Heterogeneous Atmospheric Nitrogen Deposition Effects Upon the Nitrate Concentration of Stream Waters in a Forested Mountain Area

Nitrogen compounds generated by anthropogenic combustion deposits in forest watersheds and induce nitrogen saturation of the area. Because excess nitrogen is derived from atmospheric deposition, this action is expected to uniformly affect a wide area of forest soils. Geographically, heterogeneous nitrate concentration of stream water within a small area has been attributed to the tree type, geological setting and tree cut. In this article, we hypothesized that the effect of the atmospheric nitrogen deposition in the forest watershed may vary within a small area, and that such variation is induced by the degree of air mass containing a high concentration of nitrogen deposition of combustion origin. We measured major ion concentrations, including nitrate, nitrite oxygen and nitrogen stable isotope of nitrate sampled at 24 water streams in the Chichibu region, which is 50?C100 km from the Tokyo metropolitan area. The nitrate concentration showed a wide range (25.6?C237 ??mol L^?1) within 300 km², which was explained sufficiently by the air mass advection path and its contact with the mountain??s surface. The nitrate concentration showed a significant positive correlation with chloride (r?=?0.73; p?<?0.001). As chloride originates outside of the Chichibu region, the positive correlation between two ions showed that the nitrate concentration of the stream water was affected by the nitrogen compound from the Tokyo Metropolitan area as a form of atmospheric deposition. Between the nitrate concentration and the stable isotope ratio of oxygen of nitrate, there was a positive correlation until nitrate concentration of 100 ??mol L^?1. When the nitrate is over 100 ??mol L^?1, ??¹⁸O shows a stable value of ca. 5.7??. This indicates that the nitrification proceeds when the nitrate concentration was low to middle, but the reaction slowed when the nitrate concentration became high. Oxygen stable isotope of nitrate along with a set of nitrate concentrations can be used as a good indicator of nitrogen saturation.     

High Carbon Dioxide Evasion from an Alpine Peatland Lake: The Central Role of Terrestrial Dissolved Organic Carbon Input

We measured carbon dioxide (CO₂) fluxes across air?Cwater interface with floating chambers in Lake Medo (a small, shallow lake in peatland) on the eastern Tibetan Plateau in the warm season of 2009. During the study period, mean CO₂ fluxes was 488.63?±?1,036.17?mg?CO₂?m^?2?h^?1. The flux rate was high compared to those of lakes in other regions, and represented a ??hotspot?? of CO₂ evasion. Temporal variation of CO₂ flux was significant, with the peak value in the beginning and lowest point in the end of warm season. High concentration of dissolved organic carbon (DOC) in lake water (WDOC) was found to highly correlated to CO₂ flux (R?=?0.47, P?<?0.01, n?=?54). Besides, fluorescence index of WDOC showed its terrestrial origin character. In accordance with lakes in northern and boreal regions, terrestrial DOC concentration in water column was the most important regulator of CO₂ flux from this lake. We suggest that large area of peatlands in catchments support high concentration of DOC in this lake, and consequently high CO₂ evasion.     

Analysis of the Relationship Between Submerged Aquatic Vegetation (SAV) and Water Trophic Status of Lakes Clustered in Northwestern Hillsborough County, Florida

This study examined the relationship between abundance of submerged aquatic vegetation (SAV) and the water trophic status of a group of lakes located in northwestern Hillsborough county. SAV abundance was expressed by the percent of lake volume infested with SAV (PVI) and the percent of lake area covered with SAV (PAC). The group of lakes was divided into two subgroups based on SAV abundance less than 20 PVI (PVI?<?20) and lakes with more than 20 PVI (PVI?>?20). Mean concentrations of total phosphorus (TP), total nitrogen (TN), and chlorophyll-?? in lake water were used as indicators of trophic status, with the concentration of each nutrient in one group of lakes compared to its corresponding concentration in the other group. Lakes with PVI?<?20 had a mean concentration of TP and chlorophyll-?? of 28 and 11 µg/l, respectively, while those with a PVI?>?20 had a mean concentration of 18 and 4 µg/l for the same parameters, respectively. The results of a t test and one-way ANOVA performed at the 95% confidence level indicated that the differences were significant for the concentrations of TP and chlorophyll-?? but not for TN, the last of which had a mean lake water concentration of 0.8 and 0.7 mg/l for the PVI?<?20 and PVI?>?20 subgroups, respectively.     

