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排序方式： 共有91条查询结果，搜索用时 15 毫秒
31.
João Canning-Clode Manfred Kaufmann Markus Molis Martin Wahl & Mark Lenz 《Marine Ecology》2008,29(1):115-124
Disturbance and productivity are often cited as the main factors determining temporal and spatial patterns in species distribution and the diversity of communities. A field experiment was conducted to test the role of these factors in the structuring of early successional fouling communities in a nutrient limited system at the south coast of Madeira Island. Macro‐benthic sessile communities, established on artificial settlement substrata, were manipulated and surveyed over a 9‐week period. We applied mechanical disturbances of four different frequencies crossed with three levels of inorganic nutrient enrichment. Fertilization enhanced community diversity by favouring the establishment and growth of macroalgae. Disturbance reduced diversity by eliminating species – but only at the highest nutrient level. This is explained by a multiple‐stressor model; species most sensitive to nutrient deficiency (only present in the highest enrichment treatment) were simultaneously the most sensitive to disturbance. 相似文献
32.
膜过滤在污水处理中的应用研究进展 总被引：3，自引：0，他引：3
膜滤是借助一定的外加压力使液体穿过膜后分离成浓缩液和渗透液的分离技术。常用于水处理的膜滤依据过滤膜孔径、被截留物质的尺寸和施加的过滤压力不同可分为微滤、超滤、纳滤和反渗透等。介绍了不同膜滤技术的渗透原理、膜的类型、过滤模型以及膜的污染与防治,概述了膜过滤在处理垃圾填埋场渗沥液和处理纺织印染工业废水以及中水回用等领域的应用,并探讨了膜滤技术今后的研究方向。 相似文献
33.
Ultrafiltration (UF) can remove natural organic matter (NOM) effectively. Moreover, chlorine dioxide (ClO2) has been an alternative disinfectant as it forms fewer disinfection by‐products with NOM than chlorination does. Therefore, combining ClO2 with UF may improve conventional purification processes. In this study, feed water containing humic acid with 4.07 mg/L total organic carbon (TOC) was dosed directly with various amounts of ClO2 (0, 2, 5, 10, and 15 mg/L) before being filtered through a 5‐kDa UF membrane. With a low dose (2 mg/L ClO2), UF removed humic acid effectively, as TOC was not detected in the permeate, and the permeate flux increased to about 80% of the initial permeate flux by cross flow. Moreover, the concentrations of ClO, ClO, and trihalomethanes in the permeate were below the United States Environmental Protection Agency guidelines. 相似文献
34.
35.
烟台市龙口港污损生物生态研究 总被引：1，自引：0，他引：1
于2007年03月22日至2008年03月21日在山东省烟台市龙口港附近海域,进行了为期1年的挂板试验,本次调查共记录该海域污损生物32种,优势种为内枝多管藻(Polysiphonia morrowii)、软丝藻(Ulothrix flacca.)、肠浒苔(Entermorpha intestinalis)、中胚花筒螅(Tubularia mesembryanthemum)等.该海域全年均有污损生物附着,月板平均生物量为525.18 g/m2,5-11月的生物附着量较高,最高值出现在7月;季板平均生物量为1569.39 g/m2,生物群落的种类组成和生物量变化明显,其中秋季板生物量最高,龙口海域污损生物的附着种类受季节性水温变化的影响比较明显,藻类开始附着的温度低于动物.4个季度污损生物的种群多样性指数(H忆)春季最高,均匀度指数(J)和种群丰富度指数(M)则夏季最高.统计分析表明,龙口港海域污损生物群落可大致划分为 4个组群,秋季附着的污损生物代表了试验海域的主要特征,同时揭示出污损生物附着季节、演替时间长短等是影响群落种类组成的重要因素 相似文献
36.
