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A three-dimensional hydrodynamic-ecological lake model combined with field measurements and sampling was applied to investigate the impacts of floating photovoltaic (PV) systems on hydrodynamics and water quality in a shallow tropical reservoir in Singapore. The model was validated using field data and subsequently applied to predict temperature and water quality changes for a hypothetical 42 ha placement of floating photovoltaic panels, covering about 30% of the water surface and capable of generating up to 50 MW of energy. The impact of the panel placement was studied numerically. The area of the reservoir where panels are placed experiences both light limiting and reduced wind stress conditions. The model indicated an average water temperature increase of 0.3 °C beneath the panels, consistent with the field observation from a 1 ha demonstration installation. Comparisons of model results between the uncovered and covered areas reveal greater stability of the water column (increase in Richardson number from 2.3 to 3.3) and reduction in mixing energy (from 9 × 10–7 to 7 × 10–7 W/kg) under the PV panels. Furthermore, the model predicted that chlorophyll a, total organic carbon and dissolved oxygen concentrations would decline by up to 30%, 15% and 50%, respectively, under the photovoltaic panels. Total nitrogen and total phosphorus, averaged over the water column, increased by 10% and 30%, respectively, under the panels. Distant from the floating solar panels, temperature, stability and water quality were unaffected.

Water Sensitive Urban Design (WSUD) features increasingly are used for urban water management, green urban design, and improved community liveability, but relatively less data are available on the ecosystem services that WSUD provides. We used hedonic pricing, supported by qualitative surveys, in Geelong, Australia and Singapore, to evaluate benefits related to large WSUD features. For both locations there was a significant (α=0.05) inverse relationship between sale price of a residence and distance to the WSUD features. Qualitative surveys corroborated the hedonic pricing analysis, as a majority of people appreciated benefits accrued from living near WSUD features.

The abilities of Long short-term memory (LSTM), Gated recurrent units (GRU), Adaptive-network-based fuzzy inference system (ANFIS), Artificial neural networks (ANN), and Group method of data handli...

This study applied the waterscapes framework to investigate the socio-political contestations associated with water use patterns and community–environment interactions in District 12, Ho Chi Minh City, Vietnam. In particular, groundwater resources were investigated via a mixed-method study combining water sampling, social surveys, a Groundwater Quality Index (GWQI), and GIS. In total, 33 groundwater samples were collected between June and August 2018, measuring pH, electrical conductivity, total dissolved solids, nitrite, nitrates, ammonia, sulfates, aluminum, iron, arsenic, and total coliform. An in-depth interview was conducted with a key stakeholder providing water service to the District, and 100 household surveys were administered via face-to-face interviews with community residents. Despite piped water availability throughout the district, we found that the community still utilizes groundwater for general domestic use. High concentrations of relevant pollutants were detected in the wells, substantially consistent with the respondents complains about the water smells and turbidity. The gastrointestinal disease was a known issue, yet less than a quarter of respondents associated these symptoms with the polluted water resources. Extensive groundwater use implies an economic artifact associated with the recent social experiences of the predominantly migrant worker community. Results from individual water quality measurements were incorporated into a GWQI following the Canadian Council of Ministers of the Environment approach. The calculated values were subsequently incorporated into GIS to visualize the spatial distributions of the groundwater quality across the study area, which were strongly associated with the results from the large-scale survey. The government of Vietnam has developed an official WQI guideline; however, it only addresses surface water with a different format than the GWQI applied in this study. Our GWQI henceforth contributed a prototype evaluation tool that could be applied in other urban areas of Vietnam to help assess groundwater resource health.

Background. In parts of Cambodia and in many other parts of the world, irrigation of rice with groundwater results in arsenic (As) accumulation in soil and rice, leading to health concerns associated with rice consumption. At times, some As is present as relatively nontoxic, non-regulated, dimethylarsinic acid (DMA). Low levels of zinc (Zn) have been found in rice from Bangladesh, Cambodia, and China where As levels in rice are high. Furthermore, there have been claims that Zn deficiency is responsible for stunting the growth of children in Cambodia and elsewhere, however in rural Asia, rice is the major source of Zn. Current data are inadequate for both Zn and DMA in Cambodian rice.Objectives. The present study aimed to provide a preliminary evaluation of the relationship between the content of Zn and DMA in rice grain in Preak Russey, an area with elevated levels of As in groundwater and to improve the management of Zn deficiency in rice.Methods. Rice agriculture was evaluated along the Mekong River in Cambodia. Analyses for metals, total As, and As species in rice and water were conducted by inductively coupled plasma mass spectrometry. Analysis of total Zn and As in soils and total Zn in rice were analyzed using X-ray fluorescence (XRF) spectrometry.Results. Rice in Preak Russey had Zn concentrations less than a third the level recommended by the United Nations World Food Programme. There was a significant (p < 0.05) negative correlation between the Zn content of rice and DMA in rice with the lowest Zn and highest DMA levels occurring near irrigation wells, the source of As.Conclusions. The highest levels of DMA in rice were associated with Zn deficiency in rice.Competing Interests. The authors declare no competing financial interests

This qualitative study examines the influence of teachers’ subject identities on how four secondary school teachers in Singapore conduct field-based enquiry about water quality in geography. Given ...