Fluoride Removal from Water Using Combined Moringa oleifera/Ultrafiltration Process

The occurrence of fluoride in groundwater has been reported in many countries, mainly because the excess fluoride in drinking water can lead to dental or skeletal fluorosis. Fluoride removal by coagulation with Moringa oleifera seeds, followed by separation with membranes, was investigated in this work. Artificially fluoridated water, at a starting fluoride concentration of 10?mg?L^?1, was submitted to a coagulation process with aqueous extracts of M. oleifera seeds. The coagulation process was followed by ultrafiltration with membranes at different pressures. The coagulation process with 2.5?g?L^?1 of M. oleifera promoted a reduction of 90.90?% in the fluoride content of the treated water, making it possible for poor communities to consume this water. It is noteworthy that the combined coagulation/filtration process using raw coagulant showed the highest values of colour and turbidity, which, however, were still below the limits set for drinking water by Brazilian legislation. The advantage of proposing a sequential process using membrane separation is that it removes colour and turbidity, caused by the use of M. oleifera as a coagulant, resulting in water that meets potability standards.     

Sorption of Fluoride Ions by Hydroxyapatite in a Column System

The sorption behavior of fluoride ions by hydroxyapatite in a column system from both fluoride aqueous solutions and drinking water from Ojocaliente, Zacatecas, Mexico, was evaluated. The time between two consecutive elutions allowed the rearrangement of the active sites and diffusion of fluoride ions in the hydroxyapatite, resulting in an increase of its sorption capacity. This behavior was not observed with drinking water, probably due to its high bicarbonate ion concentration. The maximum value of C _e/C ₀ reached for both drinking water and fluoride solutions was 0.73?±?0.05. The data were fitted to the model of Thomas. Both values of K _Th and q ₀ increased with the number of elutions, and their maximum values were 1.72?×?10^?3?L?min^?1?mg^?1 and 9.91 mg?g^?1, respectively.     

Development of actinomycetes in brown semidesert soil under low water pressure

Under laboratory conditions, the spores of a xerotolerant Streptomyces odorifera strain germinated in brown semidesert soil even at extremely low soil water pressure (P = ?96.4 MPa, ?964 atm, a _w 0.50); the plantlets increased in length and formed mycelium, on which a new generation of spores was produced (a complete development cycle of the actinomycetes??from a spore to the formation of new spores??passed). The duration of the first cycles of the actinomycetes?? development varied from 13 days at P = ?27 atm to 57 days at P = ?964 atm and was directly proportional to the absolute value of the soil water pressure (P). In the first cycles of the actinomycetes?? development, the rate of increase of the concentration of the germinated spores and mycelium, as well as the logarithms of the mycelium-to-germinated spore concentration ratios, was inversely proportional to the logarithm of P. These relationships indicated that the energy state of the water determined its availability to soil biota and, hence, the activity of its physiological and biochemical processes.     

Evaluation of the Ability of a Natural Wetland to Remove Heavy Metals Generated by Runways and Other Paved Areas from an Airport Complex in Brazil

In recent years, wetlands have received increasing attention in environmental engineering. Both natural and constructed wetland systems are now being used to treat a wide range of industrial, urban, and agricultural effluents. In the present study, we measured the heavy metal uptake of a wetland area in Brazil that receives runoff water from runways and paved areas. We analyzed the water, sediments, and emergent macrophytes and compared the data with the results of other studies of the retention of pollutants by wetlands. We also determined the heavy metal accumulation by the dominant macrophyte using transfer coefficients to determine metal transfer among sediments, roots, and leaves. We found that although the wetland removed significant amounts of pollutants from the airport??s drainage water through sedimentation, precipitation, and uptake by plants, additional work must be done to increase water retention times in the wetland to improve the wetland??s ability to immobilize pollutants.     

