Water uptake by two river red gum (Eucalyptus camaldulensis) clones in a discharge site plantation in the Western Australian wheatbelt

The heat-pulse technique was used to estimate year-long water uptake in a discharge zone plantation of 9-year-old clonal Eucalyptus camaldulensis Dehnh. near Wubin, Western Australia. Water uptake matched rainfall closely during weter months but exceeded rainfall as the dry season progressed. Average annual water uptake (1148 mm) exceeded rainfall (432 mm) by about 2.7 fold and approached 56% of pan evaporation for the area. The data suggest that at least 37% (i.e. (1/2.7) × 100) of the lower catchment discharge zone should be planted to prevent the rise of groundwater.

Water uptake varied with soil environment, season and genotype. Upslope trees used more water than did downslope trees. Water uptake was higher in E. camaldulensis clone M80 than in clone M66 until late spring. The difference reversed as summer progressed. Both clones, however, have the potential to dry out the landscape when potential evapotranspiration exceeds rainfall. This variation in water uptake within the species indicates the potential for manipulating plantation uptake by matching tree characteristics to site characteristics.

Controlled experiments on the heat-pulse technique indicated accuracy errors of approximately 10%. This, combined with the ability to obtain long-term, continuous data and the superior logistics of use of the heat-pulse technique, suggests that results obtained by it would be much more reliable than those achieved by the ventilated chamber technique.     

Geochemical Characteristics of Particulate Organic Carbon in the Kocebu Seamount Waters of the Western Pacific Ocean in Spring 2018

The study of the geochemical characteristics of the POC in the seamount area will be of great significance for further understanding the material cycle process in the seamount ecosystem. Based on a comprehensive survey of the Kocebu seamount in the Western Pacific Ocean in March, 2018, the distribution, source and composition of Particulate Organic Carbon (POC) in the seawater of the Kocebu seamount area were discussed. The results showed that the concentration of POC in the Kocebu seamount area gradually decreased with the increasing water depth, and slightly rose in the water layers near the bottom of the seamount. The average concentration of POC in each water mass was sorted from high to low in the order of North Pacific Tropic Water, North Pacific Intermediate Water and Deep Water (DW), and the concentration of POC at stations near the seamount summit was lower than that far from the seamount in the DW. There was upwelling at the water layers of 750~1 500 m above the seamount summit, causing the uplift of the 12.50 μg/L POC isoline in this region, however, no “seamount effect” was formed. The POC was mainly imported from the sea with an average POC/PON of 3.75. At the water layers of 0~300 m, only the POC/chlorophyll a (Chl a) at deep chlorophyll maximum layer was less than 200, indicating that the POC in this region was mainly in a form of life, while at the water layer of 300 m, the POC/Chl a increased sharply, indicating that the non-living POC contributed the most to the total POC.     

Middle Miocene to Pleistocene radiolarian biostratigraphy in the Northwest Pacific Ocean, ODP Leg 186

Abstract The Upper Cenozoic sedimentary sequences drilled at Sites 1150 and 1151, Ocean Drilling Program Leg 186, enabled establishment of radiolarian zonation and calibration of the age of bioevents in the forearc area of the northern Japan Islands. The sequences were divided into nine zones from the Pleistocene Botryostrobus aquilonaris Zone to the Upper Miocene Lipmanella redondoensis Zone at Site 1150, and 11 zones from the Pleistocene Stylatractus universus Zone to the Middle Miocene Dendrospyris? sakaii Zone at Site 1151. These zones correlate successfully with the studied sequences of many of deep‐sea cores in the Northwest Pacific Ocean and with some sections of onshore Japan. Of 67 important radiolarian bioevents recognized during the study, 29 Pleistocene to Upper Miocene events were directly tied to the geomagnetic polarity time scale through the well‐defined paleomagnetic polarity records, and 21 Upper Miocene events were calibrated based on the diatom biostratigraphy. Of these events, 24 geographically widespread events were selected to test synchroneity and usefulness as time‐horizons within the mid‐to‐high latitude of the Northwest Pacific, involving eight other offshore and onshore sections. Examination showed that most of the zonal boundary events are synchronous within the considered region, and that many diachronous events, most of which are eliminated from the zonal scheme, are unreliable events linked to rare and sporadic occurrences of the species. Radiolarian biostratigraphy of the studied cores clearly indicates three major hiatuses in the Middle Pleistocene, Late Miocene and late Middle Miocene. The latter two hiatuses can be correlated to two global oceanic hiatuses, NH6 and NH3, respectively.     