The exponential washoff model was originally developed based on observations of particulate pollutants, however, its applicability when applied to different forms of pollutants is not well understood. Data from a previous study of 6 stormwater pollutants from 126 events at 12 sites in Singapore was used for event based model parameter calibration using a Monte Carlo technique. The accuracy of the calibrated exponential washoff model was clearly best for particulate pollutant total suspended solids (TSS), and worst for dissolved pollutants Ortho-Phosphate (PO 4 ), nitrate (NO 3 ) and ammonium-nitrogen (NH 4 ). Model accuracy for mixed forms of pollutants total Phosphorus (TP) and total Nitrogen (TN) were in between these two extremes. Relationships between model parameters with rainfall and flow characteristics were also investigated. Statistically significant relationships could only be found for TSS, where the total rainfall depth was identified as being the most significant variable to explain model parameter behaviour. Antecedent dry period (ADP) was shown to have little or no importance across all land uses and pollutant forms. The results showed that the model parameter behaviour could be explained only for particulate pollutants and small (≤10 ha) sub-catchments, and that replicating washoff of mixed or dissolved forms of pollutants as a fraction of solids is likely to lead to misleading results.

This chapter shares efforts to conceptualize, develop, and implement two signature labs to support Humanities education in Singapore—the Historian’s Lab and the Sustainability Learning Lab. In particular, we focus on lessons learned in innovation (e.g., the necessity of creative and collaborative synergies among disciplinary experts, curriculum specialists, ICT designers, and teacher leaders, among others) and managing the challenges and constraints of educational innovation in a centralized, results-oriented system that at the same time continually encourages innovation.

Using a case study approach from past projects in Singapore, Australia, Cambodia, Thailand and Vietnam, we examine the benefits, but also some of the challenges, to implementing green space in urban design. Green space can have multiple physical and psychological wellbeing benefits, as well as environmental benefits, including urban runoff quantity and quality management, urban heat island abatement, air quality improvement, and noise reduction. Water sensitive urban design (WSUD) can be an important element of green space design and here we explore how modeling of ecosystem services and dynamic modeling of WSUD can help to facilitate sound planning and management decision making in support of green space implementation. As we illustrate with examples for Australia, Singapore and Cambodia, we believe that application of an urban ecosystem services modeling approach can elucidate environmental benefits of urban green space that otherwise may not be considered. Engineers may include dynamic modeling of WSUD in support of an urban master plan, or urban redevelopment, but generally urban planners are less conversant in applying models. We discuss some of the challenges to integrating multidisciplinary visioning and modeling of green space design and performance evaluation through our experience with a stormwater and wastewater design study for Cha Am, Thailand, that included landscape architecture and engineering classes at Thammasat University, Mahidol University, and AIT. Through a case study of Phnom Penh, we illustrate how modeling and 3D visualization can be used to effectively explore the benefits of green space. We conclude that a user-friendly decision support system is needed to integrate modeling and visualization tools and thereby bridge the gap between form and function in urban green space design.

For school geography in Singapore, geographical inquiry is identified as a “signature pedagogy” (Shulman 2005a) that can socialize students into the distinctive practices, concepts, and values of t...

Background. In parts of Cambodia, irrigation of rice with groundwater results in arsenic accumulation in soils and rice, leading to health concerns associated with rice consumption. In Bangladesh and China, low zinc levels in rice have been found in regions where arsenic levels in rice are high. Furthermore, there have been claims that zinc deficiency is responsible for stunting of children in Cambodia. There are limited data on zinc in Cambodian rice, but in rural Asia, rice is the major source of zinc. Objectives. To provide a preliminary evaluation of the zinc content in rice grain in Preak Russey, an area with elevated levels of arsenic. The importance of zinc in rice for infants was also assessed. Methods. Rice cultivation was evaluated in sixty farms along the Mekong River in Cambodia. Analyses for metals, total arsenic, and arsenic species in the water and rice were conducted at the University of Ottawa, Canada by inductively coupled plasma – mass spectrometry. Analysis of total zinc and arsenic in soils were analyzed in Phnom Penh using X-ray fluorescence spectrometry (XRF). Total zinc in rice was also measured by XRF analysis. Results. Rice in the Preak Russey area contained zinc with ½ to ¼ of the 1987 Codex standard for rice in Infant Formula. Moreover, our average zinc concentration in rice samples was less than a third that recommended for zinc fortification in rice by the United Nations World Food Programme. There was a significant (α=0.05) negative correlation between the arsenic and zinc content of rice with the lowest zinc levels occurring near the irrigation wells, the source of arsenic. There was a significantly higher content of zinc in rice from farms that fertilized with cow manure. Conclusions. Handheld XRF spectrometers are useful tools for detection of zinc levels in rice. The potential for zinc deficiency in farmers in areas of Cambodia with arsenic toxicity is high. Competing Interests. The authors declare no competing financial interests.

