A numerical model of periodically forced circulation near the shore of a lake

Numerical calculations for a model of the near-shore circulation in a lake subject to two diurnal forcing mechanisms are presented. The first mechanism is a heating/cooling term in the heat equation representing the daytime heating and nighttime cooling of the diurnal cycle. The second is a periodic surface stress modelling a sea-breeze/gully wind system typical of some coastal regions. The two forcing mechanisms can either act together or against each other depending on their relative phase. The numerical solutions are compared with previously published analytical solutions and used to explore the extra dynamics associated with non-linear effects (specifically advection). The latter dynamics include the formation of gravity currents and unstable density profiles leading to secondary circulation.     

建立组织外植体的共培养模型(in vitro)用于预测内分泌干扰效应(in vivo)：以黑头软口鲦(Pimephales promelas)的下丘脑-垂体-性腺（HPG）轴内分泌干扰作用为例

内分泌干扰物 （Endocrine Disrupting Compounds, EDCs）可以通过干扰下丘脑-垂体-性腺（HPG）轴来影响生殖系统。虽然目前已有筛选内分泌干扰物的体外检测方法,但这些方法在用于体内实验时却有着不稳定的准确性。本文记录了以黑头呆鱼（Pimephales promelas）的下丘脑-垂体-性腺轴与肝（HPG-L）的共培养组织作为组织外植体来模拟体内反应的结果。我们对成年鱼的大脑（下丘脑）,垂体,性腺和肝进行了单独和共同培养的检测来确定可以在体内重复的情况与组合。只有共培养体表现出去甲雄三烯醇酮对于雌二醇,睾酮和卵黄生成素生成趋势的影响。较低的暴露剂量会抑制激素生成,而较高的暴露剂量则会促进激素生成,形成U型作用曲线。这些数据表明下丘脑-垂体-性腺-肝轴的全部组织的共同培养可以作为体内实验与体外实验的连接,从而预测在完整生物体内内分泌系统的扰乱。本实验中以组织为基础的下丘脑-垂体-性腺-肝系统作为一个灵活的体内系统的解构版本得到了更好的实验控制。通过分离、审查和重组需要的组织,我们能够检测到生物系统功能与对于内分泌干扰物反应中的微小变化。
精选自Theresa K. Johnston, Edward Perkins, Duncan C. Ferguson, Donald M. Cropek. Tissue explant co-culture model of the hypothalamic-pituitary-gonadal-liver axis of the fathead minnow (Pimephales promelas) as a predictive tool for endocrine disruption. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2530–2541, October 2016. DOI: 10.1002/etc.3415
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3415/full
     

Antipredator responses of koomal (Trichosurus vulpecula hypoleucus) against introduced and native predators

Antipredator behavior studies generally assess prey responses to single predator species although most real systems contain multiple species. In multi-predator environments prey ideally use antipredator responses that are effective against all predator species, although responses may only be effective against one predator and counterproductive for another. Multi-predator systems may also include introduced predators that the prey did not co-evolve with, so the prey may either fail to recognize their threat (level 1 naiveté), use ineffective responses (level 2 naiveté) or succumb to their superior hunting ability (level 3 naiveté). We analyzed microhabitat selection of an Australian marsupial (koomal, Trichosurus vulpecula hypoleucus) when faced with spatiotemporal differences in the activity/density levels of one native (chuditch, Dasyurus geoffroii) and two introduced predators (red fox, Vulpes vulpes; feral cat, Felis catus). From this, we inferred whether koomal recognized introduced predators as a threat, and whether they minimized predation risk by either staying close to trees and/or using open or dense microhabitats. Koomal remained close to escape trees regardless of the predator species present, or activity/density levels, suggesting koomal employ this behavior as a first line of defense. Koomal shifted to dense cover only under high risk scenarios (i.e., with multiple predator species present at high densities). When predation risk was low, koomal used open microhabitats, which likely provided benefits not associated with predator avoidance. Koomal did not exhibit level 1 naiveté, although further studies are required to determine if they exhibit higher levels of naiveté (2–3) against foxes and cats.     

A comparative global assessment of potential negative emissions technologies

The paper summarises a global assessment of around 30 prospective negative emissions techniques (NETs) found in the literature. Fourteen techniques including direct air capture, BECCS, biochar, and ocean alkalinity enhancement are considered in more detail.The novel functional categorisation of NETs developed in the course of the assessment is set out and a comparative quantitative summary of the results is presented, focusing on the relative readiness, global capacity, costs and side-effects of the prospective NETs.Both technology specific and more generic potential limitations are discussed, notably those arising from energy requirements, from availability of geological storage capacity and from sustainable supply of biomass.Conclusions are drawn regarding the overall scope of NETs to contribute to safe carbon budgets, and challenges arising in the future governance of NETs, with particular reference to the potential role of carbon markets.     

