Eutrophication,health risk assessment and spatial analysis of water quality in Gucheng Lake,China

The water characteristics of the Gucheng Lake, such as eutrophication, health and spatial distribution, were investigated. On the basis of the trophic state index (TSI) and entropy weight, a synthesized trophic state index (STSI) model was established to assess lake eutrophication condition through calculating STSI, choosing TP, TN, COD, BOD and NH₃-N as trophic variables. The STSI ranged from 50.58 to 62.44, which showed that the water has been between eutrophic and supereutrophic. A histogram was applied to health risk assessment which was analyzed from carcinogenic substances (Cr⁺⁶, As and Cd) and non-carcinogenic substances (hydroxybenzene, Pb, Hg, CN⁻ and NH₃), and the results showed that the former was much greater than the latter for effect. The total risk for each resident caused by all pollutants ranged from 5.18E-05 to 8.34E-05, which is far higher than the standard, recommended by Sweden Bureau of Environment Protection and Holland Ministry of Building and Environment Protection (1.0E-05). Cluster analysis was used to detect similarities and dissimilarities among the seven sampling sites and explain the observed clustering in terms of affected conditions. Twenty-one variables were used to divide seven sampling sites into three groups, namely, north lake, south lake and lake center.     

The spatial distribution of archaeal lipids in a mesoscale subtropical watershed,Southeast China

Archaea play an important role in global carbon and nitrogen cycles. Archaeal lipids, such as isoprenoid glycerol diakyl glycerol tetraethers (iGDGTs), are important biomarkers tracing change in archaeal community structure and biogeochemical processes in the natural environments. In this research, the spatial distributions of archaeal lipids in the surface sediments of the Jiulong River (JR) and the Jiulong River estuary (JRE) were examined. GDGT-0 (containing zero cyclopentyl ring) and crenarchaeol were the most abundant iGDGTs in the JR and JRE. From the rivers to the estuary, the total iGDGTs, GDGT-0, crenarchaeol and archaeol concentrations showed significant spatial variation; in particular, GDGT-0 and archaeol in the river may be predominantly derived in situ from methanogens, whereas crenarchaeol in the estuary mainly derived in situ from Thaumarchaeota. We inferred that archaeal community was dominated by methanogens in the Jiulong River and by Thaumarchaeota in the Jiulong River estuary, which are consistent with change in archaeal community structure observed in other estuarine environments.     

Linking Tarim Basin sea retreat (west China) and Asian aridification in the late Eocene

The Tarim Basin in western China formed the easternmost margin of a shallow epicontinental sea that extended across Eurasia and was well connected to the western Tethys during the Paleogene. Climate modelling studies suggest that the westward retreat of this sea from Central Asia may have been as important as the Tibetan Plateau uplift in forcing aridification and monsoon intensification in the Asian continental interior due to the redistribution of the land‐sea thermal contrast. However, testing of this hypothesis is hindered by poor constraints on the timing and precise palaeogeographic dynamics of the retreat. Here, we present an improved integrated bio‐ and magnetostratigraphic chronological framework of the previously studied marine to continental transition in the southwest Tarim Basin along the Pamir and West Kunlun Shan, allowing us to better constrain its timing, cause and palaeoenvironmental impact. The sea retreat is assigned a latest Lutetian–earliest Bartonian age (ca. 41 Ma; correlation of the last marine sediments to calcareous nannofossil Zone CP14 and correlation of the first continental red beds to the base of magnetochron C18r). Higher up in the continental deposits, a major hiatus includes the Eocene–Oligocene transition (ca. 34 Ma). This suggests the Tarim Basin was hydrologically connected to the Tethyan marine Realm until at least the earliest Oligocene and had not yet been closed by uplift of the Pamir–Kunlun orogenic system. The westward sea retreat at ca. 41 Ma and the disconformity at the Eocene–Oligocene transition are both time‐equivalent with reported Asian aridification steps, suggesting that, consistent with climate modelling results, the sea acted as an important moisture source for the Asian continental interior.     

Estimating open boundary conditions from coastal tidal observations by adjoint approach

A numerical study for estimating the tidal open boundary conditions of a shelf current modrl from tb coastal tidal observations is presented. The method is based on the optimal control/adjoint method. A lrast square fitting of the model state to simulated data is used. Two ideal domains and coastlines are considered. Using the IAP shallow. water model and its adjoint model, some identical twin experiments are carried out to test efficiency and lirnilsd of the method. The results show that the adjoint method can efficiently estimate the open boundary conditions well for gulf/bay like domains. The adjoint method seems to have great potential to improve the accuracy of tide and shelf current modeling in coastal regions. Project supported hy the National Natural Science Fuundation of China (Grant No. 49376256)     

沟槽内海底管道的水动力特性研究

基于水力模型实验，引入相对沟形系数αｒ，获得了以αｒ为表征的相对水动力系数与ＫＣ数的关系；对于浅沟而言，这种关系较有规律性。根据所设计沟形的αｒ值和所选定的ＫＣ值，应用本文结果，可以方便地判断其力折减程度和掩护效果     

