Development of nutrient cycle through agricultural activities of a rural area in the North of Vietnam

Material flow analysis (MFA) has been applied to assess the environmental impact of human activities on nutrient flows at the commune scale. This paper reports the assessment of human excreta and animal manure as a nutrient source for paddy fields and fishponds in Hoang Tay commune, Ha Nam province, Vietnam. The quality of MFA model was confirmed through modified uncertainty analysis, then was used to originally quantify and visualize the interlinks of livestock with the environmental sanitation and agricultural system in terms of nutrients. Currently, half of the pig manure was collected to the biogas, and the remainders were freely discharged to the commune’s drainage system (25%) or directly reused in the paddy fields (25%). While wastewater in the drainage system was the biggest source of nitrogen (contributed 46%), paddy field was the biggest source of phosphorous (contributed 55%) discharged to the Nhue River, totaling 57 ± 9 ton N and 29 ± 6 ton P, annually. Consequently, mitigation measures for nutrient resource management were proposed, and reducing half of chemical fertilizers applied and reusing all excreta and manure in the paddy fields were the most effective option.     

Coral reef aerosol emissions in response to irradiance stress in the Great Barrier Reef,Australia

We investigate the correlation between stress-related compounds produced by corals of the Great Barrier Reef (GBR) and local atmospheric properties—an issue that goes to the core of the coral ecosystem’s ability to survive climate change. We relate the variability in a satellite decadal time series of fine-mode aerosol optical depth (AOD) to a coral stress metric, formulated as a function of irradiance, water clarity, and tide, at Heron Island in the southern GBR. We found that AOD was correlated with the coral stress metric, and the correlation increased at low wind speeds, when horizontal advection of air masses was low and the production of non-biogenic aerosols was minimal. We posit that coral reefs may be able to protect themselves from irradiance stress during calm weather by affecting the optical properties of the atmosphere and local incident solar radiation.     

The evolving local social contract for managing climate and disaster risk in Vietnam

How do disasters shape local government legitimacy in relation to managing climate‐ and disaster‐related risks? This paper looks at how local authorities in Central Vietnam perceive their social contract for risk reduction, including the partial merging of responsibilities for disaster risk management with new plans for and investments in climate change adaptation and broader socioeconomic development. The findings indicate that extreme floods and storms constitute critical junctures that stimulate genuine institutional change. Local officials are proud of their strengthened role in disaster response and they are eager to boost investment in infrastructure. They have struggled to reinforce their legitimacy among their constituents, but given the shifting roles of the state, private sector, and civil society, and the undiminished emphasis on high‐risk development models, their responsibilities for responding to emerging climate change scenarios are increasingly nebulous. The past basis for legitimacy is no longer valid, but tomorrow's social contract is not yet defined.     

Recycling nickel from spent catalyst of Phu My fertilizer plant as a precursor for exhaust gas treatment catalysts preparation

In this study, a very promising way of treating and recycling spent nickel catalysts of fertilizer plants in Vietnam was proposed. Firstly, nickel was recovered from spent catalyst using HNO₃—leaching process. Results show that nickel recovery of over 90% with a purity of over 90% can be achieved with HNO₃ 2.1–2.5 M at 100?°C in 75 min. The residue after leaching is not considered as a hazardous waste according to the Vietnamese regulations. Then, the leachate solution was used as a precursor to prepare a model catalyst for exhaust gas (CO, HC, NO_x) treatment. In comparison with the catalyst prepared from the commercial nickel nitrate solution, the catalyst synthesized from recovered nickel exhibits similar properties and activities. The influence of Ni loading of Ni/alumina catalyst as well as the modification of active phase by some metals addition (Mn, Ba, Ce) was also investigated. It is feasible to modify active phase by transition metals such as Mn, Ba, and Ce for complete oxidation of CO and HC at 270?°C and a reduction of NO_x below 350?°C at high volumetric flow condition (GHSV?=?110.000 h^?1).     

Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam

This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam. Arsenic levels in groundwater ranged from <1.8 to 486 μg/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 μg/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 μg/week/kg body wt.) by FAO/WHO for 92% of the residents examined. Inorganic As and its metabolite (monomethylarsonic acid and dimethylarsinic acid) concentrations in human urine were positively correlated with estimated inorganic As intake. These results suggest that residents in these areas are exposed to As through consumption of groundwater and rice, and potential health risk of As is of great concern for these people. Urinary concentration ratios of dimethylarsinic acid to monomethylarsonic acid in children were higher than those in adults, especially among men, indicating greater As methylation capacity in children.     

