Gordon Chesters

Metal composition of soil, sediments, and urban dust and dirt samples from the Menomonee River Watershed, Wisconsin, U.S.A.

The Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn contents of the sand, silt, and clay fractions were determined for soils, urban street dust and bottom- and suspended-sediments sampled in the Menomonee River watershed, Wisconsin. The samples were dispersed by ultrasound prior to fractionation. The ultrasound dispersion avoids chemical contamination or alteration resulting from use of chemical dispersants and insures the dispersion of aggregates present in mechanically-sieved samples.Chemical analyses of fractionated samples were more precise than analyses of unfractionated samples in identifying areas in the watershed receiving pollutant inputs. Higher levels of Cr, Cu, Fe, and Ni were found in the coarser particles than in the finer particles of urban street dust samples. The Cd, Pb and Zn contents of some bottom and suspended sediments were greater than in the soils of the watershed. Contents of these metals were correlated significantly with each other in the clay-sized fraction of sediments but not in soils. The metal contents of sediments were largely controlled by vehicular emission.

Particle-size distribution and phosphorus levels in soil, sediment, and urban dust and dirt samples from the Menomonee River Watershed, Wisconsin, U.S.A.

Abstract Soil, bottom sediment, suspended sediment, and urban street dust and dirt samples from the Menomonee River Watershed, Wisconsin, were dispersed by ultrasound, fractionated and analyzed for the P content of each of three particle-size fractions. The major soil types in the watershed were used as a reference for comparing particle-size distribution and P content in urban street dust and dirt, and in sediments. Phosphorus level was found to be greater in the clay-sized particles than in the sand- or silt-sized particles of urban street dust and dirt samples, but 48% of the P was in the sand-sized fraction because of the predominance of sand-sized particles in these samples. The highest P level in the clay-sized fraction of the bottom sediments occurred at the site below a sanitary treatment plant (STP) outfall with secondary treatment capability. The P level found below a tertiary STP outfall was equal to the level found in agricultural areas. When using P level in sediment for locating areas of possible P input to the river, the clay-sized fraction of bottom sediments was more precise than P levels in unfractionated samples.

Simulation of atrazine and metabolite transport and fate in a sandy-till aquifer

In a 2.5-yr field study we determined the distribution of atrazine and its metabolites in a sandy-till aquifer overlying Cambrian sandstone in a dairy farming area. Flow paths are predominantly downward at piezometer nests where vertical hydraulic gradients dominate. Atrazine and desethylated atrazine concentrations along those flow paths generally decrease with increasing estimated groundwater travel time to the monitoring points. A one-dimensional contaminant transport model is developed in FORTRAN incorporating major chemical processes and dispersion along simulated flow paths. Separate simulations of atrazine and desethylated atrazine transport to individual piezometers are made, each with an appropriate average groundwater velocity. Regression equations are developed, based on an extensive literature review, to estimate acceptable sorption and dispersivity coefficients for the transport model. The one-dimensional simulations are calibrated using the field concentration-travel time relationships for atrazine and desethylated atrazine. The calibration procedure provides estimates of atrazine and desethylated atrazine degradation rates in groundwater corresponding to half-lives of 3470 and 2770 days, respectively. Although uncertain, the estimates provide evidence of much slower degradation in the aquifer than indicated by laboratory experiments. Using the calibrated transport parameter values, simulations of long-term steady-state leaching to the water table demonstrate that even with such slow degradation rates, steady-state concentrations at most piezometers are reached within ∼ 20 yr. Concentrations in the underlying sandstone aquifer are therefore not expected to increase substantially over time due to continued atrazine use. However, the slow degradation rates mean that even with the most optimistic condition, i.e. all input to the aquifer ceases in response to a cessation of atrazine application, it may take more than a decade for concentrations deeper in the aquifer to drop to half of what they were during the period of atrazine use.

Persistence of Diquat in the aquatic environment

Abstract Diquat (a commonly-used aquatic herbicide) added to a weed-infested simulated lake impoundment was sorbed initially by the weeds. Following rapid weedkill, profuse proliferation of microorganisms occurred, promoting degradation of the herbicide sorbed on the decomposing weeds. Within 22 days, Diquat was degraded extensively to water-soluble products (32%) and only minimal sediment adsorption occurred (19%). In weed-free sediment-water incubation systems. Diquat in water was adsorbed rapidly by Lakes Mendota and Tomahawk sediments, and the major portion of the herbicide persisted in its intact form throughout the experiment (up to 180 days). Slow microbial degradation occurred in the Lake Mendota system, as indicated by 14 CO 2 evolution which was favored by aerobic conditions and a small volume of overlying water. Microbial degradation in the Lake Tomahawk system was negligible.

