Organic biomarkers in the twilight zone—Time series and settling velocity sediment traps during MedFlux

The transfer of material through the twilight zone of the ocean is controlled by sinking particles that contain organic matter (OM) and mineral ballast. During the MedFlux field program in the northwestern Mediterranean Sea in 2003, sinking particulate matter was collected in time series (TS) and settling velocity (SV) traps and analyzed for amino acids, lipids, and pigments (along with ballast minerals) [Lee, C., Armstrong, R.A., Wakeham, S.G., Peterson, M.L., Miquel, J.C., Cochran, J.K., Fowler, S.W., Hirschberg, D., Beck, A. Xue, J., 2009b. Particulate matter fluxes in time series and settling velocity sediment traps in the northwestern Mediterranean Sea. Deep-Sea Research II, this volume [doi:10.1016/j.dsr2.2008.12.003]]. The goal was to identify how organic chemical compositions of sinking particles varied as a function of their in-situ settling velocity. The TS record was used to define the biogeochemical character and temporal pattern in flux during the period of SV trap deployment. Temporal variations in organic and mineral compositions are consistent with particle biogeochemistry being driven by the seasonal succession of phytoplankton. Spring diatom bloom conditions led to a high flux of rapidly sinking aggregates and zooplankton fecal matter; summer oligotrophy followed and was characterized by a higher proportion of slowly sinking phytoplankton cells. Bacterial degradation is particularly important during the low-flux summer period. Settling velocity traps show that a large proportion of particulate organic matter sinks at 200–500 m d⁻¹. Organic compositions of this fast-sinking material mirrors that of fecal pellets and aggregated material that sinks as the spring bloom terminates. More-slowly sinking OM bears a stronger signature of bacterial degradation than do the faster-sinking particles. The observation that compositions of SV-sorted fractions are different implies that the particle field is compositionally heterogeneous over a range of settling velocities. Thus physical and biological exchange between fast-sinking and slow-sinking particles as they pass down the water column must be incomplete.     

Potential source and diagenetic signatures of oceanic dissolved and particulate organic matter as distinguished by lipid biomarker distributions

Potential biogenic sources of ultrafiltered dissolved and suspended particulate organic matter (UDOM and POM, respectively) from the Sargasso Sea (SS) and North Central Pacific (NCP) Ocean were investigated using lipid biomarker compounds. Organic carbon (OC) concentrations were ~ 20–40 times greater in UDOM than POM and decreased with depth. However, total OC-normalized lipid concentrations were 2–3 orders of magnitude higher in POM than in UDOM. Particulate total lipids decreased 3–10-fold with depth, compared to 10–20% for dissolved total lipids. Total fatty acids (FA), the most abundant lipids, showed similar patterns as total lipids, comprising ~ 62–88% of the total lipids analyzed in UDOM and ~ 57–84% in POM.FA were dominated by straight-chain saturated compounds followed by monounsaturated, polyunsaturated, and branched FA. Polyunsaturated FA were enriched in POM vs. UDOM and in surface vs. deep waters for both UDOM and POM, likely reflecting the algal origins and greater reactivity of surface-derived materials. In both UDOM and POM, sterols of planktonic origin dominated, including cholest-5-en-3β-ol (C₂₇Δ⁵), 24-methylcholesta-5,24(28)E-dien-3β-ol (C₂₈Δ^5,24(28)) and 24-ethylcholest-5-3β-ol (C₂₉Δ⁵), with varying contributions from cholesta-5,22E-3β-ol (C₂₇Δ^5,22), 24-methylcholesta-5,22E-3β-ol (C₂₈Δ^5,22) and 24-ethylcholesta-5,22E-3β-ol (C₂₉Δ^5,22).Factor analysis of lipid biomarkers showed major differences between the UDOM and POM pools and for each pool as a function of depth, but not between the SS and NCP. While UDOM and POM biomarkers were both dominated by autochthonous sources, differences between the two pools suggest potential effects from some combination of source and diagenetic factors. The lipid biomarker data are further evaluated relative to previous studies of radiocarbon (¹⁴C) and elemental (C:N:P) characteristics of UDOM and POM in the SS and NCP.     

