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Simulation of the fate and seasonal variations of α-hexachlorocyclohexane in Lake Chaohu using a dynamic fugacity model.

Kong XZ, He W, Qin N, He QS, Yang B, Ouyang H, Wang Q, Yang C, Jiang Y, Xu F - ScientificWorldJournal (2012)

Bottom Line: Seasonal patterns in various media were successfully modeled and factors leading to this seasonality were discussed.Sensitivity analysis found that parameters of source and degradation were more important than the other parameters.Uncertainty analysis showed that the model uncertainty was relatively low but significantly increased in the second half of the simulation period due to the increase in the gas-water diffusion flux variability.

View Article: PubMed Central - PubMed

Affiliation: MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.

ABSTRACT
Fate and seasonal variations of α-hexachlorocyclohexane (α-HCH) were simulated using a dynamic fugacity model in Lake Chaohu, China. Sensitivity analyses were performed to identify influential parameters and Monte Carlo simulation was conducted to assess model uncertainty. The calculated and measured values of the model were in good agreement except for suspended solids, which might be due to disregarding the plankton in water. The major source of α-HCH was an input from atmospheric advection, while the major environmental outputs were atmospheric advection and sediment degradation. The net annual input and output of α-HCH were approximately 0.294 t and 0.412 t, respectively. Sediment was an important sink for α-HCH. Seasonal patterns in various media were successfully modeled and factors leading to this seasonality were discussed. Sensitivity analysis found that parameters of source and degradation were more important than the other parameters. The sediment was influenced more by various parameters than air and water were. Temperature variation had a greater impact on the dynamics of the model output than other dynamic parameters. Uncertainty analysis showed that the model uncertainty was relatively low but significantly increased in the second half of the simulation period due to the increase in the gas-water diffusion flux variability.

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α-HCH fluxes in and out of the Lake Chaohu area and between the adjacent compartments. T01t: air advection flows into the area; T10t: air advection flows out of the area; T12d: diffusion from air to water; T12p: dry deposition from air to water; T12w: wet deposition from air to water; T12r: rain scavenging; T21d: diffusion from water to air; T42d: diffusion from sediment to water; T42r: resuspension from sediment to water; T24d: diffusion from water to sediment; T24s: sedimentation from water to sediment; T02t: water advection flows into the area; T20t: water advection flows out of the area; T02h: locative wastewater discharge; T23h: industry and agriculture water usage; T10m: degradation in air; T20m: degradation in water; T40m: degradation in sediment.
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fig4: α-HCH fluxes in and out of the Lake Chaohu area and between the adjacent compartments. T01t: air advection flows into the area; T10t: air advection flows out of the area; T12d: diffusion from air to water; T12p: dry deposition from air to water; T12w: wet deposition from air to water; T12r: rain scavenging; T21d: diffusion from water to air; T42d: diffusion from sediment to water; T42r: resuspension from sediment to water; T24d: diffusion from water to sediment; T24s: sedimentation from water to sediment; T02t: water advection flows into the area; T20t: water advection flows out of the area; T02h: locative wastewater discharge; T23h: industry and agriculture water usage; T10m: degradation in air; T20m: degradation in water; T40m: degradation in sediment.

Mentions: As shown in Figure 4, the net input of α-HCH into the Lake Chaohu environment is approximately 0.115 mol/h (approximately 0.294 t/a), while the net output is 0.162 mol/h (approximately 0.412 t/a). It can be observed that the α-HCH content in the Lake Chaohu watershed is diminishing. The atmospheric advection input was found to be the main source (T01t) (0.278 t/a), which corresponded to the atmospheric advection output (T10t) (0.277 t/a). By contrast, the α-HCH input from water inflows was very small (0.016 t/a). An important output was the degradation in the sediments (0.119 t/a), which accounted for 89.05% of the total degradation in the environment, while the degradation in the water was 0.015 t/a, which accounted for 10.86% of the total degradation.


