The fate of metal contaminated sediments in Foundry Cove, New York

The distribution of heavy metal contaminated sediments in Foundry Cove, a freshwater embayment of the Hudson River, was examined twelve years after the discharging of wastes from a battery factory had ceased. Concentrations of Cd, Ni and Co were measured in surficial sediments (top 5 cm) and seven detailed depth profiles. Comparison with earlier surveys showed that metal levels of surficial sediments have been considerably reduced throughout the cove. Evidence suggests that this reduction may be largely due to burial rather than transport of metals out of the cove or a redistribution (via sediment resuspension and redeposition) within the cove. This is suggested by the presence of a peak in metal concentrations at a depth of several centimetres in depositional environments, a calculation showing the loss of waterborne cadmium to be much less than the amount of cadmium lost from the surficial sediment, and the absence of increased pollution in the cleaner parts of the cove. Despite improvement, metal levels remain extremely high, including a persistent 'hot-spot' with levels higher than 10 000 ppm Cd.     

Comparative effects of mine wastes on the benthos of an acid and an alkaline pond

Benthic invertebrates collected from an acid (pH 3.2) and an alkaline (pH 7.9) tailing pond in the Rouyn-Noranda mining region were compared with those of a control pond in order to assess the effects of the pH on the benthic community structure and on metal accumulation by invertebrates. The acid pond showed high mean soluble concentrations of aluminium (2600 ppb), copper (230 ppb), iron (6500 ppb) and zinc (4900 ppb) in the water and high mean concentrations of copper (340 ppm), iron (15,238 ppm) and zinc (445 ppm) in the sediments. The benthic fauna was dominated by Chironomus spp and the water beetle Ilybius sp. The Shannon-Weaver diversity index was 0.04. The alkaline pond had high mean sediment concentrations of cadmium (21 ppm), iron (15,823 ppm), manganese (658 ppm) and nickel (146 ppm). A total of 37 insect genera and a diversity index of 3.4 were recorded for this pond. Of the seven metals studied only copper and aluminium showed greater accumulations in the biota of the contaminated ponds than in that of the control. Insects dominated the benthic fauna in both contaminated ponds and crustacea in the control.     

Dissolved organic matter fractions formed during composting of winery and distillery residues: evaluation of the process by fluorescence excitation-emission matrix

The aim of the present paper is to assess the maturity degree reached by different samples of several mixtures from winery and distillery residues composted using the Rutgers composting system, by means of excitation-emission matrix (EEM) fluorescence spectroscopy. The composts were sampled once a week for about 200d. EEM spectra indicate the presence of different fluorophores. The fluorescence intensities of these peaks show trends related to the maturity of the composting samples selected. The "contour density" of EEM maps is strongly modified through time. We have used the quantitative method of fluorescence regional integration (FRI). The EEMs were delineated into five excitation-emission regions. The degree of compost maturity could be correlated with the percentage of the volumetric integration under the EEM within each region. Further refinement of these techniques should provide a relatively rapid method for assessing the suitability of the compost to soil application.     

The sensitivity of surface waters of Great Britain to acidification predicted from catchment characteristics

Using a combination of soil, land use and geological information, a map of Great Britain has been derived which indicates the sensitivity of surface waters to acidification. For the geological information, a slightly modified version of an available map was used which indicated the sensitivity of groundwaters to acidification. For soils, 1-km databases of soil information for England and Wales and for Scotland were employed to map the soil sensitivity as determined by buffering capacity. The derived soils map was modified to take account of agricultural liming in arable and managed grassland areas using the ITE Land Classification. The final map of surface water sensitivity was obtained by using a geographic information system overlay procedure which enabled each combination of soil and geology sensitivity to be uniquely defined. The final sensitivity classification was based upon expert knowledge and the experience of a similar sensitivity mapping exercise for Wales.     

