The persistence of chronically accumulated hydrocarbons in the hard shell clam Mercenaria mercenaria

Hard shell clams, Mercenaria mercenaria, from the chronically polluted environment of the Providence River, USA, were transferred to a clean laboratory system located in lower Narragansett Bay, Rhode Island. The hydrocarbon contents of these transplanted clams were monitored for 120 days after transfer. After this period only slight depuration had occurred. A 41.9 g g wet weight^-1 average initial hydrocarbon burden decreased to 29.3 g g^-1, a decrease that became statistically significant (P<0.1) only after 120 days. At most, only 30% of the clams' hydrocarbons were lost. These findings indicate that the duration of the exposure period and the chemical nature of the source hydrocarbons are both instrumental in determining the persistence of these compounds in filter-feeding bivalves. Chronically accumulated petroleum hydrocarbons are strongly retained by the organisms and are only very slowly depurated.     

Subject Index

Subject Index

Subject Index     

Improving rigor in polycyclic aromatic hydrocarbon source fingerprinting

Source identification of polycyclic aromatic hydrocarbons in environmental samples has advanced greatly in the last 20 years and continues to advance. To realize potential benefits and avoid possible pitfalls, however, great care is needed as one applies published diagnostic tools to data sets. This commentary reflects some recent observations, concerns, and recommendations.     

A method to determine the effect of mineral dust aerosols on air quality

Natural mineral dust storms (DS) from the Arabo-African region blow over the Mediterranean, reach Israel, and add to the anthropogenic particulate pollution. The effects of mineral dust on air quality in Israel were investigated using only PM10 and PM2.5 automatic measurements. The method does not require any other inputs such as satellite observations, model back-trajectories, dust forecast models, or mineralogical analyses. The method employs an automatic algorithm with three thresholds: the half-hour PM10 average must be above 100, this level is maintained for at least 3 h, and the maximum concentration recorded is above 180 μg m^?3. The algorithm was designed for Israel, but can be adapted for other locations.The contribution of DS caused PM10 values to exceed the Israeli annual standard of 60 μg m^?3 year^?1 in 6 of the 12 years examined. The DS contribution to PM10 annual average ranged from 9.4% to 29.5%. The level recommended by WHO, 20 μg m^?3 year^?1, was exceeded every year even without the DS contribution. The number of days in which the daily Israeli standard (150 μg m^?3) was exceeded during the 12 years was 6–20 days per year. The number of days in which the daily standard was exceeded shows an increasing trend of 7 days per decade.PM2.5 in Israel is in the range 40–56% of PM10. PM2.5 values were over the recommended standard with and without DS. The contribution of DS to annual average of PM2.5 ranged from 3.6% to 19.1%.The automatic algorithm was calibrated with a list of Dust Storms identified by visual means supported by mineralogical analysis. Mineralogical analyses of single particles were performed using Environmental Scanning Electron Microscope (ESEM). Two representative samples are given. The main difference is that the particles of the Saudi-Arabian storm had much more palygorskite, while the North-African storm had more sea-salt and organic particles. The mineral composition differences indicate that analysis can differentiate between sources.     

A novel methodology to estimate the evolution of construction waste in construction sites

This paper focuses on the accumulation of construction waste generated throughout the erection of new residential buildings. A special methodology was developed in order to provide a model that will predict the flow of construction waste. The amount of waste and its constituents, produced on 10 relatively large construction sites (7000-32,000 m² of built area) was monitored periodically for a limited time. A model that predicts the accumulation of construction waste was developed based on these field observations. According to the model, waste accumulates in an exponential manner, i.e. smaller amounts are generated during the early stages of construction and increasing amounts are generated towards the end of the project. The total amount of waste from these sites was estimated at 0.2 m³ per 1 m² floor area. A good correlation was found between the model predictions and actual data from the field survey.     

The “Tsesis” oil spill: Acute and long-term impact on the benthos

The “Tsesis” oil spill in October 1977 resulted in the release of over 1 000 tons of medium grade fuel oil in an archipelago in the brackish Baltic Sea. Considerable oil quantities reached the benthos by sedimentation. Within 16 d benthic amphipods of the genus Pontoporeia, as well as the polychaete Harmothoe sarsi Kinberg, showed reduction to less than 5% of pre-spill biomasses at the most impacted station. The clam Macoma balthica (L.) was more resistant, and showed little or no mortality, but was heavily contaminated by oil (about 2 000 μg g^-1 dry wt total hydrocarbons). The meiofauna was strongly affected, with ostracods, harpacticoids, Turbellaria and kinorhynchs showing clear reductions in abundance, while nematodes, as a group, were more resistant. In the winter following the spill gravid Pontoporeia affinis Lindström females showed a statistically significant increase in the frequency of abnormal or undifferentiated eggs. Food-chain transfer of oil to flounder [Platichthys flesus (L.)] was indicated. Not until the second summer after the spill were the first signs of recovery noted at the most heavily impacted station: Amphipods, H. sarsi and harpacticoids increased and the oil concentrations in M. balthica decreased (to about 1 000 μg g^-1). In the area where amphipods had been virtually eliminated, there was an unusually heavy recruitment of M. balthica, reaching 4 000 juveniles, of 1.5–2 mm length, per square metre, probably from settling in summer 1978. Three years after the spill Pontoporeia spp. biomass was still depressed in the most affected area, while H. sarsi showed normal biomass, and M. balthica abundance was inflated. Oil concentrations in M. balthica (about 250 μg g^-1) and flounder were only slightly elevated and the oil could no longer be confidently ascribed to “Tsesis” origin, even using GC/MS-analysis. Recovery was thus underway, but the long lifespan of M. balthica implies that the disturbed community composition may persist for many years at this station. Full recovery is likely to require more than 5 yr and may take a decade or more. An effort to evaluate the accumulated monetary loss to fishery from the accident indicates that direct costs of shoreline cleanup and vessel damage were considerably greater.     

The functions of social service workers at a time of war against a civilian population

This article identifies the nature of functions that social service workers employed by municipal organisations have to perform during a community disaster and subsequent reorganisation at a time of war. The article also explores to what extent the functions of workers change as a result of the transition from a peacetime routine to a war situation. Using focus groups the study assesses the knowledge of social service workers and ordinary citizens who had direct experience of the second Lebanese war in Israel (2006). Eight major functions needed at a time of disaster are distinguished among various employees. The article discusses the significance of these functions, and the need to make changes in the network of functions at a time of disaster.