Challenges with tracing the fate and speciation of mine-derived metals in turbid river systems: implications for bioavailability

The fast-flowing and highly turbid Lagaip River (0.5–10 g/L suspended solids) in the central highlands of Papua New Guinea receives mine-derived metal inputs in both dissolved and particulate forms. Nearest the mine, metal concentrations in suspended solids were 360, 9, 90, 740 and 1,300 mg/kg for As, Cd, Cu, Pb and Zn, while dissolved concentrations were 2.7, 0.6, 3.1, 0.1 and 25 μg/L, respectively. This creates a significant metal exposure source for organisms nearer the mine. However, because the Lagaip River is diluted by a large number of tributaries, the extent to which mine-derived metals may affect biota in the lower catchments is uncertain. To improve our understanding of the forms of potentially bioavailable metals entering the lower river system, we studied the partitioning and speciation of metals within the Lagaip River system. Dissolved and particulate metal concentrations decreased rapidly downstream of the mine due to dilution from tributaries. As a portion of the particulate metal concentrations, the more labile dilute acid-extractable forms typically comprised 10–30 % for As and Pb, 50–75 % for Cu and Zn, and 50–100 % for Cd. Only dissolved Cd, Cu and Zn remained elevated relative to the non-mine-impacted tributaries (<0.03, 0.5 and 0.3 μg/L), but the concentrations did not appreciably change with increasing dilution downriver. This indicated that release of Cd, Cu and Zn was likely occurring from the more labile metal phases of the mine-derived particulates. Chelex-labile metal analyses and speciation modelling indicated that dissolved copper and lead were largely non-labile and likely complexed by naturally occurring organic ligands, while dissolved cadmium and zinc were predominantly present in labile forms. The study confirmed that mine-derived particulates may represent a significant source of dissolved metals in the lower river system; however, comparison with water quality guidelines indicates the low concentrations would not adversely affect aquatic life.     

Insecticidal activity of raw ethanolic extracts from Magnolia dealbata Zucc on a tephritid pest

Ethanolic extracts from Magnolia dealbata (Zucc.) (Magnoliaceae); leaves, bark, seeds, sarcotesta and flowers were evaluated for insecticidal activity against adults of the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae). Using feeding bioassays composed from sugar-extract mixtures, only the extract from sarcotesta indicated insecticidal activity against the flies. The extracts from the other four plant tissues (leaves, bark, seeds and flowers) did not manifest any biological activity. The most effective extract was obtained from oven-dried sarcotesta, whereas extracts from fresh sarcotesta were inactive. Our results suggest that M. dealbata sarcotesta contains secondary metabolites with insecticidal activity against A. ludens adults. These metabolites are as potent as natural pyrethins and represent a potential substance for controlling this type of pest.     

Determination of Source Contributions to Ambient Volatile Organic Compound Concentrations in Berlin

ABSTRACT

During three measuring campaigns in June, July, and August 1996, volatile organic compound (VOC) concentrations were measured at a rural background site, a city residential site, and a street site in Berlin. In addition, samples were taken near relevant sources of VOCs. The meaurements covered the volatile hydrocarbons in the range C₁-C₁₄ and included aldehydes and ketones. Samples were taken at four characteristic periods of 2 hr/day: during the night, during the early morning rush hour, at midday, and during the evening rush hour. An assessment of the contribution of emission categories to the observed concentrations was made with the chemical mass balance (CMB) modelling technique.

The VOC concentrations at the residential area and at the street site in the inner city were, respectively, a factor of 3 and 7 above the background concentration. Traffic exhaust contributed approximately 80-90% of the non-methane hydrocarbon (NMHC) concentration in the inner city and approximately 60% at the background area. Evaporative losses of motor fuel are estimated to account for approximately 7% at all sites. Natural gas leakage also contributed significantly to the observed VOC concentrations: in the inner city approximately 510% and at the background area approximately 30%. The measurements also showed a contribution of smaller sources, such as dry cleaning, use of solvents, and bio-genic emissions. However, the contribution of these sources to the total observed concentrations at the sites is estimated to be very small.     

Observations and Interpretations from the Canadian Fine Particle Monitoring Program

ABSTRACT

Canadian particle monitoring programs examining PM10, PM2.5, and particle composition have been in operation for over 10 years. Until recently, the measurements were manual/filter-based with 24-hr sample collection varying in frequency from daily to every sixth day, using GrasebyAnderson dichotomous samplers. In the past few years, these monitoring activities have been expanded to include hourly measurements using tapered element oscillating microbalances (TEOMs). This continuous monitoring program started operation focusing on PM_10, but now emphasizes PM_2.5 through the addition of more TEOMs and switching of the inlets of some of the existing units. The data from all of these measurement activities show that there are broad geographical differences and also local- to regional-scale spatial differences in mass and composition of PM2.5. Due to variations in sources, significantly different PM2.5 concentrations are not uncommon within the same city. Comparison of nearby urban and rural sites indicates that 30 and 40% of the PM_2.5 is from local urban sources in Montreal and Toronto, respectively. Hourly PM_2.5 measurements in Toronto suggest that vehicular emissions are an important contributor to urban PM_2.5. There has been a decreasing trend in urban PM_2.5, with annual average concentrations between the 1987–1990 and 1993–1995 periods decreasing by 11 to 39%, depending upon the site. The largest declines were in Montreal and Halifax, and the smallest decline was in Toronto. Comparison of 24-hr TEOM and manual dichotomous sampler PM_2.5 measurements from a site in Toronto indicates that the TEOM results in lower concentrations. The magnitude of this difference is relatively small in the warmer months, averaging about 12%. During the colder months the difference averages about 23%, but can be as large as 50%.     