南海东北部海陆联测与海底地震仪探测

利用三分量海底地震仪、陆上便携式地震仪和海上气枪震源在南海东北部首次进行了海陆联合的深地震探测,测线呈北北西-南南东方向,垂直于区域构造走向,总长达500km,所获得的数据质量好,深部信息丰富,可分辨出Pg、Pn、PmP等地震相,为南海东北部深部地壳结构及油气盆地形成演化的研究提供了重要的基础数据。     

热带太平洋上层热力状况季节变化的正压特征——海表至深400m热储量的季节变化

使用斯克里普斯海洋研究所（SIO）整编的海洋上层（海表至400m）热储量资料，研究了热带太平洋上层热力状况季节变化的正压特征，指出与SST的分布不同，热储量在北纬5°N～10°N之间有一东西贯穿整个太平洋的带状热储量低值区，其季节变化率的分布特征分为两种，一是11月至2月为代表的“北半球冬季型”和5～8月的“北半球夏季型”，3月、4月和9月、10月为过渡阶段. 北半球10°N和2°N的季节变率的时间变化反位相，南半球的10°S、2°S?其季节变率随时间变化的位相则比较一致且与沿10°N位相大致相反. 东太平洋季节变化明显早于中、西太平洋，具有明显自东向西传播的特征. 10°S与10°N之间东、西太平洋的季节变率随时间的演变也基本上呈现反位相特征.     

Investigations on distributions and fluxes of sea-air CO_2 of the expedition areas in the Arctic Ocean

揋reenhouse effect?causing global warming has been an important issue of studying climate change. In the latest 100 years, the earth surface temperature has been increased by about 0.4℃—0.8℃[1,2]. And this has been becoming a hotspot of the world[3,4]     

太平洋环流速度减慢的原因

对南极气温资料、环南极海冰资料、太平洋海温资料、厄尔尼诺和拉尼娜资料的模拟验证，发现厄尔尼诺事件发生与德雷克海峡海冰减少在时间上有对应关系。南极半岛海冰减少是太平洋环流速度减慢的原因，德雷克海峡的海冰起重要作用。这一综合检验结果给出以日食—厄尔尼诺系数预测厄尔尼诺事件的有效性和准确性。两年周期的太平洋海温振荡使日食与厄尔尼诺之间存在12～24个月的位相差。     

Detrital footprint of the Mozambique ocean: U–Pb SHRIMP and Pb evaporation zircon geochronology of metasedimentary gneisses in eastern Madagascar

The southern East African Orogen is a collisional belt where the identification of major suture zones has proved elusive. In this study, we apply U–Pb isotopic techniques to date detrital zircons from a key part of the East African Orogen, analyse their possible source region and discuss how this information can help in unravelling the orogen.U–Pb sensitive high-mass resolution ion microprobe (SHRIMP) and Pb evaporation analyses of detrital zircons from metasedimentary rocks in eastern Madagascar reveal that: (1) the protoliths of many of these rocks were deposited between 800 and 550 Ma; and (2) these rocks are sourced from regions with rocks that date back to over 3400 Ma, with dominant age populations of 3200–3000, 2650, 2500 and 800–700 Ma.The Dharwar Craton of southern India is a potential source region for these sediments, as here rocks date back to over 3400 Ma and include abundant gneissic rocks with protoliths older than 3000 Ma, sedimentary rocks deposited at 3000–2600 Ma and granitoids that crystallised at 2513–2552 Ma. The 800–700 Ma zircons could potentially be sourced from elsewhere in India or from the Antananarivo Block of central Madagascar in the latter stages of closure of the Mozambique Ocean. The region of East Africa adjacent to Madagascar in Gondwana reconstructions (the Tanzania craton) is rejected as a potential source as there are no known rocks here older than 3000 Ma, and no detrital grains in our samples sourced from Mesoproterozoic and early Neoproterozoic rocks that are common throughout central east Africa. In contrast, coeval sediments 200 km west, in the Itremo sheet of central Madagascar, have detrital zircon age profiles consistent with a central East African source, suggesting that two late Neoproterozoic provenance fronts pass through east Madagascar at approximately the position of the Betsimisaraka suture. These observations support an interpretation that the Betsimisaraka suture separates rocks that were derived from different locations within, or at the margins of, the Mozambique Ocean basin and therefore, that the suture is the site of subduction of a strand of Mozambique Ocean crust.