Groundwater Pollution in a Karstic Region (NE Yucatan): Baseline Nutrient Content and Flux to Coastal Ecosystems

The quality of groundwater is threatened in karstic regions with very high population growth, such as the eastern coast of Yucatan. As polluted groundwater flows towards the ocean, coastal ecosystems and coral reefs may also be affected. Pollution and the interaction between the coastal aquifer and the reef lagoon were assessed at a developing area (Puerto Morelos, NE Yucatan Peninsula) within the Mesoamerican Coral Reef System. Coastal environments along the land?Csea gradient (wells, mangroves, beaches, submarine springs, the reef lagoon, and the open sea) were sampled. Silicate and salinity were used as tracers of groundwater and seawater, respectively. Their patterns evidence water flow and mixing among these coastal environments. High nitrate concentrations (268.6 ??M) and coliform bacteria densities indicate groundwater pollution in most of the wells sampled and also in mangroves, beaches, and submarine springs. Phosphorous content peaks (14.2 ??M) in mangroves, where it is likely released due to reducing conditions in the sediments. Nitrogen flux toward the lagoon reef through groundwater discharge is estimated at 2.4 ton N km^?1 year^?1 and phosphorous at 75 to 217 kg P km^?1 year^?1. These results provide evidence of the need for more detailed groundwater studies and for the integrated management of aquifers and coastal ecosystems in karstic regions.     

Relation of soil organic matter concentration to climate and altitude in zonal soils of China

With a total of 886 data sets distributed in different regions of China, the relation of soil organic matter (SOM) concentration to climate and altitude was investigated. These data sets were obtained from the 2nd National Soil Survey of China that was completed in early 1980s. According to climate gradient and vegetation community succession, six geographical regions, including eastern, southern, northern, northeastern, northwestern and southwestern China, were divided to identify the key factors regulating surface SOM concentration in different geographical regions. Correlation analysis indicates that surface SOM concentration is in general negatively correlated with annual mean temperature (T) and positively correlated with annual mean precipitation (P) and altitude (H). A further investigation suggested that multiple regression models with different combination of T, P and H could explain 41.5%–56.2% of the variability in surface SOM concentration for different geographical regions, while the driving variables are different. Variables of T and P determined surface SOM concentration in northern, northeastern and northwestern China. In eastern and southern China, variables of P and H are key factors regulating surface SOM concentration. Surface SOM concentration in southwestern China is determined by a linear combination of T, P and H.     

Temporal Synchronization Analysis for Improving Regression Modeling of Fecal Indicator Bacteria Levels

Multiple linear regression models are often used to predict levels of fecal indicator bacteria (FIB) in recreational swimming waters based on independent variables (IVs) such as meteorologic, hydrodynamic, and water-quality measures. The IVs used for these analyses are traditionally measured at the same time as the water-quality sample. We investigated the improvement in empirical modeling performance by using IVs that had been temporally synchronized with the FIB response variable. We first examined the univariate relationship between multiple ??aspects?? of each IV and the response variable to find the single aspect of each IV most strongly related to the response. Aspects are defined by the temporal window and lag (relative to when the response is measured) over which the IV is averaged. Models were then formed using the ??best?? aspects of each IV. Employing iterative cross-validation, we examined the average improvement in the mean squared error of prediction, MSEP, for a testing dataset after using our temporal synchronization technique on the training data. We compared the MSEP values of three methodologies: predictions made using unsynchronized IVs (UNS), predictions made using synchronized IVs where aspects were chosen using a Pearson correlation coefficient (PCC), and predictions using IV aspects chosen using the PRESS statistic (PRS). Averaging over 500 randomly generated testing datasets, the MSEP values using the PRS technique were 50?% lower (p?<?0.001) than the MSEP values of the UNS technique. The average MSEP values of the PCC technique were 26?% lower (p?<?0.001) than the MSEP values of the UNS technique. We conclude that temporal synchronization is capable of significantly improving predictive models of FIB levels in recreational swimming waters.     

