The influence of the Po River discharge on phytoplankton bloom dynamics along the coastline of Pesaro (Italy) in the Adriatic Sea

In recent years, eutrophic phenomena have frequently been reported in the Italian coastal waters of the northern Adriatic Sea. The aim of the present study was to determine that the phytoplankton blooms occurring along the Italian coastline in the area of Pesaro are caused by the Po River waters. In fact between October and December 2000 the nutrient load flushed into the sea from local rivers is not significant (phosphorus 10 tons and nitrogen 110 tons), instead N and P load from the Po River are: 650 and 8969 tons. The bloom episodes occurred during this period, at which time hypoxia developed on the sea bottom. The phytoplankton cell concentrations were 40.0 x 10(6) cells L(-1), and a significant presence of diatoms was observed. This issue is important in analysing the anthropogenic disturbances and environmental changes. The eutrophic seawater conditions were also analysed using the eutrophic index.     

Seasonalizing mountain system recharge in semi-arid basins-climate change impacts

Climate variability and change impact groundwater resources by altering recharge rates. In semi-arid Basin and Range systems, this impact is likely to be most pronounced in mountain system recharge (MSR), a process which constitutes a significant component of recharge in these basins. Despite its importance, the physical processes that control MSR have not been fully investigated because of limited observations and the complexity of recharge processes in mountainous catchments. As a result, empirical equations, that provide a basin-wide estimate of mean annual recharge using mean annual precipitation, are often used to estimate MSR. Here North American Regional Reanalysis data are used to develop seasonal recharge estimates using ratios of seasonal (winter vs. summer) precipitation to seasonal actual or potential evapotranspiration. These seasonal recharge estimates compared favorably to seasonal MSR estimates using the fraction of winter vs. summer recharge determined from isotopic data in the Upper San Pedro River Basin, Arizona. Development of hydrologically based seasonal ratios enhanced seasonal recharge predictions and notably allows evaluation of MSR response to changes in seasonal precipitation and temperature because of climate variability and change using Global Climate Model (GCM) climate projections. Results show that prospective variability in MSR depends on GCM precipitation predictions and on higher temperature. Lower seasonal MSR rates projected for 2050-2099 are associated with decreases in summer precipitation and increases in winter temperature. Uncertainty in seasonal MSR predictions arises from the potential evapotranspiration estimation method, the GCM downscaling technique and the exclusion of snowmelt processes.     

Organotin levels in Nazaré canyon (west Iberian Margin, NE Atlantic) and adjacent coastal area

Organotin compounds (OTs) are ubiquitous in the marine environment and high concentrations (μg g(-1) range) in sediments from different coastal areas around the world have been reported. However, few reports have described the OTs contamination status in the offshore and deep sea environment. This work investigated organotin levels in Nazaré canyon for the first time. Levels of monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPT), triphenyltin (TPT), dioctyltin (DOT) and trioctyltin (TOT) were quantified in sediment samples from the upper flanks of the canyon and from the adjacent coastal area. TBT levels detected in the canyon flanks are about two to three orders of magnitude lower than those found in the coastal area. Nevertheless, when quantifiable, TBT levels in the canyon samples were higher than the Environmental Assessment Criteria set for TBT in sediments by the OSPAR Commission indicating that at those locations negative ecological impacts are likely to occur.     

Bivalve larvae transport and connectivity within the Ahe atoll lagoon (Tuamotu Archipelago), with application to pearl oyster aquaculture management

Patterns of bivalve larvae dispersal in the deep Ahe atoll lagoon was studied by using a numerical 3D transport model (MARS3D) coupled with a vertical swimming sub-model, forced mainly by tide and wind-induced currents. The simulations were validated against observations of larval dispersal monitored several days throughout the lagoon. Connectivity matrices describing larval exchanges inside the lagoon were inferred. Larvae displayed a significant dispersal capacity at the lagoon scale, especially with dominant eastern winds. With southeastern winds, larvae mostly remained in their origin sector. The total export rate of the larvae, toward the ocean through the pass and shallow lagoon borders, was independent of the wind conditions, with 1% of the total concentration exported per day. However, the tide-driven currents efficiently flushed larvae in sectors close to the pass. Connectivity matrices suggest that the south and west sectors were more suitable for spat collecting and that central sectors would be efficient sanctuaries if genitors were accumulated.     

