The radiation dose and environmental health risk of radon concentration in the Lantian karst cave of China to guides and visitors were estimated based on the continuous radon concentration monitoring. Distinct seasonal variations were observed in the radon concentration of the air inside the cave. The maximum concentration occurred in the summer, whereas the minimum radon concentration occurred during the winter. The annual average radon concentration in the caves investigated is slightly higher than the upper bound of radon action level for underground space used in China and less than the upper bound of radon action level recommended by the International Commission on Radiation Protection (ICRP) for workplaces. The annual effective dose to tour guides working in two investigated caves varies from 4.1 to 16.5mSv, depending on different equilibrium factors together with different dose conversion factors proposed in the literature. The annual maximum time that a tour guide or other worker can safely be inside the cave is estimated to be 1,250 or 2,246h, depending on whether one bases this on the high or mean radon concentration, with an equilibrium factor of one in both cases. Given the synergistic effects of smoking, tour guides who are smokers should be in the cave only 10-20% of these hours. In all cases, the annual effective doses to visitors are well below the 1mSv maximum suggested dose for a member of the public for 1 year.

A study was conducted to determine nitrogen budget and ammonia volatilization in Japanese paddy fields supplemented with liquid cattle waste (LCW). A series of four, 2 x 10 m experimental plots was established in a paddy field with silty clay soil planted with forage rice (Oryza sativa L.). In addition to 195 kg N ha⁻¹ of chemical or compost-based basal fertilizer, LCW was applied as an additional fertilizer at total nitrogen rates of 0, 255, 255, and 405 kg N ha⁻¹ to the four plots C195, T450-1, T450-2, and T600, respectively. The mass balance showed that after application of LCW, 32-39% of total input nitrogen was assimilated into aboveground parts of rice plants, 11-15% leached downward, 2.5-4.0% was lost via ammonia volatilization, 1.6-5.1% was retained in roots or was adsorbed onto soil, and approximately 30-40% was lost via denitrification. Compared to animal waste slurries applied to unsaturated soils, nitrogen loss via ammonia volatilization was relatively lower, probably due to the dilution effect of floodwater. Nitrogen loss via denitrification was markedly higher in areas where LCW was applied compared to areas without LCW application. On the other hand, nitrogen leaching downwards represented a substantial loss and may be an environmental concern. However, after LCW application only, the ammonium ion was detected, at a maximum nitrogen concentration of 11.4 mg L⁻¹. In this system, therefore, nitrogen has a different fate to that in animal waste slurries applied to unsaturated soil. In that situation, the major nitrogen form in leaching water is nitrate nitrogen, which moves readily into groundwater.

The paper summarizes results of chemical analyses of fog and rime water samples. The samples were collected at Milesovka, the Czech meteorological observatory. The input data set contains the samples acquired during 234 fogs and 14 rime events. The fog and rime samples were collected in the period of 2000-2004. Methods employed for sampling fog and rime water and differences in the pollutant concentrations are described. The following components were analyzed: conductivity, acidity (pH), cations Na⁺, K⁺, NH₄ ⁺, Mg²⁺, Ca²⁺, and anions F⁻, Cl⁻, NO₃ ⁻, SO₄ ²⁻. The attention was exclusively devoted to the precipitation originating in fogs (no falling precipitation particles were considered). Differences in the relative content of selected ions in the annual average samples of rime and fog are presented together with their absolute values. The importance of rime contributions to total precipitation amounts is demonstrated by maximum values of the rime weight detected at the Milesovka Observatory. The absolute maximum of 52.3 kg m⁻² was registered at Milesovka Mt. on December 28, 2002.

Effluents from petroleum refineries contain a diverse range of pollutants including heavy metals. They also contain oil and grease, phenols, sulphides, dissolved solids, suspended solids and BOD-bearing materials. An overview of heavy metal removal from industrial effluents with emphasis on biological methods is given. Results of studies to remove heavy metals in effluents from a petroleum refinery by water hyacinth were presented. Limited success has been demonstrated for the case of iron and zinc, but further work needs to be done. There is a need to strike the right balance between the possible amount of uptake of heavy metal ions and the tendency to suffocate the ecosystem through the depletion and reduction of light and dissolved oxygen. Similarly there is a need for better understanding of the process of enhancement of the capability the water hyacinth to uptake heavy metal ions before the on-set of toxic accumulation.

Pilot-scale experiments were performed to investigate the role of equalization basins used with constructed wetland systems for treatment of flue gas desulfurization (FGD) waters. Analysis of FGD water samples indicated that aqueous concentrations of Hg, As, and Se remained constant or changed very slightly in a pilot-scale equalization basin during a 24-h hydraulic retention time (HRT). No change in toxicity of FGD water occurred after one HRT. FGD particles were predominantly silt size, and approximately 99% of particles suspended in FGD water settled to the bottom of a 2.5-m-deep equalization basin during the first 4 h of the 24-h HRT. Approximately 90% of the total As, and smaller percentages of Hg and Se, in FGD water and particles were removed by particle settling in the equalization basin. Results of this investigation lend support to the use of equalization basins for treating FGD waters in constructed wetland treatment systems.

