Contaminant transport modeling in marine clays

Rajasekaran, G.; Murali, K.; Nagan, S.; Amoudhavally, V.; Santhaswaruban, V.

doi:10.1016/j.oceaneng.2004.06.010

Cited by 14 publications

(6 citation statements)

References 13 publications

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“…Coastal and estuarine areas are the ultimate recipients of both natural and anthropogenic inputs, including pesticides and organic matter from continental ecosystems and rivers (Mitra and Zaman, 2016;Rajasekaran et al, 2005). Terrestrial organic matter inputs (namely allochthonous), composed of particulate (>0.45 μm) and dissolved matter (<0.45 μm), favour biological production.…”

Section: Introductionmentioning

confidence: 99%

The influence of natural dissolved organic matter on herbicide toxicity to marine microalgae is species-dependent

Coquillé

Ménard²,

Rouxel³

et al. 2018

Aquatic Toxicology

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Microalgae, which are the foundation of aquatic food webs, may be the indirect target of herbicides used for agricultural and urban applications. Microalgae also interact with other compounds from their environment, such as natural dissolved organic matter (DOM), which can itself interact with herbicides. This study aimed to evaluate the influence of natural DOM on the toxicity of three herbicides (diuron, irgarol and S-metolachlor), singly and in ternary mixtures, to two marine microalgae, Chaetoceros calcitrans and Tetraselmis suecica, in monospecific, non-axenic cultures. Effects on growth, photosynthetic efficiency (Ф') and relative lipid content were evaluated. The chemical environment (herbicide and nutrient concentrations, dissolved organic carbon and DOM optical properties) was also monitored to assess any changes during the experiments. The results show that, without DOM, the highest irgarol concentration (I0.5: 0.5 mg.L) and the strongest mixture (M2: irgarol 0.5 μg.L + diuron 0.5 μg.L + S-metolachlor 5.0 μg.L) significantly decreased all parameters for both species. Similar impacts were induced by I0.5 and M2 in C. calcitrans (around -56% for growth, -50% for relative lipid content and -28% for Ф'), but a significantly higher toxicity of M2 was observed in T. suecica (-56% and -62% with I0.5 and M2 for growth, respectively), suggesting a possible interaction between molecules. With DOM added to the culture media, a significant inhibition of these three parameters was also observed with I0.5 and M2 for both species. Furthermore, DOM modulated herbicide toxicity, which was decreased for C. calcitrans (-51% growth at I0.5 and M2) and increased for T. suecica (-64% and -75% growth at I0.5 and M2, respectively). In addition to the direct and/or indirect (via their associated bacteria) use of molecules present in natural DOM, the characterization of the chemical environment showed that the toxic effects observed on microalgae were accompanied by modifications of DOM composition and the quantity of dissolved organic carbon excreted and/or secreted by microorganisms. This toxicity modulation in presence of DOM could be explained by (i) the modification of herbicide bioavailability, (ii) a difference in cell wall composition between the two species, and/or (iii) a higher detoxification capacity of C. calcitrans by the use of molecules contained in DOM. This study therefore demonstrated, for the first time, the major modulating role of natural DOM on the toxicity of herbicides to marine microalgae.

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Section: Introductionmentioning

confidence: 99%

The influence of natural dissolved organic matter on herbicide toxicity to marine microalgae is species-dependent

Coquillé

Ménard²,

Rouxel³

et al. 2018

Aquatic Toxicology

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“…Therefore, the anti-seepage and contaminant sorption capability of liners is crucial for landfill design. Rajasekaran et al (2005) pointed out that the transport of contaminants through liner systems mainly depends on the permeability of bottom liner. To prevent leachate from leaking out of landfill, the standard for MSW sanitary landfill (CJJ 176-2012, China) requires that a compacted clay liner should have a minimum depth of 2 m, and have a maximum hydraulic conductivity of 1 × 10 −7 cm/s.…”

Section: Introductionmentioning

confidence: 99%

Impact of biological clogging on the barrier performance of landfill liners

Tang

Zhang

et al. 2018

Journal of Environmental Management

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The durability of landfill mainly relies on the anti-seepage characteristic of liner system. The accumulation of microbial biomass is effective in reducing the hydraulic conductivity of soils. This study aimed at evaluating the impact of the microorganism on the barrier performance of landfill liners. According to the results, Escherichia coli. produced huge amounts of extracellular polymeric substances and coalesced to form a confluent plugging biofilm. This microorganism eventually resulted in the decrease of soil permeability by 81%-95%. Meanwhile, the increase of surface roughness inside the internal pores improved the adhesion between microorganism colonization and particle surface. Subsequently, an extensive parametric sensitivity analysis was undertaken for evaluating the contaminant transport in landfill liners. Decreasing the hydraulic conductivity from 1 × 10 m/s to 1 × 10 m/s resulted in the increase of the breakthrough time by 345.2%. This indicates that a low hydraulic conductivity was essential for the liner systems to achieve desirable barrier performance.

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“…The published literature entails that clay can be used as a liner material for containment of heavy metals generated in leachates. The migration of heavy metals through soil liners, especially clay liners, is significantly affected by the permeability (hydraulic conductivity), and cation exchange and adsorption capacity of the soil (Sharma and Reddy 2004;Rajasekaran et al 2005;Vaishya et al 2008). Moreover, Cr 6+ reduction in soils can take place owing to surface chemical reactions.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Chromium Containment by Admixed Soil Liner

et al. 2012

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Chrome tanneries generate large quantities of chromium-laden sludge which require proper disposal in engineered landfills to prevent contamination of subsurface soils and groundwater and reduce the risk to public health and the environment. This study investigates the feasibility of using a fine-grained soil as a suitable landfill liner material for the effective containment of chromium in the sludge leachate. Several series of laboratory permeability, adsorption and column tests were conducted using the soil without and with selected additives (rice husk, bentonite, and flyash) to determine permeability and adsorption and transport of chromium in the soil. Permeability tests showed that the field soil amended with 17% rice husk and 2% bentonite provides the desired hydraulic conductivity of 10 -7 cm/s (or less) to minimize the leachate migration into the surrounding subsurface environment. The rice husk and bentonite admixtures significantly reduced the permeability of the soil from 3x10 -7 to 2.8x10 -9 cm/s, and this admixture was further tested for its effect on the adsorption and transport of chromium in the

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Contaminant transport modeling in marine clays

Cited by 14 publications

References 13 publications

The influence of natural dissolved organic matter on herbicide toxicity to marine microalgae is species-dependent

The influence of natural dissolved organic matter on herbicide toxicity to marine microalgae is species-dependent

Impact of biological clogging on the barrier performance of landfill liners

Experimental Study on Chromium Containment by Admixed Soil Liner

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