The drag coefficients of one mature Khaya Senegalensis tree and one Eugenia Grandis tree in Singapore were analysed using computational fluid dynamics (CFD) modelling and validated with field measurements. For the numerical method, an innovative laser scanning approach was used to generate the tree geometries and to calculate the three-dimensional (3D) leaf area density distribution within the canopies. The canopies were represented by multiple porous domains and the turbulent effect of leaves was simulated by source and sink terms as a function of the calculated leaf area density. Computational fluid dynamics analyses using ANSYS 17.2 software were carried out on both leafless and leafed tree models. Three turbulent models, the Realizable k-ε model, Transition Shear Stress Transport model and Reynolds Stress Model were compared, and it was found that the differences in the drag forces among the turbulent models were negligible when they were meshed appropriately based on the grid independence study. The computed drag coefficient of the Khaya Senegalensis tree and the Eugenia Grandis tree from CFD modelling were similar within the range between 0.6 and 0.7. From field monitoring including the wind velocity and stem strains, the drag coefficients of both trees were calculated to be 0.51 and 0.40. Possible reasons causing the difference and limitations of the numerical method are discussed. Accepted version

Too often, taxonomies treat cultural aspects of Ecosystem Services (ES) as a broadly labeled, residual category after accounting for other utilitarian benefits. Such an approach overlooks several important inter-relationships among the largely different integrated components of cultural ES, i.e. recreational, spiritual, education concerns, etc. In this paper, the need of more explicit typologies is underscored via a case study, where the authors represented the discrepancies between two tiers of Cultural ES: those associated with Spiritual Values and Recreational Opportunities using a socio-georaphically-based tri-indicator analytical framework. More specifically, two survey-based (Richness and Quality of ES), and one GIS-based (Willingness to Travel (WTT)) indices were proposed to evaluate a full range of cultural benefits derived from seven popular tourism sites of Ha Tien Town, Kien Giang, Vietnam. These numerical indicators pointed out the significant differences between ritual values and recreational based benefits, underlining the crucial need of fuller taxonomies of cultural services within the ES analytical framework. With respect to the study area, the measurements of Quality and Richness detected major synergies and tradeoffs among the evaluated benefits, supporting the need to balance management between developing tourism activities and preserving cultural identity of the landscapes. The last indicator, WTT utilizes map data from OpenStreetMap to produce an objective metric in evaluating landscape quality, taking into account the frequency and the potential costs in traveling to respective sites. This indicator constitutes a reliable and equitable method to represent relevant Cultural ES of landscapes besides the popular yet controversial money-based indices, e.g. Willingness to Pay or Willingness to Accept.

Ecosystem economic valuation has been proposed as an appropriate approach to account for natural resources. More specifically, the tangible and intangible values of ecosystem services (ES) associated with specific land uses/land covers have been appreciated by practitioners both in academia and policy arenas as useful accounting means for land use management. This paper explored how the outcomes from ecosystem valuation studies could be utilized to improve the current agricultural land pricing system in Vietnam's Mekong Delta. By reviewing the relevant legal documents, we highlighted some limitations of the current land pricing system and suggested reforms utilizing ES valuation results. By comparing the results of ES evaluation study for the prawn-rice rotational crops (PRRC) areas with their regulated agricultural land prices, one major limitation of the current pricing method was identified, that being its inability to capture the actual land profitability resulting from the classification system of lands which currently typifies PRRC areas as annual crops, similar to rice and vegetables. However, to register a dedicated classification for PRRC can be time consuming and costly due to the complexity of the relevant legal framework. As a response, an ES-based index to account for the differences between PRRC and other cultivation systems without having to thoroughly reform the legal system was recommended. Our recommendation is essentially in harmony with the Ministry of Environment and Natural Resources Decree, which allows for the application of correction factors according to local conditions. As a methodological contribution, this attempt to include ES information in legal systems could facilitate the better standardization of core terminologies and practical guidelines, two of the most important challenges to the mainstreaming of the ES concept in decision making and policy planning.

Background. Arsenic bioaccumulation in rice is a global concern affecting food security and public health. Objective. The present study examined arsenic species in rice in Cambodia to characterize health risks with rice consumption and to clarify uncertainties with Codex guidelines. Methods. The present study collected 61 well water samples, 105 rice samples, 70 soil samples, and conducted interviews with 44 families in Preak Russey near the Bassac River and Kandal Province along the Mekong River in Cambodia. Analyses of metals, total arsenic and arsenic species were conducted in laboratories in Canada, Cambodia and Singapore. Results. Unlike in Bangladesh, rice with the highest total arsenic concentrations in Cambodia contains mostly organic arsenic, dimethylarsinic acid (DMA), which is unregulated and much less toxic than inorganic arsenic. The present study found that storing surface runoff in ditches prior to irrigation can significantly reduce the arsenic concentration in rice. It is possible to remove > 95% of arsenic from groundwater prior to irrigation with natural reactions. Conclusions. The provision of high quality drinking water in 2015 to Preak Russey removed about 95% of the dietary inorganic arsenic exposure. The extremes in arsenic toxicity that are still obvious in these farmers should become less common. Rice from the site with the highest documented levels of arsenic in soils and water in Cambodia passes current Codex guidelines for arsenic. Informed Consent. Obtained Competing Interests. The authors declare no competing financial interests.

