Transport and behavior of marine oil spill containing polycyclic aromatic hydrocarbons in mesocosm experiments

Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs in marine environment after an oil-spill incident.However,interaction between petroleum PAHs and microbial communities in a marine environment remains unclear.Therefore,a series of mesocosm experiments were conducted.in which water-accommodated fraction(WAF)of oil was generated to simulate an oil-spill scenario and to analyze the transport and behavior of marine oil spill containing PAHs with and without dispersants.Results indicate that the application of dispersant could increase the concentration of total PAHs in water column due mainly to significant increase in the concentration of highmolecular weight(HMW)PAHs at a lower removal rate.At the end of the 7-day experiment,significant amount of HMW PAHs were accumulated in sediment.In general,the application of dispersant did not increase the sediment uptake of PAHs but increased the PAHs concentration in water column.

Study on Different Size-fractionated Phytoplankton Assemblage Change in the Mesocosm Ecosystem

A algal bloom process had been simulated via field mesocosm experiment, and the change of phytoplankton assemblage of different sizes in different growing phases had been studied. Nutrients addition could promote the growth of phytoplankton In the mesocosm of Prorocentrum donghaiense （M1） and the mesocosm of natural waters （M2）, and the peaks of chlorophyll a were 112.79 mg/m and 235.60 mg/m, respectively. The restraining effect of nano-phytoplankton on pico-phytoplankton growth was stronger in M2 than in M1. When nutrients were abundant, the relative growth rate of diatom was higher than that of P. donghaiense, and they reached the peak quickly and then came to die out very fast. The decreasing of Si promoted diatom bloom to die out.

Interspecies competition for nutrients between Prorocentrum donghaiense Lu and Skeletonema costatum(Grev.) Cleve in mesocosm experiments

Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms（HABs）.The results showed that there was interspecies competition between P.donghaiense and Skeletonema costatum（Grev.） Cleve.The cell number of P.donghaiense and S.costatum accounted for about 85% and 11% of the total cell number of phytoplankton respectively at the beginning of the experiment in May 1998.In May 2002,at the beginning of the experiment,the cell number of P.donghaiense accounted for 55%-66% of the total and S.costatum accounted for 32%-42%.The density of P.donghaiense and S.costatum was over 95% and 1%-5% respectively in May 2003.The results of these three mesocosm experiments showed that the dominant species in this specific community varied with different nutrient availability.Under low-phosphate conditions,the dominant species was P.donghaiense,while S.costatum became dominant in phosphate-replete cases.The average growth rate（1.08 d-1） of S.costatum in exponential growth phase was higher than that（0.39 d-1） of P.donghaiense.In the mesocosm,S.costatum predominated in the mesocosm by its rapid growth.When phosphorus was depleted,the cell number of S.costatum dropped rapidly,while P.donghaiense Lu decreased more slowly.The results from mesocosm experiment may explain why：（1） P.donghaiense bloom usually occurs in May,when phosphate concentration is low;（2） the bloom of S.costatum appears in early spring and summer time,when nutrients increase with increasing Changjiang River（Yangtze River） runoff;（3） the bloom of S.costatum is short and that of P.donghaiense Lu can last more than a month in the East China Sea.

A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem in the Jiaozhou Bay in China

A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem was established according to the summary and synthesis of the models available, in which seven state variables （DIN, PO4-P, DON, DOP, phytoplankton, zooplankton and detritus） were included. Logically it had five modules--phytoplankton, zooplankton, dissolved inorganic nutrients, dissolved organic nutrients and detritus. The results showed that this model could simulate the variations of DIN, PO4-P, DON, DOP, POC and phytoplankton biomass in pelagic ecosystem in mesocosm properly, based on the site experiment data in the Jiaozhou Bay in the autumn of 1999 and the summer of 2000. Not only the logical structure but also the model parameters were feasible, and about 20 parameters were made to fit for the Jiaozhou Bay during the simulation. All of these are necessary to study the control mechanism of nutrients biogeochemical cycling in the Jiaozhou Bay and other China＇ s coastal waters.