Enhanced Phenol and Chlorinated Phenols Removal by Combining Ozonation and Biodegradation

Water treatment for wastewater containing phenols and their chlorinated variations has attracted important research efforts. Phenol??s high toxicity makes them a good model to test possible water treatment based on biological and/or chemical methods. High concentrations of phenols may be treated by pure biological schemes. However, chlorinated phenols are very toxic for many microorganisms. Therefore, mixed treatment trains can be proposed to solve the treatment of this class of organics. In this study, the ozonation was used as pretreatment to decompose chlorinated phenols. Besides, this study describes how the microbial consortiums were adapted to handle ozonation by-products. The biodegradation of different phenol concentrations from 50 to 1,500?mg/L was evaluated using preadapted microbial consortia in batch and in a trickling packed-bed reactor (TPBR). Under batch conditions, phenol was efficiently removed up to 500?mg/L. For every phenol concentration evaluated, higher degradation rates were obtained in TPBR. The chlorophenols were found to be poorly degraded by the pure biological treatment, 4-CPh was not degraded during the biological process and 2,4-DCPh was only 40?% degraded after 250?h of culture. By combining the chemical (as pretreatment) and the biological processes, 85?% of 4-CPh was removed, while the degradation of the 2,4-DCPh was enhanced from 40 to 87?%. The predominant bacteria found in the preadapted cultures were Xanthomonas sp., Ancylobacter sp., and Rhodopseudomonas. Total treatment period was reduced from several weeks to some days. This information reflects the benefits offered by the mixed water treatment train proposed in this paper.     

Removal of Fluoride from Water by Locally Available Sand Modified with a Coating of Iron Oxides

Locally available low-cost material viz. sand from the Kaliani river of Kanaighat area of Golaghat district Assam, India, was collected. The sand was fractionated and the different fractions were characterized by classical chemical analysis, powder XRD, SEM-EDXA, DTA-TGA, and by FT-IR. The chemical analysis of the size fraction of a 600–850-μm range gave more than 90% silica. This fractionated portion was modified by coating with iron oxide. Coating was carried out on the washed and separated sand by repeated treatment of Fe(NO₃)₃ at 110 and 600 °C, respectively. From FESEM analysis, formation of iron oxide coating over sand surface is clearly observed. The coated sand was used to remove toxic fluoride ion from the drinking water. Iron oxide-coated sand shows highly improved fluoride removal capacity compared to raw sand. The defluoridation capacity of coated sands rose up to 89% from 7% in uncoated raw sand. The effects of different parameters like adsorbent dose, contact time, temperature, initial fluoride concentration, and pH and the effects of different anions present in water along with arsenic on defluoridation capacity of the material were studied in a batch mode.     

氟对水稻生长及铝?氟交互对水稻吸氟规律的影响研究

通过盆栽试验研究水稻对氟的吸收规律及硫酸铝存在对水稻吸氟量的影响。结果表明: 单施氟处理下, 施氟量与水稻植株含氟量间存在极显著正相关关系, 说明水稻对氟存在奢侈吸收。随着水稻的生长, 其对氟的吸收达到平衡, 吸氟量逐渐减少, 植株体内氟含量呈下降趋势。各施氟水平下, 水稻植株的生长无明显差异, 但分蘖数却随施氟量的增加呈极显著降低趋势。铝?氟交互条件下, 水稻植株各部位的含氟量顺序为稻壳>米>根>茎叶, 这可能与植物的吸氟部位和氟的吸收形态有关。植株体内氟含量随生长时间的延长也呈下降趋势, 施硫酸铝处理会在此基础上进一步降低水稻植株各部位的含氟量, 但同一处理在不同时间取样, 降氟效果有较大差别。氟、铝处于何种比例和作用时间才能达到理想的降氟效果还有待于进一步研究。     

Fluoride in bones of small rodents living in areas with different pollution levels

