Review of impact categories and environmental indicators for life cycle assessment of geotechnical systems

Life cycle assessment (LCA) has only had limited application in the geotechnical engineering discipline, though it has been widely applied to civil engineering systems such as pavements and roadways. A review of previous geotechnical LCAs showed that most studies have tracked a small set of impact categories, such as energy and global warming potential. Accordingly, currently reported environmental indicators may not effectively or fully capture important environmental impacts and tradeoffs associated with geotechnical systems, including those associated with land and soil resources. This research reviewed previous studies, methods, and models for assessment of land use and soil‐related impacts to understand their applicability to geotechnical LCA. The results of this review show that critical gaps remain in current knowledge and practice. In particular, further development or refinement of environmental indicators, impact categories, and cause–effect pathways is needed as they pertain to geotechnical applications—specifically those related to soil quality, soil functions, and the ecosystem services soils provide. In addition, many existing methods emerge from research on land use and land use change related to other disciplines (e.g., agriculture). For applicability to geotechnical projects, the resolution of many of these methods and resulting indicators need to be downscaled from the landscape/macro scale to the project scale. In the near term, practitioners of geotechnical LCA should begin tracking changes to soil properties and report impacts to land and soil resources qualitatively.     

Dual-curing resin cement with colour indicator for adhesively cemented restorations to dental tissues: Change of colour by curing and some physical properties

The study was aimed to investigate a color indicator containing dual curing resin composite luting cement and to plot the color change to the time of solidification of the cement. In addition some physical properties were studied. Specimens were made of a dual-cure resin cement (Maxcem Elite™ Chroma, Kerr, Orange, CA, USA) and polymerized by autopolymerization only, or with light initiated polymerization. A spectrophotometer was used to quantify the color change of the cement as plotted with the curing time. The efficacy of the curing process was studied by measuring water sorption and the ultimate flexural properties of the cement. The results showed that the flexural strength of cement after autopolymerization was 27.3 MPa and after light initiated polymerization 48.1 MPa. Young’s modulus of bending was 2089.3 MPa and 3781.5 MPa respectively for the same cement samples. Water sorption after two weeks for the autopolymerization cement samples was −1.12 wt% and for the light initiated polymerization samples 0.56 wt%. Non-parametric Spearman’s correlation was measured for autopolymerized cement samples between variables for color and solidification load (N), which showed a strong correlation between curing process and color change (p < 0.05). There was a correlation between the color change and degree of monomer conversion of the dual curing resin composite luting cement which contained a color indicator system for polymerization reaction. The study also suggested that autopolymerization only resulted in suboptimal polymerization of the cement. By additional light curing considerably higher flexural properties were obtained.     

Afforestation for climate change mitigation: Potentials,risks and trade‐offs

Afforestation is considered a cost‐effective and readily available climate change mitigation option. In recent studies afforestation is presented as a major solution to limit climate change. However, estimates of afforestation potential vary widely. Moreover, the risks in global mitigation policy and the negative trade‐offs with food security are often not considered. Here we present a new approach to assess the economic potential of afforestation with the IMAGE 3.0 integrated assessment model framework. In addition, we discuss the role of afforestation in mitigation pathways and the effects of afforestation on the food system under increasingly ambitious climate targets. We show that afforestation has a mitigation potential of 4.9 GtCO₂/year at 200 US$/tCO₂ in 2050 leading to large‐scale application in an SSP2 scenario aiming for 2°C (410 GtCO₂ cumulative up to 2100). Afforestation reduces the overall costs of mitigation policy. However, it may lead to lower mitigation ambition and lock‐in situations in other sectors. Moreover, it bears risks to implementation and permanence as the negative emissions are increasingly located in regions with high investment risks and weak governance, for example in Sub‐Saharan Africa. Afforestation also requires large amounts of land (up to 1,100 Mha) leading to large reductions in agricultural land. The increased competition for land could lead to higher food prices and an increased population at risk of hunger. Our results confirm that afforestation has substantial potential for mitigation. At the same time, we highlight that major risks and trade‐offs are involved. Pathways aiming to limit climate change to 2°C or even 1.5°C need to minimize these risks and trade‐offs in order to achieve mitigation sustainably.     

