Carbendazim sorption-desorption in Vietnamese soils

Four Vietnamese soils (denoted AG, CT, ST and TG) which differed with respect to pH (pH 2.9-5.4), clay (17-50%) and organic matter (0.3-9.8%) content, were selected for sorption and desorption studies of carbendazim using the batch equilibration technique. Sorption increased with increasing organic carbon (OC) and clay content. Kd values for carbendazim sorption on AG, CT, ST, TG soils at initial concentration of 20 microg/g were 12.5, 127, 8.1 and 9.6 ml/g, respectively. The OC partition coefficients (Koc) for AG, CT, ST and TG were 1140, 1300, 2700 and 960 ml/g, respectively. Carbendazim was strongly sorbed and the binding was less reversible in the acid sulfate soil (CT), than in the other soils. The CT soil had both the highest OC content (9.8%) and the highest clay content (49.8%). The influence of pH on carbendazim sorption was studied in the ST and CT soils. Sorption of carbendazim by the sandy ST soil (OC 0.3%; clay content 26.3%) increased as the pH decreased, while sorption of carbendazim by the CT soil decreased as pH decreased.     

Optimal Control Models and Elicitation of Attitudes towards Climate Damages

This paper examines the consequences of various attitudes towards climate damages through a family of stochastic optimal control models (RESPONSE): cost-efficiency for a given temperature ceiling; cost-benefit analysis with a pure preference for current climate regime and full cost-benefit analysis. The choice of a given proxy of climate change risks is actually more than a technical option. It is essentially motivated by the degree of distrust regarding the legitimacy of an assessment of climate damages and the possibility of providing in due time reliable and non controversial estimates. Our results demonstrate that (a) for early decades abatement, the difference between various decision-making frameworks appears to matter less than the difference between stochastic and non stochastic approach given the cascade of uncertainty from emissions to damages; (b) in a stochastic approach, the possibility of non-catastrophic singularities in the damage function is sufficient to significantly increase earlier optimal abatements; (c) a window of opportunity for action exists up to 2040: abatements further delayed may induce significant regret in case of bad news about climate response or singularities in damages.     

Performance of RBC coupled to a polyurethane foam to biodegrade petroleum refinery wastewater

Biological treatment of petroleum refinery wastewater was studied in a rotating biological contactor (RBC) coupled to a polyurethane foam (PUF) as a porous biomass support. The PUF was attached on both sides of biodisks. The biodegradation studies were carried out at varying hydraulic and organic loadings. COD removal efficiency of up to 87% was achieved. The results obtained in terms of biodegradation of COD, NH3-N, phenol, hydrocarbons and suspended solids in this study were compared with those in the literature. The RBC-PUF bioreactor was found to have a better performance than a conventional RBC for the biodegradation of the above mentioned parameters. A higher concentration of active biomass (77 g TVS/m2) was observed in the RBC-PUF as compared to other treatment systems. A linear relationship between COD applied and COD removed was observed for the combined four stage system as well as for the individual stages.     

Removal of arsenic (V) from aqueous medium using manganese oxide coated lignocellulose/silica adsorbents

Arsenic (V) adsorption on manganese oxide coated rice wastes was investigated in this study. The modified adsorbents were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and pH measurements to determine the point of zero charge. Batch adsorption equilibrium experiments were conducted to study the effects of pH, contact time, and initial concentration on arsenic removal efficiency. The adsorption capacity of rice waste was significantly improved after modification with permanganate. The Langmuir isotherm model fitted the equilibrium data better than the Freundlich model which confirms surface homogeneity of the adsorbent. Maxima adsorption capacities are determined as 10 and 12 mg/g at pH 3 for manganese oxide coated rice husk and straw, respectively. The adsorption energy indicates that the adsorption process may be dominated by chemisorption. Pseudo-second-order rate equation described the kinetics sorption of arsenic with good correlation coefficients, better than a pseudo-first-order equation. Manganese oxide coated rice husk and straw appear to be promising low cost adsorbents for removing arsenic from water.     

Modelling nature-like fishway flow around unsubmerged obstacles using a 2D shallow water model

In the scope to create efficient nature like fish ramps using large-scale roughness elements, the present study is an audit of modelling such complex 3D free surface flows using an industrial 2D code solving shallow water equations. Validation procedure is based upon the comparison between numerous experimental measurements and numerical runs around large-scale roughness patterns disposed on the flume bottom in order to determine what 2D reliable numerical results can be expected. In this paper, we focused on cases of unsubmerged obstacles. The results demonstrate that 2D shallow water modelling using an industrial code such as TELEMAC-2D can be a convenient way for the hydraulic engineer to help design a nature-like fishway. This article emphasizes the limitations due to 2D depth integration of velocities and turbulence modelling and gives the domain of validity of the method.     

Towards an integrated approach of disaster and environment management: A case study of Thua Thien Hue province,central Viet Nam

Disasters and environmental degradation create serious problems all around the world. They are inherently linked, but little attention is paid to their interaction, particularly at local levels. The degree of integration of disaster management and risk analysis with environmental management programs in relation to human vulnerability has been examined in Thua Thien Hue Province, Central Viet Nam. Unsustainable agricultural practices, and inappropriate development programs have contributed substantially to the increase of disaster risks. On the other hand, disasters damage natural resources and reduce environmental quality, indirectly contributing to increasing poverty which in turn, adds to the vulnerability of both natural and human systems, so further increasing disaster losses. Notwithstanding, in Viet Nam, there is a big gap between disaster and environment management policies and programs. In order to bridge the gap, an integrated approach in which environment-disaster linkage, rural—urban linkage, and poverty are brought into focus as core aspects of disaster management.     

Design of a Domain Specific Language for modelling processes in landscapes

The modelling of processes that occur in landscapes is often confronted to issues related to the representation of space and the difficulty of properly handling time and multiple scales. In order to investigate these issues, a flexible modelling environment is required. We propose to develop such a tool based on a Domain Specific Language (DSL) that capitalises on the service-oriented architecture (SOA) paradigm. The modelling framework around the DSL is composed of a model building environment, a code generator and compiler, and a program execution platform. The DSL introduces five language elements (entity, service, relation, scenario and datafacer) that can be combined to offer a wide range of possibilities for modelling in space and time at different scales. When developing a model, model parts are either built using the DSL or taken from libraries of previously built ones, and adapted to the specific model. The practical usage of the DSL is illustrated first with the Lotka–Volterra model, and then with a landscape modelling experiment on the spread of a mosquito-borne disease in the Sahelian region of West Africa. An interesting characteristic of this approach is the possibility of adding new elements into an existing model, and replacing others with more appropriate ones, thus allowing potentially complex models to be built from simpler parts.     

Plant extract-mediated synthesis of aluminum oxide nanoparticles for water treatment and biomedical applications: a review

Environmental Chemistry Letters - Nanotechnologies have contributed to disease control and prevention, but conventional synthesis of nanoparticles rarely meets the strict requirements of green...     

Removal of metronidazole and amoxicillin mixtures by UV/TiO2 photocatalysis: an insight into degradation pathways and performance improvement

Environmental Science and Pollution Research - The degradation efficiencies and pathways of metronidazole (MNZ) and amoxicillin (AMX) in binary mixtures by UV/TiO2 photocatalysis were studied. The...     

Potential health risks of toxic heavy metals and nitrate via commonly consumed bivalve and vegetable species in Ho Chi Minh City,Vietnam

Environmental Science and Pollution Research - This study aimed to evaluate the health risks of cadmium (Cd), lead (Pb), inorganic arsenic (As), and nitrate exposure through the consumption of...