Bacteria transport and deposition under unsaturated conditions: the role of the matrix grain size and the bacteria surface protein

Unsaturated (80% water saturated) packed column experiments were conducted to investigate the influence of grain size distribution and bacteria surface macromolecules on bacteria (Rhodococcus rhodochrous) transport and deposition mechanisms. Three sizes of silica sands were used in these transport experiments, and their median grain sizes were 607, 567, and 330 microm. The amount of retained bacteria increased with decreasing sand size, and most of the deposited bacteria were found adjacent to the column inlet. The deposition profiles were not consistent with predictions based on classical filtration theory. The experimental data could be accurately characterized using a mathematical model that accounted for first-order attachment, detachment, and time and depth-dependent straining processes. Visual observations of the bacteria deposition as well as mathematical modelling indicated that straining was the dominant mechanism of deposition in these sands (78-99.6% of the deposited bacteria), which may have been enhanced due to the tendency of this bacterium to form aggregates. An additional unsaturated experiment was conducted to better deduce the role of bacteria surface macromolecules on attachment and straining processes. In this case, the bacteria surface was treated using a proteolitic enzyme. This technique was assessed by examining the Fourier-transform infrared spectrum and hydrophobicity of untreated and enzyme treated cells. Both of these analytical procedures demonstrated that this enzymatic treatment removed the surface proteins and/or associated macromolecules. Transport and modelling studies conducted with the enzyme treated bacteria, revealed a decrease in attachment, but that straining was not significantly affected by this treatment.     

Sorption of the veterinary antimicrobials sulfadimethoxine and ormetoprim in soil

Currently, limited research on the fate of antimicrobials in the environment exists, once they are discharged in human and animal wastes. Sorption of two antimicrobials, sulfadimethoxine (SDM) and ormetoprim (OMP), was investigated in two soils and sand using a series of batch experiments. Because OMP and SDM are often administered in combination, their sorption was also investigated in combination as co-solutes. The rate of SDM and OMP sorption was rapid over the first few hours of the experiments, which then slowed considerably after 16 to 68 h. OMP sorption was enhanced at high concentrations when in combination with SDM, with linear sorption coefficients ranging from 1.3 to 58.3 L.kg(-1) in the single solute experiments and 4.96 to 89.7 L.kg(-1) in the co-solute experiments. Sorption of OMP as a single solute seems to provide a better fit with the Freundlich equation, which became more linear (n approached 1) when SDM was present. Overall, SDM sorbed less than OMP in the two soils and sand. SDM linear sorption coefficients ranged from 0.4 to 25.8 L.kg(-1) as a single solute and 2.5 to 22.1 L.kg(-1) as a co-solute. Sorption of SDM becomes more nonlinear (n < 1) when SDM is present in combination with OMP. Overall, sorption of both antimicrobials increased in the selected soils and sand as the organic matter, clay content, and cation exchange capacity increased. These experiments indicate relatively low sorption of SDM and OMP in natural soils, making them a potential threat to surface and ground water.     

Estimated occupational risk from bioaerosols generated during land application of class B biosolids

Some speculate that bioaerosols from land application of biosolids pose occupational risks, but few studies have assessed aerosolization of microorganisms from biosolids or estimated occupational risks of infection. This study investigated levels of microorganisms in air immediately downwind of land application operations and estimated occupational risks from aerosolized microorganisms. In all, more than 300 air samples were collected downwind of biosolids application sites at various locations within the United States. Coliform bacteria, coliphages, and heterotrophic plate count (HPC) bacteria were enumerated from air and biosolids at each site. Concentrations of coliforms relative to Salmonella and concentrations of coliphage relative to enteroviruses in biosolids were used, in conjunction with levels of coliforms and coliphages measured in air during this study, to estimate exposure to Salmonella and enteroviruses in air. The HPC bacteria were ubiquitous in air near land application sites whether or not biosolids were being applied, and concentrations were positively correlated to windspeed. Coliform bacteria were detected only when biosolids were being applied to land or loaded into land applicators. Coliphages were detected in few air samples, and only when biosolids were being loaded into land applicators. In general, environmental parameters had little impact on concentrations of microorganisms in air immediately downwind of land application. The method of land application was most correlated to aerosolization. From this large body of data, the occupational risk of infection from bioaerosols was estimated to be 0.78 to 2.1%/yr. Extraordinary exposure scenarios carried an estimated annual risk of infection of up to 34%, with viruses posing the greatest threat. Risks from aerosolized microorganisms at biosolids land application sites appear to be lower than those at wastewater treatment plants, based on previously reported literature.     

