Simulations of the flow in the Mahakam river–lake–delta system,Indonesia

Large rivers often present a river–lake–delta system, with a wide range of temporal and spatial scales of the flow due to the combined effects of human activities and various natural factors, e.g., river discharge, tides, climatic variability, droughts, floods. Numerical models that allow for simulating the flow in these river–lake–delta systems are essential to study them and predict their evolution under the impact of various forcings. This is because they provide information that cannot be easily measured with sufficient temporal and spatial detail. In this study, we combine one-dimensional sectional-averaged (1D) and two-dimensional depth-averaged (2D) models, in the framework of the finite element model SLIM, to simulate the flow in the Mahakam river–lake–delta system (Indonesia). The 1D model representing the Mahakam River and four tributaries is coupled to the 2D unstructured mesh model implemented on the Mahakam Delta, the adjacent Makassar Strait, and three lakes in the central part of the river catchment. Using observations of water elevation at five stations, the bottom friction for river and tributaries, lakes, delta, and adjacent coastal zone is calibrated. Next, the model is validated using another period of observations of water elevation, flow velocity, and water discharge at various stations. Several criteria are implemented to assess the quality of the simulations, and a good agreement between simulations and observations is achieved in both calibration and validation stages. Different aspects of the flow, i.e., the division of water at two bifurcations in the delta, the effects of the lakes on the flow in the lower part of the system, the area of tidal propagation, are also quantified and discussed.     

Site-specific and integrated adaptation to climate change in the coastal mangrove zone of Soc Trang Province, Viet Nam

The dynamic coastline of Soc Trang Province in the Mekong Delta of Viet Nam is in most parts protected from erosion, storms and flooding by a narrow belt of mangroves. However, the unsustainable use of natural resources and development in the coastal zone is threatening the protection function of this forest belt. This situation is exacerbated by the impacts of climate change, particularly by the increased intensity and frequency of storms, floods and by rising sea levels. Based on analysis of past experience of mangrove planting and historical changes in mangrove cover, an integrated and site-specific approach to adaptation to climate change has been put in place, which comprises mangrove planting and rehabilitation with emphasis on resilience to climate change, and participatory involvement of local communities in effective mangrove management and protection through co-management. To address uncertainties associated with the impacts of climate change, testing of new mangrove planting techniques has started. This includes mimicking successful natural regeneration for small-scale planting in sites with high wave energy and transformation of existing even-aged plantations into more diverse forests—both in terms of structure and species composition. The pre-requisite for mangrove rehabilitation in erosion sites has successfully been put in place: breakwaters made from bamboo have reduced erosion and stimulated sedimentation. The design and construction of the wave-breaking structures, which was based on a numerical model which simulates hydrodynamics and shoreline development, ensures that downdrift erosion can be avoided as far as possible. A comprehensive monitoring program has been established and initial results provide evidence for the effectiveness of the bamboo breakwaters. Early experience shows that co-management is an effective way of maintaining and enhancing the protection function of the mangrove forest belt and at the same time providing livelihood for local communities. Payment for ecosystem services contributes to sustainability of co-management as well as livelihood improvement.     

Anthropogenic influence on surface water quality of the Nhue and Day sub-river systems in Vietnam

In order to investigate the temporal and spatial variations of 14 physical and chemical surface water parameters in the Nhue and Day sub-river systems of Vietnam, surface water samples were taken from 43 sampling sites during the dry and rainy seasons in 2007. The results were statistically examined by Mann–Whitney U-test and hierarchical cluster analysis. The results show that water quality of the Day River was significantly improved during the rainy season while this was not the case of the Nhue River. However, the river water did not meet the Vietnamese surface water quality standards for dissolved oxygen (DO), biological oxygen demand (BOD₅), chemical oxygen demand (COD), nutrients, total coliform, and fecal coliform. This implies that the health of local communities using untreated river water for drinking purposes as well as irrigation of vegetables may be at risk. Forty-three sampling sites were grouped into four main clusters on the basis of water quality characteristics with particular reference to geographic location and land use and revealed the contamination levels from anthropogenic sources.     

Lead contamination in surface soil on roads from used lead–acid battery recycling in Dong Mai,Northern Vietnam

Used lead–acid battery (ULAB) recycling has caused numerous health and environmental issues in developing countries. Surface soil pollution from ULAB recycling activities has been linked with elevated levels of lead in human blood. We measured surface soil lead in and surrounding the ULAB recycling village of Hung Yen in northern Vietnam in 2011, 2013, and 2014. The data were analyzed statistically and discussed with respect to distance from the contamination source, year of measurement, contamination pathway, and countermeasures against the contamination. Transportation routes from the smelter or collection site displayed the greatest concentration of surface soil lead (median 6400–10,000 mg/kg). Surface soil lead decreased significantly with distance along the road from the ULAB recycling site, although such a decrease was not observed for rice fields, agricultural roads, or garden soil. Re-suspension and adherence by traffic were identified as key pollution pathways. Distance from the source, covering of the surface of roads, construction of walls, and position relative to the source were shown to be the most effective factors in the reduction of surface soil lead pollution. Application of a combination of these measures should result in improvement in the health of residents.     

