共查询到20条相似文献，搜索用时 691 毫秒
1.
Based on the data of phytoplankton concentration and environmental factors in Bohai Bay from May to September in 2003. the relationship between environmental factors and phytoplankton biomass was analyzed. By analysis of variance, the weather condition was found to have no direct relation with phytoplankton biomass. Correlation coefficients showed that temperature, pH value,the concentrations of silicate and nitrate exhibited linear relationship with phytoplankton biomass.With principal component analysis, pollution types which affected the abundance of phytoplankton included point sources such as municipal and industrial effluents, agricultural runoff and earth＇s surface water. Using multivariate stepwise regression method and taking the correlation analysis results into consideration, a multi-step regression equation was developed to predict the concentration of phytoplankton in September 2003. Combined results show that temperature, pH value, the concentrations of silicate and nitrate are the critical ecological factors affecting the phytoplankton biomass in Bohai Bay. 相似文献
2.
钦州湾表层海水温度盐度及pH值时空变化 总被引：2，自引：0，他引：2
根据2009年春夏秋冬4个季节调查资料,分析钦州湾表层海水温度、盐度及pH值的季节变化和分布特征。结果表明：钦州湾海水平均温度春季20．4℃,夏季30．1℃,秋季16．0℃,冬季14．6℃,变化特征与气温的季节变化相同,空间分布为夏秋季河口区的水温都略高于湾口区,而春冬季则相反。海水平均盐度春季20．067,夏季17．975,秋季23．864,冬季23．660,表现为秋季〉冬季〉春季〉夏季,各季节空间分布总体表现为河口区低,湾口区高的趋势。海水pH平均值春季7．82,夏季8．11,秋季8．01,冬季8．10,全年空间分布高值区均出现在大风江口外海域。钦州湾海水比较适宜大蚝、对虾、文蛤等广温广盐性品种的海水养殖。 相似文献
3.
Mechanisms and assessment of water eutrophication 总被引：4，自引：0，他引：4
Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent ad- vances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is increasing, especially in the developing countries like China. The assessment of water eutrophication has been ad-vanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance, etc., and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated. 相似文献
4.
In order to investigate the eutrophication degree of Yuqiao Reservoir, a hybrid method, combining principal component regression (PCR) and artificial neural network (ANN), was adopted to predict chlorophyll-a concentration of Yuqiao Reservoir’s outflow. The data were obtained from two sampling sites, site 1 in the reservoir, and site 2 near the dam. Seven water variables, namely chlorophyll-a concentration of site 2 at time t and that of both sites 10 days before t, total phosphorus(TP), total nitrogen(TN), dissolved oxygen(DO), and temperature from January 2000 to September 2002, were utilized to develop models. To remove the collinearity between the variables, principal components extracted by principal component analysis were employed as predictors for models. The performance of models was assessed by the square of correlation coefficient, mean absolute error (MAE), root mean square error (RMSE) and average absolute relative error (AARE). Results show that the hybrid method has achieved more accurate prediction than PCR or ANN model. Finally, the three models were applied to predicting the chlorophyll-a concentration in 2003. The predictions of the hybrid method were found to be consistent with the observed values all year round, while the results of PCR and ANN models did not fit quite well from July to October. 相似文献
5.
A two-dimensional numerical model of extratropical storm surge and inundation in Bohai Bay was built based on the unsteady flow Navier-Stokes equations. The model included two sections, one was for the simulation of storm surge tidal level and the other for the simulation of storm surge inundation in the coastal area. While simulating the storm surge tidal level, the alternating direction implicit (ADI) method was applied to dispersing and solving 2D storm surge equations. In the simulation of storm surge inundation, the 2D unsteady flow equations were dispersed and solved using the structureless grids of finite volume method (FVM). A coupling calculation mode of the process of inundation and storm surge tidal level variation was proposed, therefore the storm surge inundation process and area could be calculated while simulating and forecasting the process of storm surge tidal setup. Furthermore, an extratropical storm surge and inundation in Bohai Bay were simulated using this numerical model. Simulation results are in good agreement with the measured data, which shows that this numerical model provides a new method of simulating and forecasting storm surge and inundation in Bohai Bay. 相似文献
6.