Ecosystem Services (ES), a pro-conservation paradigm often linked to a Western planning and development approach, has been applied in Asia but has yet to be mainstreamed by policy-makers and practitioners for decision-making within the region. In this chapter, we explore notable achievements, as well as barriers, to mainstreaming ES within the environmental public policies of Southeast Asia. A detailed case study examination of four Southeast Asian nations (Singapore, Thailand, Cambodia and Vietnam) revealed that inclusion, or even consideration, of ES in public policy has been uneven throughout the region, ranging from essentially no consideration to quite sophisticated ES policy underpinnings; and even within a country there can be considerable difference in ES uptake. In general, we conclude the concern that ES concepts are too western-centric have been overcome in Southeast Asia, although some barriers to the mainstreaming of ES into public policy still faces barriers. The principal barriers common across Thailand, Cambodia, and Vietnam are related to mandate and policy fragmentation and insufficient human and finance capacity. On the other hand, Singapore has successfully included ES concepts within it planning structure due to a number of factors, including a less fragmented policy-making approach, public-private partnerships and buy-in, and visionary leadership. Singapore’s economic status also provides some flexibility to ES policy implementation. Interestingly, however, Singapore has not relied on monetization approaches to support implementation of ES concepts. Finally, we recommend potential ways forward for the three not-yet-so-successful nations by highlighting the roles of academies, government, and major international agencies, (e.g. World Bank (WB), Asian Development Bank (ADB) or Japan International Cooperation Agency (JICA)) in furthering efforts to mainstream ES in policy-making.

Boeng Cheung Aek is a large peri-urban wetland in south Phnom Penh, Cambodia that provides multiple ecosystem services, but increasing urban development has initiated an ambitious program of in-filling. In an effort to demonstrate the importance of the wetland to city planners, we have undertaken this research to document and value the ecosystem services provided by Boeng Cheung Aek. Using a mixed method approach of geospatial technology, household surveys, market value, and avoided cost assessments, we determined the economic value for wastewater treatment, food, and water provisioning in the wetlands is $30.12 millionUSD per year, but with a range of $15.71-$48.96 million USD per year.

Cha am, a popular beach destination in Thailand, uses an aerated lagoon system with four ponds in series to treat its municipal wastewater. This study investig…

Background. Lead is a heavy metal that is well known to pose a threat to human health. Although the sale and use of lead paint has been banned in much of the developed world, lead is still commonly used in enamel paints in the developing world, including Cambodia. As Cambodia's economy grows, this may increase the purchase and use of lead-based paints, thus potentially exposing more of the population to the toxic effects of lead. Objective. This study was performed to evaluate the concentration of lead in enamel paints in Cambodia using a method that is quick, effective, and cost-efficient. Methods. A handheld X-ray fluorescence analyzer was used to evaluate 21 samples of enamel paint, including 8 replicates that were randomly purchased from three shops in Phnom Penh, Cambodia to evaluate the level of metals. All of the paint samples in the current study were manufactured in Thailand. Discussion. Ninety percent of the enamel paints sampled in Cambodia exceeded the voluntary standard of 100 μg/g lead of the producing country, Thailand. The mean and median levels for lead were 11,833 μg/g, and 4,961 μg/g, respectively. Conclusion. Based on our pilot-scale assessment, high levels of lead appear to be common in enamel paints in Cambodia, and a fuller assessment of the situation is warranted. Import and production of such toxic products should be avoided and appropriate labeling and public warnings should be provided.

