Variations in Epilimnion Thickness in Small Boreal Shield Lakes: Relationships with Transparency, Weather and Acidification

We used multiple linear regression analysis to investigate relationships between late-summer epilimnion thickness, transparency, lake area, acidity and summer weather conditions in a large ($n = 116$) multi-year data set for 9 small Boreal Shield lakes. Dissolved organic carbon (DOC) was the best individual predictor of late summer epilimnion thickness ($r^{2} = 0.69$). Total chlorophyll~$a$, the number of days between ice-out and late-summer stratification, and lake area collectively explained an additional 14% of the variation in epilimnion thickness. The three attributes of summer weather that we examined, mean daily temperature, mean daily wind speed, and mean daily hours of bright sunshine, did not add to the predictive ability of our regression model. Lake acidity also did not add directly to the predictive ability of the model, likely because DOC concentrations already reflected the effects of pH. Our study supports an increasing body of evidence indicating that the dominant effects of climate change on lake thermal structure in small lakes will be through effects on processes that affect lake transparency.     

Urban tinkering

Cities are currently experiencing serious, multifaceted impacts from global environmental change, especially climate change, and the degree to which they will need to cope with and adapt to such challenges will continue to increase. A complex systems approach inspired by evolutionary theory can inform strategies for policies and interventions to deal with growing urban vulnerabilities. Such an approach would guide the design of new (and redesign of existing) urban structures, while promoting innovative integration of grey, green and blue infrastructure in service of environmental and health objectives. Moreover, it would contribute to more flexible, effective policies for urban management and the use of urban space. Four decades ago, in a seminal paper in Science, the French evolutionary biologist and philosopher Francois Jacob noted that evolution differs significantly in its characteristic modes of action from processes that are designed and engineered de novo (Jacob in Science 196(4295):1161–1166, 1977). He labeled the evolutionary process “tinkering”, recognizing its foundation in the modification and molding of existing traits and forms, with occasional dramatic shifts in function in the context of changing conditions. This contrasts greatly with conventional engineering and design approaches that apply tailor-made materials and tools to achieve well-defined functions that are specified a priori. We here propose that urban tinkering is the application of evolutionary thinking to urban design, engineering, ecological restoration, management and governance. We define urban tinkering as:

A mode of operation, encompassing policy, planning and management processes, that seeks to transform the use of existing and design of new urban systems in ways that diversify their functions, anticipate new uses and enhance adaptability, to better meet the social, economic and ecological needs of cities under conditions of deep uncertainty about the future.

This approach has the potential to substantially complement and augment conventional urban development, replacing predictability, linearity and monofunctional design with anticipation of uncertainty and non-linearity and design for multiple, potentially shifting functions. Urban tinkering can function by promoting a diversity of small-scale urban experiments that, in aggregate, lead to large-scale often playful innovative solutions to the problems of sustainable development. Moreover, the tinkering approach is naturally suited to exploring multi-functional uses and approaches (e.g., bricolage) for new and existing urban structures and policies through collaborative engagement and analysis. It is thus well worth exploring as a means of delivering co-benefits for environment and human health and wellbeing. Indeed, urban tinkering has close ties to systems approaches, which often are recognized as critical to sustainable development. We believe this concept can help forge much-closer, much-needed ties among engineers, architects, evolutionary ecologists, health specialists, and numerous other urban stakeholders in developing innovative, widely beneficial solutions for society and contribute to successful implementation of SDG11 and the New Urban Agenda.

     

Bacterial periphytic communities related to mercury methylation within aquatic plant roots from a temperate freshwater lake (South-Western France)

Environmental Science and Pollution Research - Macrophyte floating roots are considered as hotspots for methylmercury (MeHg) production in aquatic ecosystems through microbial activity....     

Culture,nature and particulate matter – Hybrid reframings in air pollution scholarship

Air pollution is a thoroughly hybrid phenomenon. It is composed of inseparable physical, scientific, cultural, social, economic and political dimensions. It is both an object of environmental science and embedded in our everyday social and cultural worlds. Nevertheless, much air pollution scholarship focuses solely on the physical dimensions of air pollution which are expressed quantitatively and pays little or no regard to the identities, discourses, bodies and emotions which constitute and are constituted by air pollution as a physical reality. This article argues for a more reflexive and hybrid approach to air pollution research which bridges intellectually confining binaries. Drawing on the work of Bruno Latour and other actor–network theorists, it argues that if we can let go of a foundational nature, disrupt our humanism and take non-scientific knowledges seriously, we might develop a new respect for the atmospheric environment and begin the task of building a better common world.     