Cryptosporidium parvum oocysts may reach soil through direct deposition of human or animal fecal material, irrigation with raw wastewater or untreated effluents, and contaminated runoff. Examination of soil samples for oocyst presence is of primary importance in order to prevent secondary contamination of crops and groundwater. Several methods were proposed for oocyst recovery from soil samples; however, their efficiency was very low. In the present study, four known methods used to recover oocysts from water and fecal samples (sedimentation, sedimentation with reduced water content, sucrose floatation, water-ether separation) were compared to a method used in the past to recover bacterial spores from bottom sediments (two-phase separation). The two-phase separation technique proved to be the best method of choice resulting in a recovery average of 61.2 ± 15.6%. According to this method, the lowest and highest recoveries were 37% to 95%, respectively. Two other important outcomes were observed with the soil experimental set-up: (1) recovery efficiency is influenced by oocyst viability (high viability was directly correlated with increased recovery efficiency) and (2) high sand content of soil samples reduced oocyst recovery by its detrimental effect on oocyst viability.

Flooded post-harvest rice paddies were examined as systems for reducing diazinon (organophosphate insecticide) concentrations in stormwater runoff. Two paddies were cultivated in Oryza sativa L. and amended with a 3-h simulated stormwater diazinon runoff event. Initial diazinon adsorption peaked at 347 and 571 μg kg⁻¹ (3% mass load reduction) for mean above-ground plant tissue concentrations in each pond, respectively. Subsequent senescence of above-ground tissue showed significant decreases in tissue mass (r ² = 0.985) and adsorbed diazinon mass (90 ± 4% and 82 ± 1%) within 1 month of amendment. There were no corollary increases in water column diazinon concentrations. Furthermore, control O. sativa tissue placed within the treatment ponds had below-detectable levels of diazinon throughout the decomposition phase, suggesting a lack of within pond transference of dissipated diazinon. This study shows the relative effectiveness of diazinon adsorption by post-harvest rice plants and a potential mitigation strategy of senescence and pesticide degradation for contaminated tailwater.

Effects of elevated arsenic (As) concentrations on hydroponic Kalmi (Ipomoea aquatica L.) were investigated. Plants were treated with 0, 10, 25, and 50 μM As in the greenhouse for 14 days. Arsenic was added from sodium meta-arsenite (NaAsO₂). Visible toxicity symptom could not easily be recognized without visible growth reduction. Little brown spots on the leaf blade were found at 50 μM As treatment. Dry matter yields decreased by 18.8%, 43.2%, and 78.2% in leaves; 23.6%, 56.4%, and 81.8% in stems; and 11.0%, 28.6%, and 63.7% in roots in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentrations increased in leaves (except in 50 μM As treatment), stems, and roots with increasing As concentrations in the medium. Roots contained 12.7, 11.3, and 10.5 times higher As concentrations as compared to stems and 15.5, 15.9, and 52.8 times higher as compared to leaves in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentration followed the trend of roots > stems > leaves. Kalmi concentrated unaccepted levels of As in leaf and stem tissues for human consumption in the As-treated plants. Based on 10% dry weight (DW) reduction, the critical toxicity level (CTL) of As in the leaves was 7.02 and 23.6 μg g⁻¹ DW in stems.

An experiment was set up to assess the factors affecting metal mobility in five wetland soils of the Scheldt estuary at different sampling depths when subjecting the soils to various water table levels. Pore water metal concentrations were monitored for 10 months at four sampling depths (10, 30, 60 and 90 cm) upon adjusting the water table level to 0, 40 and 80 cm below the surface of the soils. Nickel (Ni) release is facilitated by reductive conditions. These reductive conditions mainly occur below the water table. The fate of chromium (Cr) under reductive conditions seems to be promoted by the presence of dissolved organic matter. However, Cr fate seems to be inconsistent between the soils, as it is affected by a series of counteracting mechanisms. Copper (Cu), zinc (Zn) and especially cadmium (Cd) are all primarily released above the water table under high salinity conditions. These elements are also released below or just above the water table when organic matter is being decomposed, resulting in calcium (Ca), manganese (Mn), Ni and/or iron (Fe) release upon CO₂ accumulation and Fe/Mn oxide reduction, without being accompanied by sulphide production. Their mobility is low under reducing conditions, i.e. in the presence of sulphides, whereas the complexation by soluble organic matter especially seems to promote Cu mobility.