The biomass of macro- and interstitial fauna on clean and wrack-covered beaches in Western Australia

The benthic faunal spectrum including bacteria, protozoans, meiofauna, wrack epifauna and macrofauna, was quantitatively surveyed on two modally reflective, moderate energy, Western Australian beaches. The more exposed beach had coarser sand, no intertidal macrofauna and a poor interstitial fauna. The less exposed beach had a large deposit of wrack totalling 161 kg m^?1 dry mass concentrated on the lower shore. The amphipod Allorchestes compressa was abundant in the fresh wrack comprising most of the macrofauna. There were also fairly abundant small epifauna on the wrack. Dry biomass of macrofauna, epifauna, meiofauna, protozoans and bacteria was 0, 0, 15, 4 and 180 g m^?1 on the more exposed beach and 160, 3, 112, 9 and 901 g m^?1 on the less exposed beach with wrack. On the latter beach there was an inverse correlation between meiofaunal densities and the densities of protozoans and bacteria, suggesting grazing by the former on the latter. On both beaches meiofauna was concentrated in the mid- to upper beach, protozoans near the surface and bacteria in the mid- to lower beach. It is estimated that bacteria are responsible for most of the secondary production on both beaches.     

Impact of oasis establishment on underground environment in salinized sandy lands

The salinized sandy lands are the important reclaimable reserve wastelands in thesouth area of the Xinjiang Uygur Autonomous Region of China. But it is necessary that the eco-logical environment of the area is not destroyed by action of oasis development. The main factor tohinder oasis development is land salinization. Rational oasis establishment rebuilds wastelandswith lower productivity and utilization efficiency for the growth of agriculture, forestry, and stock raising. The results of surveying sub-soil environment of Aimugaike. Awati oasis in Hotian County ofthe Xinjiang Uygur Autonomous Region show that the underground water and soil environment arenot deteriorated under the rational management and administration, which could be coordinatedfor obtaining economic and environmental benefit. During the oasis establishment period from1997 to 1999, the plowland area has reached 166.7 hm2, and the seed cotton yield per unit areahas reached 2250 kg @ hm-2, the area of timber forest and active sand break forest has reached 20hm2, the area of fruit trees is 71.5 hm2; and the soil moisture has decreased from 22.07% to18.12%. In the first year of oasis establishment, the soil type has changed salt soil into light saltsoil, in the second year the soil has been out of salt harm; and the content of soil organic matter intopsoil has increased obviously.     

Comparison of the biology, dynamics, and secondary production of Talorchestia brito (Amphipoda, Talitridae) in Atlantic (Portugal) and Mediterranean (Tunisia) populations

The biology, population dynamics, and production of Talorchestia brito were studied at two sandy beaches located on the Atlantic (Portugal) and on the Mediterranean (Tunisia) coasts, respectively. The seasonal variation in abundance and the overall densities were similar in both populations. Reproduction occurred from February to September in the Atlantic, and from March to early November in the Mediterranean. The sex ratio was male biased in the Atlantic, and female biased in the Mediterranean. Based on data from the Atlantic population, both abundance and the proportion of reproductive females were positively correlated with temperature, while the proportion of juveniles in the population was positively correlated with temperature and sediment moisture. On average, individuals from the Atlantic were larger than the ones from the Mediterranean. Life span was estimated at six to nine months in the Atlantic, and five to eight months in the Mediterranean. Talorchestia brito was shown to be a semiannual species, with iteroparous females producing two broods per year, and exhibited a bivoltine life cycle. The minimum age required for males' and females' sexual differentiation and for female sexual maturation was shorter in the Mediterranean. Growth production (P) was estimated at 0.19 g m⁻² y⁻¹ ash free dry weight (AFDW; 4.3 kJ m⁻² y⁻¹) in the Atlantic population, and 0.217 g m⁻² y⁻¹ AFDW (4.9 kJ m⁻² y⁻¹) in the Mediterranean one. Elimination production (E) was estimated at 0.35 g m⁻² y⁻¹ AFDW (7.9 kJ m⁻² y⁻¹) in the Atlantic, and 0.28 g m⁻² y⁻¹ AFDW (6.3 kJ m⁻² y⁻¹) in the Mediterranean. The average annual biomass ( ) (standing stock) was estimated at 0.032 g m⁻² in the Atlantic beach, and 0.029 g m⁻² in the Mediterranean one, resulting, respectively, in ratios of 5.9 and 7.5 and ratios of 10.8 and 9.6. Like other talitrids, T. brito exhibited geographic variation in morphometrical characteristics, sex ratio, growth rates, life span, and reproduction period, with the Atlantic population presenting a slower life history.     

