An impingement plate method to detect deposits of pyrethroid insecticides

Abstract

A silica gel impingement plate for monitoring pyrethroid deposits in environmentally sensitive areas is described. The plate is simple, commercially available, and inexpensive. A residue analysis method is given for deltamethrin deposits with 83.3% mean recovery and a minimum quantifiable limit of 0.005 μg/plate. Pyrethroid deposits are strongly adsorbed to the silica gel, which prevents wash‐off by rainfall and slows photodegradation. In two field experiments, deltamethrin was readily detected 3 weeks after direct spray applications at 6 and 10 g ai/ha. Deltamethrin dissipation on the plates was first‐order with a half‐life of 2.9 ‐ 3.7 d. Photoisomers of deltamethrin were also detected on the plates and the ratio of photoisomers to deltamethrin increased over time. This ratio will indicate the age of deposits in monitoring situations.     

Source and material balance of total organic halogen pollution in the Ayase River system,Japan

The total organic halogen (TOX) pollution in the highly polluted Ayase River system was investigated. Using the concentration of coexisting linear undecylbenzenesulfonate and the difference in the flowing water volume between summer and winter, the fractions of domestic and agricultural wastewaters in the whole water column were calculated and the variety of the TOX sources in the river was estimated. The river carried about 100 kgCl of TOX materials in one day; about 50 kgCl of the materials was from residential area in the basin. The contribution of agricultural drainage from paddy field was not negligible in summer. Highly contribution of industrial wastewater was observed in a tributary Furuayase River basin while the amount of TOX loaded in the area was widely varied; 0–105 kgCl of the materials was discharged as industrial wastewater.     

An impingement plate method to detect deposits of pyrethroid insecticides

A silica gel impingement plate for monitoring pyrethroid deposits in environmentally sensitive areas is described. The plate is simple, commercially available, and inexpensive. A residue analysis method is given for deltamethrin deposits with 83.3% mean recovery and a minimum quantifiable limit of 0.005 microgram/plate. Pyrethroid deposits are strongly adsorbed to the silica gel, which prevents wash-off by rainfall and slows photodegradation. In two field experiments, deltamethrin was readily detected 3 weeks after direct spray applications at 6 and 10 g ai/ha. Deltamethrin dissipation on the plates was first-order with a half-life of 2.9-3.7 d. Photoisomers of deltamethrin were also detected on the plates and the ratio of photoisomers to deltamethrin increased over time. This ratio will indicate the age of deposits in monitoring situations.     

Comparative study of the effects of infrasound and low-frequency sound with those of audible sound on sleep

In order to compare the effects of infrasound and low-frequency sound on sleep with those of audible sound, healthy students were exposed to two kinds of sound, (a) infrasound and low-frequency sound (10, 20, 40, and 60 Hz), and (b) synthesized traffic noise with peak sound pressure level in low-frequency range (sound composed of low and audible frequency), throughout their sleep with the recording of the students' EEG. The effects were evaluated by the “reaction rate”. Concerning sound (a), the sound pressure level which causes the reactions of over 50% for the first time was used as the threshold sound pressure level signifying the occurrence of sleep disturbance. The threshold sound pressure levels of 10 and 20 Hz could not be evaluated. The threshold sound pressure levels of 40 and 63 Hz were 95 and 90 dB, respectively. With both sounds, the reaction rate was the highest in sleep stage 1 and the lowest in sleep stage 3+4. The pattern of sleep was little affected by sound (a). On the other hand, it was considerably affected by sound (b). These results suggest that audible sound has more harmful effects on sleep, compared with infrasound and low-frequency sound.     

Uptake and distribution of 90Sr and stable Sr in rice plants

The stable Sr content in the aboveground parts of rice plants at various growth stages, and the distributions of 90Sr and stable Sr in rice plant components, such as polished rice, rice bran, hull, straw and root, at harvest time, were determined. The total Sr content in the aboveground rice plants was dependent on the growth stage and followed the sigmoidal shape of the growth curve. The concentration of 90Sr among the different components of rice plants varied within two orders of magnitude, whereas the 90Sr/Sr concentration ratio had a constant value. Therefore, the translocation rate of 90Sr in rice plants had similar values to that of stable Sr. However, the 90Sr/Sr concentration ratio for the rice plants was different for each study site. Only 0.6% of the total Sr was found in polished rice, while more than 99% was found in the non-edible components, of which 87% was present in the straw. These findings suggest that 90Sr in the non-edible parts could have been transferred to humans through the soil-plant system and/or feed-livestock pathway. The soil-to-plant transfer factor of 90Sr in polished rice was 0.0021 +/- 0.00007, which was two orders of magnitude lower than that in the straw. The percentage of 90Sr removed from the upper soil layer to the aboveground biomass of rice plants at harvest time was calculated as 0.094%. It is possible that approximately 0.1% of the total 90Sr content in the surface soil layer is removed from the soil-plant system by human activities every year.     

