近800年来巢湖沉积物营养元素富集特点及其环境演变意义   总被引：1，自引：0，他引：1  

贾铁飞  张卫国  俞立中  余铁桥 《地理科学》2009,(6)

通过对巢湖CH1孔沉积物进行年代学、粒度和营养元素(TOC、TN、TP、C/N比值)分析,可将巢湖近800 a来的环境变化划分为4个沉积时期:沉积年代1177~1271 a A.D.是气候暖湿高湖面阶段;1271~1747 a A.D.,总体上为湿润环境下有机质快速积累阶段,其中1477~1747 a A.D.显示小冰期气候特点;1747~1865 a A.D.气候开始转暖,湖面上升;1865 a A.D.至今,气候转干旱。1880′s以来的TOC、TN非自然水平富集,1660′s以来的TP非自然水平富集,是巢湖历史时期开始出现富营养化的征兆。  相似文献   

<Emphasis Type="Italic">In vitro</Emphasis> iron enrichment experiments in the Prydz Bay,the Southern Ocean: A test of the iron hypothesis     

Song Sun  XinMing Pu  YongShan Zhang 《中国科学D辑(英文版)》2009,52(9):1426-1435

In "high nitrate, low chlorophyll" (HNLC) ocean regions, iron has been typically regarded as the limiting factor for phytoplankton production. This "iron hypothesis" needs to be tested in various oceanic environments to understand the role of iron in marine biological and biogeochemical processes. In this paper, three in vitro iron enrichment experiments were performed in Prydz Bay and at the Polar Front north of the Ross Sea, to study the role of iron on phytoplankton production. At the Polar Front of Ross...  相似文献   

The diapcynal nutrient flux and shear-induced diapcynal mixing in the seasonally stratified western Irish Sea   总被引：1，自引：0，他引：1  

Tom P. Rippeth  Phil Wiles  Matt R. Palmer  Jonathan Sharples  Jacqueline Tweddle 《Continental Shelf Research》2009

We estimate the diapcynal nitrate flux in the seasonally stratified western Irish Sea using the dissipation method. By comparing the divergence of the reported benthic and diapcynal nitrate fluxes, we are able to explain much of the observed annual summer decline in deep-water nitrate at this location. We then show that the new production, fuelled by the diapcynal nitrate flux, is of a similar magnitude to that associated with the spring bloom. This suggests that the physical processes responsible for the diapcynal nitrate flux will set the limit on new production at this location. High-resolution mid-water column ADCP measurements show an average thermocline gradient Richardson number of 1, thus suggesting episodes of enhanced shear could result in shear instability, and therefore mixing within the thermocline. Bulk shear measurements reveal episodes of enhanced shear in the form of spikes, during which time the bulk shear vector takes the form of a clockwise rotating vector which has a period close to the local inertial period. The episodes of shear spikes are correlated to the wind and are consistent with observations made elsewhere. Estimates of profiles of the rate of dissipation of turbulent kinetic energy, based on microstructure velocity measurements, show that during a shear spike the dissipation rate within the thermocline, and therefore the buoyancy (and nitrate) flux, is enhanced by a factor of 4 when compared to periods with no shear spikes. Intermittent shear spikes are, therefore, an important mechanism for enhancing mixing across the shelf sea seasonal thermocline, and therefore delivery of nitrate to the euphotic zone, at this location.  相似文献   

Effects of mariculture on macrobenthic assemblages in a western mediterranean site   总被引：2，自引：0，他引：2  

Paolo Tomassetti  Emma Persia  Isabel Mercatali  Danilo Vani  Veronica Marussso  Salvatore Porrello 《Marine pollution bulletin》2009,58(4):533-541

The effects of solid organic wastes from a marine fish farm on sediment was tested using macrobenthic fauna as biological indicators. Impact on benthic fauna was evaluated in the vicinity of a fish farm in the Tyrrhenian Sea (Western Mediterranean) between July 2001 and October 2002. Changes in benthic community structure were investigated using multivariate, distributional and univariate analyses (diversity indices, AMBI and M-AMBI). The results showed sharp disturbance of assemblages under the cages and no effects in the area more than 25 m from the cages. Sediment alterations were related to an increase in farmed biomass and its wastes, as well as to low current speed that allowed accumulation of organic matter on the sea floor. It was possible to follow the ecological succession from slightly altered assemblages to heavily polluted ones in the very short period of a single fish fattening cycle (15 months).  相似文献   

辽河口水域溶解氧与营养盐调查与分类   总被引：6，自引：0，他引：6  

王继龙  郑丙辉  秦延文  齐凤霞  雷坤  万峻  张雷 《海洋技术学报》2004,23(3):92-96

根据2003年9月辽河口水域营养盐和溶解氧的调查结果,讨论了辽河口水体中的溶解性无机氮(NO3-N、NO2-N、NH3-N)、活性磷酸盐(PO4-P)和溶解氧(DO)的含量、分布与变化特征以及相关关系。结果表明：辽河口溶解态无机氮含量范围为3．26～59．67μmol／L,活性磷酸盐含量范围为0．05～0．95μmol／L,溶解氧范围为0．086～0．208mmol／L。溶解氧、营养盐关系的统计分析结果表明：DIN与AOU(表观耗氧量),PO4-P与AOU之间显著或高度显著相关,营养盐之间也存在相关性,并对调查区域水质进行评价分类。  相似文献   