盖清霞 《青岛教育学院学报》2014,(5):20-24
莱州湾是渤海的三大海湾之一。从古至今,莱州湾的鲐鱼资源变动就十分明显,显著特征是时有时无。其主要原因为鲐鱼不适宜在浑浊的海水里生存。黄土高原的水土流失导致了黄河泥沙含量的提高,而黄河注入到渤海中则影响了莱州湾海水的透明度。近几十年来,莱州湾还受到了沿岸的工业污染和地上河流的陆源污染,这使得莱州湾的海洋环境更加恶化。现如今,多种因素交织导致鲐鱼基本上在莱州湾消失了。 相似文献
7.
A new approach to coastal water quality assessment was put forward through study on self-organizing map （ SOM ）. Firstly, the water quality data of Bohai Bay from 1999 to 2002 were prepared. Then, a set of software for coastal water quality assessment was developed based on the batch version algorithm of SOM and SOM toolbox in MATLAB environment. Furthermore. the training results of SOM could be analyzed with single water quality indexes, the value of N ： PC atomic ratio） and the eutrophication index E so that the data were clustered into five different pollution types using k-means clustering method. Finally, it was realized that the monitoring data serial trajectory could be tracked and the new data be classified and assessed automatically. Through application it is found that this study helps to analyze and assess the coastal water quality by several kinds of graphics, which offers an easy decision support for recognizing pollution status and taking corresponding measures. 相似文献
8.
INTRODUCTIONPigmentsarecloselyrelatedtothephysiolog icalfunctionofleaves.Chlorophyllsabsorblightenergyandtransferitintothephotosyntheticpro cess.Carotenoids (yellowpigments)canalsocontributeenergytothephotosyntheticsystem .Becauseoftheimportanceofpigments… 相似文献
9.
10.
Artificial neural network modeling of water quality of the Yangtze River system: a case study in reaches crossing the city of Chongqing 总被引：2，自引：0，他引：2
An effective approach for describing complicated water quality processes is very important for river water quality management. We built two artificial neural network （ANN） models, a feed-forward back-propagation （BP） model and a radial basis function （RBF） model, to simulate the water quality of the Yangtze and Jialing Rivers in reaches crossing the city of Chongqing, P. R. China. Our models used the historical monitoring data of biological oxygen demand, dissolved oxygen, ammonia, oil and volatile phenolic compounds. Comparison with the one-dimensional traditional water quality model suggest that both BP and RBF models are superior; their higher accuracy and better goodness-of-fit indicate that the ANN calculation of water quality agrees better with measurement. It is demonstrated that ANN modeling can be a tool for estimating the water quality of the Yangtze River. Of the two ANN models, the RBF model calculates with a smaller mean error, but a larger root mean square error. More effort to identify out the causes of these differences would help optimize the structures of neural network water-quality models. 相似文献
11.
车志伟 《海南师范学院学报》2006,19(4):362-365
根据2002—2005年三亚榆林湾海域巡航监测结果，分析评价了该海域水质营养化状况，结果表明：榆林湾大部分海域水质良好，湾内红沙港养殖区水体受到营养盐、有机质污染．营养化程度呈现加剧趋势，提出了防止该海域水体富营养化，控制水质恶化的对策． 相似文献
12.
13.
Nitrogen doping of activated carbon (AC) was performed by annealing both in ammonia and nitric oxide, and the activities of the modified carbons for NO reduction were studied in the presence of oxygen. Results show that nitrogen atoms were incorporated into the carbons, mostly in the form of pyridinic nitrogen or pyridonic nitrogen. The effect of nitrogen doping on the activities of the carbons can be ignored when oxygen is absent, but the doped carbons show desirable activities in the low temperature regime (≤500 ℃) when oxygen is present. The role of the surface nitrogen species is suggested to promote the formation of NO2 in the presence of oxygen, and NO2 can facilitate decomposition of the surface oxygen species in the low temperature regime. 相似文献
14.
15.
环渤海湾经济圈文化支撑的构建路径与价值取向 总被引：1，自引：0，他引：1
YANG Si-yuan 《石家庄法商职业学院教学与研究》2007,(4)
实践证明,要实现区域经济的协调发展,须有统一的思想基础、共同的价值目标和行为规范,这是一个地区保持健康、稳定、和谐发展的保证。环渤海湾经济发展圈的构建也不例外,其文化支撑与制度建设的衔接至关重要。 相似文献
16.