陕北典型地区乡村聚落水蚀泥沙规律的初步研究

通过定位观测资料的分析,发现陕北多沙粗沙区乡村聚落的平均年侵蚀强度达5434.3t/km2,户间道路、户间空地、庭院的平均侵蚀强度分别达7348t/km2.6873.2 t/km2,2081.7t/km2.除庭院属轻度级侵蚀外,其它已达强度级侵蚀.同时延安的户间道路(14190.8t/km2),榆林的户间空地(13547.4t/km2),已达极强度侵蚀.应加强研究和防治.水蚀泥沙的粒度以0.01～0.05 mm的粗粉沙和0.001～0.005 mm的粘粒为主,分别占到43.98%和19.81%,≥0.05mm的粗泥沙含量明显小于聚落以外的坡面,而且区域变化比较明显,从南到北,细粒成分愈来愈少,粗粒成分越来越多;与土壤粒度相比,粗泥沙水蚀系数在庭院、户间道路、户间空地分别达到0.54,0.55,0.75,平均为0.61.     

科尔沁沙质草甸土壤微生物数量的垂直分布及季节动态

通过对中国农牧交错带科尔沁沙质草甸土壤微生物数量的垂直分布及其季节动态的研究分析表明:(1)微生物总数、细菌和放线菌数量均表现出与降雨量同步的季节动态,即6月份较5月份有所减少,7月份增至最多,7月份以后微生物数量逐渐下降,真菌则表现出从5月份到8月份一直增加,9月份开始回落;(2)土壤微生物具有明显的垂直分布差异.细菌和放线菌的垂直分布表现出随土壤深度增加逐渐减少的趋势,真菌数量表层最高,20 cm以下变化不够规律;(3)土壤微生物的层化比率均大于2(5月份放线菌除外);(4)不同土壤生态因子对微生物的影响不同,相同因子对不同微生物类群的影响也不相同.细菌受水分影响较大,真菌与地温的变化趋势相近,放线菌与水热条件的共同作用有关.土壤养分(有机碳和全氮)与微生物数量呈显著的正相关.     

Development of the cyclic p–y curve for a single pile in sandy soil

Pile foundations that support transmission towers or offshore structures are dominantly subjected to cyclic lateral load induced by wind and waves. For a successful design, it is crucial to investigate the effect of cyclic lateral loads on the pile behavior that is loaded laterally. Although the p–y curve method is generally utilized to design the cyclic laterally loaded pile foundations, the effect of cyclic lateral loads on the pile has not been properly implemented with the p–y curve. This reflects a lack of consideration of the overall stiffness change in soil–pile interaction. To address this, a series of model pile tests were conducted in this study on a preinstalled aluminum flexible pile under various sandy soil conditions. The test results were used to investigate the effect of cyclic lateral loads on the p–y behavior. The cyclic p–y curve, which properly takes into account this effect, was developed as a hyperbolic function. Pseudo-static analysis was also conducted with the proposed cyclic p–y curve, which showed that it was able to properly simulate cyclic laterally loaded pile behavior in sandy soil.     

基于盐度动态模拟估算潮间带地下淡水排泄量

目前关于砂质潮间带海底地下淡水排泄速率、海水再循环速率及相应比例随潮位的变化研究较少。文章以厦门湾某砂质潮滩为例,对地下水渗出面的盐度进行实地动态监测,采用变密度流数值模拟技术,对潮间带地下水盐度变化过程进行动态模拟,以此反演潮间带海底地下淡水排泄量。研究结果显示：（1）潮间带不同位置地下水盐度随潮汐发生不同规律的变化,通过数值模型估算出典型剖面海底地下水排泄量为17.47 m³/（m·d）,其中海底地下淡水排泄量为3.19 m³/（m·d）,占海底地下水排泄总量的18.26%,海水再循环量为14.28 m³/（m·d）,占海底地下水排泄总量的81.74%,处于主导地位;（2）潮汐作用下,海水入渗与海底地下水排泄交替发生,落潮阶段发生交替的时间略早于平潮位,涨潮阶段发生交替的时间略晚于平潮位,海水入渗速率与海底地下水排泄速率达到峰值时刻分别早于潮位达到高潮和低潮时刻,整个潮汐周期内（从高潮时刻到下一个高潮时刻）海底地下淡水排泄量比例逐渐增大;（3）潮间带地下水盐度的变化可间接反映海底地下淡水排泄量的变化,与其他研究相比,该典型剖面的海底地下淡水排泄量占海底地下水排泄总量比例相对较高,显示潮间带存在着大量海底地下淡水排泄;（4）通过敏感性分析可知,内陆水头对海底地下淡水排泄量及盐度空间分布有重要影响。研究可为海岸带地下水开发利用和滨海环境管理提供一定参考。     

