ASSESSMENT OF METHODS FOR MEASURING EMBEDDEDNESS: APPLICATION TO SEDIMENTATION IN FLOW REGULATED STREAMS1

Abstract: Five commonly used methods for measuring embeddedness the — degree to which fine particles surround coarse substrate on the surface of the streambed — are assessed and used to evaluate the sedimentation pattern resulting from impoundment on tributaries of the Connecticut River. Results show that the U.S. Environmental Protection Agency (USEPA) method best reflects the sediment regime on these rivers. On the Ompompanoosuc River, regulated by a run-of-the-river/flood control dam, embeddedness increases significantly directly downstream of the dam. On the unregulated White River, no downstream trends in embeddedness are observed. The USEPA results on the Ompompanoosuc River reflect the movement of a local decrease in embeddedness, interpreted as a moving region of scour, with a calculated transport rate of approximately 5 to 25 m/day. Observed transport rates are similar to previously measured sediment transport rates and consistent with results from a multifraction sediment transport model. Application of the USEPA method to an additional regulated tributary demonstrates the effects of dam management on embeddedness. Flow regulation with high sediment trapping efficiency results in a decrease in embeddedness downstream of the dam. Results provide insight into the utility of available methods for evaluating the effects of management practice on streambed composition.     

The metacoupled Arctic: Human–nature interactions across local to global scales as drivers of sustainability

The Arctic is an epicenter of complex environmental and socioeconomic change. Strengthened connections between Arctic and non-Arctic systems could threaten or enhance Arctic sustainability, but studies of external influences on the Arctic are scattered and fragmented in academic literature. Here, we review and synthesize how external influences have been analyzed in Arctic-coupled human and natural systems (CHANS) literature. Results show that the Arctic is affected by numerous external influences nearby and faraway, including global markets, climate change, governance, military security, and tourism. However, apart from climate change, these connections are infrequently the focus of Arctic CHANS analyses. We demonstrate how Arctic CHANS research could be enhanced and research gaps could be filled using the holistic framework of metacoupling (human–nature interactions within as well as between adjacent and distant systems). Our perspectives provide new approaches to enhance the sustainability of Arctic systems in an interconnected world.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01729-9.     

Identifying the cause of toxicity in an algal whole effluent toxicity study - an unanticipated toxicant

Toxicity was observed in whole effluent toxicity (WET) studies with the freshwater alga, Pseudokirchneriella subcapitata, in three consecutive monthly studies, (NOEC = 50-75%). Toxicity was not observed to Ceriodaphnia dubia or the fathead minnow, Pimephales promelas in concurrent studies. Selected toxicity identification evaluation (TIE) tests were conducted in a tiered approach to eliminate possible toxicants and progressively identify the causative agent. Filtration following alkaline adjustment (pH 10 or 11) was effective in eliminating significant growth effects and also reduced phosphate concentration. The TIE studies confirmed that the observed effluent toxicity was caused by excess ortho-phosphate in the effluent not by overstimulation or related to unfavorable N:P ratios; but due to direct toxicity. The 96-h 25% inhibition concentration (IC25) of ortho-phosphate to P. subcapitata was 3.4 mg L⁻¹ while the maximum acceptable toxicant concentration was 4.8 mg L⁻¹. This study illustrates the value of multi-species testing and also provides an example of an effective TIE using algae identifying an unanticipated toxicant.     

Dynamic risk assessment using failure assessment and Bayesian theory

To ensure the safety of a process system, engineers use different methods to identify the potential hazards that may cause severe consequences. One of the most popular methods used is quantitative risk assessment (QRA) which quantifies the risk associated with a particular process activity. One of QRA's major disadvantages is its inability to update risk during the life of a process. As the process operates, abnormal events will result in incidents and near misses. These events are often called accident precursors. A conventional QRA process is unable to use the accident precursor information to revise the risk profile. To overcome this, a methodology has been proposed based on the work of Meel and Seider (2006). Similar to Meel and Seider (2006) work, this methodology uses Bayesian theory to update the likelihood of the event occurrence and also failure probability of the safety system. In this paper the proposed methodology is outlined and its application is demonstrated using a simple case study. First, potential accident scenarios are identified and represented in terms of an event tree, next, using the event tree and available failure data end-state probabilities are estimated. Subsequently, using the available accident precursor data, safety system failure likelihood and event tree end-state probabilities are revised. The methodology has been simulated using deterministic (point value) as well as probabilistic approach. This Methodology is applied to a case study demonstrating a storage tank containing highly hazardous chemicals. The comparison between conventional QRA and the results from dynamic failure assessment approach shows the significant deviation in system failure frequency throughout the life time of the process unit.     

Wild meat trade over the last 45 years in the Peruvian Amazon

The trade in wild meat is an important economic component of rural people's livelihoods, but it has been perceived to be among the main causes of the decline of wildlife species. Recently, the COVID-19 pandemic has brought to light an additional concern of wildlife markets as a major human-health challenge. We analyzed data from the largest longitudinal monitoring (1973–2018) of the most important urban wild-meat markets in Iquitos, Peru, to examine the trends in and impacts of these markets on people's livelihoods. Over the last 45 years, wild meat sales increased at a rate of 6.4 t/year (SD 2.17), paralleling urban population growth. Wild meat sales were highest in 2018 (442 t), contributing US$2.6 million (0.76%) to the regional gross domestic product. Five species of ungulates and rodents accounted for 88.5% of the amount of biomass traded. Vulnerable and Endangered species represented 7.0% and 0.4% of individuals sold, respectively. Despite growth in sales, the contribution of wild meat to overall urban diet was constant: 1–2%/year of total meat consumed. This result was due to greater availability and higher consumption of cheaper meats (e.g., in 2018, poultry was 45.8% cheaper and was the most consumed meat) coupled with the lack of economic incentives to harvest wild meat species in rural areas. Most wild meat was sold salted or smoked, reducing the likelihood of foodborne diseases. Community-based wildlife management plans and the continued trade bans on primates and threatened taxa may avoid biodiversity loss. Considering the recent COVID-19 pandemic, future management plans should include potential viral hosts and regulation and enforcement of hygiene practices in wild-meat markets.     

The effect of alkaline pretreatment on the anaerobic digestion of fruit and vegetable wastes from a central food distribution market

Journal of Material Cycles and Waste Management - Anaerobic digestion of the organic fraction of municipal solid wastes is a well-established process for biogas production and various forms of...     

Chronic exposure to lead acetate promotes changes in the alveolar bone of rats: microstructural and physical–chemical characterization

Environmental Science and Pollution Research - There are a few data relating to the effects of lead (Pb) exposure on the alveolar bone, which has very distinct morphophysiological characteristics...