Improvement of Air Quality in a Small Indoor Ice Arena by Effective Emission Control in Ice Resurfacers

ABSTRACT

The effectiveness of a new emission control system in the ice resurfacer was tested in an exhaust gas emission laboratory, and the improvement of the air quality in a small, enclosed ice arena was demonstrated in a 4.5-month follow-up study. The emission control system consisted of a lambda sensor-controlled fuel supply and a three-way metallic catalyst that were applied to a propane-fueled resurfacer. In the laboratory tests, the engine emissions of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO ) reduced simultaneously by 91, 90, and 96%, respectively. During the air quality follow-up the median 1-hour average nitrogen dioxide (N0₂) concentration inside the ice arena decreased from 430 ug/m³ (230ppb) to 58 ug/m³ (31 ppb), and that of CO decreased from 4.4 mg/m³ (3.8 ppm) to 1.5 mg/m³ (1.3 ppm). The new emission control system proved to be a feasible, reliable, and effective means to improve the indoor air quality in the ice arena. However, continuous mechanical ventilation was necessary during all business hours in order to achieve and maintain a fully acceptable air quality with this technology.     

Aerosol Particle Number Concentration Measurements in Five European Cities Using TSI-3022 Condensation Particle Counter over a Three-Year Period during Health Effects of Air Pollution on Susceptible Subpopulations

Abstract

In this study, long-term aerosol particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a condensation particle counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm^-3 and 20,000 cm^-3, whereas the summer min is ?;5000–6000 cm^-3. In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4–10. The winter maximum in both Rome and Barcelona is close to 100,000 cm^-3, whereas the summer minimum is >10,000 cm^-3. During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations.     

Thyroid ultrasound volume, structure and function after long-term high exposure of large population to polychlorinated biphenyls, pesticides and dioxin

We examined 2,046 adults (834 males and 1,212 females aged 20-75 years) from polluted district in East Slovakia (POLL) and two neighboring upstream and upwind located districts of background pollution (BCGR). By ultrasound we estimated the thyroid volume (ThV), hypoechogenicity (HYE), nodules and cysts. Serum levels of thyrotropin (TSH), thyroperoxidase antibodies (TPOab) and thyroglobulin were estimated by electrochemiluminiscent assay and these of 15 PCB congeners, p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and hexachlorocyclohexane by high-resolution gas chromatography. In 320 subjects also selected hydroxylated and methylsulfonated PCB metabolites, polychlorinated dibenzo-dioxins (PCDDs), -furans (PCDFs), five dioxin-like coplanar and eight mono-ortho PCB congeners were estimated. Urinary iodine was measured by automatic microplate method. Reciprocal positive association was found between three major POPs (PCBs, DDE and HCB), the levels of these and also PCDDs plus PCDFs in polluted area being considerably higher than in background pollution area. ThV in groups of males and females from POLL with high PCBs level was significantly higher (p<0.001 by t-test) then in age and sex matched groups from BCGR with low PCBs level. In 1,048 males and females aged <60 years with serum PCBs level >1,000 ng g(-1) lipid (median=1,756 ng g(-1)) a significant effect of age on ThV was found (p<0.01 by ANOVA), while in 921 respective subjects with PCBs level <1,000 ng g(-1) (median=661 ng g(-1)) it was not. These findings supported the view on the additional effect of PCBs on ThV other than that of age. Since the urinary iodine in both districts showed optimal range, any interfering effect of unsatisfactory iodine intake on ThV may be excluded. The frequency of autoimmune thyroiditis signs such as HYE, increased serum level of TPOab and TSH resulting in subclinical or overt thyroid hypofunction was positively associated with sex, age and organochlorine levels. The increase of such frequency in males with POPs levels was much more abrupt than that in females. No considerable differences in the frequency of thyroid nodules as related to PCBs level were found.     

Tissue heavy metal concentrations of stranded California sea lions (Zalophus californianus) in Southern California

Concentrations of nine heavy metals (As, Cd, Cu, Fe, Hg, Pb, Mn, Mo and Zn) were determined in the hepatic and renal tissues of 80 stranded California sea lions (Zalophus californianus). Significant age-dependant increases were observed in liver and kidney concentrations of cadmium and mercury, and renal zinc concentrations. Hepatic iron concentrations were significantly higher in females than males. Animals with suspected domoic acid associated pathological findings had significantly higher concentrations of liver and kidney cadmium; and significantly higher liver mercury concentrations when compared to animals classified with infectious disease or traumatic mortality. Significantly higher hepatic burdens of molybdenum and zinc were found in animals that died from infectious diseases. This is the largest study of tissue heavy metal concentrations in California sea lions to date. These data demonstrate how passive monitoring of stranded animals can provide insight into environmental impacts on marine mammals.