山前冲断带砂砾岩储层发育机制及控制因素：以柴达木盆地昆北油田切12区为例

柴达木盆地昆北断阶带为大型山前压扭冲断构造带,该构造带上的昆北油田切12区下干柴沟组下段发育厚层冲积扇沉积的砂砾岩储层.明确储层微观特征及发育控制因素,对冲断带砂砾岩储层评价与油藏治理具有重要意义.运用铸体薄片、X-衍射、扫描电镜、常规压汞与恒速压汞等测试分析资料,系统研究冲积扇砂砾岩储层微观特征,明确储层发育的主控因素.结果表明,切12区砂砾岩储层具有成分成熟度低、结构成熟度低的岩石学特征,储集空间类型具双重孔隙介质特征,发育2类储层结构模态、4类储集空间类型、4类储层孔隙结构,储层物性为低孔、特低渗型储层,成岩作用阶段为早成岩阶段B期.在砂岩动力成岩作用相同的地质背景下,成岩作用对储层改造的影响是相对均衡的,储层发育程度的差异主要受控于沉积作用差异而导致的碎屑组成与结构差异,泥质含量是储层发育程度差异的主控因素,明确泥质含量上限为8%,颗粒分选对储层性质起重要控制作用.建立了基于泥质含量、物性、孔隙结构和产能指标的储层评价分类标准,将砂砾岩储层划分为4类;运用该认识指导油藏综合治理,并取得应用实效.     

基于稳定氧同位素的毛乌素沙地旱柳和小叶杨水分来源

确定干旱地区不同植被的水分来源情况,掌握不同水分条件下植被对潜在水源的利用率,对毛乌素沙地提高水资源利用效率以及更加合理地利用水资源具有重要意义。通过分析旱柳(Salix Matsudana)和小叶杨(Populus Simonii)木质部水、土壤水和地下水的氧同位素组成,采用贝叶斯混合(MixSIAR)模型量化旱柳和小叶杨对土壤水和地下水的利用率。结果表明:旱柳和小叶杨各月土壤含水量和土壤水δ¹⁸O值均随深度的增加呈现先增加后减少的趋势。生长季旱柳和小叶杨会调节各层土壤水或地下水的利用率适应环境变化。在降雨量较少时,旱柳和小叶杨对各层土壤水的利用率较为均衡,分别为21.6%～28.2%和22.6%～28.8%; 当降雨量较多时,旱柳和小叶杨主要的水分来源均为浅层土壤水,利用率最大可达60.1%和52.1%。研究反映了旱柳和小叶杨对毛乌素沙地的水分适应情况,确定了干旱地区人工植被的水分利用模式,掌握了不同水分条件下植被对潜在水源的利用率,表明未来毛乌素沙地人工植被建设中要以水定绿,灌草结合,尽量少选择乔木等高耗水植物种作为固沙造林树种。     

鄂尔多斯盆地西缘及邻区石炭系羊虎沟组砂体成因机制与沉积过程

鄂尔多斯盆地西缘羊虎沟组时期为加里东运动后复活的坳拉槽,羊虎沟组分布面积广,厚度变化大,发育良好的生储盖组合,具有巨大的勘探潜力。由于该地区构造运动强烈,沉积环境变化频繁,致使砂体沉积成因复杂。目前对羊虎沟组砂体成因机制缺乏系统研究,单一的沉积模式无法全面概括各类砂体的沉积特征与展布规律。通过野外剖面、岩心观察、钻井资料、物源分析等方法,共识别出6种岩相组合类型。基于岩性、粒度、沉积构造及各时期砂体展布等特征,对其成因机制及沉积过程进行了系统讨论。鄂尔多斯盆地西缘羊虎沟组砂体成因主要为河控三角洲、潮控三角洲、扇三角洲、障壁岛海岸、无障壁海岸和滑塌重力流6类。羊虎沟组时期整体气候潮湿,羊三段至羊二段沉积时期海平面逐渐上升,至羊二段达到最高之后逐渐下降。羊三段沉积时期为裂陷早期,主要在研究区北部发育潮控三角洲和扇三角洲砂体,中部局部可见潮汐砂脊砂体,南部砂体整体表现为无障壁海岸沉积。羊二段沉积时期为裂陷高潮期,地貌落差加大致使水体快速变深,砂体主要分布于盆地边缘;盆地中央深水部位发育点状滑塌重力流砂体,东部靠近中央古隆起一侧的潮汐砂脊逐渐被改造为障壁沙坝,古隆起高部位则为潮坪和潟湖沉积。羊一段沉积时期,构造活动减弱且鄂尔多斯盆地逐渐东西连通,物源供应充足,地貌变缓,发育大面积具前积特征的河控三角洲砂体。羊虎沟组砂体成因机制受构造运动、古地貌演化、物源供给、古气候、海平面变化等多因素共同影响,但砂体展布与沉积过程主要受控于构造活动与古地理演化。该研究成果丰富了鄂尔多斯盆地油气勘探理论和裂陷盆地砂体成因机制。