Modelling Nitrogen and Phosphorus Dynamics in a Mesocosm Pelagic Ecosystem in Laizhou Bay in China

A model of nitrogen and phosphorus dynamics in mesocosm experiments was established on the basis of a summary and synthesis of the existing models. The established model comprised seven state variables(DIN,PO4-P,DON,DOP,phytoplankton,zooplankton and detritus) and five modules - phytoplankton,zooplankton,dissolved inorganic nutrients,dissolved organic nutrients and detritus. Comparison with the in situ experimental data in Laizhou Bay at the end of August 2002 showed that this model could properly simulate the variations of DIN,PO4-P,and phytoplankton biomass in a mesocosm pelagic ecosystem. It was found that not only the model structure but also the parameters adopted were fit for simulation. The sensitivity of the main state variables to the parameter change was assessed by sensitivity analysis. All these results are useful for studying the control mechanism of biogeochemical cycling of nutrients in Laizhou Bay and other Chinese coastal waters.

Effects of daily nitrogen and phosphorus input on planktonic community metabolism in a semi-enclosed bay by mesocosm experiment

Planktonic metabolism plays an important role in affecting the energy transportation and carbon cycle of the marine ecosystem.However,its regulation mechanism remains unclear under the continuously exogenous nutrient inputs in nearshore waters.In this study,a mesocosm experiment was conducted in a semi-enclosed bay,the Daya Bay,to explore the responses of plankton metabolic balance and community structure to a concentration gradient of daily nitrogen and phosphorus inputs.The results showed that nutrient enrichments promoted phytoplankton biomass,total primary production,and community respiration,and the promoting effect enhanced alongwith the increase of nutrient concentration.However,the net community production fluctuated more violently between autotrophic and heterotrophic with the increase of nutrient inputs and tended to be more heterotrophic from the 5 th day to the 10 th day of the experiment.In addition,the daily flux of nitrogen and phosphorus,2μmol/(L·d)and 0.066μmol/(L·d),respectively,could be regarded as a potential threshold for ecosystem stability and health,since most of the ecological characteristics related to plankton structure and function have undergone significant changes when the nutrient level is higher than that.In the nearshore enclosed or semi-enclosed waters,nutrient from continuous terrigenous input is likely to be concentrated and exceed this level,indicating the ecological risks due to the metabolic unbalance and the deterioration of plankton community structure.

The Response of Benthic Foraminiferal Assemblages to Copper Exposure: A Pilot Mesocosm Investigation

Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of mesocosm experiments are carried out to assess the impact of different concentrations of copper on benthic foraminiferal assemblages over time. This pilot investigation documents that Cu contamination has a detrimental effect on foraminifera when compared to original and control samples. In particular, increased concentrations of Cu (normally higher than 120 μg/l) lead to a lowering of foraminiferal density and diversity and an increased occurrence of abnormalities. This study thus supports that the use of an experimental approach is suitable for investigating the response of benthic foraminifera to stress including pollution. Moreover, the application of mesocosms represents an innovative tool to be placed alongside field studies and culture experiments.

CARBON CYCLE IN SHRIMP POLYCULTURE MESOCOSM

The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton community respiration rate fluctuated between 0.07 and 2.28 mgC/(L·d), average of 0.82±0.42 mgC/(L·d), which was 49 percent of the rate of phytoplankton gross production;that the average respiration rates (mgC/(L·d)) of micro , nano and pico plankton were 0.07, 0.38 and 0.31, which were 175, 30 and 207 percent of the corresponding sized phytoplankton production rates; that the sediment respiration rate (mgC/(m 2·d)) varied from 178.64 to 373.23, average of 262.60±48.68, and increased gradually with the lapse of culture time; and that the organic carbon accumulation and the respiration in the sediment of the shrimp monoculture mesocosm was higher than that in the polyculture mesocosms. The total sediment respiration per 25 m 2 mesocosm in the culture period averaged 571.16 gC, which was 10 percent of the total organic carbon input of the mesocosm.

Mesocosm Assessment of Stability Habitat for Halophyte

In this paper, we constructed the halophyte Mesocosm experimental group which was used as a substrate material that consisted of tidal flat and dredged sediment. Depending on whether the ingredients of vegetation and substrate material of Mesocosm, we constructed Mesocosm A (tidal flat sediment + Salicornia herbecea), Mesocosm B (only dredged sediment), Mesocosm C (dredged sediment + Salicornia herbecea). Monitoring was carried out of seawater quality factors (Chemical Oxygen Demand (COD), Total Nitrogen (T-N), Total Phosphorus (T-P), temperature, salinity), sediment factors (Chemical Oxygen Demand (COD), Total (T-N), Total Phosphorus (T-P) and growth of Salricornia herbecea) in each Mesocosm. Habitat Stability Index of vegetation was calculating by using the monitoring results. HSI of Mesocosm C was calculated from 0.87 to 0.95 as compared to the relatively high HSI Mesocosm A, it was evaluated to be able to be used in the restoration of the coastal salt marsh with dredged sediment.

