Heavy Metal Contamination in Soils of Urban Highways Comparison Between Runoff and Soil Concentrations at Cincinnati,Ohio

Rainfall runoff from urban roadways oftencontains elevated amounts of heavy metals in both particulate anddissolved forms (Sansalone and Buchberger, 1997). Because metalsdo not degrade naturally, high concentrations of them in runoffcan result in accumulation in the roadside soil at levels thatare toxic to organisms in surrounding environments. This studyinvestigated the accumulation of metals in roadside soils at asite for which extensive runoff data were also available.For this study, 58 soil samples, collected from I-75 nearCincinnati, Ohio, were examined using X-ray fluorescence, C-Sanalyzer, inductively coupled plasma spectroscopy, atomicabsorption spectrometry and X-ray diffraction. The resultsdemonstrated that heavy metal contamination in the top 15 cm ofthe soil samples is very high compared to local backgroundlevels. The maximum measured amount for Pb is 1980 ppm (at 10–15 cm depth) and for Zn is 1430 ppm (at 0–1 cm depth). Metal content in the soil falls off rapidly with depth, and metalcontent decreases as organic C decreases. The correlation toorganic C is stronger than the correlation to depth. The resultsof sequential soil extraction, however, showed lower amounts ofPb and Zn associated with organic matter than was expected basedon the correlation of metals to % organic C in the whole soil.Measurement of organic C in the residues of the sequentialextraction steps revealed that much of the carbon was not removedand hence is of a more refractory nature than is usual inuncontaminated soils. Cluster analysis of the heavy metal datashowed that Pb, Zn and Cu are closely associated to one another,but that Ni and Cr do not show an association with each other orwith either organic C or depth. ICP spectroscopy of exchanged cations showed that only 4.5%of Pb, 8.3% of Zn, 6.9% of Cu and 3.7% of Cr in the soil isexchangeable. Combined with the small amounts of metals bound tosoluble organic matter, this result shows that it is unlikelythat these contaminants can be remobilized into water. At thissite, clays are not an important agent in holding the metals inplace because of low amounts of swelling clays. Instead, insoluble organic matter is more important. Mass balancecalculations for Pb in soil showed that most of the Pb came fromexhausts of vehicles when leaded gasoline was in use, and thatabout 40% of this Pb is retained in the soil.This study shows that, highway environments being a relativelyconstant source of anthropogenic organic matter as well as heavymetals, heavy metals will continue to remain bound to organicmatter in-situ unless they are re-mobilized mechanically. Removalof these heavy metals as wind-blown dust is the most likelymechanism. Another possibility is surface run-off carrying themetals into surface drainages, bypassing the soil. This studyalso shows that for those countries still using leaded gasoline,important reductions in Pb contamination of soils can be achievedby restricting the use of Pb additives.     

Progress towards more uniform assessment and reporting of soil disturbance for operations, research, and sustainability protocols

International protocols, such as those of the Montreal Process (MP), specify desired outcomes without specifying the process and components required to attain those outcomes. We suggest that the process and its components are critical to achieve desired outcomes. We discuss recent progress in northwestern North America, on three topics that will facilitate development of and reporting in sustainability protocols: (1) common terms and comparable guidelines for soil disturbance, (2) cost-effective techniques for monitoring and assessing soil disturbance, and (3) improved methods to rate soils for risk of detrimental soil disturbance. Uniform terms for soil disturbance will facilitate reporting and exchange of information. Reliable monitoring techniques and tracking the consequences of soil disturbance for forest growth and hydrology are paramount for improving understanding and predictions of the practical consequences of forest practices. To track consequences, we urge creation of regional research and operations databases that can be used to: (1) address MP values, (2) define detrimental soil disturbances, (3) develop risk rating systems for operational application, and (4) improve best management practices (BMPs) and ameliorative treatments that avoid or correct detrimental disturbances.     

Spatial patterns in fish biomass and relative trophic level abundance in a wastewater enriched river

Abstract –  It is generally accepted that nutrient enrichment of aquatic systems will lead to increased production at the top trophic level (fish). We found that in the wastewater enriched Bow River, Alberta rainbow trout ( Oncorhynchus mykiss ) biomass increased over 25-fold, and brown trout ( Salmo trutta ) biomass increased 5-fold, however total sportfish biomass did not increase below the nutrient input point source. This was due to a dramatic downstream decrease in mountain whitefish ( Prosopium williamsoni ) biomass to 2% of the average biomass upstream of the municipal effluent source. The spatial pattern over a 177-km river section encompassing the city of Calgary, showed that the increase in trout abundance approximately tracked the expected nutrient concentrations in the river, but with a downstream lag of 20–30 km. Mountain whitefish biomass over the 177 km was inversely related to the dominant trout species, rainbow trout. Invertebrate abundance, macrophyte biomass and phytoplankton biomass all increased below the wastewater treatment plant outfalls. However, periphyton data were highly variable and showed no response. We propose several hypotheses as regards the factors that may have led to the decrease in mountain whitefish, based on the data from all trophic levels and the spatial pattern for fish biomass. Proposed factors influencing the mountain whitefish decline were; altered competitive ability because of macrophyte abundance, ammonia toxicity and barriers to movement (weirs).     