Genomic and phenotypic effects of inbreeding across two different hatchery management regimes in Chinook salmon

Genomic approaches permit direct estimation of inbreeding and its effect on fitness. We used genomic‐based estimates of inbreeding to investigate their relationship with eight adult traits in a captive‐reared Pacific salmonid that is released into the wild. Estimates were also used to determine whether alternative broodstock management approaches reduced risks of inbreeding. Specifically, 1,100 unlinked restriction‐site associated (RAD) loci were used to compare pairwise relatedness, derived from a relationship matrix, and individual inbreeding, estimated by comparing observed and expected homozygosity, across four generations in two hatchery lines of Chinook salmon that were derived from the same source. The lines are managed as “integrated” with the founding wild stock, with ongoing gene flow, and as “segregated” with no gene flow. While relatedness and inbreeding increased in the first generation of both lines, possibly due to population subdivision caused by hatchery initiation, the integrated line had significantly lower levels in some subsequent generations (relatedness: F₂–F₄; inbreeding F₂). Generally, inbreeding was similar between the lines despite large differences in effective numbers of breeders. Inbreeding did not affect fecundity, reproductive effort, return timing, fork length, weight, condition factor, and daily growth coefficient. However, it delayed spawn timing by 1.75 days per one standard deviation increase in F (~0.16). The results indicate that integrated management may reduce inbreeding but also suggest that it is relatively low in a small, segregated hatchery population that maximized number of breeders. Our findings demonstrate the utility of genomics to monitor inbreeding under alternative management strategies in captive breeding programs.     

Clinical features and hematological findings of COVID-19 patients with blood transfusion

This paper aims to illustrate the clinical characteristics, hematological findings, and blood transfusion information of Coronavirus disease 2019 (COVID-19) patients. Twenty-three COVID-19 patients were treated and transfused with blood products in Wuhan First Hospital from February 12 to March 20, 2020. The patients were divided into a survivor group and a non-survivor group, respectively, according to whether the patient had been discharged or died. The results demonstrated at the time of initial blood transfusion, that the non-survivor group possessed a lower platelet (PLT) than that of the survivor group (P<0.001), and PLT were below the normal range in 6 (85.7%) non-survivor group and in 2 (12.5%) survivor group (P<0.01). Over half of these patients had abnormalities in fibrinogen (FIB), activated partial thromboplastin time (APTT), prothrombin time (PT), and international normalized ratio (INR), but no significant difference was found between the non-survivor group and survivor group. The non-survivor group had a dramatically higher D-Dimers and disseminated intravascular coagulation (DIC) scores than those of the survivor group (P<0.01). Six (85.7%) non-survivors but none of the survivors had a DIC score greater than 6 (P<0.001). Fifteen (93.8%) survivors and 2 (28.6%) non-survivors were transfused with RBC (P<0.01). The non-survivors (5/7) possessed a higher proportion for using AP than the survivors (2/16). The study suggests that COVID-19 patients who undergo blood transfusion usually possess coagulation dysfunction, and DIC may be closely related to deteriorating clinical outcomes.     