Bone fluoride concentration was measured in field voles (Microtus agrestis) trapped throughout a year at a moderately polluted site 1 km south of an Al reduction plant at Holyhead, Anglesey. Fluoride values ranged from 300 to 4800 μg g^?1, with a mean of 2074 μg g^?1 and increased with age as judged by dried eye-lens weight and body weight. At a heavily polluted site about 250 m from the pot-room of the reduction plant field voles had bone fluoride concentrations which ranged from 910 to 11000 μg g^?1 with a mean of 7148 μg g^?1. Wood mice (Apodemus sylvaticus) at this same location had a mean bone fluoride concentration of 8430 μg g^?1 and ranged from 1800 to 17 200 μg g^?1. The difference in mean bone fluoride concentration between these two species at this location was not significant (P > 0.1). A sample of field voles from presumed unpolluted sites in other parts of Britain had bone fluoride concentrations which ranged from 23 to 540 μg g^?1 with a mean of 168 jig g^?1. There was a high positive correlation (r > 0.97) between fluoride concentrations in different parts of field vole skeletons. There was no correlation between bone fluoride concentration in field voles and their femur diameters (r < 0.2).     

Toxic Effects of Fluoride Ion on Survival, Reproduction and Behaviour of the Aquatic Snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)

Inorganic fluoride concentrations in aquatic ecosystems have been significantly increased by several human activities during the last decades. However, there is still relatively scarce information about its toxicity to freshwater animals, especially at long-term exposures. The aim of our study is to assess the short-term (4?days) and long-term (28?days) fluoride (F^?) toxicity to the aquatic snail Potamopyrgus antipodarum on the basis of several endpoints, including survival, reproduction (number of newborn and embryos) and behaviour (time to start movement). One control and five actual fluoride concentrations were used in triplicate (49.2, 47.0, 122.5, 194.6 and 281.4?mg?F^?/L) for the short-term (4?days) bioassay. LC50 value at 96?h was 58.5?mg?F^?/L, which is a relatively high value in comparison with previous published data on freshwater invertebrates. One control and three actual fluoride concentrations were used in quadruplicate (4.6, 9.5 and 16.2?mg?F^?/L) for the long-term (28?days) bioassay. None of the fluoride treatments increased mortality in comparison to control after 28?days of continuous exposure. Fluoride reduced the mean total and alive number of newborns per surviving adult after 28?days of exposure (at mean concentrations of 9.5 and 16.2?mg?F^?/L) respect to control. The number of embryos with shell was reduced by the highest concentration (16.2?mg?F^?/L). The behavioural activity (e.g. time to start normal movement) was affected by the highest fluoride concentration during the long-term bioassay. Our results show that fluoride is toxic at short- and long-term exposures, causing mortality (at short term) and affecting reproduction and behaviour (at long term). Additionally, field fluoride levels, corresponding to test fluoride concentrations (mean values ranged from 4.6 to 16.2?mg?F^?/L) have been found in fluoride-polluted ecosystems, either by natural or anthropogenic causes. Therefore, fluoride pollution may potentially affect natural population of invertebrates.     

Kinetics of Mercury Accumulation and Its Effects on Ulva lactuca Growth Rate at Two Salinities and Exposure Conditions

The research on metals effect on macroalgae has been focused on Cd, Cu, Zn and Pb, and no study dealt with the effects of mercury on macroalgae growth rate. Also, the kinetic of accumulation is not well known. The main aim of this work was to assess the mercury accumulation kinetics of Ulva lactuca and its effects on growth rate. Three concentrations were tested: 5, 50 and 500???g?L^?1, under static and renewal conditions and at two salinities (15 and 35), during 72?h. The mercury accumulation kinetic patterns were different according to the exposure conditions and metal concentration, but were always a very fast process (hours). Three patterns were established based on the models substrate inhibition, linear regression and Michaelis?CMenten equation. Statistical differences in the mercury accumulated were recorded depending on the salinity values and exposure conditions, being higher at salinity 15 and at renewal tests, corresponding to the lower relative growth rates. The lowest mercury concentration did not have an effect on relative growth rate, while the others caused an accentuated inhibition at 24?h. The highest concentration was toxic to algae causing its death before 48?h. Under controlled conditions, the U. lactuca??s high and fast ability for mercury accumulation could be useful for phytoremediation and for industrial wastewaters treatment.     