Mesocosm Hatcheries Using Semi-intensive Methodologies and Species Diversification in Aquaculture

Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks （40 m3） for fish larvae production at low densities （2-8 larvae/L）, with live prey production within the tank supplemented by exogenous sources of feed. Due to the high biological quality of larvae produced and low level of technological input, these methodologies are regarded as an interesting option to meet the increasing fry demand from the aquaculture industry. This study aimed to describe the experience at Centro de Maricultura da Calheta, Madeira Island, Portugal, with the establishment of a mesocosm hatchery for the production of marine fish larvae. Production trials were initiated with gilthead seabream Sparus aurata. This larval species presented faster growth in total body length （TL） per day （TL = 3.7516e~ ~293day, R2 = 0.9404）, higher survival rate （SR = 31.9%） and comparable swimbladder inflation rates （SB = 90%） to those of larvae reared with intensive methodologies. High larval performance was obtained with two candidate species for aquaculture： the red porgy Pagruspagrus （TL = 3.212e~~39day, R2 = 0.995; SR = 15.3%; SB = 95.7%） and the white seabream Diplodus sargus （TL = 3.6355e~~413day, R2= 0.9824; SR = 25%; SB --- 100%）. Testing ofa 110 m3 mesocosm rearing tank with white seabream larvae revealed limitations associated to larger tanks namely, the amount and quality of live feed required daily. First trials with striped jack （Pseudocararoc dentex） larvae resulted in low larval survival （0.04%）, but the use of a white tank avoided culture management constraints related to positive phototropism. The present results suggest that a mesocosm using semi-intensive methodologies may contribute to species diversification and consequently, to the sustainable development of aquaculture.

Temperature Responses to Infrared-Loading and Water Table Manipulations in Peatland Mesocosms

We initiated a multi-factor global change experiment to explore the effects of infrared heat loading （HT） and water table level （WL） treatment on soil temperature （T） in bog and fen peatland mesocosms. We found that the temperature varied highly by year, month, peatland type, soil depth, HT and WL manipulations. The highest effect of HT on the temperature at 25 cm depth was found in June for the bog mesocosms （3.34-4.27 ℃） but in May for the fen mesocosms （2.32-4.33 ℃） over the 2-year study period. The effects of WL in the bog mesocosms were only found between August and January, with the wet mesocosms warmer than the dry mesocosms by 0.48-2.03 ℃ over the 2-year study period. In contrast, wetter fen mesocosms were generally cooler by 0.16-3.87℃. Seasonal changes of temperatures elevated by the HT also varied by depth and ecosystem type, with temperature differences at 5 cm and 10 cm depth showing smaller seasonal fluctuations than those at 25 cm and 40 cm in the bog mesocosms. However, increased HT did not always lead to warmer soil, especially in the fen mesocosms. Both HT and WL manipulations have also changed the length of the non-frozen season.

利用实验塘及原位生物群落(mesocosm)开展农药生态毒理学研究

能接受必要的控制，并可设置重复的实验塘及原位生物（ｍｅｓｏｃｏｓｍ）是开展农药水生生态毒理学研究的理想选择。通过对该系统的研究，农药生产者可阐明复杂系统对药剂毒性的缓冲能力，污染管理者可获得农药对水生生态系统不良影响的信息。本文根据现有资料从池塘设计和建造、规格、生物构成、测定参数和结果分析等方面对该测试系统加以介绍。

Nitrate removal to its fate in wetland mesocosm filled with sponge iron:Impact of influent COD/N ratio

