Trace metals in the hair of habitants of the Ok Tedi region, Papua New Guinea

It has long been known that mining activity can markedly change the level and distribution of certain heavy metals in the adjacent environment. This pollution can be quite widespread and long lasting and often has deleterious effects on the health of local populations. In the present study scalp hair was used as the biopsy material because of its ease of collection and long history of use in this connection. Hair was collected from all the local villages in the vicinity of the mine site, as well as from Papua New Guinean nationals from other provinces, and European expatriates who were employed by the mining company and who were resident in the area. Hair from local people showed a remarkably high iron content by comparison with previously studied populations. The extreme variations in hair iron levels were reflected in the differential distribution of levels according to location, age and sex. Hair cadmium was also high in the population studied. Hair copper, lead, zinc and mercury all appeared to be within 'normal' limits by comparison with other general populations. These results are discussed in the context of the environmental and social impact of the mining operations on the local people.     

Adversarial safety analysis: borrowing the methods of security vulnerability assessments

INTRODUCTION: Safety and security share numerous attributes. The author, who heads the (Security) Vulnerability Assessment Team at Los Alamos National Laboratory, therefore argues that techniques used to optimize security might be useful for optimizing safety. OPTIMIZING SECURITY: There are three main ways to attempt to improve security-security surveys, risk assessment (or "design basis threat"), and vulnerability assessments. The latter is usually the most effective. SAFETY ANALOGS: Vulnerability assessment techniques used to improve security can be applied to safety analysis--even though safety is not ordinarily viewed as having malicious adversaries (other than hazards involving deliberate sabotage). Thinking like a malicious adversary can nevertheless have benefits in identifying safety vulnerabilities. SUGGESTIONS: The attributes of an effective safety vulnerability assessment are discussed, and recommendations are offered for how such an adversarial assessment might work. CONCLUSION: A safety vulnerability assessment can potentially provide new insights, a fresh and vivid perspective on safety hazards, and increased safety awareness.     

WalkSafe: a school-based pedestrian safety intervention program

OBJECTIVE: To evaluate the effectiveness of the WalkSafe program, an elementary school-based pedestrian safety program in a single high-risk district in Miami-Dade County. METHODS: Sixteen elementary schools were identified in a single high-risk district and enrolled in a one-year study. All schools implemented the WalkSafe program on the last week of January 2003. A pre, post, and three-month post testing of pedestrian safety knowledge was conducted. An observational component was also implemented at four schools that were randomly chosen. Engineering recommendations and law enforcement initiatives were also performed. RESULTS: A total of 6467 children from K-5th grade from 16 elementary schools participated in the program. Of these 5762 tests were collected over three different testing times. A significant difference (p-value < 0.001) was found between the pre and post testing conditions across all grade levels. There was no significant difference found between the post and three-month post testing conditions across all grade levels (p-value > 0.05). The observational data collected at four schools across the different testing times demonstrated a significant difference found between pre and post testing conditions for Group A (stop at the curb and look left, right, left) and also for Group B (midstreet crossing and darting out) (p-value < 0.05). There was no difference found between comparing the pre-test or post-test condition with the three-month post-test time. There were many environmental modifications that were recommended and actually performed. CONCLUSION: The WalkSafe program implemented in a single high-risk district was shown to improve the pedestrian safety knowledge of elementary school children. The observational data demonstrated improved crossing behaviors from pre-test to post-testing conditions. Future research will focus on sustaining the program in this district and expanding the program throughout our county.     

Denitrification in a coastal plain riparian zone contiguous to a heavily loaded swine wastewater spray field

Riparian zones are recognized as landscape features that buffer streams from pollutants, particularly nitrogen. The objectives of this experiment were to (i) assess denitrification activity within a riparian zone and (ii) determine the influence of physical, chemical, and landscape features on denitrification. This experiment was conducted from 1994 to 1997 in North Carolina on a riparian zone contiguous to a spray field that was heavily loaded with swine lagoon wastewater. Denitrification enzyme activity (DEA) was measured on soils collected from (i) the soil surface, (ii) midway between the soil surface and water table, and (iii) above the water table. The DEA ranged from 3 to 1660 microg N(2)O-N kg(-1) soil h(-1). The DEA was highest next to the stream and lowest next to the spray field. Nitrate was found to be the limiting factor for denitrification. The DEA generally decreased with soil depth; means for the surface, middle, and bottom depths were 147, 83, and 67 microg N(2)O-N kg(-1) soil h(-1), respectively. These DEA values are higher than those reported for riparian zones adjoining cropland of the southeastern United States, but are lower than those reported for a constructed wetland used for treatment of swine wastewater. Regression analysis indicated that soil total nitrogen was the highest single factor correlated to DEA (r(2) = 0.65). The inclusion of water table depth, soil depth, and distance from the spray field improved the R(2) to 0.86. This riparian zone possessed sufficient soil area with high denitrifying conditions to be a significant factor in the removal of excess nitrogen in the ground water.     

Reusability of sewage sludge in clay bricks

Bricks produced from sewage sludge in different compositions were investigated. Results of the tests indicated that the sludge proportion is a key factor in determining the brick quality. Increasing the sludge content results in a decrease in brick shrinkage, bulk density, and compressive strength. Brick weight loss on ignition was mainly due to the contribution of the contained organic matter from the sludge being burnt off during the firing process, as well as inorganic substances found in both clay and sludge. The physical, mechanical, and chemical properties of the bricks that were supplemented with various proportions of dried sludge from 10 to 40wt% and generally complied with the General Specification for Brick as per the Malaysian Standard MS 7.6:1972, which dictates the requirements for clay bricks used in walling in general. A standard leaching test method also showed that the leaching of metals from the bricks is very low.     

