Cold and wet: Diatoms dominate the phytoplankton community during a year of anomalous weather in a Great Lakes estuary

As sentinels of climate change and other anthropogenic forces, freshwater lakes are experiencing ecosystem disruptions at every level of the food web, beginning with the phytoplankton, a highly responsive group of organisms. Most studies regarding the effects of climate change on phytoplankton focus on a potential scenario in which temperatures continuously increase and droughts intersperse heavy precipitation events. Like much of the conterminous United States in 2019, the Muskegon River watershed (Michigan, USA) experienced record-breaking rainfall accompanied by unusually cool temperatures, affording an opportunity to explore how an alternate potential climate scenario may affect phytoplankton. We conducted biweekly sampling of environmental variables and phytoplankton in Muskegon Lake, a Great Lakes Area of Concern that connects to Lake Michigan. We compared environmental variables in 2019 to the previous eight years using long-term data from the Muskegon Lake Observatory buoy, and annual monitoring excursions provided historical phytoplankton data. Under cold and wet conditions, diatoms were the single dominant division throughout the entire growth season – an unprecedented scenario in Muskegon Lake. In 10 of the 13 biweekly sampling days in 2019, diatoms comprised over 75% of the phytoplankton community in the lake by count, indicating that the spring diatom bloom persisted through the fall. Additionally, phytoplankton seasonal succession and abundance patterns typically seen in this lake were absent. In a world experiencing reduced predictability, increased variability, and regional climate anomalies, studying periods of extreme weather events may offer insight into how natural systems will be affected and respond under future climate scenarios.     

Rip currents near coastal structures in Lake Michigan: Characterization and assessment for warnings

Rip currents near coastal structures commonly occur in Lake Michigan in the Great Lakes region of the United States. Lack of timely warning due to undocumented characteristics of rip currents and no assessment tool can contribute to tragic drownings incidents. In this paper, we characterized rip current occurrences near breakwater structures and developed an assessment tool for providing timely rip current warnings to beachgoers at the study site, City of Port Washington, WI. Characteristics of rip currents near the structure were observed from field measurements or visual images. Deflection rip currents had speeds of ～ 0.2 m/s and lasted for several hours. The rip current occurrences were associated with environmental proxies. It was found that rip currents can occur even when the water appears calm near the structure. A Structure Rip Checklist and Assessment Matrix (SRiCAM) with a four-tiered risk was developed and validated using observations. Furthermore, the SRiCAM was integrated into cyberinfrastructure with a data contingency plan to provide real-time warnings to the public. The applicability of the SRiCAM to other locations across Lake Michigan was further tested and results are promising. Overall, the SRiCAM has the potential to be widely extended to foster recreational water safety and resilience to rip current hazards in the Great Lakes.     

Evaluation of adult and offspring thiamine deficiency in salmonine species from Lake Ontario

Thiamine Deficiency Complex (TDC) is an ongoing problem impacting salmonine health in various waterbodies, including Lake Ontario. The prevalence of TDC has been variable and explanations for differences are limited. In the current study, thiamine concentrations were measured in eggs, liver tissue, and muscle tissue sampled from brown trout (Salmo trutta), Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), lake trout (Salvelinus namaycush), and steelhead trout (O. mykiss) that were collected from Lake Ontario and its surrounding tributaries. The occurrence of TDC was measured for each species based on TDC-induced offspring mortality rates under laboratory conditions. TDC-induced offspring mortality was observed for all species except brown trout. For affected species, egg free thiamine (Th) was consistently low compared to lake trout collected from Lake Superior that are considered thiamine replete. In addition, species with the lowest percentages of Th in their eggs were the most susceptible to TDC, suggesting that limited thiamine reserves in the form of Th may cause TDC-induced offspring mortality. Lastly, our results show that egg thiamine concentrations have yearly variation and increased for all species throughout the study. Reasons for such variation are undetermined; but, if egg thiamine concentrations continue to increase, the impacts of TDC on these salmonine species may lessen. Future monitoring is needed for determining if thiamine concentrations are increasing and the potential impacts that may have on the entire Lake Ontario fishery.     

准噶尔盆地吉木萨尔凹陷陆相页岩油地质特征与聚集机理

综合利用岩心、测井、烃源岩热解、铸体薄片、场发射扫描电镜、激光共聚焦显微镜与高压压汞等分析测试的结果，对准噶尔盆地吉木萨尔凹陷芦草沟组陆相页岩油地质特征与聚集机理进行了研究。结果表明：吉木萨尔凹陷咸化湖盆型沉积地层富含有机质，是烃源岩层也是储层，页岩油藏具有“源储一体”的地质特征，存在粉砂岩类与泥岩类和白云岩类与泥岩类两类岩性组合类型。芦草沟组大面积整体含油、“甜点”富集且原油成熟度较低。页岩油赋存岩石的润湿性为亲油性，生烃增压是页岩油运聚的主要动力。微纳米孔喉、层理缝与构造裂缝形成页岩油的有利储集空间与渗流通道。页岩油整体为源内或近源聚集，并以游离态和吸附态赋存于芦草沟组“甜点”段与泥页岩层段中。     