Identifying the possibilities and pitfalls of conducting IUCN Red List assessments from remotely sensed habitat information based on insights from poorly known Cuban mammals

The International Union for Conservation of Nature's Red List of Threatened Species (RLS) is the key global tool for objective, repeatable assessment of species’ extinction risk status, and plays an essential role in tracking biodiversity loss and guiding conservation action. Satellite remote sensing (SRS) data sets on global ecosystem distributions and functioning show exciting potential for informing range-based RLS assessment, but their incorporation has been restricted by low temporal resolution and coverage of data sets, lack of incorporation of degradation-driven habitat loss, and noninclusion of assumptions related to identification of changing habitat distributions for taxa with varying habitat dependency and ecologies. For poorly known mangrove-associated Cuban hutias (Mesocapromys spp.), we tested the impact of possible assumptions regarding these issues on range-based RLS assessment outcomes. Specifically, we used annual (1985–2018) Landsat data and land-cover classification and habitat degradation analyses across different internal time series slices to simulate range-based RLS assessments for our case study taxa to explore potential assessment uncertainty arising from temporal SRS data set coverage, incorporating proxies of (change in) habitat quality, and assumptions on spatial scaling of habitat extent for RLS parameter generation. We found extensive variation in simulated species-specific range-based RLS assessments, and this variation was mostly associated with the time series over which parameters were estimated. However, results of some species-specific assessments differed by up to 3 categories (near threatened to critically endangered) within the same time series, due to the effects of incorporating habitat quality and the spatial scaling used in RLS parameter estimation. Our results showed that a one-size-fits-all approach to incorporating SRS information in RLS assessment is inappropriate, and we urge caution in conducting range-based assessments with SRS for species for which habitat dependence on specific ecosystem types is incompletely understood. We propose novel revisions to parameter spatial scaling guidelines to improve integration of existing time series data on ecosystem change into the RLS assessment process.     

What are the implications of sea-level rise for a 1.5, 2 and 3 °C rise in global mean temperatures in the Ganges-Brahmaputra-Meghna and other vulnerable deltas?

Even if climate change mitigation is successful, sea levels will keep rising. With subsidence, relative sea-level rise represents a long-term threat to low-lying deltas. A large part of coastal Bangladesh was analysed using the Delta Dynamic Integrated Emulator Model to determine changes in flood depth, area and population affected given sea-level rise equivalent to global mean temperature rises of 1.5, 2.0 and 3.0 °C with respect to pre-industrial for three ensemble members of a modified A1B scenario. Annual climate variability today (with approximately 1.0 °C of warming) is potentially more important, in terms of coastal impacts, than an additional 0.5 °C warming. In coastal Bangladesh, the average depth of flooding in protected areas is projected to double to between 0.07 and 0.09 m when temperatures are projected at 3.0 °C compared with 1.5 °C. In unprotected areas, the depth of flooding is projected to increase by approximately 50% to 0.21–0.27 m, whilst the average area inundated increases 2.5 times (from 5 to 13% of the region) in the same temperature frame. The greatest area of land flooded is projected in the central and north-east regions. In contrast, lower flood depths, less land area flooded and fewer people are projected in the poldered west of the region. Over multi-centennial timescales, climate change mitigation and controlled sedimentation to maintain relative delta height are key to a delta’s survival. With slow rates of sea-level rise, adaptation remains possible, but further support is required. Monitoring of sea-level rise and subsidence in deltas is recommended, together with improved datasets of elevation.

     

Determination of Sulfur Oxides in the Flue Gases of the Pulping Processes

The body of information presented in this paper is directed to the operating personnel and process engineers employed in the power and recovery departments of a chemical pulping operation. The proper evaluation of the total analytical and sampling system (TASS), to be used in the determination of sulfur oxides is as important as a proper analytical and recording system (ARS). The presence of other sulfur gaseous compounds and particulates could greatly influence the results of the determination.

The analytical method employed determines sulfur dioxide and trioxide from an aliquot of the trapping solution, 3% hydrogen peroxide and 8 0% isopropyl alcohol respectively. The aliquot is titrated with barium perchlorate in the presence of Thorin indicator. The results of evaluating the method indicated negligible interference from the presence of hydrogen sulfide, mercaptans and nitrogen oxides. A blank correction of 15 parts per million (ppm) is recommended whenever 100 ppm of hydrogen sulfide or more are simultaneously present in the gas stream. Particulaies are shown to interfere either by addition or subtraction. Sulfate particulates that will add to the determination must be removed, but in doing so, care must be exerted to avoid surface-contacting conditions that promote reaction between carbonates and the sulfur oxides. The integrated method of sampling and analysis will permit determinations from a flue gas with sulfur oxides concentrations of 30 ppm and above. The relative standard deviation improves from 10% at 100 ppm SO₂ to 2.6% at 1000 ppm SO₂. In both cases, sulfides were present.