The influence of road salt on seasonal mixing, redox stratification and methane concentrations in urban kettle lakes.

Influxes of saline water from roads treated with deicers can alter the density structure of urban lakes. This can diminish or halt turnover events, such that lakes may transition from dimixis to monomixis or meromixis. In nutrient-rich lakes, this lack of turnover can produce persistent hypolimnetic anoxia.

Competitive Adsorption of Cd(II), Cr(VI), and Pb(II) onto Nanomaghemite: A Spectroscopic and Modeling Approach.

A combined modeling and spectroscopic approach is used to describe Cd(II), Cr(VI), and Pb(II) adsorption onto nanomaghemite and nanomaghemite coated quartz. A pseudo-second order kinetic model fitted the adsorption data well. The sorption capacity of nanomaghemite was evaluated using a Langmuir isotherm model, and a diffuse double layer surface complexation model (DLM) was developed to describe metal adsorption.

Surface complexation modeling of Cd(II) adsorption on mixtures of hydrous ferric oxide, quartz and kaolinite.

Cadmium adsorption was measured as a function of ionic strength (0.001-0.1M NaNO(3)), and spanning a range of sorbate/sorbent ratios, on pure hydrous ferric oxide (HFO), kaolinite, and quartz and also on binary and ternary mixtures of the three solids.

Surface complexation modeling of Cu(II) adsorption on mixtures of hydrous ferric oxide and kaolinite.

Background: The application of surface complexation models (SCMs) to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids.

Seasonal variations in pore water and sediment geochemistry of littoral lake sediments (Asylum Lake, MI, USA).

Background: Seasonal changes in pore water and sediment redox geochemistry have been observed in many near-surface sediments. Such changes have the potential to strongly influence trace metal distribution and thus create seasonal fluctuations in metal mobility and bioavailability.

Results: Seasonal trends in pore water and sediment geochemistry are assessed in the upper 50 cm of littoral kettle lake sediments.

Quantifying bioirrigation using ecological parameters: a stochastic approach†.

Irrigation by benthic macrofauna has a major influence on the biogeochemistry and microbial community structure of sediments. Existing quantitative models of bioirrigation rely primarily on chemical, rather than ecological, information and the depth-dependence of bioirrigation intensity is either imposed or constrained through a data fitting procedure. In this study, stochastic simulations of 3D burrow networks are used to calculate mean densities, volumes and wall surface areas of burrows, as well as their variabilities, as a function of sediment depth.