Nitrogen dry deposition to Lake Superior and Lake Michigan

Nitrate (NO₃^?) levels in Lake Superior have increased from historic levels of about 5?μM to its current concentration of about 25?μM. The atmosphere makes a substantial contribution to the nitrogen budgets for Lake Superior and Lake Michigan. This study provides a more well-defined estimate of nitrogen dry deposition rates derived from the measurement of over-water concentrations, and in situ meteorological measurements, which were input into the Resistance Model. We obtained a nitrogen dry deposition rate of [(3.41?±?2.26)?×?10⁷?kg?N/yr; (5.90?±?3.91)?kg?N/ha/yr] over Lake Michigan, and [(1.54?±?1.06)?×?10⁷?kg?N/yr; (1.87?±?1.27)?kg?N/ha/yr] over Lake Superior. Nitric acid (HNO₃), which originates from the combustion of fossil fuels, contributes 84% of the total nitrogen dry deposition to Lake Michigan; and 66% to Lake Superior. Ammonia (NH₃), which originates from agricultural activities and gasoline combustion, is the second highest contributor of nitrogen dry deposition to both lakes: contributing 13% to Lake Michigan and 32% to Lake Superior. The nitrogen dry deposition is approximately 68% of the nitrogen wet deposition over Lake Superior, and approximately 80% of wet deposition over Lake Michigan. The over-water dry deposition velocity of HNO₃ and NH₃ were also evaluated. We obtained morning deposition velocities of 0.099?cm/s for NH₃ and 0.095?cm/s for HNO₃; and afternoon values of 0.137?cm/s for NH₃ and 0.132?cm/s for HNO₃. Another key finding is that the atmospheric concentrations of nitrogen compounds near Lake Michigan and Lake Superior have decreased since 2003.     

超滤-纳滤组合工艺对东太湖原水的处理效果

随着工业化进程的不断加快,东太湖水质日趋恶化,给常规处理增加了很大的处理难度。针对水源污染问题和给水深度处理的需要,开展了超滤-纳滤双膜组合工艺处理东太湖原水的中试研究,考察双膜工艺对出水水质的提升效果。结果表明,超滤-纳滤双膜工艺对水质常规指标具有较好的去除效果,CODMn和TOC的去除率分别为91.7%和90%;对荧光类物质的去除主要表现在对芳香族蛋白质、类富里酸物质、溶解性微生物代谢产物的去除;此外,双膜组合工艺对小分子二甲基异莰醇(2-MIB)和土臭素(GSM)的去除率分别为70%和77%,表明该工艺对水中主要致嗅物质具有良好的去除能力。     

三塘湖盆地中—下侏罗统煤层甲烷风化带划分

以三塘湖盆地中、低煤阶煤层含气量和主要气体成分为基础,结合盆地构造、沉积及水文地质特征,对汉水泉凹陷和条湖凹陷煤层甲烷风化带进行了划分,并对库木苏凹陷、马朗凹陷、淖毛湖凹陷和苏鲁克凹陷煤层甲烷风化带进行了预测。结果表明,三塘湖盆地甲烷风化带深度为400~1000 m.由于受东北冲断隆起带的影响,三塘湖盆地北部甲烷风化带浅于南部。沉积方面,盆地东部淖毛湖凹陷、马朗凹陷和条湖凹陷深湖—半深湖和辫状河三角洲成煤环境优于盆地西部汉水泉凹陷和库木苏凹陷扇三角洲成煤环境,盆地东部甲烷风化带普遍浅于西部;水文地质方面,条湖凹陷和马朗凹陷中开启性局部滞留水文地质单元形成的甲烷风化带浅于其他凹陷封闭性弱径流水文地质单元的甲烷风化带。初步预测马朗凹陷北部为下一步煤层气勘探开发的优势区块,条湖凹陷北部为下一步煤系气勘探开发的优势区块。     

高泉背斜地层压力测井多参数综合解释与异常高压成因

目前国内外地层压力测井解释方法较多,但大多数方法基于欠压实沉积理论并局限于单一的地层岩性,尤其是针对盆地边缘山前深层构造,单一测井参数确定地层压力误差较大,且无法解释沉积压实机制以外的异常高压。为此,将多种异常高压机制相关的测井参数进行综合解释,建立适合山前复杂构造的地层压力测井多参数计算模型,评价准噶尔盆地南缘高泉背斜高探1井的地层压力剖面,其计算结果与钻井实测数据吻合,相对误差小于3.00%.同时,基于原始沉积加载—卸载过程力学原理,利用地层压力测井多参数分析判别出高泉背斜深层各层系异常高压的形成机制。