Background. In parts of Cambodia, irrigation with groundwater results in arsenic accumulation in soils and rice, leading to health concerns associated with rice consumption. A high concentration of iron in groundwater can precipitate arsenic and reduce its bioavailability, however high concentrations of arsenic and iron can also reduce rice production. Furthermore, concerns have been raised about chemical contamination from inorganic fertilizers used to grow rice. The relationship between soil geochemistry and arsenic concentrations in rice is not yet fully understood. Objectives. The primary objective of this project was to investigate the relationship between arsenic concentrations in irrigation water, soil and rice collected from different sites in Cambodia. A secondary objective was to explore arsenic and phosphorus levels in fertilizer samples obtained from the study area in Cambodia. Methods. The present study collected 61 well water samples, 105 rice samples, 70 soil samples, 11 inorganic fertilizer samples and conducted interviews with 44 families along the Mekong River in Cambodia. Analyses for metals, total arsenic, and arsenic species in the water and rice were conducted in Canada by inductively coupled plasma mass spectrometry. Analyses for metals, total arsenic and phosphorus in soils and inorganic fertilizers were conducted in Cambodia and Singapore by X-ray fluorescence. Results. The concentration of arsenic in rice paddy soils was highly variable and as much as 20 times higher near the irrigation wells than in more distal areas of the paddy. Two farmers in Preak Russey had integrated soil samples with arsenic levels above the concentration associated with toxicity to rice in Taiwan (40 mg/kg) and above the Dutch concentration requiring intervention or remediation (55 mg/kg). The highest total arsenic measured in soil was 95 mg/kg. In Preak Russey, the loading of arsenic from irrigation water was 3710 times greater than the loading of arsenic from inorganic fertilizers. Half of the commercial inorganic fertilizers had less than 50% of the labelled content of phosphorus. Conclusions. Emphasis should be placed on improving the management of irrigation water, not on inactivation of arsenic in soil. The high levels of iron in groundwater mitigate arsenic toxicity, but the accumulation of iron could later result in lower rice productivity. Irrigation of rice with groundwater is not likely sustainable. To improve rice productivity, the content of phosphorus in local inorganic fertilizers must be improved to world standards. X-ray fluorescence analysis can quickly identify poor quality fertilizers. Informed Consent. Obtained Competing Interests. The authors declare no competing financial interests

Blow flies (Diptera: Calliphoridae) are carrion-breeding flies that are commonly used as evidence in forensic investigation. An adequate knowledge of ecological and geographical data of blow fly has a direct application in forensic science, as far as estimating time of colonization or corpse relocation. The aim of this study was to evaluate the occurrence of four species of Chrysomyinae (Chrysomya pinguis, Chrysomya chani, Chrysomya villeneuvi, and Ceylonomyia nigripes) across six land use types in central Chiang Mai, northern Thailand. Eighteen study sites were selected for sampling across three districts of Chiang Mai province (Mueang Chiang Mai, Mae Rim, and Hang Dong). Adult flies were collected every two weeks using a funnel trap baited with 1-day tainted beef offal. The predicted geographic distributions of forensically important blow fly species were modeled using the computer program ArcGIS, based on selected climatic variables (temperature, relative humidity, and light intensity) recorded at study sites. During the study period, 1298 adult flies were collected, with peak fly occurrence during summer (April&ndash, May). Seasonal fluctuation patterns varied depending on fly species. Climatic factors displayed diverse impact on associated fly populations. Identified species were restricted mainly to mixed deciduous forests (MDF) especially in the mountainous area. None of these flies were trapped in an urban area.

Sediment deposited within open sewers of Phnom Penh and the natural wetland that treats the waste was sampled and analyzed by X-ray fluorescence (XRF). Mean levels of Pb, Zn (P 0.2), and Mn was greater (P

School geography curricula have been evolving in keeping abreast with the issues that affect humankind in a fast-changing world. Key elements of this evolution include increased focus on topics such as environmental change and globalisation. Furthermore, there is a more explicit articulation on the modes of instruction in curricula documents, often expounding the virtues of technology and field-based learning. This has resulted in a proliferation of ideas in response to a rising demand to prepare teachers to conduct fieldwork and to design technology-enabled lessons. What is intuitive but often ignored is that while the context of learning has been transplanted from the traditional classrooms into new spaces—the field and cyberspace—that the teaching and learning of geography exist within the framework of formal curriculum, in as far as teacher taught activities are concerned. This book provides a collection of critical pieces that support the idea that good teaching and learning of geography in fieldwork and using technology should consider the dimensions of curriculum design, instructional design and resource provision, as well as assessment for such learning activities. Further, the book is organised to clearly describe the thinking, experiences and critical comments to two broad areas of learning outside the traditional classroom—the field and technology.

Unsaturated soil mechanics has become the solution to many geotechnical challenges, including slope stability and tree stability. Compared to saturated soil, the additional cohesion from the matric suction strengthens the unsaturated soil. Slope stability problems could be analyzed using two-dimensional software such as GeoStudio by assuming soil under plane strain or plane stress condition. However, two-dimensional modelling may not be appropriate for complex analyses such as tree stability problems that involve soil-structure interaction. Such assumptions may lead to model inaccuracy since structural behaviour is three-dimensional. Unfortunately, software for three-dimensional analyses that could handle unsaturated soils is not readily available. In this study, a method for three-dimensional seepage and deformation analyses in unsaturated soils was done using ANSYS, incorporating the unsaturated soil shear strength, the permeability and the elastic modulus as functions of the net normal stress and the matric function. The results from two-dimensional GeoStudio and ANSYS analyses were compared to validate the method.

The chapter provides a summary of the various perspectives presented in this edited book volume and provides some additional concluding thoughts. The theoretical perspectives and contemporary issues and research on the topics of teaching and learning using ICT will be reiterated and explored further in the context of NIE and Singapore. There are also several chapters in the book that describe the advantages of integrating the two approaches for teaching and learning geography. The concluding chapter will end off with a critical commentary and some recommendations on the ways that teaching and learning beyond the traditional classroom can be conducted.

