Induced anti-predator responses of the green mussel, Perna viridis (L.), on exposure to the predatory gastropod, Thais clavigera Küster, and the swimming crab, Thalamita danae Stimpson

A laboratory experiment was conducted to test whether anti-predator responses could be induced in the green mussel, Perna viridis, on exposure to waterborne cues from two predators, the muricid gastropod, Thais clavigera, and the portunid crab, Thalamita danae, and from damaged conspecifics. There were five treatments in this study. Aquaria of two treatments housed either Thalamita danae or Thais clavigera. Another three treatments housed only intact mussels, broken and intact mussels, or no mussels. No significant differences were found among these five treatments in final shell weight and tissue dry weight. Induced defensive responses were predator-specific. Experimental mussels exposed to waterborne cues of T. clavigera had a higher percentage increase in shell length, height and width, whereas those exposed to waterborne cues of T. danae had a higher percentage increase in shell width and height. Mussels raised in the presence of crabs developed thicker shell at the umbo and lip margin, whereas mussels raised in the presence of gastropods had thicker shell lip. Predator preference for mussels from the control group and for those pre-exposed to waterborne cues of either of the predators was studied. T. clavigera preferentially selected mussels from the control group, whereas no prey preference was found for T. danae, although shell breaking time for mussels exposed to a crab was longer than that for the control. While the present results should be viewed with caution in the absence of a dietary control, this was the first time that prey handling was shown to be affected by defensive changes in the morphology of mussels.Communicated by T. Ikeda, Hakodate     

Effects of the mosquito larvicide GB-1111 on bird eggs

Golden Bear Oil (GB-1111; legal trade name for GB-1313) is a petroleum distillate used in the United States and other countries as a mosquito larvicide. As part of an evaluation of the potential effects of GB-1111 on birds, fertile eggs of mallards (Anas platyrhynchos) and bobwhite (Colinus virginianus) were incubated in the laboratory, and treated on day 4 of incubation with external applications equivalent to either 0, 1/3, 1, 3 or 10 times the maximum rate (X) of 47 l/ha (5 gal/A) of field application of GB-1111. Hatching success was significantly reduced in mallards treated at 3 and 10 times the maximum field application, with a calculated approximate LD50 of 1.9 times the maximum field application. Most mortality occurred within a week of treatment. Hepatic P450-associated monooxygenase activity (ethoxyresorufin-O-dealkylase; EROD) was negatively related to dose. In the 3X group there was a significant increase in the concentration of hepatic reduced glutathione (GSH) but a decrease in protein-bound thiols (PBSH). Hatching success of bobwhite was marginally reduced at the highest level of treatment (10X). Other effects at this level in bobwhite included a significant increase in incidence of abnormal embryos or hatchlings, lower body and liver weights, and a two-fold increase in hepatic microsomal EROD activity in hatchlings. The recommended maximum rate of field application of GB-1111 is unlikely to impair the survival or development of bobwhite embryos but is potentially toxic to mallard embryos under conditions of larvicide drift or spray overlap.     

Rotational application of bioinsecticide with deltamethrin-An antilarval measure for the control of filarial vector, Culex quinquefasciatus (Culicidae: Diptera)

A laboratory investigation was undertaken to study the cyclic usage of field recommended doses of Bacillus thuringiensis israelensis (Bti), Bacillus sphaericus (Bsp) and combination of Bti and Bsp (half the recommended dose of each) with deltamethrin 2.8 EC to attain better control of mosquito larvae. To understand the susceptibility status of the Culex quinquefasciatus larvae in the field, early fourth instar field collected larvae were exposed to the above treatments of biopesticides and were monitored for their persistency till 50% mortality was obtained. The larvae those survived in each treatment were transferred to the concentration of deltamethrin that gave 50% mortality. Observations on larval mortality after the treatment with deltamethrin were recorded after 24 h. The results revealed that Bti excels Bsp, as it recorded 54% mortality only on 17th day after application. The other salient finding of this study is LC50 of deltamethrin is sufficient to follow the biopesticides application for an effective control of Culex larvae.     

Correlations in the chemical composition of rural background atmospheric aerosol in the UK determined in real time using time-of-flight mass spectrometry

An aerosol time-of-flight mass spectrometer (ATOFMS) was used to determine, in real time, the size and chemical composition of individual particles in the atmosphere at the remote inland site of Eskdalemuir, Scotland. A total of 51,980 particles, in the size range 0.3-7.4 microm, were detected between the 25th and 30th June 2001. Rapid changes in the number density, size and chemical composition of the atmospheric aerosol were observed. These changes are attributed to two distinct types of air mass; a polluted air mass that had passed over the British mainland before reaching Eskdalemuir, interposed between two cleaner air masses that had arrived directly from the sea. Such changes in the background aerosol could clearly be very important to studies of urban aerosols and attempts at source apportionment. The results of an objective method of data analysis are presented. Correlations were sought between the occurrence of: lithium, potassium, rubidium, caesium, beryllium, strontium, barium, ammonium, amines, nitrate, nitrite, boron, mercury, sulfate, phosphate, fluorine, chlorine, bromine, iodine and carbon (both elemental and organic hydrocarbon) in both fine (d < 2.5 microm) and coarse (d > 2.5 microm) particle fractions. Several previously unreported correlations were observed, for instance between the elements lithium, beryllium and boron. The results suggest that about 2 in 3 of all fine particles (by number rather than by mass), and 1 in 2 of all coarse particles containing carbon, consisted of elemental carbon rather than organic hydrocarbon (although a bias in the sensitivity of the ATOFMS could have affected these numbers). The ratio of the number of coarse particles containing nitrate anions to the number of particles containing chloride anions exceeded unity when the air mass had travelled over the British mainland. The analysis also illustrates that an air mass of marine origin that had travelled slowly over agricultural land can accumulate amines and ammonium.     