Sponge iron(s-Fe°)is a porous metal with the potential to be an electron donor for denitrification.This study aims to evaluate the feasibility of using s-Fe as the substrate of wetland mesocosms.Here,wetland mesocosms with the addition of s-Fe"particles(CW-Fc)and a blank control group(CW-CK)were established.The NOj-N reduction property and water quality parameters(pH.DO.and ORP)were examined at three COD/N ratios(0.5.and 10).Results showed that the NO3--N removal efficiencies were significantly increased by 6.6 to 58.9%in the presence of s-Fe NH4+-N was mainly produced by chemical denitrification,and approximately 50% of the NO3--N was reduced to N4+-N,at the COD ratio of 0.An increase of the influent COD/N ratio resulted in lower chemical denitrification and higher bio-dcnitrification.Although chemical denitrification mediated by s-Fe led to an accumulation of NH4+-N at COD/N ratios of 0 and 5.the TIN removal efficiencies increased by 4.5#12.4#.Moreover,the effluent pll,DO.and ORP values showed a significant negative correlation with total Fe and Fe(II)(P<0.01).High-throughput sequencing analysis indicated that Trichococctis(77.2%)was the most abundant microorganism in the CW-Fc mcsocosm,while Thauera,Zoogloea.and Herbaspirillum were the primary denitrifying bacteria.The denitrifiers,Simplicispira,IXxhloronwnas,and Denirratisoma.were the dominant bacteria for CW-CK.This study provides a valuable method and an improved understanding of NOj-N reduction characteristics of s-Fc in a wetland mcsocosm.

Comparison the effects of bioaugmentation versus biostimulation on marine microbial community by PCR–DGGE： A mesocosm scale

In order to better understand the effects of biostimulation and bioaugmentation processes on a marine microbial community, three different mesocosm experiments were planned. Natural seawater（10.000 L） was artificially polluted with crude oil（1 L） and（1） inorganic nutrients（Biostimulating Mesocosm, BM）,（2） inorganic nutrients and an inoculum of Alcanivorax borkumensis SK2（Single Bioaugmentation Mesocosm, SBM）,（3） inorganic nutrients and inoculums of A. borkumensis SK2 and Thalassolituus oleivorans MIL-1（Consortium Bioaugmentation Mesocosm, CBM）. During the experimental period（20 days）, samples were taken from each mesocosm and the community structure was analyzed by PCR–DGGE. The 16 S r RNA gene DGGE banding patterns and sequence analysis demonstrated that biostimulation had the lowest effect on microbial biodiversity in the mesocosms; however, the biodiversity of the marine microbial community dramatically decreased in the CBM（Shannon index was 0.6 in T3）. The community structures among the three mesocosms were also markedly different,and major bacteria derived from DGGE bands were related to uncultured Gamma Proteobacteria. The biodegradation results show that the Single Bioaugmentation Mesocosm（SBM） system had the highest percentage of degradation（95%） in comparison to the BM mesocosm（80%） and CBM（70%）.

中国明对虾放流对鱼类生态位的影响

为探究中国明对虾(Fenneropenaeus chinensis)增殖放流对水域内鱼类的影响及其表现形式,采用原位实验生态学方法,在对虾放流河道构建围隔,设置3种虾苗放流量(模拟莱州湾近岸放流5亿尾、7.5亿尾和10亿尾)和无放流处理,经过一个对虾生长季后,比较不同处理围隔中鱼类组成和生态位特征差异。结果显示,4种处理围隔中,回捕对虾数量随放流量增加而增加,但其生物量、平均个体大小和回捕率未随放流量增加而增加;回捕率在放流围隔间差异显著,以5亿尾模拟围隔的值最高;鱼的种类组成相似,可归于杂食性、浮游动物食性和鱼/虾食性。总鱼类和鱼/虾食性的鱼类产出量在围隔间差异不显著,杂食性鱼的产出量以放流围隔较高,浮游动物食性鱼的产出量随对虾放流量增加而减少。鱼种间高生态位重叠(>0.75)配对数随对虾生物量增多而减少。相似性分析显示,放流最多的和无放流围隔的鱼类生态位相异程度最高。综上认为,在实验水体中,放流对虾并不降低鱼类总量产出,但可能会影响不同食性鱼类的相对组成和生态位重叠度,且影响效应随放流量增加更为明显。

