Nitrifying population densities and inhibition of ammonium oxidation in natural and sewage-enriched cypress swamps

The occurrence of autotrophic nitrifiers in the peat from the floors of a natural cypress dome, a cypress dome receiving deep artesian groundwater, and two cypress domes amended with secondary treated sewage effluent, were assessed by surveying their population densities. The absence of ammonium oxidation in the surface waters of the natural dome was due to the low pH and not to any toxic organic chemical effects present in the humic-colored water. This probably explains the low density (0–56 cells cm⁻³) of autotrophic nitrifiers found associated with the peat from that dome.     

The influence of heat treatment on the metallic and polycyclic aromatic hydrocarbon content of sewage sludge: A pilot plant study

Heat treatment of sewage sludge facilitates its dewatering. The liquors produced inevitably contain a portion of the heavy metal and polycyclic aromatic hydrocarbon contaminants present in the sludges. Using a pilot plant, the influence of time and temperature of treatment on the concentrations of these pollutants in the liquors and treated sludges from three types of untreated sludge have been determined. Statistical analysis of the data has been used to identify significant effects of the treatment process. It is concluded that heat treatment would not produce significant increases in the concentrations of these contaminants in sewage effluents.     

Does cadmium contribute to human hypertension

In 1962 Schroeder reported marked hypertension in rats chronically fed a very low cadmium diet and 5 ppm cadmium in water, but subsequently he reported only moderate hypertension. Using Schroeder's food and water, but a slightly less cadmium-free environment, we repeatedly induced mild hypertension with 5 ppm cadmium, mild because control pressures were higher not because cadmium-fed animals had lower pressures. Seven laboratories have observed hypertension after feeding cadmium; six have not. Thus, chronically fed cadmium can induce hypertension in rats, but conditions are important. Additional observations on cadmium-induced hypertension indicate that: (1) concentrations from 0.1 to 5 ppm cadmium in water are pressor; (2) sex, strain, and age of animals are apparently not limiting factors; (3) there is associated sodium retention; (4) there is a concomitant decrease in the high energy phosphate content of tissues. Rats with cadmium-induced hypertension have renal cadmium concentrations which bracket those of the average environmentally exposed American or European. Finally, renal cadmium concentrations in man were significantly higher (p less than 0.05) for "hypertensives" than for normotensive "matches" in five of nine reported series, lower in one, and similar in three, with all series being small and suboptimal in subject selection.     

Ion exchange and hydrolysis of Type A zeolite in natural waters

The ion exchange behavior and hydrolysis rate of the detergent builder Type A zeolite have been studied in a variety of artificial and natural surface water samples. The experiments were conducted at zeolite A and trace metal concentrations characteristic of what could occur in receiving waters. The data indicate that Type A zeolite hydrolyzed extensively in the test waters at rates which were strongly dependent on hydrogen ion concentration. Half lives of 1–2 months were typical for waters at a neutral pH. Also, the extent of trace metal ion exchange was low (< 10%) for the metals Cd, Cu, Ni and Zn. Pb exchange was slightly higher. It is concluded that the use of the zeolite in detergents will result in little effect on the trace metal distribution of surface waters owing to the low degree of ion-exchange by the zeolite and its hydrolysis products.     

On the presence of iron(II) in oxygenated surface waters: analytical implications

Iron(II) analyses using bathophenanthroline are shown to be characterized by an inherent, small positive interference when the pH of analysis is below 6.5 and iron(III) is present. The interference, which is due to a colored complex formed in the presence of FeOH²⁺ and bathophenanthroline, varies in magnitude according to the presence or generation of FeOH²⁺ during analysis. This interference necessitates reconsideration of published claims that low levels of stable iron(II) exist in oxygenated natural waters, particularly the surface layers of lakes.     

Interactions of heavy metals with bacteria

The toxicity of heavy metals to bacteria, with particular reference to metal forms and species, has been reviewed. Factors which influence metal forms and thus their potential toxicity, such as pH, chelation and competitive interactions have been discussed. The mechanisms whereby bacteria may influence the forms of heavy metals to which they are exposed have been discussed with reference to the importance of the role of bacteria in immobilisation and environmental cycling of metals. Bacterial resistance to metal toxicity is an environmentally important phenomenon. It may occur from non-specific mechanisms, such as impermeability of the cell, or it may be due to specific resistance transfer factors. The coincidence and co-selection of resistance factors for antibiotics and heavy metals in bacterial populations and the clinical implications of this have been described.     