Spectroscopic speciation and quantification of lead in phosphate-amended soils

The immobilization of Pb in contaminated soils as pyromorphite [Pb(5)(PO(4))(3)Cl, OH, F] through the addition of various phosphate amendments has gained much attention in the remediation community. However, it is difficult to fully determine the speciation and amount of soil Pb converted to pyromorphite by previously employed methods, such as selective sequential extraction procedures and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, which often lead to erroneous results in these non-equilibrated and heterogeneous systems. Statistical analysis by linear combination fitting (LCF) applied to X-ray absorption fine structure (XAFS) spectroscopic data of Pb-contaminated soil samples relative to known Pb reference material provides direct, in situ evidence of dominate Pb species in the amended soils without chemical or physical disruption to the Pb species as well as a weighted quantification output. The LCF-XAFS approach illustrated that pyromorphite concentration ranged from 0% (control soil) to 45% (1% phosphoric acid amendment, residence time of 32 mo) relative to the total Pb concentration. The Pb speciation in the nonamended control soil included Pb-sulfur species (galena + angelsite = 53%), adsorbed Pb (inner-sphere + outer-sphere + organic-bound = 45%), and Pb-carbonate phases (cerussite + hydrocerussite = 2%). The addition of P promoted pyromorphite formation and the rate of formation increased with increasing P concentration (up to 45%). The supplemental addition of an iron amendment as an iron-rich byproduct with triple superphosphate (TSP) enhanced pyromorphite formation relative to independent TSP amendment of like concentrations (41 versus 29%). However, the amendment of biosolids and biosolids plus TSP observed little pyromorphite formation (1-16% of total Pb), but a significant increase of sorbed Pb was determined by LCF-XAFS.     

Lead reduction and redistribution in the forest floor in New Hampshire northern hardwoods

Because of the affinity of organic matter for lead, atmospheric loadings of this pollutant have been strongly retained in the forest floor. With the regulation of Pb emissions, loadings have decreased. We measured changes in Pb in forest floor horizons at a variety of northern hardwood sites in New Hampshire from the late 1970s to the 1990s. In all seven of the sites in which horizons were distinguished within the forest floor, Pb was found to be declining in the upper (Oie) horizon, but not in the underlying Oa and A horizons. At the Hubbard Brook Experimental Forest (HBEF), this loss from the Oie resulted in a 36% loss of Pb from the forest floor as a whole between 1976 and 1997 (p < 0.001). In contrast, in six stands in the Bartlett Experimental Forest (BEF), losses of Pb averaging >50% from the Oi and Oe horizons (p = 0.01) between 1979 and 1994 were compensated by gains in the Oa and A horizons. Similarly, at seven additional stands in the White Mountain National Forest, changes in the forest floor as a whole from 1980 to 1995 were not statistically significant (redistribution within the forest floor was not evaluated at these sites). Lead concentrations were highest in the Oe or Oie in the 1970s, but were highest in the Oa horizon in the 1990s. There was no significant pattern of Pb loss or retention as a function of stand age across all the sites.     

Combined chemical and biological oxidation of penicillin formulation effluent

Antibiotic formulation effluent is well known for its important contribution to environmental pollution due to its fluctuating and recalcitrant nature. In the present study, the chemical treatability of penicillin formulation effluent (average filtered COD(o)=830 mg/l; average soluble COD(o)=615 mg/l; pH(o)=6.9) bearing the active substances penicillin Amoxicillin Trihydrate (C(16)H(19)N(3)O(5)S.3H(2)O) and the beta-lactamase inhibitor Potassium Clavulanate (C(8)H(8)KNO(5)) has been investigated. For this purpose, the penicillin formulation effluent was subjected to ozonation (applied ozone dose=2500 mg/(lxh)) at varying pH (2.5-12.0) and O(3)+H(2)O(2) (perozonation) at different initial H(2)O(2) concentrations (=2-40 mM) and pH 10.5. According to the experimental results, the overall Chemical Oxygen Demand (COD) removal efficiency varied between 10 and 56% for ozonation and 30% (no H(2)O(2)) and 83% (20 mM H(2)O(2)) for the O(3)+H(2)O(2) process. The addition of H(2)O(2) improved the COD removal rates considerably even at the lowest studied H(2)O(2) concentration. An optimum H(2)O(2) concentration of 20 mM existed at which the highest COD removal efficiency and abatement kinetics were obtained. The ozone absorption rate ranged between 53% (ozonation) and 68% (perozonation). An ozone input of 800 mg/l in 20 min was sufficient to achieve the highest BOD(5)/COD (biodegradability) ratio (=0.45) and BOD(5) value (109 mg/l) for the pre-treated penicillin formulation effluent. After the establishment of optimum ozonation and perozonation conditions, mixtures of synthetic domestic wastewater+raw, ozonated and perozonated penicillin formulation effluent were subjected to biological activated sludge treatment at a food-to-microorganisms (F/M) ratio of 0.23 mg COD/(mg MLSSxd), using a consortium of acclimated microorganisms. COD removal efficiencies of the activated sludge process were 71, 81 and 72% for pharmaceutical wastewater containing synthetic domestic wastewater mixed with either raw, ozonated or perozonated formulation effluent, respectively. The ultimate COD value obtained after 24-h biotreatment of the synthetic domestic wastewater+pre-ozonated formulation effluent mixture was around 100 mg/l instead of 180 mg/l which was the final COD obtained for the wastewater mixture containing raw formulation effluent, indicating that pre-ozonation at least partially removed the non-biodegradable COD fraction of the formulation effluent.