A study about remedial measures to reduce 222Rn concentration in an experimental building

Radon gas emanating from underground can spread to adjoining closed areas. It can concentrate and reach levels which represent a risk to people's health. It is well known that radon presence in most areas depends mainly on the area's geological features. Indoor radon concentrations further depend on the type of structure, construction materials and the technology used for the building. Therefore, indoor radon monitoring is of primary importance for deciding whether remedial measures are to be adopted for reducing harmful concentrations. This approach has been tried by measuring radon concentration in an experimental building situated in Milan (Italy). This building situated in a geological area that is considered at low radon risk. The results were obtained after analysing radon concentration in indoor rooms, crawl spaces, soil gas and in the atmosphere outside and by measuring before and after adoption of remedial measures. The study shows that improper building design can give rise to higher indoor radon accumulation even in an area of poor radon exhalation. Furthermore, the results enable quantification of the effectiveness of the remedial measures.     

239+240Pu, 90Sr and 137Cs inventories in surface soils of Vietnam

Fallout 239+240Pu, 238Pu, 90Sr and 137Cs inventories in surface soils were measured for 20 locations in northern Vietnam yielding the mean values (+/- standard error) of 26.5+/-3.8 Bq m(-2) for 239+240Pu, 1048+/-143 Bq m(-2) for 137Cs and 212+/-28 Bq m(-2) for 90Sr. The concentrations of 137Cs and plutonium isotopes strongly correlate with each other resulting in a stable 239+240Pu/137Cs inventory ratio of 0.025+/-0.002. Among soil parameters, organic matter and fulvic acids strongly correlate with caesium and plutonium isotopes, especially in the 0-10 cm layer. 137Cs and 239+240Pu are distributed rather similarly over the 0-10 cm and 10-20 cm layers. At locations with high contents of sand (82-93%) along the South China Sea coast, the downward percolation by rainwater results in a higher accumulation of 239+240Pu and 137Cs in the 10-20 cm layer. The mean 137Cs/ 90Sr inventory ratio is 9.3+/-2.2, and the correlation is weak between these isotopes.     

Heavy metal levels and esterase variations between metal-exposed and unexposed duckweed Lemna minor: field and laboratory studies

Environmental homogeneity is being continuously disturbed and affected by artificially introduced loads of chemical toxicants that also include heavy metals. The Tiljala wetlands of the eastern fringe of Calcutta, West Bengal (India) are a virtual sink for the deposition of urban and industrial wastes that get admixed with the aquatic environment. We have selected Lemna minor (duckweed), as a representative of the biota surviving therein for the present study. Concentrations of lead, cadmium, chromium, zinc, copper and mercury in the fronds of Lemna were measured to peep into the range of input of heavy metals in the duckweed subjects. Natural unexposed population of duckweed from a domestic pond in Batanagar area, 24 Parganas, West Bengal (India) was also found to accumulate similar concentrations of these metals when cultured in artificially contaminated water in the laboratory. The exposed individuals also exhibited polymorphism with respect to the loci of esterase, as compared to an unexposed control plants. Therefore, the present study suggests EST variations of L. minor to be a potential biomarker of heavy metal pollution.     

Foliar uptake of 134Cs and 85Sr in strawberry as function by leaf age

In this paper a study of the foliar uptake and translocation of 134Cs and 85Sr in a herbaceous fruit plant is presented. In particular, absorption, translocation and loss of these radionuclides in strawberry plants have been studied in relation to the age of contaminated leaves. Strawberry plants were contaminated by distributing droplets of an aqueous solution containing 134CsCl and 85SrCl2 on the surface of two leaves per plant. One half of the plants was contaminated through two young leaves, a second half through two old leaves. Sets of plants were collected 1 day, 7 days and 15 days after contamination. One half of them was rinsed with double distilled water before gamma analysis. Rinsing contaminated leaves removes on average 55% of the applied 134Cs and 45% of 85Sr. The activity removed decreases during the 15 days of the experimental study, both for 134Cs and for 85Sr, suggesting an increase in foliar absorption during this period. The activity removed does not differ between old and young leaves. "External loss" is lower for young than old contaminated leaves. "Internal loss" through translocation occurs mainly for 134Cs. Translocation coefficients from contaminated leaves to fruits are two orders of magnitude higher for 134Cs (4.0%), than for 85Sr (0.05%). Leaf to fruit translocation coefficients for 134Cs are higher from young leaves (5.8%), than from old leaves (2.3%).