Simulation of the fate and seasonal variations of α-hexachlorocyclohexane in Lake Chaohu using a dynamic fugacity model.

Kong XZ, He W, Qin N, He QS, Yang B, Ouyang H, Wang Q, Yang C, Jiang Y, Xu F - ScientificWorldJournal (2012)

α-HCH fluxes in and out of the Lake Chaohu area and between the adjacent compartments. T01t: air advection flows into the area; T10t: air advection flows out of the area; T12d: diffusion from air to water; T12p: dry deposition from air to water; T12w: wet deposition from air to water; T12r: rain scavenging; T21d: diffusion from water to air; T42d: diffusion from sediment to water; T42r: resuspension from sediment to water; T24d: diffusion from water to sediment; T24s: sedimentation from water to sediment; T02t: water advection flows into the area; T20t: water advection flows out of the area; T02h: locative wastewater discharge; T23h: industry and agriculture water usage; T10m: degradation in air; T20m: degradation in water; T40m: degradation in sediment.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539339&req=5

fig4: α-HCH fluxes in and out of the Lake Chaohu area and between the adjacent compartments. T01t: air advection flows into the area; T10t: air advection flows out of the area; T12d: diffusion from air to water; T12p: dry deposition from air to water; T12w: wet deposition from air to water; T12r: rain scavenging; T21d: diffusion from water to air; T42d: diffusion from sediment to water; T42r: resuspension from sediment to water; T24d: diffusion from water to sediment; T24s: sedimentation from water to sediment; T02t: water advection flows into the area; T20t: water advection flows out of the area; T02h: locative wastewater discharge; T23h: industry and agriculture water usage; T10m: degradation in air; T20m: degradation in water; T40m: degradation in sediment.
Mentions: As shown in Figure 4, the net input of α-HCH into the Lake Chaohu environment is approximately 0.115 mol/h (approximately 0.294 t/a), while the net output is 0.162 mol/h (approximately 0.412 t/a). It can be observed that the α-HCH content in the Lake Chaohu watershed is diminishing. The atmospheric advection input was found to be the main source (T01t) (0.278 t/a), which corresponded to the atmospheric advection output (T10t) (0.277 t/a). By contrast, the α-HCH input from water inflows was very small (0.016 t/a). An important output was the degradation in the sediments (0.119 t/a), which accounted for 89.05% of the total degradation in the environment, while the degradation in the water was 0.015 t/a, which accounted for 10.86% of the total degradation.

Bottom Line: Seasonal patterns in various media were successfully modeled and factors leading to this seasonality were discussed.Sensitivity analysis found that parameters of source and degradation were more important than the other parameters.Uncertainty analysis showed that the model uncertainty was relatively low but significantly increased in the second half of the simulation period due to the increase in the gas-water diffusion flux variability.

View Article: PubMed Central - PubMed

Affiliation: MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.

ABSTRACT
Fate and seasonal variations of α-hexachlorocyclohexane (α-HCH) were simulated using a dynamic fugacity model in Lake Chaohu, China. Sensitivity analyses were performed to identify influential parameters and Monte Carlo simulation was conducted to assess model uncertainty. The calculated and measured values of the model were in good agreement except for suspended solids, which might be due to disregarding the plankton in water. The major source of α-HCH was an input from atmospheric advection, while the major environmental outputs were atmospheric advection and sediment degradation. The net annual input and output of α-HCH were approximately 0.294 t and 0.412 t, respectively. Sediment was an important sink for α-HCH. Seasonal patterns in various media were successfully modeled and factors leading to this seasonality were discussed. Sensitivity analysis found that parameters of source and degradation were more important than the other parameters. The sediment was influenced more by various parameters than air and water were. Temperature variation had a greater impact on the dynamics of the model output than other dynamic parameters. Uncertainty analysis showed that the model uncertainty was relatively low but significantly increased in the second half of the simulation period due to the increase in the gas-water diffusion flux variability.

Show MeSH
Related in: MedlinePlus