SEA-LEVEL RISE IMPACT ON COASTAL AREAS OF ESTONIA

Due to long coastline (3,794 km in total) and extensive low-lying coastal areas, global climate change through sea-level rise will strongly affect the territory of Estonia. A number of valuable natural ecosystems (both, marine and terrestrial) containing rare plant communities often rich in species, but also suitable breeding places for birds will be in danger. Most sandy beaches high in recreative value will disappear. However, isostatic land uplift and location of coastal settlements at a distance from the present coastline reduce the rate of risk. Four case study areas characterizing all the shore types of Estonia have been selected for sea-level rise vulnerability and adaptation assessment. Preliminary results and estimates of vulnerability to 1.0 m sea-level rise by 2075 for two case study areas – Hiiumaa, West-Estonian Archipelago and Pärnu-Ikla, south-western coast of the mainland – are presented in this paper.     

岩土钻探工程大口径钻头设计与应用

分析对比了多种岩土钻探工程大口径钻头的优缺点，设计了适应不同地层的大口径钻头。     

Seasonal and interannual variability of the air–sea CO2 flux in the Atlantic sector of the Barents Sea

The seasonal and interannual variability of the air–sea CO₂ flux (F) in the Atlantic sector of the Barents Sea have been investigated. Data for seawater fugacity of CO₂ (fCO₂^sw) acquired during five cruises in the region were used to identify and validate an empirical procedure to compute fCO₂^sw from phosphate (PO₄), seawater temperature (T), and salinity (S). This procedure was then applied to time series data of T, S, and PO₄ collected in the Barents Sea Opening during the period 1990–1999, and the resulting fCO₂^sw estimates were combined with data for the atmospheric mole fraction of CO₂, sea level pressure, and wind speed to evaluate F.The results show that the Atlantic sector of the Barents Sea is an annual sink of atmospheric CO₂. The monthly mean uptake increases nearly monotonically from 0.101 mol C m^− 2 in midwinter to 0.656 mol C m^− 2 in midfall before it gradually decreases to the winter value. Interannual variability in the monthly mean flux was evaluated for the winter, summer, and fall seasons and was found to be ± 0.071 mol C m^− 2 month^− 1. The variability is controlled mainly through combined variation of fCO₂^sw and wind speed. The annual mean uptake of atmospheric CO₂ in the region was estimated to 4.27 ± 0.68 mol C m^− 2.     

The measurement of sand transport in two inlets of Venice lagoon,Italy

Sand transport in Lido and Chioggia inlets was measured using modified Helley–Smith sand traps equipped with 60-micron nets. The traps had an efficiency of about 4% only but provided enough material for analysis. Very fine sand (0.07 < d < 0.11 mm) only was collected in the traps. Transport of sand was greatest in the bottom 10% of the water column and followed a Rouse profile. Sand extended to a height of about 4 m above the bed during peak flows corresponding to the estimated thickness of the boundary layer; and observed in synoptic ADCP profiles. The sand in the benthic boundary layer was largely inorganic (>95%); above this layer, organic content varied widely and was greatest near the surface. The movability number Ws/U_∗$W_s/U_{\ast }$ showed a linear relationship to dimensionless grain diameter (D_*): (Ws/U_∗)=(D_∗/10)$\left(W_s/U_{\ast }\right)=\left(D_{\ast }/10\right)$; D_* < 10. Sand concentration in suspension was simulated by a mean Rouse parameter of −2.01 ± 0.66 (Lido inlet) and −0.82 ± 0.27 (Chioggia inlet). The β parameter ( Hill et al., 1988) was correlated with D_* and movability number in the form: β=2.07−2.03D_∗+59(Ws/U_∗)²$\beta =2.07-2.03D_{\ast }+59{\left(W_s/U_{\ast }\right)}^2$ (r² = 0.42). Von Karman's constant was back-calculated from a Law of the Wall relationship as a test on the accuracy of U_* estimates; a mean value of 0.37 ± 0.1 (compared to the accepted value of 0.41) suggest U_* was accurate to within 10%. The constant of proportionality (γ = 3.54 × 10⁻⁴) between reference concentration (C_a) and normalized excess bed shear stress was in line with the published literature.