Aims: A personal computer version of the Stormwater Management Model (PCSWMM) was applied to seamlessly link urban runoff, sanitary flow, pump station operations, and a natural wastewater treatment wetland in Phnom Penh, Cambodia, as a step towards developing a planning tool that could be used to explore urban development or climate change scenarios. Study Design: PCSWMM was calibrated with measured flow and water quality data and used to estimate total phosphorus, total nitrogen, detergents, and E. coli levels at the outlet of the wastewater treatment wetland for the period May 15 to July 1, 2011. Place and Duration of Study: Phnom Penh, Cambodia; January, 2011 to March, 2012. Methodology: In support of model development, a limited water quality sampling program and bathymetric survey were conducted for the sewer and wetland system in both the dry and rainy seasons, 2011. Samples were analyzed for total nitrogen, total phosphorus, detergents, and E. coli. Sewer flow was measured continuously at 5 minute intervals to determine sanitary flow characteristics as input to the model and pump operation rules were determined through interviews with the pump operators and analysis of their data log books. Results: Consistent with past studies, the sampling showed that the wetland was effective in treating municipal waste, particularly with respect to E. coli (99% reduction from sewage inputs) Original Research Article Sovann et al.; BJECC, 5(2): 104-115, 2015; Article no.BJECC.2015.009 105 and detergents (86% reduction from sewage inputs). A lower treatment efficiency was observed for total phosphorus, at around 31%, while the treatment efficiency for total nitrogen was around 71%. The wetland was divided into four zones and PCSWMM was run in continuous mode for the period May 2-July 1, 2011. The mean levels of E. coli, detergents, total phosphorus, and total nitrogen estimated by the model for that time period compared favorably with sample results from the field campaign in August, 2011. Conclusion: The naturally-occurring wetland treatment system in Phnom Penh is effective and fits well with the concepts of green infrastructure and eco-cities. PCSWMM is a useful decisionsupport and planning tool to explore various development and climate change scenarios in Phnom

Aims: In recent decades, Ho Chi Minh City, Vietnam, frequently has been affected by local floods and inundation from heavy rainfall. Conventional flood mitigation measures such as building flood gates and upgrading sewerage systems have been implemented but problems persist. The objective of this research is to assess another approach for flood control measures, namely Sustainable Urban Drainage Systems (SUDS), with application to the Nhieu Loc Thi Nghe Basin, located in the central part of Ho Chi Minh City. Methodology: A combination of the Stormwater Management Model (PCSWMM) and interviews with 140 households was used to assess the efficacy and acceptability of four of the most popular SUDS: Rainwater harvesting, green roofs, urban green space and pervious pavement. Thirteen SUDS and urban build-out scenarios were simulated under 6 design storm conditions. Results: PCSWMM results showed that inundation from intense rainfall could be reduced with proper land-use control, specifically by maintaining imperviousness at 65% or less of the surface Original Research Article Loc et al.; BJECC, 5(2): 91-103, 2015; Article no.BJECC.2015.008 92 area. With respect to SUDS performance, green roofs were best at reducing peak runoff (22% reduction), followed by pervious pavement, urban green space, and rainwater harvesting systems. Regarding environmental improvements, as represented by reduction in total suspended solids load, urban green space was best with 20% of the solids load removed compared to the base case scenario, followed by green roofs, pervious pavement, and rainwater harvesting. The household interviews revealed the majority of people preferred pervious pavement to the other SUDS options and the least preferred option was green roof technology. Conclusion: Considering the combination of water quantity and water quality controls, it seems that green roof technology was the best performer for this area of Ho Chi Minh City, followed by urban green space, pervious pavement and rainwater harvesting. However, green roof technology also was the least favored option for the public and stakeholder acceptance will impact SUDS implementation.

The objectives of this study were twofold: (i) assess the bioaccumulation characteristics of a suite of metals associated with several different species of Odonata and (ii) examine Odonata species richness as a reflection of ecosystem health in two ecologically important wetlands of southwestern Iran, the Shadegan and Hawr Al Azim wetlands. Levels of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), lead (Pb), and zinc (Zn) were determined using inductively coupled plasma optical emission spectrometry (ICP-OES) in nine different Odonata larva species. Based on these data, biota-sediment accumulation factors (BSAFs) were calculated and generally, it was found that Cr, Cu, Mn, and Zn were being taken up by the Odonata (BSAFs >1). Because of its prevalence in the wetland and its observed ability to take up metals, it is suggested that Ischnura ramburii is an appropriate indicator of ecosystem health for these wetlands with respect to metal contamination. Odonata species richness across all sites was 49, while for the individual sites, the greatest species richness was 26 and the lowest species richness was 13. The species richness value across all sites is quite healthy, given the arid climate of the region.

