Horizontal distribution of ectomycorrhizal infection in Dipterocarpus turbinatus plantations of Bangladesh

Garjan （Dipterocarpus turbinatus Gaertn. F） is a highly ectomycorrhizal tree species growing in hilly areas of Bangladesh. The horizontal distributions ofectomycorrhizas （ECM） in different distances （1, 2, 3 ＆ 4m） from the tree base were determined in 5, 10 and 20-year-old D. turbinatus plantations of Chittagong University Campus （CUC） in 2003, The ECM infection （%） in roots was counted at three hill positions （top, mid and bottom） for each of the plantations. Samples of 1000 cm^3 rhizosphere soil were collected from underneath the trees at different horizontal distances. The percentage of infection at different distances and hill elevations varied considerably. In 5 and 10-year-old plantations, the occurrence of infection （%） was rapidly declined with increasing distances, while in 20-year-old plantation, the infection increased sharply with increasing distances from the tree base. The highest infection （81.33%） was found at 4 m distance from the tree at bottom hill in 20-year-old plantation and the lowest （55.33%） at the same distance at the top of the hill in 5-year-old plantation.

Chemicohydrographic characteristics of the Yellow Sea Cold Water Mass

Based on the field data obtained during summer cruises in 2006, the overall perspective of chemical and hydrographic characteristics of the Yellow Sea Cold Water Mass （YSCWM） are discussed through the cross- YSCWM transect profiles and horizontal distributions of hydrological and chemical variables, with emphasis on the differences between the northern Yellow Sea Cold Water Mass （NYSCWM） and the southern Yellow Sea Cold Water Mass （SYSCWM）. The results show that YSCWM is characterized by low temperature （〈10℃） and dissolved oxygen （DO） concentration, high salinity （〉32.0） and nutrient concentrations. Compared to the SYSCWM, the NYSCWM possesses lower values of temperature, salinity and nutrient concentrations but higher values of DO. Also its smaller variation ranges of variables （except for temperature） demonstrate that NYSCWM is more uniform than that of SYSCWM. In addition, thermocline is more intensive in the SYSCWM than that of NYSCWM. Furthermore, DO and Chl a maxima appear at the depth of 30 m in the SYSCWM, while these phenomena are not obvious in the NYSCWM.

Effects of PHC on Water Quality of Jiaozhou Bay Ⅱ. Changing Process of Pollution Sources

Based on investigation data on PHC content in Jiaozhou Bay, China during 1979 -1983, the horizontal distribution and pollution sources of PHC in Jiaozhou Bay were analyzed. The results showed that from 1979 to 1983, PHC in the water body of Jiaozhou Bay was mainly from rivers such as Haibo River, Licun River and Loushan River, and PHC content ranged from 0.10 to 1.10 mg/L. The pollution sources of PHC were serious during 1979 -1981 and then became slight during 1982 -1983. From 1979 -1981 to 1982 -1983, PHC content, horizontal distribution and degree of pollution sources changed, but the input mode of PHC was constant, that is, PHC was brought into Jiaozhou Bay by rivers.

Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

In the research of windblown sand movement,the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle＇s motion to windblown sand flux.In this paper,we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of paticle image velocimetry（PIV） and data processing method.And then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was analyzed.The results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles,i.e.,the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution,respectively.However,it influences the center of the Gaussian distribution,the decay constant and the amplitude of the negative exponential distribution.