Some challenges of an "upside down" nitrogen budget--science and management in Greenwich Bay, RI (USA)     

DiMilla PA  Nixon SW  Oczkowski AJ  Altabet MA  McKinney RA 《Marine pollution bulletin》2011,62(4):672-680

When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Previous inventories of nitrogen (N) inputs to Greenwich Bay found that N inputs from Narragansett Bay exceeded those from the local watershed, suggesting that recent efforts to reduce local watershed N loads may have little effect on estuarine water quality. We used stable isotopes of N to characterize watershed and Narragansett Bay N sources as well as the composition of primary producers and consumers throughout Greenwich Bay. Results were consistent with previous assessments of the importance of N inputs to Greenwich Bay from Narragansett Bay. As multiple N sources contribute to estuarine water quality, effective management requires attention to individual sources commensurate with overall magnitude, regardless of the political complications that may entail.  相似文献   

横跨喜马拉雅造山带的构造运动转换与变形分配   总被引：1，自引：0，他引：1       下载免费PDF全文

马晓静  高祥林 《地球物理学报》2011,54(6):1528-1535

喜马拉雅造山带包含喜马拉雅弧和东、西构造结3个基本部分,它们是大陆碰撞后印度板块继续向北移动,并向西藏高原下俯冲产生的构造变形系统.该系统的重要地质特征之一,是同时存在多种不同样式、不同或相反性质的地壳变形,例如地壳南北向缩短与东西向伸展,高原隆起与山间盆地下沉,与造山带走向大致平行的向北倾斜或向南倾斜的逆断层,东西向...  相似文献   

新生代渤海中部强烈沉降的物理条件和深部过程   总被引：5，自引：4，他引：1       下载免费PDF全文

高祥林 《地球物理学进展》2005,20(4):889-896

新生代时期渤海中部的强烈沉降,是多种物理条件的共同作用结果,这些条件是由裂谷期和后裂谷期的深部过程产生成的.裂谷期在异常热地幔背景下的渤海地壳隆起、减薄、张裂,地幔热物质上升侵入地壳,莫霍界面位置升高,积累了重力势能;后裂谷期岩石圈（层）的冷却、收缩及下地壳的相变导致密度增大,加上巨厚沉积物的持续增生,使地壳处于重力不平衡状态,向下的垂直力远大于向上的浮托力,同时还有东部后退位移性板块边界和下地壳侧向流动的支持,使渤海中部成为下沉速率最快、沉降幅度最大的凹陷盆地.后裂谷期的早期的盆地下沉具有分散、局部性特征,表现为多个凹陷和凸起交替组合格局;晚期转变为大范围的整体沉降,显示重力均衡和补偿过程是从浅往深发展的.先存的郯庐断裂带对沉降的空间范围有局部边界控制性作用,其本身可能受到盆地发展的强烈改造影响.盆地的基本变形机制是上地壳的水平向脆性张破裂和垂直向或近垂直向的正断层-剪切破裂,地震震源机制解和大地震时的地表破裂表现的水平错动反映中、下地壳的走滑-平移型应力状态及相应的瞬间水平剪切破裂,它与上地壳残留的伸展、下沉相容并存于三维地壳体内.  相似文献   

水质与健康     

Smith  RA 詹庚申 《江苏地质科技情报》1995,(1):15-16

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节理化玄武岩类岩体的峰值强度与变形性质     

Schu.  RA 杨翠珠 《地质科学译丛》1996,13(3):64-69

本研究玄武岩类岩体的强度与变形性质，并运用岩体分类系统分析其脆性断裂效应，从而为玄武岩体脆性反应变化范围提供依据。虽然，各类玄武岩的物质组成和物理指标很分散，但其许多性质指标都在系数约为１０的范围内，在常温和低围压下完整玄琥岩岩块的强度参数的典型值为；杨氏模量７８±１９ＧＰａ；泊松比０．２５±０．０５；抗拉强度－１４．５±３．３ＭＰａ。  相似文献   

