物的形式输入森林土壤系统,并通过土壤呼吸、侧向运输及渗透流失的方式输出生态系统。从局域尺度看,DC和PC通量受根系分泌、细根分解、微生物周转等生物过程的影响较大;从区域尺度看,它们受土壤和植被特性、生态过程耦联关系、气候因子以及全球变化的综合影响。该领域应该优先考虑:(1)探索不同时空尺度下森林生态系统DC和PC通量的控制因子及其耦联关系,揭示其中的驱动机理;(2)探索DC和PC与其它森林生态系统碳组分的相互关系及转化,阐明DC和PC通量与其它养分之间潜在的生态化学计量关系;(3)探索全球变化,特别是人类活动(如森林经营)和极端干扰事件(如林火、旱涝、冰冻、冻融交替等)对森林生态系统DC和PC通量的影响。     

Variability and transport of suspended sediment,particulate and dissolved organic carbon in the tidal freshwater Hudson River

Measurements of suspended matter, particulate organic carbon and dissolved organic carbon were made over a three year period at stations spanning 150 km of the tidal freshwater Hudson River. Suspended matter concentrations varied from year-to-year and were not related to freshwater discharge. The increase in suspended matter with depth in vertical profiles suggests that, during medium to low flow conditions, resuspension of bottom sediments was as important a source of sediment as loadings from tributaries. Particulate organic carbon showed significant variability among stations, and both autochthonous primary production and detrital organic matter are contributing to POC standing stocks. Dissolved organic carbon represented over half of the total organic carbon in the water column and showed little variation among stations.Examining downstream changes in transport showed that there was significant production of both suspended matter and POC within the study reach during the ice-free season. Tributary loadings within the study reach do not appear to be the cause of these increases in downstream transport. Dissolved organic carbon behaved conservatively in that there was no evidence for net production or net consumption within the river.The spatial/temporal patterns and analyses of transport suggest that suspended matter and POC, but not DOC, were controlled to a significant extent by processes occurring within the river and were not simply related to loadings from outside.     

Incidence of mussel culture on biogeochemical fluxes at the sediment-water interface

Upward nutrient fluxes at the sediment-water interface were studied in a mussel farming zone (Carteau, Gulf of Fos, France) in order to estimate the impact of organic matter input from biodeposition. Nitrate, nitrite, ammonia, silicate, phosphate and oxygen were measured. Fluxes were estimated by means of polyacrylate benthic chambers placed at sites located under (UM) and outside (OM) the rope hanging structures. Transformation of biodeposited organic matter increases phosphate, silicate and ammonia fluxes. No variation in nitrite fluxes could be detected and only minor differences were observed in nitrate and the oxygen production/consumption equilibrium at the two stations. Phosphate and silicate fluxes, which were always higher at the UM than at the OM site, decreased from spring to winter. Ammonia fluxes were very high under mussel cultures in May and September and lower in November. The fact that ammonia flux was always higher at the UM than at the OM sites might be explained by degradation of mussel biodeposit, as well as by benthic macrafauna excretion. Discrepancies between fluxes of the nutrients studied at the UM and OM sites increased as organic particulate matter in the water column decreased. Variations of oxygen flux followed a different pattern, since they were correlated with presence and abundance of photosynthetic microphytes on the bottom and in the water. Bottom respiration exceeded production of oxygen only in May 1988 at the UM station.As it now stands, biodeposit input into the sediment under mussel ropes does not affect the ecosystem, although the flow of nutrients towards the water column is higher than in other areas.     

Biogeography of copepods in lakes and ponds of subarctic Québec,Canada

We aimed to determine whether the copepod assemblages in lakes and ponds of northern Québec, Canada, were closer in composition to those found in southern Québec, or to those reported from the subarctic and arctic. Six calanoid and five cyclopoid species were identified from 37 ponds and lakes located in the region between 55° N and 59° N. Species diversity was generally low, ranging from 0 to 4 species per lake. Dominant species were Leptodiaptomus minutus and Acanthocyclops vernalis. The species assemblages showed high affinity with those found in forested regions of southern Québec. Exceptions were Leptodiaptomus tyrrelli, previously only recorded west of Hudson Bay, and Hesperodiaptomus arcticus, hitherto recorded north of 58° N. Relationships between the lakes, species, and environmental variables were explored using multivariate analysis. Lakes situated along the coast and on two offshore islands clustered together and were characterised by higher conductivity and pH than those lakes located further inland. Leptodiaptomus tyrrelli was common in these coastal lakes. Canonical correspondence analysis revealed statistically significant relationships between copepod distributions and conductivity, dissolved organic carbon and pH. These three variables accounted for 70% of the variation in the species' distribution.     

