Simulation of phytoplankton biomass in Quanzhou Bay using a back propagation network model and sensitivity analysis for environmental variables

Prediction and sensitivity models,to elucidate the response of phytoplankton biomass to environmental factors in Quanzhou Bay,Fujian,China,were developed using a back propagation(BP) network.The environmental indicators of coastal phytoplankton biomass were determined and monitoring data for the bay from 2008 was used to train,test and build a three-layer BP artificial neural network with multi-input and single-output.Ten water quality parameters were used to forecast phytoplankton biomass(measured as chlorophyll-a concentration).Correlation coefficient between biomass values predicted by the model and those observed was 0.964,whilst the average relative error of the network was-3.46% and average absolute error was 10.53%.The model thus has high level of accuracy and is suitable for analysis of the influence of aquatic environmental factors on phytoplankton biomass.A global sensitivity analysis was performed to determine the influence of different environmental indicators on phytoplankton biomass.Indicators were classified according to the sensitivity of response and its risk degree.The results indicate that the parameters most relevant to phytoplankton biomass are estuary-related and include pH,sea surface temperature,sea surface salinity,chemical oxygen demand and ammonium.     

南通海岸带滩涂开发类型选择与空间功能配置研究

海岸带滩涂开发类型选择与空间布局是海岸带综合管理研究的重要内容,对于促进海岸带可持续发展具有重要意义。以海岸带资源环境-社会经济条件与滩涂开发类型对应关系透视为基础,结合南通海岸带滩涂条件、开发类型演变和区域发展背景分析,提出该地区生态旅游、农业和港口–工业–城镇多元化的滩涂综合利用模式,集成适宜性评价与分区、多部门规划冲突与协调等方法,探讨了南通海岸带滩涂地区生态与旅游、农业和港工城等功能区的空间配置路径。南通海岸带地区三类空间适宜比例分别23.5%,32.7%和43.8%,可以作为海岸带综合管理政策制定的参考。     

智能技术影响下的城市空间研究进展与思考

智能技术的影响已经渗透到城市的不同方面,空间要素的流动更快更复杂,城市功能需要进行调整以适应居民活动的变化,城市空间的智能化发展与运营管理也成为新的挑战。论文从城市空间要素组织、居民活动与空间功能、空间运营管理3个方面梳理当前智能技术对城市空间的影响,并展望未来5～10 a的城市空间应具有瞬时异地、空间智能化、复杂流动性以及韧性能力更强的特点,最后从城市空间组织、功能形态、运营管理与规划方法4个方面探讨了未来的城市空间研究需要关注的重点内容,以期为智能技术影响下的城市空间研究与规划设计提供参考。     

科尔沁沙地不同生境植物及叶片的C、N元素计量特征

为了研究科尔沁沙地植物及叶片的C、N元素在沙丘固定过程中的化学计量差异及变化规律,在流动沙丘、半固定沙丘、固定沙丘、草地4种生境上分别采集整株植物样品和叶片样品,测定其C、N元素含量,并在群落水平和功能型水平上展开分析。结果表明:(1)随着沙丘的固定,植物群落及群落叶片的C含量逐渐上升而N含量逐渐下降,且C含量的变异系数较N含量小;(2)各生境植物及叶片C、N含量表现为灌木一年生植物、C3植物C4植物、豆科植物非豆科植物,各功能型植物的C、N含量正相关于其叶片的C、N含量;(3)沿沙丘固定梯度,一年生、C4与非豆科植物及其叶片C含量趋于上升,而一年生、多年生、C3、非豆科植物及其叶片N含量趋于下降。沙丘固定过程中群落C含量的变化主要源于一年生、C4、非豆科植物,而N含量的下降则受草本、C3、非豆科植物的共同影响。适当补植灌木、C3植物、豆科植物对于该地区的固C效率和生物固N以及改良土壤肥力会起到积极作用。     

2002-2012年长春市城市功能空间耦合研究

以长春市多年用地现状图和统计资料为数据源,以ArcGIS和SPSS软件为分析工具,引入静态耦合度和动态耦合度概念,从居住空间视角对长春市城市功能空间耦合的空间差异特征进行了动态研究,分析了城市功能空间耦合的动力机制。研究发现：① 长春市城市空间扩展仍未摆脱圈层扩张的窠臼,居住空间表现出过高的扩张强度,是城市功能空间低耦合近域扩展的重要原因;② 城市功能空间耦合的地域差异显著,核心区动、静态耦合度均高于外围,城市功能空间处于重构期,外围则处于低耦合的快速扩张状态;③选取耦合度指标通过聚类分析方法将中心城区划分为高耦合比较成熟、高耦合趋于成熟、高耦合新兴、低耦合比较稳定、低耦合新兴和低耦合特殊城市功能空间六类。     

Characteristics of coastal phytoplankton near Cape Tastubec (northern Aral Sea), September 1993

The species composition, population density, biomass and main functional characteristics of the phytoplankton community near Cape Tastubec, northern Aral Sea in September 1993 were investigated. The characteristics investigated were daily primary production, decomposition, and photosynthetic intensity. The data indicate that certain changes in the structure and function of the phytoplankton have recently taken place.     