SnCl2还原冷原子吸收测定化探样品中的汞

样品经低温稀王水溶解 ,在选定的仪器条件下 ,用氯化亚锡还原 ,测定汞的吸收峰值。方法简便、快速、价廉 ,适用于大批化探样品的测定。     

Settling fluxes of diatoms to the interior of the Antarctic circumpolar current along 170 °W

An array of four sediment trap moorings recorded the particulate flux across the Antarctic Circumpolar Current (ACC) at 170 °W, between November 1996 and January 1998, as part of the US JGOFS-Antarctic Environment and Southern Ocean Process Study (AESOPS) program. The trap locations represent sampling within the Polar Frontal Zone, the Antarctic Polar Front, the Antarctic Zone and the Southern Antarctic Zone. Here we report observations from 1000 m below the sea-surface compared to seafloor and surface water distributions. Sub-sample splits from each trap were obtained and total diatom flux and species composition were determined. The diatom fluxes were quantified using both a dilution and a ‘spike’ method to allow for the rapid repeatability of measurements. Diatom flux was found to be highly seasonal across the ACC particularly at higher latitudes. Marine snow aggregates of intact diatom cells and chains were the major components of the biogenic flux. Siliceous particle size was noted to decrease with increasing latitude, which could be aligned with a shift of the diatom assemblage to small-size species/sea-ice affiliated species. A ‘double-structured’ diatom flux was recorded at the location of the Antarctic Polar Front trap, with a shift in the diatom assemblage from larger to smaller diatoms in the second flux episode. The sediment trap assemblage shows deviations from the surface water assemblage, while surface sediment samples indicate that significant dissolution occurs after 1000 m and at the sediment–water interface. Estimation of diatom biovolumes across the ACC shows that large diatoms have the potential to greatly impact biogenic fluxes to the ocean interior despite their low fluxes. Small species of the genus Fragilariopsis could potentially export as much C_org as Fragilariopsis kerguelensis near the retreating ice edge. However, their low abundance in the surface sediments also suggests that these diatoms are a shallow export species.     

Distribution Characteristics of Pollutants and Their Mutual Influence in Highway Runoff

Many environmental pollution issues from highway runoff increasingly become a serious concern, which has been revealed by many previous studies. However, very less information is available on the distribution characteristics of pollutants and their mutual influence in highway runoff. In this paper, the partitioning of pollutant and particle size distribution were investigated based on the initial road runoff of 47 rainfall events from July 2007 to May 2009 on the Lukou section of the Nanjing Airport Expressway, China. This study is emphasizing on the analysis of the mutual impact of pollutant distribution and the relationship between particle size and pollutant distribution. The impact of rainfall characteristics, water temperature, and pH values in runoff samples on the pollutant distribution was also studied. Result shows that partitioning of different pollutants was varying significantly. Volume of particles in different sizes was different, with the highest volume of particles of 21–75 µm size. The distribution of COD highly affected the distribution of TN, and somewhat promoted the distribution of Pb in particles. TP, Pb, and Cd promoted distribution of each other's in particles. There was better competition among Zn, Cu, and Cd, when heavy metals combined with particles. The particles ranged between 21 and 75 µm size had an obvious impact on the distribution of COD, Pb, and TN in the particulate matter. TP in the particulate matter mainly distributed in particles ranged in 151–300 µm size. Rainfall duration significantly affected the Pb in particulate matter. The distribution of Zn in the particulate matter mostly was affected by pH values.     

