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桑给巴尔海峡地貌和沉积物分布
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作者 yohanna w.shaghude Kjell O.Wanns 张甲坤 《人类环境杂志》 1998年第8期725-729,共5页
对桑给巴尔海峡的地貌研究表明研究该海峡的中部是一个深约30~40m的"中央深沟"。深沟的东侧为不规则的陡峭珊瑚台地,而西侧的地形相对平缓。地貌的特殊之处在于点礁干扰了原本光滑的地形。构造活动可部分地解释海峡东西两侧... 对桑给巴尔海峡的地貌研究表明研究该海峡的中部是一个深约30~40m的"中央深沟"。深沟的东侧为不规则的陡峭珊瑚台地,而西侧的地形相对平缓。地貌的特殊之处在于点礁干扰了原本光滑的地形。构造活动可部分地解释海峡东西两侧地貌的差异。通过陆伍(Ruvu)河和瓦密(Wami)河输入的陆源沉积物在更大程度上控制了海峡西部海底沉积物的分布型式。沉积物中碳酸盐含量和粒度参数分布可对此予以证明。桑给巴尔岛没有一条大的河流,这意味着海峡的东侧没有重要的运输机制能将陆源物质输入海底。海峡东侧高含量的碳酸盐(>70%)既有生物成因的也有来自珊瑚系统和更新世珊瑚礁侵蚀物的。 展开更多
关键词 海洋沉积 沉积物分布 海峡地貌 桑给巴尔海峡
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桑给巴尔海峡的沉积物分布和输送
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作者 yohanna w.shaghude Kjell O.Wanns 郑斯中 《人类环境杂志》 1995年第7期519-522,共4页
引言坦桑尼亚的海岸带是一条沿着本土海岸的狭长地带,它包括三个岛屿,即奔巴岛、桑给巴尔岛和马菲亚岛。海岸的高原以厚的沉积岩为特征,断层大致呈南北方向。晚期地壳构造的发育影响了现在陆上和海内的地貌。桑给巴尔海峡的长度大约为12... 引言坦桑尼亚的海岸带是一条沿着本土海岸的狭长地带,它包括三个岛屿,即奔巴岛、桑给巴尔岛和马菲亚岛。海岸的高原以厚的沉积岩为特征,断层大致呈南北方向。晚期地壳构造的发育影响了现在陆上和海内的地貌。桑给巴尔海峡的长度大约为120km,宽约35km(图1)。海峡底部以水的深度浅(10~50m)为特征,具有延伸的沙洲和有礁结构的小珊瑚台地。孤立的小礁石结构(块礁)也是常见的。 展开更多
关键词 坦桑尼亚 桑给巴尔海峡 海峡沉积物
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Local Persistence of Large Benthic Foraminifera(LBF)under Increasing Urban Development:A Case Study from Zanzibar(Unguja),East Africa 被引量:1
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作者 Gita R.Narayan Natalia Herrán +2 位作者 Claire E.Reymond yohanna w.shaghude Hildegard Westphal 《Journal of Earth Science》 SCIE CAS CSCD 2022年第6期1434-1450,共17页
Coastal marine management is vital for socio-ecological sustainability of developing,tropical ecosystems,which calls for diverse tools to monitor and assess water quality.The carbonatedominated habitats off Zanzibar w... Coastal marine management is vital for socio-ecological sustainability of developing,tropical ecosystems,which calls for diverse tools to monitor and assess water quality.The carbonatedominated habitats off Zanzibar were chosen for study due to potential water quality degradation in a rapidly developing tourist destination heavily reliant on its coral reefs.These reefs are largely unmonitored and subject to local and global stressors.A widely used method for assessing reef health,as an early detection method of ecological changes,is the application of large benthic foraminiferal bioindicators,i.e.,the Fo RAM Index.We expected to find poor water quality conditions in the unmanaged reefs supported by stress-toelerant(opportunistic)foraminiferal assemblages.The dissolved inorganic nitrogen and phosphate values derived from untreated sewage effluent from Stone Town were highly variable(ranging 0.05–3.77 and 0.05–1.45μM,respectively),moderate,and occasionally approached or exceeded critical threshold values for oligotrophic ecosystems.The analysis of total assemblages indicated an abundance of symbiont-bearing large benthic foraminifera,dominated by prolific Amphistegina species,comparatively low-moderate diversity,high FI values(7.6 on average),and high coral cover.A water quality gradient was reflected by subtle assemblage differences,suggesting that LBF can provide early warning signals of benthic changes,indicating the importance of long-term monitoring programs in vulnerable,rapidly developing coastal ecosystems exposed to increasing pressures. 展开更多
关键词 CARBONATE coral reef BIOINDICATOR Fo RAM Index NUTRIENTS sewage effluent Western Indian Ocean coastal development coastal marine management
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