AGP试验在珠江口监测中的应用   总被引：2，自引：0，他引：2  

韦桂秋  李兰生  欧强  余汉生  易斌 《海洋通报》2004,23(4):55-59

通过进行珠江口一个航次7个站位海水藻类增长能力(Algal Growth Potential,AGP)试验,同时补充了温度和光照对藻类生长影响的试验,探讨了珠江口水域富营养化的程度。试验结果表明,珠江口的主要营养限制因素是磷(P),存在磷一氮双重限制;在试验设计的温度和光照中,中肋骨条藻的AGP值与温度、光照具有一定的相关关系,适合生长的温度是25℃,光照度是4500|X。  相似文献   

滇中武定高桥镇土地质量地球化学评价     

徐杰  向经纬  王浩宇 《地质与资源》2022,31(2):193-200

在武定县高桥镇以1.12个/km²的密度共采集453件表层土壤样品. 对重金属元素砷、铬、镉、铜、汞、铅、镍和锌做土壤环境地球化学等级评价, 最终评级为一等和二等. 一等区面积约350 km², 占比84.95%;二等区面积约62 km², 占比15.05%, 部分地区铜和镉显示异常但未达到污染级别. 对养分元素氮、磷、钾含量值做土壤养分地球化学等级评价, 中等以上约378 km², 占比91.74%. 养分缺乏地块靠近人口密集区, 推测该评价单元受人为因素影响严重. 最终得到土地质量地球化学评价结果, 高桥镇土地质量相对均衡, 优质区约101 km², 占比24.51%, 良好区约224 km², 占比54.37%, 中等区约80 km², 占比19.42%, 无劣等区.  相似文献   

Benthic recovery during open sea fish farming abatement in Western Mediterranean, Spain   总被引：1，自引：0，他引：1  

Sanz-Lázaro C  Marin A 《Marine environmental research》2006,62(5):374-387

Fish farming is an important source of organic matter input in coastal waters, which contributes to eutrophication. In this study, the macrofaunal benthic community was studied after the cessation of fish farming with the aim of improving our understanding of benthic succession and sediment recovery in a marine ecosystem. The results showed that the best environmental variables for assessing organic pollution were acid-volatile sulfides (AVS) and redox potential. Succession and recovery was best explained by macrofaunal analysis based on community composition as well as on trophic groups. The patterns of recovery differed between each impacted station. For this reason, succession could not be accurately predicted due to the unique environmental parameters and the singular community functional structure of each location. The Azti Marine Benthic Index (AMBI) proved its validity for assessing pollution but did not distinguish between successional stages.  相似文献   

浮游植物生长上行效应的研究进展   总被引：6，自引：0，他引：6  

彭欣  宁修仁  蔡昱明  郝锵 《海洋学研究》2006,24(3):64-75

归纳了海洋浮游植物生长营养盐限制的研究方法,综述了国内外关于海水中氮、磷、硅、铁等营养元素限制浮游植物生长的研究结果。在氮、磷营养元素限制时,海水中上述两个元素的浓度不仅限制了浮游植物的生长,而且还改变了浮游植物的种群结构,随着营养盐浓度的降低,浮游植物从小型向微型、微微型转变;而硅的缺乏,使浮游植物由硅藻向非硅藻转变;在大洋海域,铁的限制,甚至还影响到浮游植物对常量营养盐的吸收。铁施肥虽然促进了浮游植物的生长,降低了大气中CO2的浓度,缓解了温室效应,但同时也伴随着有毒藻类的生长以及DM S气体增加等带来的诸多问题。  相似文献   

Nitrate-nitrogen isotopic patterns in surface waters of the western and central equatorial pacific     

Chisato Yoshikawa  Yasuhiro Yamanaka  Takeshi Nakatsuka 《Journal of Oceanography》2006,62(4):511-525

To understand the processes transporting nitrate to the surface layer of the western and central equatorial Pacific, we measured the nitrogen isotopic ratio of nitrate (δ ¹⁵NO ₃ ⁻ ), which is a very useful tracer of the source of nitrate, above 200 m depth in this region in December 1999. δ ¹⁵NO ₃ ⁻ is higher (about 13.0‰) in the surface water than in the subsurface water (where it is about 6.5‰) due to isotopic fractionation during nitrate uptake by phytoplankton. The δ ¹⁵NO ₃ ⁻ value has a roughly linear relationship with the natural logarithm of nitrate concentration (ln[NO ₃ ⁻ ]). However, for values above 150 m depth, the intercept of this linear relationship varies with position from east to west. On the other hand, the data at 200 m depth at all observation stations are concentrated around a single point (ln[NO ₃ ⁻ ] = 2.5 and δ ¹⁵NO ₃ ⁻ = 6.5‰) and do not fit the linear relationships for the shallower values. To examine the meaning of the observed distributions of δ ¹⁵NO ₃ ⁻ and nitrate concentration we developed a box model including nitrogen and nitrogen isotopic cycles. By reproducing the observed relationship between δ ¹⁵NO ₃ ⁻ and nitrate concentration using this model we found that most nitrate is transported horizontally from the eastern equatorial Pacific. We also conducted case studies and investigated the effects of differences in pathways of nitrate transport on the distributions of δ ¹⁵NO ₃ ⁻ and nitrate concentration. From these studies we concluded that the observed linear relationships between δ ¹⁵NO ₃ ⁻ and ln[NO ₃ ⁻ ], having a common slope around 6‰ but different intercepts at each station, are evidence of the significant horizontal transport of nitrate to the surface water in this area.  相似文献