Canine faecal contamination contributes to environmental degradation and increases the exposure of humans – mainly children – to helminth infections. We studied the magnitude and spatial distribution of faecal contamination on the pavements of two neighbourhoods representative of Buenos Aires suburbs. The pavements of a low-income neighbourhood (LIN) and a middle-income neighbourhood (MIN) were selected at random. Field maps including all substrates and objects observed on each pavement were drawn, viewed from above, on millimetre paper at 1:100 scale. Data were then loaded into a geographic information system (GIS) Arc View 3.1 with a digitiser board. The spatial distribution of faeces and its association with substrates or standing elements were analysed at three scales: substrate, pavement and neighbourhood.
Permeable substrate cover was higher in LIN (75%) than in MIN (35%). The faeces were not homogeneously distributed on the substrates. In both neighbourhoods, the substrates with >50 per cent grass cover showed a significantly higher proportion of faeces than those with <50 per cent grass cover, bare soil and tile. At pavement scale, the number of faeces on pavements was not related to either the number of trees, posts and domiciled dogs in the block, or with the number of faeces and percentage cover of each substrate. At patch scale, substrate patches with faeces were larger than those without faeces. Patches with faeces did not differ in shape between neighbourhoods and were more regularly shaped than patches without faeces.
The spatial distribution of faeces relative to each other was almost random, even when analysed in relation to trees or standing objects. Strategies for the sustainable control of this problem are suggested. 相似文献
Permeable substrate cover was higher in LIN (75%) than in MIN (35%). The faeces were not homogeneously distributed on the substrates. In both neighbourhoods, the substrates with >50 per cent grass cover showed a significantly higher proportion of faeces than those with <50 per cent grass cover, bare soil and tile. At pavement scale, the number of faeces on pavements was not related to either the number of trees, posts and domiciled dogs in the block, or with the number of faeces and percentage cover of each substrate. At patch scale, substrate patches with faeces were larger than those without faeces. Patches with faeces did not differ in shape between neighbourhoods and were more regularly shaped than patches without faeces.
The spatial distribution of faeces relative to each other was almost random, even when analysed in relation to trees or standing objects. Strategies for the sustainable control of this problem are suggested. 相似文献
37.
东海污损生物群落研究Ⅲ.群落结构 总被引：1，自引：0，他引：1
计算东海29 个试验点污损生物群落之间的相似系数,并进行聚类分析。根据分析结果,东海污损生物群落可分为4 个类型: 河口群落、近岸群落、内湾群落和远岸群落 相似文献
38.
39.
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40.
Biofouling is an important factor that affects the bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitors for food resource with the cultured species. The present study was conducted to measure the impact of fouling on food uptake and nutrient release in April and June, 2006 in Daya Bay near Guangzhou, China. Results showed that fouling organisms had significant effect on food uptake and nutrient release. The chlorophyll a uptake rate of fouled scallops was 7.53Lh-1±1.416Lh-1 and 11.94Lh-1±2.497Lh-1 in April and June, respectively, significantly higher than those of cleaned scallops, i.e., 4.23 Lh-1 ±2.744Lh-1 and 2.57Lh-1± 1.832 Lh-1 respectively.The consumption of total particulate matter by fouled scallops in April and June was 5.52Lh-1±0.818Lh-1 and 3.07Lh-1±0.971 Lh-1,respectively; the corresponding results for cleaned scallops are 2.49Lh-1 ±0.614Lh-1 and 2.37± 1.214Lh-1, respectively. Fouling increased ammonia release significantly. The ammonia release rate of fouled scallops was 33.81Lh-1±7.699Lh-1 and 76.39Lh-1 ±9.251Lh-1 in April and June, while cleaned scallops released 2.46Lh-1± 0.5 1 1Lh-1 and 7.23Lh-1± 1.026Lh-1 ammonia, respectively. Phosphate release of fouled scallops was 22.72Lh-1 ± 9.978 Lh-1 in June and cleaned scallops released phosphate 6.01Lh-1 ±0.876 Lh-1 in April. Therefore, fouling contributed much to food reduction and concentration increase of ammonia and phosphate in water. 相似文献