Factors influencing densities and distributions of Pontoporeia hoyi in Lake Ontario

The physical and chemical characteristics of the sediment-water interface greatly influence distributions of the bottom-feeding amphipod Pontoporeia hoyi which is a major component of the Great Lakes aquatic food-webs. Sediment-water interface samples from the Great Lakes indicate that Pontoporeia densities are positively correlated with sediment concentrations of organic carbon, particularly in the upper depth range of the species. Pontoporeia is not found in anoxic sediments. Growth rates and production of Pontoporeia are influenced by the quality of food supplies and there appears to be a seasonal response to the down-flux of plankton detritus. Comparisons of numerations and distribution patterns also revealed an apparent positive relationship between Pontoporeia and sediment-associated bacteria. Interlake comparisons of population densities provide no clear evidence of any large scale impact by contaminated sediment on this species. Depending upon the extent to which organic carbon (OC) is assimilated in the water column, bottom sediments may store and buffer the quantity of OC available to Pontoporeia. Thus, if the annual down-flux of OC remains generally constant, populations of Pontoporeia should also remain constant unless influenced by changes in predation intensity.Numerations of Pontoporeia revealed that populations of this amphipod are much larger in Lake Michigan than in Lake Ontario. We suggest that much of this difference can be accounted for by different forms of predator-prey interaction near the base of the benthic food-web. Commercial fisheries data tend to support this idea. We also speculate that differences in the concentration of dissolved silica may figure prominantly among factors that affect Pontoporeia population densities.Under proposed new taxonomy (Bousfield, 1989), Pontoporeia hoyi is now classified as Diporeia hoyi. However, for convenience, we have retained the commonly used genus Pontoporeia throughout this text.     

Transport and fate of dissolved organic carbon in the Lake Pontchartrain esutary,Louisiana, U.S.A.

Cycling dynamics of dissolved organic carbon (DOC) were examinedin Lake Pontchartrain estuary, Louisiana, in relation to changesin freshwater inputs. DOC concentrations ranged from 5.3 to 8.5mg C L-1 reaching their highest during high river inflow.The percentage of DOC represented by HMW DOC (or colloidal material)was greatest (ca. 11%) at stations where freshwaterdischarge from rivers and surrounding wetlands was most significant.Moreover, the lignin-phenol content of this material (ranged from 0.09 to 0.33 and from 0.11 to 0.39)confirmed that a significant fraction of colloidal organic carbon wasderived from terrestrial sources. Riverine and benthic fluxes representedthe dominant sources of DOC to the estuary. On an annual basis, riverineand benthic DOC concentrations were estimated to be 2.8 ×10 10 g C yr-1 and 8.8 × 10 10 g C yr-1, respectively, while the totalDOC pool in the estuary was 3.8 × 10 10 gC. Annual average concentrations of dissolved inorganic carbon (DIC)(1298 M) and pCO2 (5774 atm)were comparable to those found in other freshwater systems that reachedCO2 saturation levels. Net losses of DOC in the LakePontchartrain estuary appeared to be primarily controlled by heterotrophicconsumption (conversion of CO2) – whichmay have been amplified by the long residence time (approximately 120days) of DOC in this system.     

土地利用变化对川西米亚罗林土壤活性碳库的影响

为了揭示土地利用变化对土壤活性有机碳库的影响,在四川省亚高山米亚罗林区,以原始冷杉林(M-Y)和由原始林转化成的45年龄云杉人工林(M-60)、25年龄云杉人工林(M-80)和菜地(M-C)等4种土地利用类型为研究对象,进行了土壤的微生物量碳(MBC)、水溶性有机碳(WDOC)和易氧化有机碳(LOC)的含量和季节变化研究.结果表明,土地利用变化明显影响土壤活性有机碳组分的含量,其中微生物量碳和水溶性有机碳的变化趋势为M-Y>M-60>M-80>M-C,易氧化有机碳的变化趋势则为M-60>M-Y.土地利用变化没有改变活性有机碳各组分的垂直分布,各组分均随着土层深度的增加而降低,季节变化幅度较小,但枯落物层和表层土壤的变化幅度明显高于深层土壤,而各组分的分配比例变化幅度明显小于活性有机碳含量的变化.