Low shear rheological behaviour of two-phase mesophase pitch

The low shear rate rheology of two phase mesophase pitches derived from coal tar pitch has been investigated. Particulate quinoline insolubles (QI) stabilised the mesophase spheres against coalescence. Viscosity measurements over the range 10–10⁶ Pa s were made at appropriate temperature ranges. Increasing shear thinning behaviour was evident with increasing mesophase content. At low mesophase contents the dominant effect on the near Newtonian viscosity was temperature but at higher contents it was the shear rate; temperature dependence declined to near zero. The data indicated that agglomeration could be occurring at intermediate mesophase volume fractions, 0.2–0.3. The Krieger–Dougherty function and its emulsion analogue indicated that in this region the mesophase pitch emulsions actually behaved like ‘hard’ sphere systems and the effective volume fraction was estimated as a function of shear rate illustrating the change in extent of agglomeration. At the higher volume fractions approaching the maximum packing fraction, which could only be measured at higher temperatures, the shear thinning behaviour changed in character and it is considered that this is possibly due to shear induced deformation and breakup of dispersed drops in the shear field.     

Invader amphipods Gmelinoides fasciatus (Stebbing, 1899) inhabiting distant waterbodies demonstrate differences in tolerance and energy metabolism under elevated temperatures

Gmelinoides fasciatus is a successful invasive amphipod (Amphipoda, Crustacea) that dispersed from Lake Baikal to various waterbodies. Here we studied whether Baikal conditions are optimal for G. fasciatus in terms of thermotolerance and investigated lethal temperatures, 70 kDa heat shock protein level, energy metabolism, and antioxidant defense of animals from three geographically distant waterbodies under changing temperatures. We used acute heat exposure to 28 °C to assess the median lethal times and gradual temperature increase from 6 °C to determine the lethal temperatures. Mortality under heat shock was explainable by the baseline content of Hsp70 that correlated with thermal history. But it was not the case under gradual temperature increase where Hsp70 levels became similar and the mortality pattern changed. The most thermotolerant amphipods from the Gulf of Finland demonstrated a higher amount of free glucose during the temperature increase that may be related to the higher salinity of this waterbody and less energy required for ion regulation. Even though concentrations of major physiological ions in Lake Baikal are lower than in Lake Ladoga, G. fasciatus from Ladoga was slightly more sensitive to the gradual temperature increase. This difference could be explained by the influence of high levels of humic and other potentially toxic substances in Lake Ladoga indicated by increased activities of catalase and glutathione S-transferase. Importantly, all G. fasciatus populations accumulated relatively low levels of lactate during the temperature increase, which may reflect the ability of this invasive species to effectively maintain aerobic metabolism under various conditions.     

Wild juvenile salmonid abundance in Wisconsin tributaries indicates limited contributions to Lake Michigan fisheries

Natural reproduction of salmonids occurs in many Lake Michigan tributaries, yet little is known about abundance and the potential contribution of wild fish hatching in Wisconsin tributaries. The objectives of our study were to determine if: 1) abundance of wild juvenile salmonids (primarily adfluvial rainbow trout, Oncorhynchus mykiss, referred to as steelhead) varied among selected Wisconsin streams based on available spawning and age-0 habitat; 2) stream temperature regimes could limit survival of juvenile salmonids, and 3) wild juvenile salmonids outmigrate from Wisconsin tributaries into Lake Michigan or larger tributaries. In 2016 and 2017, juvenile salmonid abundance was estimated in six Wisconsin tributaries to Lake Michigan by multiple-pass depletion sampling using backpack electrofishing. Habitat assessments included steelhead redd surveys, age-0 habitat surveys, and stream temperatures were monitored using in-stream loggers. Passive integrated transponder (PIT) tagging and PIT antennas were used to detect outmigration from three streams (Willow, Stony and Hibbard creeks). Population estimates for individual streams ranged from 75 to 2276 for juvenile steelhead and from 0 to 243 for juvenile coho salmon, Oncorhynchus kisutch. No correlation was detected between juvenile steelhead abundance and quality age-0 habitat. Stream temperatures rarely exceeded the thermal limit for steelhead (27 °C). Outmigration rates for three streams ranged from 0.6% to 3.1%, but these estimates were considered minimum values. Low abundance of wild juvenile steelhead and coho salmon alone suggest that the contributions of these tributaries to Lake Michigan fisheries are likely small. Furthermore, relying on returns of wild steelhead produced in these streams is probably insufficient to maintain stream fisheries.     

An Objective Method to Prioritize Socio‐Environmental Water Management Tradeoffs Using Multi‐Criteria Decision Analysis

Rivers provide many social and environmental services that benefit humanity. A critical role of water mangers is to prioritize water allocation options that trade off socio‐economic and hydro‐ecological benefits in rivers. Methods for multi‐criteria decision analysis (MCDA) provide a structured and systematic manner for researchers to aid in this process. In this paper, we describe a new MCDA method that prioritizes large multi‐dimensional sets of tradeoffs to support well‐informed water management in rivers. The method was developed based on an environmental flows planning study in the Goulburn‐Broken River catchment, Victoria, Australia. A combined simulation and heuristic optimization procedure was previously integrated into a hydrological catchment network model. That process resulted in a large set of viable daily water allocation schedules that traded off long‐term irrigation and hydro‐ecological benefits at the catchment outlet. We provided new guidance procedures to identify priority tradeoffs that can be used in stakeholder deliberations and catchment decision‐making. Our MCDA method included combined multi‐dimensional ordination and cluster analysis to spread the water allocation alternatives onto a two‐dimensional plane to discover alternatives with similar criteria tradeoffs. A geometric distance‐based method was performed on the full set of alternatives and on the identified clusters to rank the alternatives in accordance with minimizing the distance of the alternatives to an ideal but non‐feasible reference point in multi‐dimensional space. This method complements the use of elicitation procedures when water manager or other stakeholder interaction is not an option or when objectivity is desired. Copyright © 2016 John Wiley & Sons, Ltd.     