典型工业城市土壤重金属元素形态特征及生态风险评估

城市工业化发展易造成土壤重金属污染等环境问题。已有研究表明, 土壤重金属对生态环境的危害不仅与其总量有关,更大程度上取决于重金属的赋存形态。为查明河套平原某典型工业城市城区土壤重金属的含量特征、赋存状态和风险状况,本文在该市不同功能区采集土壤样品52件,利用电感耦合等离子体质谱法(ICP-MS)、原子荧光光谱法(AFS)等分析技术测定土壤重金属元素含量和赋存形态状况的基础上,采用风险评价编码法(RAC)对城区土壤重金属的生态风险进行评价。结果表明: ①表层土壤重金属元素含量(除As外)均不同程度地高于河套平原背景值,Pb、Cr、Mn、Cd、Zn的变异系数较大,空间分布不均匀,受人类活动影响显著;工业区重金属含量超过背景值程度最重,尤其是Cd(背景值的5.83倍)和Pb(背景值的3.58倍);道路重金属含量也明显高于背景值,Cd是背景值的近4倍。②重金属Cr、Mn、Ni、Cu、Zn、Pb、As元素形态以残渣态为主;Cr、Ni、Cu和As的残渣态平均占比都大于70%,Cd的残渣态在各功能区约占30%。③RAC风险评价结果显示各功能区的Cd和工业区的Pb达到高风险等级,生态风险较大。研究结果可为城区土壤重金属潜在生态风险防范提供科学依据。     

Lagged response of phytoplanktonic photosynthetic competence to variation of nitrogen concentration in Jiaozhou Bay, China

Fluorescence-based maximal photochemical efficiency, Fv/Fm, is widely used as an indicator to photosynthetic competence in marine systems. It has been considered a useful parameter diagnosing the nutrient stress on phytoplankton photosynthesis, but many studies argue its usefulness. In the present study, we try to find a temporal relationship between Fv/Fm and nitrogen concentration, and provide a possible explanation on the controversy. We continuously measured Fv/Fm and nitrogen concentration once every 10 days from September 2003 to March 2004 at two stations in Jiaozhou Bay, northern China. It was found that Fv/ffm did not significantly correlate to synchronous nitrogen concentration, but the variation （i.e. the change between two adjacent cruises） of nitrogen concentration of the previous cruise and the variation ofFv/Fm of the current cruise were strongly correlated. This result indicates that a time lag exists between the variation of nutrient status and the subsequent Fv/Fm response. Length of the time lag seems just matched the interval of our measurements （10 days）. In the field, direct dependence of Fv/Fm on nitrogen concentration may not be found because of the lagged response of Fv/Fm to nitrogen concentration variations or physiological acclimation. Our results provide a possible way to explain the previously reported conflicting results on the relationship between Fv/Fm and nutrient status. To give a more-accurate estimate about the length of the time lag, an investigation that includes more frequent measurements is needed.     

The structure and evolution of M 51-type galaxies

We discuss the integrated kinematic parameters of 20 M 51-type binary galaxies. A comparison of the orbital masses of the galaxies with the sum of the individual masses suggests that moderately massive dark halos surround bright spiral galaxies. The relative velocities of the galaxies in binary systems were found to decrease with increasing relative luminosity of the satellite. We obtained evidence that the Tully-Fisher relation for binary members could be flatter than that for local field galaxies. An enhanced star formation rate in the binary members may be responsible for this effect. In most binary systems, the direction of the orbital motion of the satellite coincides with the direction of the rotation of the main galaxy. Seven candidates for distant M 51-type objects were found in the Northern and Southern Hubble Deep Fields. A comparison of this number with the statistics of nearby galaxies provides evidence for the rapid evolution of the space density of M 51-type galaxies with redshift z. We assume that M 51-type binary systems could be formed through the capture of a satellite by a massive spiral galaxy. It is also possible that the main galaxy and its satellite in some of the systems have a common cosmological origin.