Hazardous lead release from glazed dinnerware: a cautionary note

Numerous pieces of contemporary glazed pottery dinnerware made in Italy and Mexico have been shown to release excessive amounts of lead, greater than 1000 ppm in several instances. Extended use with frequent scouring increased the lead release. This pottery, manufactured under obsolete conditions, may be imported into the United States by tourists, retail merchants and immigrants, and used for daily cooking and storage of food and beverages. Our findings demonstrate a potentially widespread health hazard both in the countries of origin of the pottery and the countries of importation.     

Heavy metals in aquatic plants,clams, and sediments from the Chesapeake Bay,U.S.A. implications for waterfowl

Dry weight concentrations of cadmium, lead, copper and zinc were measured in clams, submerged aquatic macrophytes and sediments from several locations in the Chesapeake Bay region. Clam species included Macoma balthica, Mya arenaria, and Rangia cuneata; plant taxa included Najas spp., Potamogeton spp., Ruppia maritima, Vallisneria americana, and Zostera marina. Cadmium and lead concentrations were generally greater in whole plants than in soft tissues of clams, while the reverse was true for zinc; no marked trend was observed in copper concentrations. These results suggest that the changes occurring in the food habits of some Chesapeake Bay waterfowl towards increased clam utilization as a result of declining submerged plant abundances is not increasing ingestion of the nonessential metals cadmium and lead. Highest lead, copper and zinc concentrations were observed in sediments from the Patapsco River, which is probably due to the proximity of Baltimore Harbor. Highest cadmium concentrations were observed in sediments in the Port Tobacco River, a tributary of the Potomac River. These observations were generally consistent with high concentrations of the respective metal(s) in biota from these locations. Concentrations of the four metals in sediments were highly correlated to organic matter content.     

Blood lead levels in Papua New Guinea children living in a remote area

Improved contamination-free micro blood sampling and chemical analysis techniques were used to study the lead in blood (PbB) levels in 100 Papua New Guinea children living in a remote area. Six soil samples from different locations in the area were also chemically analysed as a check on environmental conditions. The mean value for PbB was 5.2 μg/100 ml with a range of 1.0–13.0 μg/100 ml. The standard deviation was 2.5 μg/100 ml. The results indicate much lower PbB levels for children living in a remote area than the earlier commonly reported levels for similar areas. These results indicate a need to reappraise the comparisons often made with PbB levels for urban children.     

Growth responses of selected freshwater algae to trace elements and scrubber ash slurry generated by coal-fired power plants

In laboratory studies, the freshwater algae Ankistrodesmus falcatus, Scenedesmus obliquus, Selenastrum capricornutum, and Microcoleus vaginatus were exposed to potential pollutants from coal-fired power plants, and their growth responses were evaluated. Using a modification of the EPA Algal Assay Procedure Bottle Test, algae were incubated in media containing As(V) as Na₂HAsO₄ · 7H₂O, Cd(II) as CdSO₄, Hg(II) as HgSO₄, Se(VI) as Na₂SeO₄, in solution, and scrubber ash slurry generated at a western U.S. coal-fired power plant complex. First significant inhibition levels as well as algistatic-algicidal levels are reported. The median effective concentration (EC50) values for the potential pollutants ranged from 0.048–30.761 mg l⁻¹ (0.00064–0.41058 M) As(V), 0.005–0.019 mg l⁻¹ (0.00004–0.00017 M) Cd(II), 0.033–0.253 mg l⁻¹ (0.00016–0.00126 M) Hg(II), 0.033–8.511 mg l⁻¹ (0.00042–0.10779 M) Se(VI), and 3.048–15.417% scrubber ash slurry extract (SASE).     