A comprehensive approach to evaluating watershed models for predicting river flow regimes critical to downstream ecosystem services

Selection of strategies that help reduce riverine inputs requires numerical models that accurately quantify hydrologic processes. While numerous models exist, information on how to evaluate and select the most robust models is limited. Toward this end, we developed a comprehensive approach that helps evaluate watershed models in their ability to simulate flow regimes critical to downstream ecosystem services. We demonstrated the method using the Soil and Water Assessment Tool (SWAT), the Hydrological Simulation Program–FORTRAN (HSPF) model, and Distributed Large Basin Runoff Model (DLBRM) applied to the Maumee River Basin (USA). The approach helped in identifying that each model simulated flows within acceptable ranges. However, each was limited in its ability to simulate flows triggered by extreme weather events, owing to algorithms not being optimized for such events and mismatched physiographic watershed conditions. Ultimately, we found HSPF to best predict river flow, whereas SWAT offered the most flexibility for evaluating agricultural management practices.     

Correlation Between Phytotoxicity on Annual Ryegrass (Lolium rigidum) and Production Dynamics of Allelochemicals Within Root Exudates of an Allelopathic Wheat

An improved allelopathic correlation between phytotoxicity measured in root growth bioassay upon annual ryegrass (Lolium rigidum Gaud.) and the concentrations of a selection of dynamically produced allelochemicals quantified in the root exudates of cv. Khapli wheat (Triticum turgidum ssp. durum (Desf.) Husn.) monitored during the first 15 days of wheat seedling growth in a sterile, agar–water medium, has been established. Changes over the 15-day growth period in the quantities of five exuded benzoxazinones and seven phenolic acids were measured simultaneously using GC/MS/MS. Substantiating pure compound dose–response measurements were conducted over a range of concentrations for the putative allelochemicals within the wheat exudates. One synergism-based proposal using the monitored compounds to explain the observed low-exudate-concentration phytotoxicity was explored, but was found to be experimentally inadequate.     

石油烃、Cu2+单一与复合污染对沙蚕的毒性效应

在实验室模拟条件下研究了石油烃、Cu2+单一与复合污染对沙蚕的毒性效应.试验的结果表明,沙蚕的死亡率与石油烃、Cu2+的浓度呈显著相关关系.其半数致死浓度LC50分别为:30.2～116.26μg/L(石油烃);449.52～1130.34μg/L(Cu2+).沙蚕体内Cu2+的积累量随着暴露溶液中Cu2+浓度的上升而增加,当Cu2+的浓度>500μg/L时,这一变化十分显著;而沙蚕体内石油烃的含量随着暴露溶液中石油烃浓度的升高无显著变化.而Cu2+和石油烃复合污染对沙蚕的毒性作用较为复杂,在不同的处理中,表现出了协同和拮抗两种作用方式.同时,在Cu2+与石油烃复合污染条件下,沙蚕体内Cu2+的积累量也有显著变化.在复合处理组中,当Cu2+的浓度达到500μg/L时,Cu2+在沙蚕体内的积累量与Cu2+单一污染相比,Cu2+在沙蚕体内积累量相比显著降低.     

虎杖根提取物及分离组分对黄瓜白粉病的作用效果

在实验室内进行了虎杖（Polygonum cuspidatum Sieb.etZucc.）根提取物及其活性组分分离研究,并且对黄瓜白粉病进行了活性测定及温室小区试验。结果表明,无论提取率还是作用效果,乙醇较适合于做为虎杖根提取物的提取溶剂。虎杖根乙醇提取物和乙醚提取物对黄瓜白粉病的EC90值分别为537.85、35.38mg/L,而乙醚提取后残留物的活性很弱,说明乙醇提取物中具有杀菌作用的成分主要存在于乙醚提取物中。用pH梯度分离法对乙醚提取物进行分离,得到3个不同组分,其中以氢氧化钠分离得到的组分对黄瓜白粉病显示了极高的杀菌活性。在温室条件下虎杖乙醇提取物在800～1600mg/L下对黄瓜白粉病的防效相当或优于对照药剂三唑酮。     

A reservoir serves as refuge for adults of the endangered Macquarie perch

Home‐range estimates are an important input to species recovery plans. Our aim was to estimate the home‐range size of the endangered Macquarie Perch in the lower Cotter River catchment, Australia. In total, fourteen home‐range estimates were calculated from intensive radio‐tracking of adult individuals over a minimum of five diel periods in either autumn (n = 5) or spring (n = 9). Home‐range (95% Kernel) and core area (50% Kernel) were calculated by Kernel estimation and corrected for overlap with land. Seasonal estimates of home‐range and core area were not asymptotic in relation to cumulative number of radio‐fixes in four of fourteen cases. The mean within‐season home‐range of adult Macquarie perch was 5.5 ha ranging from 0.2 to 18.4 ha, based on 10 cumulative estimates that were asymptotic in relation to radio‐tracking effort. All five individuals radio‐tracked in autumn occupied a single core area, whereas in spring, six individuals occupied a single core area and three individuals each occupied three core areas. Despite individuals moving on a scale almost comparable to Cotter Reservoir (48.5 ha), only a single radio‐tagged individual was found to leave the reservoir and enter the river. Regional fisheries managers are generally aware of the requirement for Macquarie perch to access flowing water for spawning in south‐eastern Australia; however, in the Cotter River catchment, the protection of habitat for this species within Cotter Reservoir is also paramount. Our study highlights the importance of reservoirs for conserving a threatened aquatic species.