Farm factors associated with reducing Cryptosporidium loading in storm runoff from dairies

A systems approach was used to evaluate environmental loading of Cryptosporidium oocysts on five coastal dairies in California. One aspect of the study was to determine Cryptosporidium oocyst concentrations and loads for 350 storm runoff samples from dairy high use areas collected over two storm seasons. Selected farm factors and beneficial management practices (BMPs) associated with reducing the Cryptosporidium load in storm runoff were assessed. Using immunomagnetic separation (IMS) with direct fluorescent antibody (DFA) analysis, Cryptosporidium oocysts were detected on four of the five farms and in 21% of storm runoff samples overall. Oocysts were detected in 59% of runoff samples collected near cattle less than 2 mo old, while 10% of runoff samples collected near cattle over 6 mo old were positive. Factors associated with environmental loading of Cryptosporidium oocysts included cattle age class, 24 h precipitation, and cumulative seasonal precipitation, but not percent slope, lot acreage, cattle stocking number, or cattle density. Vegetated buffer strips and straw mulch application significantly reduced the protozoal concentrations and loads in storm runoff, while cattle exclusion and removal of manure did not. The study findings suggest that BMPs such as vegetated buffer strips and straw mulch application, especially when placed near calf areas, will reduce environmental loading of fecal protozoa and improve stormwater quality. These findings are assisting working dairies in their efforts to improve farm and ecosystem health along the California coast.     

Influence of prairie restoration on CT-measured soil pore characteristics

Restored prairies are expected to improve soil physical properties, yet little is known about the extent of change to soil properties and how rapidly these changes take place. The objective of this study was to compare effects of prairie restoration on computed tomography (CT)-measured pore parameters. Undisturbed soil cores (76 mm diam. by 76 mm long) from native prairie (NP), restored prairie (RP), conservation reserve program (CRP), and no-till corn (Zea mays L.)-soybean (Glycine max (L.) Merr.; CS) sites were collected with six replicates from the 0- to 40-cm depth in 10-cm increments. Five CT images were acquired from each soil core using a medical CT scanner with 0.2 by 0.2 mm pixel resolution with 0.5 mm slice thickness, and then images were analyzed. Soil bulk density and hydraulic conductivity (K(sat)) were also measured. Soils under NP, RP, CRP, and CS areas had 83, 43, 48, and 26 pores on a 2500 mm(2) area, respectively, for the 0- to 40-cm depth. The number of pores, number of macropores (>1000 microm diam.), macroporosity, mesoporosity (200-1000 microm diam.), and fractal dimension were significantly higher and pore circularity was lower for NP, RP, and CRP than the CS treatment. The CT-measured mesoporosity and macroporosity of the CS treatment were 20 and 18% of the values for the NP site. CT-measured number of pores and macropores explained 43 and 40% of the variation for K(sat). The study showed that prairie restoration improves CT-measured soil pore parameters and decreases bulk density which are related to soil water infiltration.     

An Approach for Evaluating the Effectiveness of Various Ozone Air Quality Standards for Protecting Trees

We demonstrate an approach for evaluating the level of protection attained using a variety of forms and levels of past, current, and proposed Air Quality Standards (AQSs). The U.S. Clean Air Act requires the establishment of ambient air quality standards to protect health and public welfare. However, determination of attainment of these standards is based on ambient pollutant concentrations rather than prevention of adverse effects. To determine if a given AQS protected against adverse effects on vegetation, hourly ozone concentrations were adjusted to create exposure levels that “just attain” a given standard. These exposures were used in combination with a physiologically-based tree growth model to account for the interactions of climate and ozone. In the evaluation, we used ozone concentrations from two 6-year time periods from the San Bernardino Mountains in California. There were clear differences in the level of vegetation protection achieved with the various AQSs. Based on modeled plant growth, the most effective standards were the California 8-hr average maximum of 70 ppb and a seasonal, cumulative, concentration-weighted index (SUM06), which if attained, resulted in annual growth reductions of 1% or less. Least effective was the 1-hr maximum of 120 ppb which resulted in a 7% annual reduction. We conclude that combining climate, exposure scenarios, and a process-based plant growth simulator was a useful approach for evaluating effectiveness of current or proposed air quality standards, or evaluating the form and/or level of a standard based on preventing adverse growth effects.