Interaction Between DEHP and Particulate in a Eutrophic Lake 总被引：2，自引：0，他引：2
Characteristics of interaction between di-2-ethylhexyl phthalate(DEHP) and particulate in a eutrophic lake were studied in this paper. DEHP concentrations ranged from 89.9 to 247 μg/L with an average value of 146 μg/L in subsurface water (SSW) samples, and from 82.0 to 390 μg/L with an average value of 211 μg/L in water surface microlayer (SM) samples. The results indicate that there was only a weak correlation between the DEHP concentrations and suspended particulate material(SPM) concentrations in both SSW and SM,while the significant correlation between DEHP concentrations and chlorophyll a concentrations was found,which suggestes that DEHP was principally bound to phytoplankton in the eutrophic lake. Correlation between DEHP concentrations and total phosphor (TP) concentrations was also found in this investigation. Enrichment factors (EF) of DEHP in SM were in the range of 0.85 to 2.12 with an average value of 1.35..DEHP EFs were significantly related to the enrichment of chlorophyll a in SM. The results suggest that the enrichment of DEHP in SM of this eutrophic lake was mainly due to DEHP accumulation in phytoplankton and was controlled by distribution of phytoplankton between SM and SSW. 相似文献
17.
Engineeringrisk analysis is an integrated margin-al science, which has been rapidly developed in thepast two decades. It includes a series of methods toanalyze different problems induced by various uncer-tainties. Project risk assessment involves risk identifi-cation, risk estimation and risk evaluation, etc[1].Recently, researchers have been paying more andmore attention to the development of the quantitativerisk analysis methods[2], especially to the evaluationmethods of risk probability.Som… 相似文献
18.
To predict the economic loss of crops caused by acid rain, we used partial least squares （PLS） regression to build a model of single dependent variable - the economic loss calculated with the decrease in yield related to the pH value and levels of Ca^2＋, NH4^＋, Na^＋, K^＋, Mg^2＋, SO4^2-, NO3^-, and Cl^- in acid rain. We selected vegetables which were sensitive to acid rain as the sample crops, and collected 12 groups of data, of which 8 groups were used for modeling and 4 groups for testing. Using the cross validation method to evaluate the performace of this prediction model indicates that the optimum number of principal components was 3, determined by the minimum of prediction residual error sum of squares, and the prediction error of the regression equation ranges from -2.25% to 4.32%. The model predicted that the economic loss of vegetables from acid rain is negatively corrrelated to pH and the concentrations of NH4^＋, SO4^2-, NO3^-, and Cl^- in the rain, and positively correlated to the concentrations of Ca^2＋, Na^＋, K^＋ and Mg^2＋. The precision of the model may be improved if the non-linearity of original data is addressed. 相似文献
19.
虾塘水体理化因子与气候的关系 总被引：1，自引：0，他引：1
通过对4口虾塘水体部分理化因子的检测及气候特征的记录，分析了水体理化因子之间的相互作用及气候的影响作用．结果表明，盐度升高时，pH值升高，而氨氮、亚硝酸氮和硫化物则下降；亚硝酸氮升高时硫化物也升高；pH值升高时氨氮含量下降．氨氮和亚硝酸氮的最大值均出现在刮西南风的时候，最小值均出现在刮东风的时候；风力7～8级以上可明显地升高氨氮、亚硝酸氮和硫化物的含量．氨氮、亚硝酸氮和硫化物在阴天和雨天时有升高的趋势． 相似文献
20.
2012年全球镉产量已增至2.3万t,镉污染对人类的伤害日趋严重。在芥菜型油菜（Brassica juncea）晋油6号、川油A-6和内引I号中,筛选出一个对重金属镉有较强耐受力的品种。水培条件下,利用不同浓度的外源镉对油菜幼苗进行处理,研究镉胁迫对芥菜型油菜幼苗叶绿素和丙二醛（MDA）含量、可溶性蛋白质浓度以及过氧化氢酶（CAT）活性的影响。3个参试品种中,晋油6号对重金属镉的耐受力最强。随着镉处理浓度的增大,晋油6号叶绿素含量的降低最为缓和,丙二醛的增长量最低,且通过产生新的可溶性蛋白质和提高过氧化氢酶活性来抵御逆境的能力最强。晋油6号在作为镉污染修复的植物材料上具有应用价值。 相似文献