生物炭负载蒽醌-2-磺酸钠对厌氧消化的影响

为提高厌氧消化系统的降解效率,以生物炭(BC)为载体负载蒽醌-2-磺酸钠(AQS),制备复合材料BC/AQS并应用于厌氧消化系统.在中温条件(35℃)下开展批式厌氧消化试验,探究BC/AQS对玉米秸秆厌氧消化的影响.结果表明,当AQS浸渍浓度为1mmol/L时,BC/AQS强化厌氧消化的产甲烷效率最高,此时最大产甲烷速率Rmax达到10.64mL/(d·g),最大累积甲烷产量Pmax达到240.41mL/g,单位挥发性固体(VS)累积产甲烷量分别比空白对照组和添加BC的试验组提高20.60%和12.11%(P<0.05).产甲烷古菌中甲烷八叠球菌属(Methanosarcina)和甲烷泡菌属(Methanofollis)得到富集.此外,BC/AQS在发酵前期促进了挥发性脂肪酸(VFA)的生成,使总VFA浓度在第10d比对照组提高了7.73%~18.54%;在中后期促进了VFA的降解,其中BC/AQS-1mmol/L使总VFA浓度下降77.43%,降幅最大.BC/AQS提高了水解产酸菌群Ruminofilibacter、Proteiniphilum、Fermentimonas和不动杆菌属(Acinetobacter)的丰度.

围隔生态系内浮游植物对富磷的响应

在长江口外应用围隔生态系实验方法 ,研究了富磷与浮游植物生物量的相关性以及浮游植物对磷吸收的种间竞争。结果表明 ,可溶性磷 (主要是 PO- 34 )在实验的第 5天以前呈指数函数减少 ,浮游植物生物量则反之。当浮游植物细胞数量和叶绿素 a达到最高峰时 ,种类多样性指数和均匀性指数处于最小值 ,分别为 0 .0 0 8和 0 .0 0 3。这次实验引发了中肋骨条藻 ( Skeletonema costatum)赤潮。文中还探讨了中肋骨条藻的分裂速度以及对磷的吸收速度。

东海两种赤潮生物种间竞争的围隔实验

1998年 5月和 2 0 0 2年 5月在东海赤潮高发区进行了两次添加营养盐诱发赤潮的围隔实验 ,结果表明 ,1998年 5月实验开始时 ,具齿原甲藻和中肋骨条藻分别占群落总量的 85 %和 11% ,对照围隔中 ,具齿原甲藻一直处于优势 ,高峰时所占比例接近 99% .加磷围隔中 ,中肋骨条藻显示出很强的竞争能力 ,第五天的数量与具齿原甲藻相等 .2 0 0 2年 5月用 4个围隔装置进行实验 ,在不同营养状况下两个种的增殖速率不同 ,营养盐浓度高的围隔中 ,中肋骨条藻的增殖速率比具齿原甲藻快得多 ,在营养盐限制条件下 ,具齿原甲藻比中肋骨条藻存活的要好 ,表明在营养盐丰富情况下 ,中肋骨条藻以其快速的繁殖在竞争中取得优势地位 ,导致中肋骨条藻形成的赤潮持续时间较短 ,消亡也快 ,而具齿原甲藻赤潮形成期较长 ,但在营养盐很低的情况下 ,还能维持较长时间 .

磷酸盐对两种东海典型赤潮藻影响的围隔实验

采用了围隔生态实验方法,研究了围隔中营养盐含量及结构变化和磷酸盐对东海典型赤潮藻种(东海原甲藻和中肋骨条藻)生长的影响。结果表明,在高磷条件下,中肋骨条藻快速增殖,稳定期缩短,细胞数很快下降,而东海原甲藻由于氮源的限制生长期明显缩短。在磷限制条件下,中肋骨条藻细胞增殖受到明显抑制,生物量偏低,而东海原甲藻受到的影响较小。磷可能是东海原甲藻及中肋骨条藻生长的限制因子。氮磷比会影响浮游生物的生长,较高的氮磷比可能对东海原甲藻的生长有利,较低氮磷比则可能有利于中肋骨条藻生长。东海原甲藻能在营养盐浓度较低的生长环境中占有优势,相反,营养盐浓度较高的环境更适合中肋骨条藻的生长,中肋骨条藻具有更强的竞争能力。

微宇宙理论及其在生态毒理学研究中的应用

简述微宇宙理论、发展史和主要类型 ,并着重综述了微宇宙在生态毒理学研究中的主要应用情况 ,以及与实验室单物种试验和野外试验比较微宇宙的优缺点 ,并对微宇宙的未来发展趋势也作了简要讨论。