云南富源—弥勒1∶5万化探异常的发现及意义

1∶5万水系沉积物测量表明,该区属浅成低温热液型金多金属成矿区,除受构造控制外,岩浆岩、地层亦有控矿作用。金矿主要分布在裂谷带中,成矿潜力巨大,测区西部杨梅山中部支壁找铜金、东南部大得克找铅锌有较好前景。     

Export and mesopelagic particle flux during a North Atlantic spring diatom bloom

Spring diatom blooms are important for sequestering atmospheric CO₂ below the permanent thermocline in the form of particulate organic carbon (POC). We measured downward POC flux during a sub-polar North Atlantic spring bloom at 100 m using thorium-234 (²³⁴Th) disequilibria, and below 100 m using neutrally buoyant drifting sediment traps. The cruise followed a Lagrangian float, and a pronounced diatom bloom occurred in a 600 km² area around the float. Particle flux was low during the first three weeks of the bloom, between 10 and 30 mg POC m⁻² d⁻¹. Then, nearly 20 days after the bloom had started, export as diagnosed from ²³⁴Th rose to 360-620 mg POC m⁻² d⁻¹, co-incident with silicate depletion in the surface mixed layer. Sediment traps at 600 and 750 m depth collected 160 and 150 mg POC m⁻² d⁻¹, with a settled volume of particles of 1000-1500 mL m⁻² d⁻¹. This implies that 25-43% of the 100 m POC export sank below 750 m. The sinking particles were ungrazed diatom aggregates that contained transparent exopolymer particles (TEP). We conclude that diatom blooms can lead to substantial particle export that is transferred efficiently through the mesopelagic. We also present an improved method of calibrating the Alcian Blue solution against Gum Xanthan for TEP measurements.     

贵州红枫湖水面挥发性汞释放通量的测定

应用通量箱方法研究Hg在贵州红枫湖水表面挥发性汞的释放通量。当水温在20－24℃时,湖面汞的释放量在89－196mg/(h.m^2)之间,汞的释放通量白天达到最大值,而夜间降到最小,湖泊表面挥发性汞的释放通量均具有显著的昼夜变化规律,湖面汞的流通量与太阳辐射相关,与底泥中汞含量也明显相关。     

基于偏最小二乘法的土壤汞含量高光谱反演

采集新疆准东煤田典型土壤样品44个,在实验室测定风干后的土样汞含量和光谱反射率,经预处理后分析两者的相关性,运用偏最小二乘法(PLSR)建立土壤汞含量高光谱估算模型,由均方根误差RMSE和决定系数R2检验模型的预测能力和稳定性,并比较不同预处理方法的适用性。结果表明:反射率一阶微分光谱是估算土壤汞含量较好的指标,估算R2为0.77、RMSE为0.032。通过各种光谱预处理方法可提高土壤汞含量的估算精度,为研究区生态环境的恢复和评价提供依据。     

微波消解-电感耦合等离子体质谱法测定铁矿石中铬砷镉汞铅

铁矿石中Cr、As、Cd、Hg和Pb不仅影响冶炼设备和产品性能,同时污染环境。文章以铁矿石标准物质为研究对象,对电感耦合等离子体质谱法(ICP-MS)测定铁矿石中Cd、As、Cr、Hg和Pb等5种元素进行了适用性探讨。结果表明,与常规的单元素原子吸收光谱法或多元素同步分析电感耦合等离子体发射光谱法相比,用微波消解方法处理铁矿石,具有样品消耗量少(0.1000±0.0200)g、消解用酸少(2.5 mL HCl+0.5 mL HF+1.0 mL HNO3)、排放降低、节约成本等优点,且无需配制铁底液,无需添加任何掩蔽剂,质谱干扰小,适用于分析Cr含量为5.5×10-10～2.5×10-4,As含量为7.6×10-10～1.9×10-4,Cd含量为4.5×10-11～5.5×10-6,Hg含量为1.88×10-9～1.9×10-7,Pb含量为1.2×10-10～3.2×10-5的铁矿石样品。优化后的前处理方法节约了能源、试剂和样品消耗,降低了二次污染和有效损失。