A numerical modeling approach to support decision-making on design of integrated multitrophic aquaculture for efficiently mitigating aquatic waste

As a bio-mitigation strategy of aquafarming pollutants, the integrated multitrophic aquaculture (IMTA) system has been proposed and developed to mitigate the waste produced during co-cultivation. Although there have been considerable implementations of IMTA worldwide, its optimal design needs a further study. Through a numerical modeling approach, this study aims to facilitate decision-making when designing IMTA to more efficiently mitigate the negative change caused by aquaculture. An improved three-dimensional numerical model is adopted to simulate the dynamics of water current and organic waste in Gokasho Bay, Japan. Results show that (1) the maximum main surface water current velocity in Hazama-ura area is less than 10 cm s^?1, where nutrient absorbers and/or suspended feeders can easily attach to a substratum; (2) southern-eastern direction water flow is dominant through the year suggesting that seaweeds (e.g., Laminaria japonica, Ulva ohnoi) or mussels (e.g., Mytilus edulis) are better arranged in the same direction; (3) horizontal distribution of organic waste on sea bottom indicates that when releasing sea cucumbers (e.g., Apostichopus japonicus), priority is given to the areas where the accumulated amount of particulate organic waste is high. Our case study provides a general idea on the optimal design of IMTA and can be scaled to the globe, especially regarding decision-making on locations for the extractive organisms. In conclusion, to improve the bio-mitigation efficiency of IMTA, location for nutrient absorbers and/or suspended feeders can be selected based on local water flow, and sea cucumbers need to be placed with a careful consideration of the waste distribution in local area.     

Development of injury criteria for pelvic fracture in frontal crashes

OBJECTIVE: This article assesses the position-dependent injury tolerance of the hip in the frontal direction based on testing of eight postmortem human subjects. METHODS: For each subject, the left and right hemipelvis complex was axially loaded using a previously developed test configuration. Six positions were defined from a seated femur neutral condition, combining flexed, neutral, and extended femur positions with abducted, neutral, and adducted positions. RESULTS: Axial injury tolerances based on peak force were found to be 6,850 +/- 840 N in the extended, neutral position and 4,080 +/- 830 N in the flexed, neutral position. From the flexed neutral orientation, the peak axial force increased 18% for 20 degrees abduction and decreased 6% for 20 degrees adduction. From the extended, neutral orientation, the peak axial force decreased 4% for 20 degrees abduction and decreased 3% for 20 degrees adduction. However, as there is evidence that increases in loading may occur after the initiation of fracture, the magnitude of the peak force is likely related to the extent of injury, not to the initial tolerance. Using the axial femur force at the initiation of fracture (assessed with acoustic crack sensors) as a potentially more relevant indicator of injury may lower the existing injury criteria. This fracture initiation force varied by position from 3,010 +/- 560 N in the flexed, neutral position to 5,470 N in the extended, abducted position. Further, there was a large position-dependent variation in the ratio of fracture initiation force to the peak axial force. The initiation of fracture was 83% of the peak axial force in the extended, abducted position, but the ratio was 34% in the extended, adducted position. CONCLUSIONS: This may have significant implications for the development of pelvic injury criteria by automobile designers attempting to mitigate pelvis injuries.     

Contamination status of persistent organochlorines in human breast milk from Japan: recent levels and temporal trend

Contamination levels of persistent organochlorines (OCs) such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), and chlordane compounds (CHLs) was examined in human breast milk collected during 2001-2004 from Fukuoka prefecture in Japan. The concentrations of OCs such as dioxins and related compounds, DDTs, CHLs and HCB in human breast milk from primiparae were comparable to or slightly higher than the data obtained during 1998, indicating that the levels of these contaminants in Japanese human breast milk have not decreased since 1998 and Japanese are continuously exposed to these chemicals, presumably via fish intake. In addition, OC levels in human breast milk from primiparae were significantly higher than those from multiparae, implying elimination of OCs via lactation. Furthermore, significant positive correlations were observed between levels of OCs in human breast milk and the age of primiparae. These results indicate that the mothers with higher age may transfer higher amounts of OCs to the first infant than to the infants born afterwards through breast-feeding, and hence the first born children might be at higher risk by OCs.     

Impact of COVID-19 type events on the economy and climate under the stochastic DICE model

Environmental Economics and Policy Studies - The classical DICE model is a widely accepted integrated assessment model for the joint modeling of economic and climate systems, where all model state...     

Hydrodynamic forces on emergent cylinders in non-uniform flow

Environmental Fluid Mechanics - The main objective of conducting numerical simulations of flows in rivers with vegetation is to investigate the complex flow dynamics involved in non-equilibrium...     

Methods for selenium removal from contaminated waters: a review

Environmental Chemistry Letters - Worldwide contamination of waters by metals, metalloids, and organometallic pollutants is a major health issue. In particular, the occurrence of the selenium...