Understanding how medically important flies respond to abiotic factor changes is necessary for predicting their population dynamics. In this study, we investigated the geographical distribution of the medically important blowfly, Achoetandrus rufifacies (Macquart) (Diptera: Calliphoridae), and ascertained the response to climatic and physio-environmental factors in Chiang Mai, northern Thailand. Adult fly surveys were carried out every 2 weeks from May 2009 to May 2010 at 18 systematically randomized study sites in three districts of Chiang Mai province (Mueang Chiang Mai, Mae Rim, and Hang Dong), using reconstructable funnel traps with 1-day tainted beef offal as bait. During the study period, 8,861 adult A. rufifacies were captured, with peak densities being observed at the end of winter (i.e., late February) and throughout most of the summer (May to March). Population density had a weak but significant (α = 0.05) positive correlation with temperature (r = 0.329) and light intensity (r = 0.231), and a weak but significant (α = 0.05) negative correlation with relative humidity (r = -0.236). From the six ecological land use types (disturbed mixed deciduous forest, mixed deciduous forest, mixed orchard, lowland village, city town, and paddy field), greater fly densities were observed generally in the disturbed mixed deciduous forest and lowland village, but not in the paddy fields. In conclusion, A. rufifacies are abundant from the end of winter and throughout most of the summer in northern Thailand, with population density being weakly positively correlated with temperature and light intensity, but weakly negatively correlated with relative humidity. The greatest densities of this fly species were collected in disturbed mixed deciduous forest and lowland village land uses. The prediction of annual and season specific distributions of A. rufifacies were provided in each season and all-year patterns using a co-kriging approach (ArcGIS9.2).

An approach to model the effect of weather conditions on tree stability is presented, where the weather conditions include wind, rainfall, temperature, humidity and solar radiation. The weather conditions could affect the rainwater infiltration and evapotranspiration, hence change the water content in the soil and influence the soil properties such as stiffness and strength when resisting the wind drags on the tree. One-dimensional (1D) modelling in GeoStudio 2012 was used to analyse the pore-water pressure head distribution in soil under the recorded weather conditions for 20 days. Three-dimensional (3D) modelling in ANSYS 19.1 was then used to analyse the leans of one Eugenia Grandis tree deformed by wind drags in Singapore during the 20 days. The soil modulus and soil strength were considered as functions of the water content in the soil, which were computed from VADOSE modelling in GeoStudio 2012 under the real time weather conditions measured from the field instrumentations. Moreover, the wind drags were calculated from a previous study that analysed the drag coefficient on the same Eugenia Grandis tree. The leans of the Eugenia Grandis tree under wind drags during the studied period were computed by incorporating the change in soil stiffness and soil strength due to the change in water content of the soil. The computed tree leans from the analyses increased by 16.5% when the soil strength and soil modulus changed with water content of the soil as compared to the computed tree leans without the incorporation of the changes in soil strength as an effect of weather conditions and assuming a constant soil modulus of 20 MPa. It is suggested that effect of weather conditions on soil should be considered in the analyses related to tree deformations. Nanyang Technological University National Parks Board Accepted version This study was supported by Nanyang Environment and Water Research Institute (NEWRI), Interdisciplinary Graduate School, Nanyang Technological University, as well as National Parks Board, Singapore.

Aims: In February and March 2014, more than 300,000 households were affected by water rationing in Kuala Lumpur, Malaysia and the surrounding State of Selangor. Further south, reservoir levels in Singapore were dropping, prompting the government to raise the water conservation rhetoric, but falling short of implementing water rationing schemes. The region experienced a dry spell that was unprecedented in the last 30 years. Preparedness for storms has been the "talk of the town" since the 2001, 2006 and 2007 extreme high precipitation events in the southern parts of the peninsula and in Singapore resulted in costly flood damage. While resilience has been a concept used frequently in climate change adaptation, it is derived from ecology, where it refers to the capacity of the system to respond to a disturbance and resist the impact or recover from the damage of the disturbance. This paper examines the case of Singapore as an urban area in responding to a similar extreme hydrologic phenomenon by examining the climate Original Research Article British Journal of Environment & Climate Change, 4(3): 328-354, 2014 329 change resilience of the small city-state, with a view to recommending some considerations in designing climate change adaptation strategies. Place of Study: Singapore and peninsular Malaysia. Methodology: The paper reviews the rainfall extremes statistics covering the last 30 years for Singapore and then takes a hydrologic event-based case study approach to more closely examine the impact of record storms and the drought of March 2014 to discuss aspects of resilience that can serve as lessons for tropical cities in future adaptation to a climate-changing world. Results: Extreme rainfall events have become more frequent in Singapore over the past 30 years, while February, 2014 was the driest February since 1869. February, 2014 also had the lowest recorded daily relative humidity at 74.5%. Tropical cyclones are not expected to hit Singapore because of its location near the equator, yet Typhoon Vamei made history by delivering 210 mm of rain on 27 December, 2001. Between 19 and 20 December, 2007 Singapore received 366 mm of rain and within the same week another storm deposited 140 mm of rain in a 24 hour period. While there were some environmental and health impacts related to the February 2014 drought, including low dissolved oxygen levels in water and a localized fish kill, as well as reports of greater human respiratory problems, Singapore was able to weather the drought by requesting voluntary conservation measures, prudent reservoir management, and increasing the output of NEWater and desalinized water. Recent extreme rainfall events have produced localized flooding, but Singapore has progressively pursued a program of improved drainage, stream naturalization, and implementation of Low Impact Development (LID) technology to reduce flood-prone areas from 3,200 ha in the 1970’s to 36 ha today. Conclusion: We do not suggest that all countries need to have NEWater or desalinated water to solve drought problems. We do suggest that in managing rainfall related hazards, droughts and extremes have been treated rather independently. Based on the case study of extremes presented for Singapore we propose the importance of establishing a three-step preparedness program for extremes that includes Preparation (vulnerability and risk identification, adaptive capacity building, and monitoring), Response (information dissemination and relief action), and Recovery.