Environmental Integrated Assessment via Monte Carlo Simulation with a Case Study of the Mid-Atlantic Region,USA

Environmental integrated assessments are often carried out via the aggregation of a set of environmental indicators. Aggregated indices derived from the same data set can differ substantially depending upon how the indicators are weighted and aggregated, which is often a subjective matter. This article presents a method of generating aggregated environmental indices in an objective manner via Monte Carlo simulation. Rankings derived from the aggregated indices within and between three Monte Carlo simulations were used to evaluate the overall environmental condition of the study area. Other insights, such as the distribution of good or bad values of indicators at a watershed and/or a subregion, were observed in the study.     

Indoor air pollution levels in public buildings in Thailand and exposure assessment

Levels of pollutants including PM2.5 and PM2.5 composition (black carbon and water soluble ions), SO(2), NO(2), CO, CO(2), and BTEX (benzene, toluene, ethylbenzene, xylene) were monitored for indoor and outdoor air at a university campus and a shopping center, both located in the Northern suburb of Bangkok. Sampling was done during December 2005-February 2006 on both weekdays and weekends. At the university, indoor monitoring was done in two different air conditioned classrooms which shows the I/O ratios for all pollutants to be below 0.5-0.8 during the weekends. However, on weekdays the ratios for CO(2) and most detected BTEX were above 1.0. The concept of classroom occupancy was defined using a function of the student number in a lecture hour and the number of lecture hours per day. Classroom 2, which had a higher occupancy than classroom 1, was characterized by higher concentrations of most pollutants. PM2.5 was an exception and was higher in classroom 1 (37 microg/m(3), weekdays) as compared to classroom 2 (26 microg/m(3), weekdays) which was likely linked to the dust resuspension from the carpeted floor in the former. Monitoring was also done in the shopping mall at three different sites. Indoor pollutants levels and the I/O ratios at the shopping mall were higher than at the university. Levels of all pollutants measured at the car park, except for toluene and CO(2), were the highest. I/O ratios of the pollutants at the mall were above 1.0, which indicates the relatively higher influence of the indoor sources. However, the black carbon content in PM2.5 outdoor is higher than indoor, which suggest the important contribution from outdoor combustion sources such as the traffic. Major sources of outdoor air pollution in the areas were briefly discussed. Exposure modeling was applied using the time activity and measured pollutant concentrations to assess the exposure of different groups of people in the study areas. High exposure to PM2.5, especially for the people working in the mall, should be of health effect concern.     

Reproductive biology of a deep-sea brittle star Amphiura carchara (Echinodermata: Ophiuroidea)

 New information on the brooding reproduction of Amphiura carchara, and previous studies of several deep-sea congeners, contradict the prevailing notion that direct development is exceptional among deep-sea echinoderms. Over 500 specimens of A. carchara from 2,850 to 4,100-m depths off the coast of California, USA, were studied. The species was found to be gonochoric, although most brooding species of ophiuroids are hermaphroditic. Females each brooded up to 72 embryos at a time, with up to 10 in a single bursa. The embryos of individual adults were often at different stages of development, but those brooded in a single bursa tended to be at the same stage. Thus, the species has characteristics that breach the distinctions between sequential and simultaneous brooding exhibited by shallow-water ophiuroids. The embryos developed from yolky eggs that are large for an ophiuroid, with the mean largest oocytes 0.45 mm, and ranging to 1.28 mm in diameter. Almost all late-stage embryos were positioned with their mouth and arms pressed against the wall of the bursa, possibly to facilitate the uptake of nutrients from the parent. Thus, A. carchara may be matrotrophic. The largest embryos examined had a rudimentary disk skeleton, and arms with four joints and a terminal plate. Emerging juveniles probably differ in disk diameter. The species appears to brood year round, although differences in gonad size, the incidence of brooding, and the relative numbers of early developmental stages in summer and winter samples indicated that there are seasonal trends in reproduction. Received: 14 February 2000 / Accepted: 3 July 2000     

Nanotechnology for improved production of algal biofuels: a review

Environmental Chemistry Letters - Fossil fuel depletion and carbon dioxide emissions are calling for carbon neutral energies such as algal biofuels, yet actual production of agal biofuels is...