Trace metal composition of colloidal organic material in marine environments

Marine colloidal material (1 kDa–0.2 μm) was isolated by cross-flow ultrafiltration followed by diafiltration and freeze-drying from surface waters of the Gulf of Mexico and the Middle Atlantic Bight (MAB), as well as from estuarine waters of Galveston Bay. Elemental characterization of isolated colloidal material included organic carbon (OC) and selected trace metal (Cu, Pb, Zn, Cd, Co, Ni, Cr, Be, Fe, Al, Mn, V, Ba, and Ti) determinations. It was found that levels of these metals in marine colloids ranged from <0.1 to 50 μg/g colloidal matter, except for Fe which generally had a concentration >120 μg/g. Most metals (Cu, Pb, Zn, Ni, Al, Mn, V, and Ti) had an average concentration >1 μg/g while concentrations of Cd, Co and Be were usually <1 μg/g. Metal concentrations (μg/g) in isolated colloids were, in general, higher in Galveston Bay than in the Gulf of Mexico, suggesting either high abundance of trace metals in estuarine waters or differences in organic matter composition. Higher colloidal metal concentrations in the MAB than in the Gulf of Mexico might be due to higher terrestrial inputs in the MAB. Colloidal metal concentrations (μg/g) were generally lower than those in average soils, continental crust and suspended particles. However, metal/aluminum ratios (Me/Al) in isolated marine colloids were significantly higher than those for average soils and continental crust. Most importantly, colloids had a metal composition and metal/OC ratio (Me/C) similar to humic substances and marine plankton, suggesting that marine colloids largely originate from planktonic sources and are composed of predominately organic components. The Me/C ratios of Galveston Bay colloids followed the sequence of Cu>Ni, Cr, Zn>Mn>Co>Pb, Cd, which is similar to the Irving–Williams order except for Mn, suggesting that the interaction of metals with marine colloids is determined by the affinity of metals for specific organic ligands.     

瘤背石磺体腔细胞分类、免疫相关酶特性及初步转录组学分析

瘤背石磺(Onchidium struma)广泛分布于潮间带和潮下带,是海洋生物向陆地生物辐射进化的重要代表,也是环境监测的指示生物.为丰富瘤背石磺的基础免疫学资料,本文研究了瘤背石磺体腔细胞的类别、细胞密度和体腔液免疫相关酶活性,并通过RNA-Seq测序获得体腔细胞转录本,进行生物信息学分析.结果表明,瘤背石磺主要有...     

锦州湾表层海水微塑料分布特征

海洋微塑料是全球关注的新兴环境问题,海湾由于特殊的地理环境特征,成为微塑料分布研究的热点区域。本研究以锦州湾为研究海域,于2017年10月布设了11个点位开展表层海水微塑料样品采集,在实验室采用湿式氧化法开展样品前处理,应用傅立叶变换显微红外光谱仪分析鉴定微塑料成分。研究结果表明,锦州湾表层水体微塑料平均丰度为(0.93±0.59)个/m³,微塑料数量占全部塑料样品的96.2%。微塑料的主要成分为聚丙烯和聚乙烯,分别占55.0%和23.5%;线状和片状塑料的比例最高,分别占41.7%和26.2%;白色、蓝色和半透明微塑料分别占35.1%、26.0%和21.4%。受水动力条件和陆域河流输入等影响,锦州湾表层水体中微塑料的空间分布整体呈现北部偏高,向南部递减的趋势。     

Self-Weight Penetration Characteristics of the Suction Foundation with Different Diameters in Sand

During the self-weight penetration process of the suction foundation on the dense sand seabed, due to the shallow penetration depth, the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure. Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation. The new suction anchor foundation has been proposed, and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis. For the above two foundation types, by considering five foundation diameters and two bottom shapes, 20 models are tested with the same penetration energy. The effects of different foundation diameters on the penetration depth, the soil plug characteristics, and the surrounding sand layer are studied. The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation. With the same penetration energy, the penetration depth of the suction foundation becomes shallower as the diameter increases. The smaller the diameter of the suction foundation, the more likely it is to be fully plugged, and the smaller the height of the soil plug will be. In the stage of self-weight penetration, the impact cavity appears around the foundation, which may affect the stability of the suction foundation.

     

西沙海槽沉积模式

晚中新世琼东南盆地快速构造沉降,沉积欠补偿形成了西沙海槽。西沙海槽上部高陡带为悬浮沉积体系,下部低缓带为浊流滑塌沉积体系,槽底平缓带为河流沉积体系。不同于浊流沉积小而散,深海河流沉积为稳定的贯穿整个海槽的大储层。由于深海河流沉积体系稳、远、大的特点,其注定成为世界深水油气勘探的主要目标。