Sodium retention in rats with cadmium-induced hypertension

Chronic feeding of non-toxic doses of cadmium induces an average increase of 15 to 20 mm Hg in indirectly measured systolic pressure of lightly anaesthetized rats. The mechanism of this increase is not known, but cadmium has several potentially pressor effects, including increased sodium retention. This report describes both sodium balance and blood pressure in a pair of experiments where cadmium was fed and in a pair where it was injected. All four cadmium challenges induced sodium retention and also induced hypertension. Thus, rats with either low or moderate chronic exposure to fed cadmium (well below the exposures required to induce toxicity) retained more intraperitoneally injected radiosodium than controls and at the same time developed higher systolic pressures than controls. Immediately following intraperitoneally injected cadmium, rats lost a radiosodium load more slowly than controls or alternately accumulated dietary radiosodium more rapidly than controls; in both situations the blood pressure was higher than in controls. These data indicate that some of the pressor effect associated with cadmium exposure could result from its concomitant antinatriuretic effect.     

The effect of copper and protein on iron metabolism in rats fed a cereal diet

Weanling male white rats were fed a diet containing a commercially available breakfast cereal. In 28 days they developed a mild anemia coupled with an increased amount of iron in the liver. In parallel work, this same diet was supplemented in a factorial fashion with casein, iron, copper and zinc. The zinc had no effect. Copper supplementation increased the hemoglobin level. Casein decreased liver iron. The copper and casein, when fed together, produced results approaching normal control levels. Supplementation of the diet with additional iron did not increase the hemoglobin or hematocrit but it did further increase iron storage in the liver. It is suggested that cereal enrichment programs might do well to consider copper and protein rather than focus total attention on additional iron and zinc.     

Theoretical and experimental study of factors affecting capillary suction time (CST)

Factors affecting capillary suction time (CST) were studied theoretically and experimentally. The factors were elucidated from a linearly measured capillary suction time (LCST), which was obtained with a simpler device than conventional radial equipment. The LCST should be correlated with the specific resistance to filtration of sludge under the condition that a quantity, i.e. the product of specific resistance and cake mass deposited per unit filtrate volume, is greater than some critical value. If this quantity is greater than the critical value, the LCST is not always correlated with the filterability, but the LCST can always be correlated well with the solid concentration of suspension.     

Speciation (including adsorbed species) of copper, lead, nickel and zinc in the Meuse River: Observed results compared to values calculated with a chemical equilibrium computer program

The adsorption of trace metals on sediments of the Meuse River was interpreted in terms of competition between metals and protons for surface sites. Surface constants (^*β₁^surf) were determined for Cu, Zn and Cd (10^−1.8, 10^−3.6 and 10^−3.7). The constants for Pb, Ni, Ca and Mg (10^−1.7, 10^−3.8, 10^−6.5 and 10^−5.2) were estimated using a correlation between hydrolysis and surface constants. A chemical equilibrium computer program in which surface sites (for adsorption reactions) are treated as conventional ligands was used to calculate the speciation of Cu, Pb, Ni and Zn in the Meuse River. Calculated values of the adsorbed/dissolved distribution agreed well with observed values, after some realistic data manipulation. This work indicates that dissolved trace metal concentrations in the Meuse River are controlled by adsorption and not by precipitation mechanisms. The relationship between organic matter and suspended matter greatly influences the adsorption of metals like Cu and Pb.     

Beyond the code: Energy, carbon, and cost savings using conventional technologies

As states in the U.S. adopt new energy codes, it is important to understand the benefits for each state and its building owners. This paper estimates life-cycle energy savings, carbon emission reduction, and cost-effectiveness of conventional energy efficiency measures in new commercial buildings using an integrated design approach. Results are based on 8208 energy simulations for 12 prototypical buildings in 228 cities, with 3 building designs evaluated for each building-location combination. Results are represented by easy-to-understand mappings that allow for regional and state comparisons. The results show that the use of conventional energy efficiency technologies in an integrated design framework can decrease energy use by 15-20% on average in new commercial buildings, and over 35% for some building types and locations. These energy reductions can often be accomplished at negative incremental life-cycle costs and reduce a building's energy-related carbon footprint by 9-33%. However, generalizing these results on energy use, life-cycle costs, and carbon emissions misses exceptions in the results that show the importance of location-specific characteristics. Also, states do not appear to base energy code adoption decisions on either potential energy savings or life-cycle cost savings.