A—型花岗岩再探残余源区模式评述     

Grea.  RA 王晓霞 《国外地质与勘测》1992,(2):9-14

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海平面变化和波浪潮汐为主沿海层序的保存潜力     

D.  RA  Jr 王建芬 《国外第四纪地质》1991,(4):72-80

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Cross-Correlation of Tenerife Data with Galactic Templates-Evidence for Spinning Dust?     

de Oliveira-Costa A  Tegmark M  Gutiérrez CM  Jones AW  Davies RD  Lasenby AN  Rebolo R  Watson RA 《The Astrophysical journal》1999,527(1):L9-L12

The recent discovery of dust-correlated diffuse microwave emission has prompted two rival explanations: free-free emission and spinning dust grains. We present new detections of this component at 10 and 15 GHz by the switched-beam Tenerife experiment. The data show a turnover in the spectrum and thereby support the spinning dust hypothesis. We also present a significant detection of synchrotron radiation at 10 GHz, which is useful for normalizing foreground contamination of cosmic microwave background experiments at high galactic latitudes.  相似文献   

Composition and distribution of organochlorine pesticide residues in surface sediments from the Wu-Shi River Estuary,Taiwan   总被引：23，自引：0，他引：23  

Doong RA  Peng CK  Sun YC  Liao PL 《Marine pollution bulletin》2002,45(1-12):246-253

The contamination of organochlorine pesticides (OCPs) in sediments from the Wu-Shi River estuary was investigated to evaluate the pollution potentials and distribution of OCPs in central Taiwan. A total of 19 sediment samples were collected at five sampling stations along the River estuary. The concentrations of OCPs were in the range of 0.99–14.5 ng/g-dry weight (dw) for ΣHCH (-, β-, γ-, δ-HCH), 0.46–13.4 ng/g-dw for Σcyclodiene and 0.53–11.4 ng/g-dw for ΣDDT (p,p^′-DDD, p,p^′-DDE, p,p^′-DDT). The mean concentrations of ΣHCH, Σcyclodiene and ΣDDT were 3.79, 4.87 and 2.51 ng/g-dw, respectively. The total concentrations of OCPs correspond to 1.73–71.9 μg/g-OC when normalized to TOC contents. Among the organochlorine pesticides, endosulfan sulfate, β-HCH, and p,p^′-DDD were the most dominant compounds in the sediments with the average concentrations of 1.97, 3.43 and 2.08 ng/g, respectively. Also, different contamination patterns among sampling seasons were observed. The measured concentrations of OCPs collected in spring were higher than those in autumn and winter. A linear relationship between sediment characteristics and OCP residues was also demonstrated. The results obtained in this study show that there still exist a variety of organochlorine pesticide residues in the sediments from the near shore of central Taiwan.  相似文献   

中、新生代全球尺度地质过程及其对自然环境的影响   总被引：1，自引：0，他引：1  

杜品仁  马宗晋  高祥林 《地学前缘》2003,10(Z1):38-44

中、新生代是地球岩石圈经历重大构造演化 ,最终形成现今地球面貌的时代。研究对中、新生代全球级环境变化有重大影响的地质作用过程 ,对从整体上把握和理解环境演变的规律和原因 ,最终实现对环境变化的预测有重要意义。中生代开始不久 ,位于赤道附近的联合古陆便解体分裂 ,全球大陆和大洋逐渐演变成现今的分布格局。与此相伴 ,地球的地形、地貌也发生了重大变化。中生代造山运动造就的山脉和其后由构造隆升形成的高原 ,也是影响全球气候的主要因素之一。中、新生代的多次大规模火山活动 ,造成气候、环境的快速变化 ,甚至导致大规模生物灭绝。在中白垩世期间 ,发生了一系列全球规模的构造运动现象 ,它们与地球深部的超地幔柱有关。文中也通过天体撞击作用探讨了地外因素对地球环境和生命演化的影响。  相似文献