Geochemical and solute transport modelling for CO2 storage, what to expect from it?

Geochemistry plays an important role when assessing the impact of CO₂ storage. Due to the potential corrosive character of CO₂, it might affect the chemical and physical properties of the wells, the reservoir and its surroundings and increase the environmental and financial risk of CO₂ storage projects in deep geological structures. An overview of geochemical and solute transport modelling for CO₂ storage purposes is given, its data requirements and gaps are highlighted, and its progress over the last 10 years is discussed. Four different application domains are identified: long-term integrity modelling, injectivity modelling, well integrity modelling and experimental modelling and their current state of the art is discussed. One of the major gaps remaining is the lack of basic thermodynamical and kinetic data at relevant temperature and pressure conditions for each of these four application domains. Real challenges are the coupled solute transport and geomechanical modelling, the modelling of impurities in the CO₂ stream and pore-scale modelling applications.     

Study of the spatial variation of the biodegradation rate of the herbicide bentazone with soil depth using contrasting incubation methods

Vertical and horizontal spatial variability in the biodegradation of the herbicide bentazone was compared in sandy-loam soil from an agricultural field using sieved soil and intact soil cores. An initial experiment compared degradation at five depths between 0 and 80 cm using sieved soil. Degradation was shown to follow the first-order kinetics, and time to 50% degradation (DT(50)), declined progressively with soil depth from 56 d at 0-10 cm to 520 d at 70-80 cm. DT(50) was significantly correlated with organic matter, pH and dehydrogenase activity. In a subsequent experiment, degradation rate was compared after 127 d in sieved soil and intact cores from 0 to 10 and 50 to 60 cm depth from 10 locations across a 160x90 m portion of the field. Method of incubation significantly affected mean dissipation rate, although there were relatively small differences in the amount of pesticide remaining in intact cores and sieved soil, accounting for between 4.6% and 10.6% of that added. Spatial variability in degradation rate was higher in soil from 0 to 10 cm depth relative to that from 50 and 60 cm depth in both sieved soil and intact core assessments. Patterns of spatial variability measured using cores and sieved soil were similar at 50-60 cm, but not at 0-10 cm depth. This could reflect loss of environmental context following processing of sieved soil. In particular, moisture content, which was controlled in sieved soil, was found to be variable in cores, and was significantly correlated with degradation rate in intact topsoil cores from 0 to 10 cm depth.     

地下水脆弱性评价方法研究

地下水脆弱性评价是区域进行地下水资源保护和管理的重要依据。本文回顾了现有地下水脆弱性评价的方法,提出了应用地理信息系统平台和模糊逻辑与神经网络对地下水进行脆弱性评价的模型,并实际应用于美国与中国选定区域,创新并拓展了地下水脆弱性评价方法。     

Bioventing of No. 2 Fuel Oil: Effects of Air Flowrate,Temperature, Nutrient Amendment,and Acclimation

A 14‐month pilot‐scale bioventing study, sponsored by the New Hampshire Department of Environmental Services, was conducted by the University of New Hampshire to determine the effects of the time between the contamination event and the onset of bioventing, as well as air flowrate, temperature, and nutrient amendments. Freshly contaminated soil was not readily amenable to bioventing. Bioventing was effective (82–92.5 percent removal) for acclimated soil amended with nutrients at 10 °C and 20 °C for the 275 cm³/min and 140 cm³/min air flowrates, respectively. First order degradation rates after nutrient addition were ?6.11 ± 0.83 (×10^?3)/day and ?6.57 ± 1.71 (×10^?3)/day, respectively. The results indicate that bioventing will be best applied when the contamination has occurred at least two years before the onset of treatment. © 2014 Wiley Periodicals, Inc.     

Fate of pharmaceutical compounds and steroid hormones in soil: study of transfer and degradation in soil columns

Numerous chemical products are dispersed into the environment, and the consequences can be sometimes harmful to humans and ecosystems. Pharmaceutical compounds and hormone steroids are among these substances that concern the scientific community. Currently, little data are available on the presence and fate of these compounds in the environment and, in particular, for solid matrices. Therefore, the aim of this work was to perform soil column experiments to evaluate the accumulation, transfer and degradation of these substances in soil. The analyses were based on efficient sample preparation followed by sensitive and selective liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). For this purpose, 23 compounds were chosen including both pharmaceutical compounds as well as steroid hormones. In addition, this experiment was performed on two soils with different properties (% clay, pH, etc.). To the best of our knowledge, no soil column experiments have been performed previously on a large number of pharmaceutical compounds and steroid hormones. Significant transfer was observed only for sulphonamides that can be justified by their polarity (log K _ow ?相似文献