Concentration and specific activity of fallout 137Cs in extracted and particle-size fractions of cultivated soils

Fallout (137)Cs and stable Cs in soils were separated with two extractants (1M CH(3)COONH(4) solution and 0.8M CH(3)COONH(4) in 5% HNO(3) solution after H(2)O(2) oxidization). The residue remaining after removal of the oxidizable organic-bound fraction was separated into the particle-size fractions including clay, silt, fine sand and coarse sand with a sieving and sedimentation method. Then, the concentrations of (137)Cs and stable Cs in the extracted fractions and the particle-size fractions were determined. The (137)Cs contents in the exchangeable and organic-bound fractions in the soil were approximately 10 and 20%, respectively. The (137)Cs content in the strongly bound fraction was about 70%, and the concentration of (137)Cs in the clay was the richest among the particle-size fractions. The specific activity of (137)Cs (concentration ratio of fallout (137)Cs/stable Cs) decreased in the order exchangeable, organic-bound and strongly bound fractions. The data suggest that equilibrium between (137)Cs and stable Cs was not reached among those fractions, even though most of the (137)Cs that had been deposited on the soil was derived from fallout weapons tests that occurred several decades ago. The concentration of (137)Cs among the particle-size fractions in each soil was different, whereas the specific activity of (137)Cs in the particle-size fractions had a relatively similar value.     

Effects of dissolved organic matter on toxicity and bioavailability of copper for lettuce sprouts

It is well known that dissolved organic matter in soil solution may affect the toxicity or bioavailability of heavy metals to plants, but existing information on various organic substances is insufficient for treating problems with heavy metal-contaminated soils. To clarify how dissolved organic matter alters the toxicity and bioavailability of metals, we germinated lettuce seeds exposed to solutions containing Cu and several kinds of dissolved organic matters. Low molecular weight organic acids (citric, malic, and oxalic acids) increased the toxicity and bioavailability of Cu, but low concentrations of the synthetic chelators ethylenediamine tetra-acetic acid (EDTA) and diethylenetriamine penta-acetic acid (DTPA) decreased the toxicity and bioavailability of Cu. In contrast, humic acid appeared to be the most effective organic substance for detoxifying Cu, even though it did not significantly decrease the bioavailability of Cu. Consequently, the bioavailability and toxic effects of Cu in soil depend on the nature of coexisting organic substances in the soil solution.     

On‐target deposition of aerially applied deltamethrin

Abstract

The mean amount of deltamethrin deposited on natural substrates (i.e., soil and vegetation) in three experiments was 63, 73, and 76% of applied. Composite samples taken from 16 sites/replicate gave representative and repeatable measures of deposition. The use of Teflon discs as artificial targets to measure aerial deposition was investigated. The discs had only 34–71% mean trapping efficiency for the spray droplets. Deposition was quite variable among different sampling sites within a field (CV=73–83%). Much of this variation was caused by irregular overlapping of spray swaths.     

Centralization of dairy farming facilities for improved economics and environmental quality

In Japan, most farm animal excreta has been stored directly on farmland. Runoff from this storage has often caused water pollution. Biogasification is anticipated as an important technology to manage excreta properly, but complex problems hinder its introduction. Economic aspects of management have been especially difficult for dairy farmers. For this study, structural problems regarding introduction of biogasification into dairy farming were identified. Subsequently, a desirable system of dairy farming including biogasification was suggested, and an evaluation model of the financial balance was constructed. A case study using current financial balances of several systems of dairy farming was evaluated using the constructed model and actual data. The systems were based on several policy alternatives including the suggested system mentioned above. Results show that a farmer can obtain sufficient income from a system featuring centralization of dairy housing and biogasification facilities and coordinated management by over six farmers.     

Radon concentration in indoor occupational environments in Aomori Prefecture,Japan

The (222)Rn concentrations in indoor workplaces were measured in Aomori Prefecture, Japan, and the results are reported here. This survey was part of a program to measure background natural radiation dose rate in the prefecture where the first Japanese nuclear fuel cycling facilities are now under construction.The survey of the (222)Rn concentrations in indoor workplaces was carried out at 107 locations from 1996 to 1998. The (222)Rn concentrations were measured for approximately one year at each site with passive Rn detectors, which used a polycarbonate film for counting alpha-rays and could separate concentrations of (222)Rn from (220)Rn. Weeklong measurements of (222)Rn concentration and working level were carried out with active detectors to get the ratio of (222)Rn concentration during working hours to non-working hours as well as equilibrium factors in selected locations.Diurnal variation of (222)Rn concentration depended on building structure, air-conditioning, time of day and day of the week (week days or weekend). The (222)Rn concentration during working hours was generally lower than that in non-working hours. Although the annual average (222)Rn concentration in indoor occupational environments was higher than that in dwellings, radiation dose for Aomori Prefecture residents from Rn in the former was 14% of the total indoor dose by Rn because of the lower concentration in working hours and lower occupancy factor.