Disentangling the spatial and temporal causes of decline in a bird population

The difficulties in understanding the underlying reasons of a population decline lie in the typical short duration of field studies, the often too small size already reached by a declining population or the multitude of environmental factors that may influence population trend. In this difficult context, useful demographic tools such as integrated population models (IPM) may help disentangling the main reasons for a population decline. To understand why a hoopoe Upupa epops population has declined, we followed a three step model analysis. We built an IPM structured with respect to habitat quality (approximated by the expected availability of mole crickets, the main prey in our population) and estimated the contributions of habitat‐specific demographic rates to population variation and decline. We quantified how much each demographic rate has decreased and investigated whether habitat quality influenced this decline. We tested how much weather conditions and research activities contributed to the decrease in the different demographic rates. The decline of the hoopoe population was mainly explained by a decrease in first‐year apparent survival and a reduced number of fledglings produced, particularly in habitats of high quality. Since a majority of pairs bred in habitats of the highest quality, the decrease in the production of locally recruited yearlings in high‐quality habitat was the main driver of the population decline despite a homogeneous drop of recruitment across habitats. Overall, the explanatory variables we tested only accounted for 19% of the decrease in the population growth rate. Among these variables, the effects of spring temperature (49% of the explained variance) contributed more to population decline than spring precipitation (36%) and research activities (maternal capture delay, 15%). This study shows the power of IPMs for identifying the vital rates involved in population declines and thus paves the way for targeted conservation and management actions.     

Comparative analysis of root sprouting and its vigour in temperate herbs: anatomical correlates and environmental predictors

Background and AimsRoot sprouting (RS), i.e. the ability to form adventitious buds on roots, is an important form of clonal growth in a number of species, and serves as both a survival strategy and a means of spatial expansion, particularly in plants growing in severely and recurrently disturbed habitats. Occurrence and/or success of plants in severely and recurrently disturbed habitats are determined by two components, namely the ability to produce adventitious buds on roots and the vigour of their production. As mechanisms behind different magnitudes of RS remain unclear, our study investigates: (1) whether the presence or absence of specific tissues in roots can promote or limit RS; and (2) whether there is some relationship between RS ability, RS vigour and species niche.MethodsWe studied RS ability together with RS vigour in 182 Central European herbaceous species under controlled experimental conditions. We used phylogenetic logistic regressions to model the presence of RS, RS vigour, the relationship between RS and anatomical traits and the relationship between RS and parameters of species niches.Key ResultsA quarter of herbs examined were able to produce adventitious buds on roots. They were characterized by their preference for open dry habitats, the presence of secondary root thickening and the occurrence of sclerified cortical cells in roots. Root sprouting vigour was not associated with any specific anatomical pattern, but was correlated with the environmental niches of different species, indicating that preferred disturbed and dry habitats might represent a selection pressure for more vigorous root sprouters than undisturbed and wet habitats.ConclusionsOur study shows that sprouting from roots is quite common in temperate dicotyledonous herbs. Two components of RS – ability and vigour – should be considered separately in future studies. We would also like to focus more attention on RS in herbs from other regions as well as on external forces and internal mechanisms regulating evolution and the functions of RS in both disturbed and undisturbed habitats.     

Relationship between aquifer biofilms and unattached microbial indicators of urban groundwater contamination

Aquifers, springs and other groundwater‐dependent ecosystems are threatened by urban land use, which causes water quality deterioration through nutrient loading, sewage infiltration, groundwater extraction and, along coasts, seawater intrusion. The presence of certain microbes in groundwater can indicate that an aquifer is anthropogenically contaminated. Interpretations made from observations of indicator microbes in groundwater are limited because the relationship between the presumably allochthonous indicator microbes and relevant autochthonous microbial communities has not been characterized. This study addressed whether autochthonous aquifer biofilms can influence the presence of presumed microbial indicators in groundwater, and simultaneously used microbial indicators to trace sources of urban contamination at a karst spring of conservation concern. These questions were approached using a 17‐month time series analysis of attached biofilm and adjacent unattached bacteria in the submerged karst aquifer conduit associated with this spring. Environmental 16S rRNA gene sequencing was performed to characterize these communities, and community structure data were contextualized with groundwater geochemical and hydrogeological measurements. Linear regression models were developed to explain the relative abundance patterns of indicator microbes and other unattached microbes at this site. The results of this study suggest that dominant aquifer biofilms do not influence the presence of unattached microbial taxa that are presumed to be indicators of groundwater contamination, and generated new information about the origin of coliform bacteria at the study site. These results build confidence in the use of microbial indicators in groundwater‐dependent ecosystem conservation strategies and inform future management plans for urban aquifers and springs worldwide.