Effect of ash disposal ponds on groundwater quality at a coal-fired power plant

Abstract The impact of fly and bottom ash disposal ponds on groundwater quality was investigated at the coal-fired Columbia Power Plant at Portage, Wis. Groundwater sampling was conducted utilizing a network of piezometers and multilevel wells located at various cross-sections of the ash disposal facility. Analyses were performed for 16 major and minor elements, pH and conductivity. Data for a 3-yr monitoring program established the existence of large B, Na and SO4 plumes in the groundwater system surrounding the ash disposal area. Substantial amounts of B, Na and SO4 were present in the plume and portions were discharged into an adjacent wetland as the plumes moved with groundwater flow. The secondary fly ash settling pond was the major source of B and SO4, while the main source of Na was from previous releases to the aquifer from the use of Na2CO3 to condition fly ash to enhance removal of SO2 from flue gas by electrostatic precipitation. Movement into the groundwater of heavy metals such as Cu and Zn was not observed and their concentrations are likely attenuated in the pond.

Evaluation of the great lakes nearshore index

Abstract The Great Lakes Nearshore Index is a model designed to evaluate overall quality of aquatic environments in 3 km segments of mixing zones along the shoreline of the North American Great Lakes. The structural characteristics and performance of this model have been tested to determine its validity and reliability in producing water quality ratings. Model components were examined in light of the goals of those who sponsored its development, the concerns of water quality managers and other residents in the Great Lakes Basin, and by reference to the literature of water quality management. The validity of each component as a partial measure of water quality was assessed by comparing the laboratory results of water sample analyses for each variable with the models ratings for the same data sets. Validity of ratings for ambient conditions in the Great Lakes was evaluated by comparison with classifications of the U.S./Canada International Joint Commission and with classifications based on biological surveys. Reliability of ratings was calculated statistically and expressed in terms of confidence intervals and required sample size for data sets averaged annually. Results of the study generally support the validity and reliability of the model as a measure of average, annual quality for nearshore aquatic environments of the Great Lakes. However, recent publications and new legislation necessitate a revision in the toxic substance parameters.

Influence of detergent formulation on nutrient movement through sand columns simulating mound and conventional septic system drainfields

Abstract The effects of phosphate (P) and zeolite (Z) -built detergents on leaching of N and P through sand columns simulating septic system drainfields were examined in laboratory columns. To simulate mound septic system drainfields, paired sets of columns were dosed intermittently with septic tank effluent from households using P- or Z-built detergent. Two other paired sets of columns were flooded with P- or Z-effluent to simulate new conventional septic system drainfields; after clogging mats or “crusts” developed at infiltration surface, the subsurfaces of the columns were aerated to simulate mature (crusted) conventional septic system drainfields. NO 3 loading in leachate was 1.1 times higher and ortho-P loading was 4.3 times lower when columns were dosed with Z- than with P-effluent. Dosed columns removed P poorly; total phosphorus (TP) loading in leachate was 81 and 19 g m −2 yr −1 with P- and Z-effluent, respectively. In flooded columns 1.3, 2.0 and 1.8 times more NH 4 , organic nitrogen (ON) and total nitrogen (TN) respectively, were leached with Z- than with P-effluent; NO 3 leaching was similar. Flooded columns removed P efficiently; TP leached through flooded systems was 2.5 and 1.4 g m −2 yr −1 with P- and Z effluent, respectively. Crusted columns fed Z-effluent leached 1.2, 2.6, 1.4 and 2.1 times more NH 4 , NO 3 , ON and TN, respectively, than those with P-effluent but 1.8 times less TP. Crusted columns removed P satisfactorily: 8.2 and 4.6 g m −2 yr −1 TP with P- and Z-effluent, respectively. The P-built detergent substantially improves the efficiency of N removal with satisfactory P removal in columns simulating conventional septic system drainfield. Simultaneous removal of N and P under flooded conditions might be explained by precipitation of struvite-type minerals. Dosed system drainfields were less efficient in removing N and P compared to flooded and crusted system drainfelds.

Availability and extractability of soil manganese in a liming experiment

Abstract The availability of soil Mn to corn in relation to extractability of soil Mn by EDTA, Mg(NO3)2, CH3COONH4, hydroquinone, H3PO4, and NH4H2PO4 as affected by liming was evaluated under field conditions on a single soil type. EDTA, Mg(NO3)2 and CH3COONH4‐extractable Mn were related inversely to available Mn. No useful relationships were found between hydroquinone, H3PO4, and NH4H2PO4‐extractable soil Mn and Mn uptake by sweet corn.