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71.
Abstract

The capability of the Surface inFiltration Baseflow (SFB) conceptual rainfall-runoff model to simulate streamflow for three catchments selected from northern Iraq is investigated. These catchments differ in their climatic regimes and physical characteristics. Three versions of the model were tested: the original three-parameter model (SFB), the modified five-parameter model (SFB-5), and the modified six-parameter model (SFB-6). The available daily precipitation, potential evapotranspiration and runoff data were used in conjunction with a simulated annealing (SA) optimization technique to calibrate the various versions of the SFB model. A simple sensitivity analysis was then carried out to determine the relative importance of the model parameters. The study indicated that use of the original three parameter model was not adequate to simulate monthly streamflow in the selected catchments. The modified version (SFB-5) provided better runoff simulation than the original SFB model; overall a 19% increase was observed in the coefficient of determination (R2) between simulated and observed monthly runoff. The SFB-5 model performed with varying degrees of success among the catchments. The model performance in the validation stage was reasonable and comparable to that of the calibration stage. The sensitivity analysis of the SFB model for arid catchments revealed that the baseflow parameter (B) was the most sensitive one, while the S and F parameters were less sensitive than the B parameter.  相似文献   
72.
海洋微藻脂肪酸组成的比较研究   总被引:82,自引:5,他引:77  
于1995 ̄1997年在中国科学院海洋研究所培养20种海洋微藻,采用Bligh-Dyer法和气相色谱法进行脂肪酸组成的比较研究。结果表明,除个别藻外,海洋微藻的总脂含量均超过其干重的10%,每一纲藻种都有其特征脂肪酸或几种脂肪酸的组合作为其化学分类的标记:绿藻纲中除小球藻的20:5(n-3)含量较高以外,一般含有较高的16:4(n-3),不含22:6(n-3);硅藻纲的16:1(n-7)含量高于1  相似文献   
73.
We examined the effects of sediment on fish communities at 38 sites in the East Cape region of New Zealand. Many streams in this region are subject to high sediment loads, a natural situation that has been exacerbated by the conversion of native forest to pasture. The fish community consisted of diadromous native species common throughout New Zealand that require access to and from the sea. We found that site altitude and distance inland were important factors in determining the abundance and composition of the fish community. We used four measures as indices of sediment load: suspended sediment concentration, median substrate size, substrate stability, and the ratio of the wetted width to the width of the active (non‐vegetated) stream channel. Although all indices were correlated, the ratio of wetted width to width of active channel was most closely related to fish abundance and diversity. Fish abundance and diversity reduced as sediment load increased among streams, with up to nine fish species in streams with low sediment loads and only two species in streams with high sediment loads. In‐stream habitat also varied with sediment load; as load increased, depth and substrate size decreased and velocity increased. These results suggest that activities that increase sediment loads in rivers will have a negative impact on native fish communities in New Zealand.  相似文献   
74.
为了利用荧光技术对北极浮游植物的生理生态信息进行系统研究, 本文以实验室培养条件下的两种北冰洋微型浮游植物——柔弱伪菱形藻(Pseudo-nitzschia delicatissima)和海链藻(Thalassiosira sp.)为研究对象, 先采用流式细胞术(Flow Cytometry, FCM)和全荧光光谱法对其活体中色素的静态荧光进行测量, 后利用脉冲调制方法(Pulsed Amplitude Modulation, PAM)对其叶绿素动态荧光信息进行测定, 对两种浮游植物的三类荧光信息进行综合比较分析, 结果表明: 柔弱伪菱形藻的丰度、基础荧光(F0)、光合系统Ⅱ(PSⅡ)光化学的有效量子产量(ΦPSⅡ)及光合电子传递效率(ETR)分别为22×105cell/mL、844、0.247和42.8, 皆高于海链藻的相应值(8×105cell/mL、464、0.185及33.0); 静态荧光和基础荧光分析表明柔弱伪菱形藻细胞内叶绿素a (chl a)含量较高; 海链藻细胞内则具有较高含量的类胡萝卜素, 其对光保护机制依赖性较强。本文初步展示了三类荧光分析法在极地微型浮游植物生理生态研究方面的联合应用。  相似文献   
75.