Overlap between Atlantic bluefin tuna spawning grounds and observed Deepwater Horizon surface oil in the northern Gulf of Mexico

The 2010 Deepwater Horizon oil spill impacted the northern Gulf of Mexico (GOM) during the spring spawning season of Atlantic bluefin tuna (BFT). Overlap between BFT spawning habitat and surface oil in the northern GOM was examined using satellite-derived estimates of oil coverage, and spawning habitat models. Results suggested that although eggs and larvae were likely impacted by oil-contaminated waters in the eastern GOM, high abundances of larvae were located elsewhere, especially in the western GOM. Overall, less than 10% of BFT spawning habitat was predicted to have been covered by surface oil, and less than 12% of larval BFT were predicted to have been located within contaminated waters in the northern GOM, on a weekly basis. Our results provide preliminary but important initial estimates of the effects of the spill on larval BFT mortality, as concern continues over the appropriate management responses to impacts of the spill.     

岩石层—大气层—电离层耦合作为震前大气层和电离层短临事件的影响机制

介绍了大气层和电离层震前现象机制的基本观念。简短回顾了观测结果后,我们得出结论：1．流体下层物质（气泡）向上迁移能导致近地表的热水／气体被逐出,并在强度弱化的地区引发地震;2．因此,气泡出现的时间和地点是随机的,但是地震、地球化学异常和前震（地震、SA和超低频电磁异常）是随机关联的;3．大气温度和密度扰动跟随着震前热水／气体释放,导致产生周期为6～60min的大气重力波（AGW）;4．地震引发的大气重力波能导致电离层扰动变化并导致大气层中地平线上无线电波传播、下部电离层低频波扰动和地面超低频辐射衰减的变化。     

利用长期的地震存档资料进行近实时双差事件定位及对北加州的应用

介绍了一种利用互相关和双差方法快速对新地震事件相对于过去已精确定位的事件进行高精度重定位的实时方法。本方法自动将新事件的波形记录与它附近发生过的已归档事件进行互相关,以精确测量震相到时的差分。利用双差算法将这些数据以及从到时拾取中计算出的延迟时间,转换成新事件与它相邻事件的相对位置向量。利用来自北加州地震台网（NCSN）和北加州地震数据中心近实时的数据,及当地储存的北加州地震台网地震档案的拷贝等数据,将这项新的监测技术应用于加州北部的地震记录。与加州北部高分辨率双差地震目录相关的新的事件将被进行近实时（几十秒内）自动重新定位。利用北加州已发生的事件进行逆向测试,结果显示实时双差定位结果水平向的分辨率平均为0.08km,深度方向为0.24km。研究发现,因为地震记录的密度会持续增加及数字地震档案的积累,利用本方法定位新事件的精度随着时间的推移将不断地得以改善。实时双差地震定位能以前所未有的分辨力来监测活动断层在孕震特征上的时空变化,因此它在快速评估及减轻地震灾害的过程中具有显著的社会和经济效应。     

Hack's law of debris-flow basins

Hack's law was originally derived from basin statistics for varied spatial scales and regions.The exponent value of the law has been shown to vary between 0.47 and 0.70,causing uncertainty in its application.This paper focuses on the emergence of Hack's law from debris-flow basins in China.Over 5,000 debris-flow basins in different regions of China with drainage areas less than 100km2 are included in this study.Basins in the different regions are found to present similar distributions.Hack's law is derived fi'om maximum probability and conditional distributions,suggesting that the law should describe some critical state of basin evolution.Results suggest the exponent value is approximately 0.5.Further analysis indicates that Hack's law is related to other scaling laws underlying the evolution of a basin and that the exponent is not dependent on basin shape but rather on the evolutionary stage.A case study of a well known debris-flow basin further confirms Hack's law and its implications in basin evolution.