Plastic waste as a valuable resource: strategy to remove heavy metals from wastewater in bench scale application

Environmental Science and Pollution Research - Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by...     

Assessment of total concentrations of heavy metals in industrial sludges from the North of Vietnam and their potential impact on the ecosystem

Environmental Science and Pollution Research - Industrial sludges from wastewater treatment plants of industrial parks and a drinking water treatment plant in northern Vietnam were investigated in...     

The protective effect of green space on heat-related respiratory hospitalization among children under 5 years of age in Hanoi,Vietnam

Environmental Science and Pollution Research - Combined effects of global warming and rapid urbanization replace green spaces with urban facilities. Children in urban areas are at a higher risk of...     

Changes in motorcycle-related injuries and deaths after mandatory motorcycle helmet law in a district of Vietnam

Objective: Our study measured the change in head injuries and deaths among motorcycle users in Cu Chi district, a suburban district of Ho Chi Minh City.

Methods: Hospital records for road traffic injuries (RTIs) were collected from the Cu Chi Trauma Centre and motorcycle-related death records were obtained from mortality registries in commune health offices. Head injury severity was categorized using the Abbreviated Injury Score (AIS). Rate ratios (RRs) were used to compare rates pre- and post-law (2005/2006–2009/2010). Cu Chi's population, stratified by year, age, and sex, was used as the denominator.

Results: Of records identifying the transportation mode at the time of injury, motorcyclists accounted for most injuries (3,035, 87%) and deaths (238, 90%). Head injuries accounted for 70% of motorcycle-related hospitalizations. Helmet use was not recorded in any death records and not in 97% of medical records. Males accounted for most injuries (73%) and deaths (88%). The median age was 28 years and 32 years for injuries and deaths, respectively. Compared to the pre-law period, rates of motorcycle injuries (RR = 0.53; 95% confidence interval [CI], 0.49–0.58), head injuries (RR = 0.35; 95% CI, 0.31–0.39), severe head injuries (RR = 0.47; 95% CI, 0.34–0.63), and deaths (RR = 0.69; 95% CI, 0.53–0.89) significantly decreased in the post-law period.

Conclusions: Rates of head injuries and deaths among motorcycle riders decreased significantly after implementation of the mandatory helmet law in Vietnam. To further examine the impact of the motorcycle helmet law, including compliance and helmet quality, further emphasis should be placed on gathering helmet use data from injured motorcyclists.     

Are older drivers’ driving patterns during an on-road driving task representative of their real-world driving patterns?

Abstract

Objective: The current study investigated whether older drivers’ driving patterns during a customized on-road driving task were representative of their real-world driving patterns.

Methods: Two hundred and eight participants (male: 68.80%; mean age?=?81.52 years, SD?=?3.37 years, range?=?76.00–96.00 years) completed a customized on-road driving task that commenced from their home and was conducted in their own vehicle. Participants’ real-world driving patterns for the preceding 4-month period were also collected via an in-car recording device (ICRD) that was installed in each participant’s vehicle.

Results: During the 4-month period prior to completing the on-road driving task, participants’ median real-world driving trip distance was 2.66?km (interquartile range [IQR]?=?1.14–5.79?km) and their median on-road driving task trip distance was 4.41?km (IQR?=?2.83–6.35?km). Most participants’ on-road driving task trip distances were classified as representative of their real-world driving trip distances (95.2%, n?=?198).

Conclusions: These findings suggest that most older drivers were able to devise a driving route that was representative of their real-world driving trip distance. Future research will examine whether additional aspects of the on-road driving task (e.g., average speed, proportion of trips in different speed zones) are representative of participants’ real-world driving patterns.     

PCBs,PBDEs and dioxin-related compounds in floor dust from an informal end-of-life vehicle recycling site in northern Vietnam: contamination levels and implications for human exposure

Floor dusts from Vietnamese end-of-life vehicle (ELV)-processing households were investigated to elucidate the contamination levels and exposure risk of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and dioxin-related compounds (DRCs). The concentrations were in order of PBDEs (260–11,000, median 280 ng/g overall) > PCBs (19–2200, median 140 ng/g) > dioxin-like PCBs (8.8–450, median 22 ng/g) ? polybrominated dibenzo-p-dioxin/dibenzofurans (PBDD/Fs, 2000–28,000, median 8500 pg/g) > polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs, 440–4100, median 1800 pg/g) > MoBPCDD/Fs (1.9–1200, median 250 pg/g). Concentrations of PCBs and DRCs were higher than those reported for Vietnamese urban houses, indicating ELV processing as a significant source of these contaminants. Higher concentrations of PCBs relative to PBDEs suggest the abundance of old electrical capacitors/transformers in ELVs. The PBDD/F and PCDD/F profiles were indicative of DecaBDE-containing materials and combustion sources, respectively. PBDFs, PCDFs and DL-PCBs were the most important dioxin-like toxic equivalent (TEQ) contributors. The estimated PCB and TEQ intake doses from dust ingestion approached or exceeded the reference doses for children living in some ELV-processing households, indicating potential health risk. More comprehensive risk assessment of the exposure to PCBs and DRCs is required for residents of informal ELV recycling sites.