Breeding in the freshwater crayfish paranephrops planifrons white   总被引:2,自引:2,他引:0  
The breeding cycle of female Paranephrops planifrons is described. The incubation of eggs and young takes place between April and December and covers about 25–26 weeks. The winter population contains some apparently adult females which do not breed. The number of eggs laid increases with the size of the parent, and in the population studied varied from some 20 to 30 eggs at 17 mm carapace length to 150 eggs at 30 mm carapace length. After hatching the young pass through two moults while still attached to the parent.  相似文献   
76.
Newly metamorphosed Evechinus chloroticus (Val.) were observed in three larval cultures 36, 30, and 28 days after fertilisation, indicating that the free swimming larval life may last about 1 month.  相似文献   
77.
Pseudocycnus appendiculatus Heller is described and recorded, for the first time from New Zealand, on Thunnus alalunga (Bonnaterre, 1788). Pseudocycnus spinosus Pearse, 1951 and P. thynnus Brandes, 1955 are thought to be synonyms of P. appendiculatus. Other species previously placed in the genus are discussed and the action of Yamaguti (1963) in removing them to other genera supported. It is suggested that the family Pseudocycnidae Yamaguti, 1963 cannot be differentiated from the family Dichelesthiidae Bassett‐Smith, 1898.  相似文献   
78.
From a trawling at 448–512 m in Palliser Bay, Cook Strait, New Zealand, molluscs associated with. Tertiary siltstone concretions and with a large colony of Goniocorella dumosa (Alcock) are listed. A juvenile Acesta, extremely tall and extremely broad forms of Emarginula striatula Quoy & Gaimard, and the animals of Stilifer neozelanica Dell and of Waipaoa marwicki Dell are described. Sculptifer, a new genus provisionally included in the Fossaridae, is proposed for Stilifer neozelanica. New species of Danilia and Pholadidea are described and their relationships discussed. Emarginula lophelia Beu, 1967 is synonymized with E. striatula Quoy & Gaimard, 1834, and the recent New Zealand forms of Emarginula are reviewed.  相似文献   
79.
The grazing turbinid gastropod Lunella smaragda was sampled regularly over 3.5 y from precise sites of different microtopography and height on the platform shore at Goat Island Beach near Leigh, Northland, New Zealand. Growth is linear for over 3 y, and the year‐classes distinct. The position of the different size‐classes is related to both the shelter afforded by the microtopography, and to the height on the shore. The populations in the mid‐eulittoral turf flats, low eulittoral bare rock areas, and the sublittoral fringe are distinct, and there is a general movement down the shore with age and size. Wave action apparently dislodges the animals from higher areas when they grow to a critical size and transports them to sites lower on the shore, where wave disturbance is less. Field experiments with marked animals and laboratory studies with a wave tank confirm that the wave‐effected distribution is size related. However measurements showed that the ratio of foot attachment area to the shell area presented to the wave does not vary with animal size. The possible benefits of wave dislodgment and wave‐effected distribution are considered.  相似文献   
80.
Sixteen rock samples were collected from the continental shelf and slope between Napier and Cape Turnagain, southern Hawkes Bay, most coming from offshore anticlinal ridges. Nine of the samples have a foraminiferal fauna of Upper Miocene and Pliocene age. The remainder cannot be dated, but most are probably of similar age. The foraminiferal. faunas are considered to have lived at depths ranging down to at least 1600 m deeper than the depth from which they were collected. Thus, the post‐depositional history of the samples includes tectonic uplift of similar magnitude since Upper Tertiary times. Because most of the samples arc very fine grained, unlike Recent sediments from ridges, it is suggested that the present regime of folding is largely post‐Pliocene in age.  相似文献   
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