Calcium concentration and the exudation of sugars from pegs and fruits of axenic peanut plants

Higher populations of total fungi, bacteria and actinomycetes occur in the geocarposphere of peanuts than in bulk soil. One of the factors that affects exudation of organic substrate is Ca²⁺ concentration in the pegging medium. Plants of Arachis hypogaea L. cv. Argentine were grown axenically and the effect of three concentrations of Ca²⁺ on exudation of sugars from excised fruits at different stages of development was measured. The amount of total sugar exuded was greatest at 10 mg Ca²⁺ 1^?1 in the bathing solution after 48 h. More sugar was exuded from peg sections than from older fruits and the difference depended upon whether results were expressed as mg sugar g^?1 fruits or μg per fruit. Of the three sugars exuded the quantities decreased in the order sucrose, fructose, and glucose.     

Effects of adding fat to the sow lactation diet on lactation and rebreeding performance

One-hundred-three multiparous sows were randomly assigned to one of two lactation diets containing either no supplemental animal fat (C) or 10% added fat (F) during two seasons, summer (S) and winter (W), in a 2 X 2 factorial arrangement of treatments. Sows were placed on their respective dietary treatments 1 wk prior to farrowing and were fed these diets ad libitum throughout the 28-d lactation period. Weekly feed intake and total feed intake were not affected by diet or season, while weekly metabolizable energy (ME) intake tended to be higher during week 1 and 3, and was higher (P less than .04) during wk 2 for sows fed diet F. Sow weight loss from farrowing to 21 d of lactation and to weaning (28 d) were unaffected by diet or season. Average pig birth weight was .15 kg higher (P less than .01) for pigs born during S compared with those born in W. Sows receiving diet F had heavier litters at 21 d (P less than .01) and heavier average pig 21-d weights (P less than .01). This was primarily due to the 13.1% increase (P less than .04) in estimated milk yield and the higher fat concentration (P less than .001) of milk consumed by the pigs nursing sows fed diet F. Interval between weaning and rebreeding was shortened by 5.9 d (P less than .01) for sows during W than during S, and tended to be lower for sows fed diet F (7.3 d) compared with that of sows fed diet C (9.7 d).(ABSTRACT TRUNCATED AT 250 WORDS)     

Crustal Layer of Seismic Velocity 6.9 to 7.6 Kilometers per Second under the Deep Oceans

Refraction measurements made in the deep ocean between the Marshall and Hawaiian islands reveal a layer of seismic velocity 7.3 kilometers per second between the 6.8 kilometer per second oceanic crustal layer and the mantle. This layer, normally masked as a second arrival, is revealed by continuous air gun refraction data. The layer may be widespread in the deep oceans.     

Comparison of two shampoos for the treatment of canine Malassezia dermatitis: a randomised controlled trial

Objectives : Two antimicrobial shampoos for treatment of canine Malassezia dermatitis (CMD) were compared in a prospective, randomised, single‐blinded, field clinical trial. Methods : Sixty‐seven dogs with pedal or generalised dermatitis associated with Malassezia overgrowth (MO) were treated with 3% chlorhexidine shampoo (3%CHX) or 2% miconazole‐2% chlorhexidine shampoo (2%MIC/CHX) and evaluated for up to 6 weeks until cytological recovery. Pruritus, erythema, papules, greasy seborrhoea, scaling, malodour, excoriations, secondary hairloss, lichenification, hyperpigmentation and lesion extent were each scored on a 0‐3 severity scale and combined making an aggregate score. Results : Among 54 dogs with good treatment compliance, reduction of yeast counts by at least 88% was recorded in 21 of 22 dogs with 3%CHX and 30 of 32 dogs with 2%MIC/CHX. No significant difference was detected between products for yeast count reduction (P=0·592). Time to cytological recovery was not significantly different between groups (P=0·960). Lesion score was significantly reduced in both groups after treatment (72·5 ±25·7% with 3%CHX versus 78·7 ±22·3% with 2%MIC/CHX, P=0·309). Four dogs treated with chlorhexidine shampoo showed minor adverse effects. Clinical Significance : In this study, 3%CHX was clinically as effective as 2%MIC/CHX for treatment of CMD.