This study investigated the spatial and temporal variations in dissolved oxygen (DO) in the Cha-Am wastewater treatment ponds to assess treatment dynamics and …

Water quality around Cha-Am, Thailand is of prime concern because of its extensive oceanfront beach area. Cha-Am uses an aerated lagoon system consisting of th…

Background. The existence of lead-contaminated consumer products is a global issue. Toys and low-cost jewelry may contain toxic metals and Cambodia is known to have consumer products with toxic metals. Objectives. It is important to inform Cambodians about sources of toxic metals so that they can reduce their exposure risk, particularly for children. Methods. Student volunteers purchased, or brought from home, low-cost jewelry and toys to either the University of Health Science or a Don Bosco Institute in Phnom Penh, Cambodia, where they were analyzed using X-ray fluorescence (XRF). The initial analysis was performed in 2011. A subset of the 2011 samples was re-analyzed in 2015 using new preparation techniques and a new x-ray fluorescence (XRF) unit. Discussion. The analysis of low-cost jewelry in Phnom Penh in 2015 indicated that lead in jewelry clasps is a more serious health concern than was first perceived in 2011. Mercury, nickel, cadmium and copper were also found in toys, and occasionally these toys had been produced by well-known companies. Sources of jewelry production of samples in the present study are unknown. Lead in clasps in low-cost jewelry appeared to be the greatest risk to children in our sampling. Conclusion. One-third of toys and low-cost jewelry exceeded the United States and European Union guidelines for heavy metals. XRF analysis allows for rapid screening of lead and other toxic metals and could be used to reduce the sales of low-cost jewelry and toys containing toxic metals.

Washoff behavior in the tropics is expected to behave differently from temperate areas due to differences in rainfall characteristics. In this study, rainfall, runoff and total suspended solids (TSS) were monitored from 9 catchments distinguished by different types of land use, in Singapore. The catchments ranged in size from 5.7ha to 85.2ha. Over 120 rain events were studied and more than 1000 storm samples were collected and analyzed. Monte Carlo analysis was applied to obtain the best fit values of the washoff model parameters consisting the washoff coefficient c3, washoff exponent c4 and initial mass on surface Bini. The exponent c4 was found to be approximately unity for all the events monitored, in agreement with other studies. The values of c3 and Bini were found to vary between events. Among all the rainfall and runoff characteristics studied, rainfall depth of the current event (d) was found to be the single parameter that significantly influenced the values of c3 and Bini. Contrary to expectations, Bini did not correlate well with antecedent dry period or with rainfall depth of the prior storm event. The results show that the common modeling practice where Bini is assumed to vary with antecedent dry period and previous rainfall depth should be reassessed when applied to catchments in the tropics. ANCOVA analysis showed that land use was not significant, but rather the variation of c3 and Bini with d was found to correlate well with the catchment area.

Background. A well-documented source of mercury contamination is skin-whitening cream. The heavy metal is sometimes added to the cream to block production of melanin. Past studies have shown that about one third of skin whitening creams for sale in Phnom Penh contained mercury levels considerably higher than both United States and Association of Southeast Asian Nations (ASEAN) guidelines. Developing nations such as Cambodia do not have the resources for monitoring and enforcement. Objectives. Evaluate the utility of handheld X-ray fluorescence analyzers for detection of mercury in skin-whiteners. Methods. A handheld XRF unit was used to measure the total mercury content of 676 skin-whitening creams collected from volunteers from a cross-section of Phnom Penh's residents. Results. About 16% of bleaching creams collected contained more than 20 ug/g of mercury. The highest concentration was about 35,000 ug/g. A third of the samples that were custom-made or modified by beauty shops contained more than 20 ug/g of mercury. Conclusions. The handheld XRF analyzer proved an excellent tool for screening mercury in skin creams, and could be particularly useful in developing countries because it is relatively inexpensive, requires no sample preparation or extraction, can be used by staff with little technical background, and can facilitate on-site education.