Evaluating Plant Species-Specific Contributions to Nutrient Mitigation in Drainage Ditch Mesocosms

Eutrophication of surface water bodies is a worldwide concern. In the USA alone, excessive nutrients are blamed for nearly 5,700 impairments of surface water bodies. Innovative measures, such as maximizing drainage ditch nutrient retention, are being examined to decrease the amount of nitrogen (N) and phosphorus (P) running off agricultural lands and into aquatic receiving systems. The goal of this experiment was to measure the nutrient mitigation ability of six aquatic plants typically found in agricultural drainage ditches in the lower Mississippi River Basin. Experimental mesocosms (1.25?×?0.6?×?0.8 m) were filled with sediment and planted with monocultures of one of six obligate wetland plant species (Typha latifolia (broadleaf cattail), Panicum hemitomon (maidencane), Thalia dealbata (powdery alligator-flag), Echinodorus cordifolia (creeping burhead), Myriophyllum spicatum (Eurasian watermilfoil), and Saururus cernuus (lizard??s tail)), while three replicates were left non-vegetated to serve as controls. Mesocosms were amended with 5 mg?L^?1 (each) of nitrate, ammonia, dissolved inorganic phosphorus, and total inorganic phosphorus, while nitrite amendments (1 mg?L^?1) were also made over a 4-h hydraulic retention time. Following the 4-h exposure, ??clean?? (non-amended) water was flushed through mesocosms for an additional 8 h to assess residual leaching of nutrients. Outflow water concentrations and loads decreased for all examined forms of N and P. In certain cases, there were significant differences between plant species; however, for the majority, there was no statistical difference in percent decrease between plant species. While native aquatic vegetation shows promise for mitigation of nutrient runoff, further studies altering the hydraulic retention time for improved efficiency should be conducted.     

Variability in Mucuna pruriens L. germplasm for L-Dopa, an anti parkinsonian agent

Mucuna pruriens L. (Fabaceae) is a popular Indian medicinal plant, which has long been used in traditional Ayurvedic system of Indian medicine for diseases including parkinsonism. The seeds of M. pruriens contain 3,4-dihydroxyphenyl-L-alanine (L-dopa) as a major constituent, an intermediate precursor of the neurotransmitter dopamine. L-dopa extracted from seeds of Mucuna is more effective as drug than the synthetic counterpart. The plant is widely distributed throughout the India and in other parts of the tropics including Central and South America. The present study was aimed to screen thirty-eight accessions of Mucuna germplasm collected from different geographical regions of India for L-dopa content, an effective drug used for Parkinson’s disease. The L-dopa content in seeds of M. pruriens was quantitatively analyzed by high performance thin-layer chromatography (HPTLC) at 280?nm wavelength. Results indicated wide variability among thirty-eight accessions of M. pruriens for seed characters like seed colour, size and shape. The L-dopa content in seeds of M. pruriens ranged between 3.29 and 5.44?% (on dry weight basis) among different germplasm collections augmented from various parts of India. Promising accessions identified having high L-dopa content were IC551549 (5.44?%), IC551514 (5.41?%), IC331536 (5.40?%), IC552857 (5.36?%), IC385844 (5.32?%) and IC439197 (5.32?%). Due to the economic importance of the drug, these promising M. pruriens accessions can be exploited for large scale cultivation for their pharmacological important constituents mainly L-dopa content.     

On the Influence of Hot-Water Discharges on Phytoplankton Communities from a Coastal Zone of the Gulf of Mexico

The influence of thermal discharges on thephytoplankton community from a coastal zone of theGulf of Mexico was evaluated through their structureand photosynthetic behaviour focusing on responses tochanges in light and temperature. Biological andphysicochemical parameters were measured over a periodof two years in an area with permanent hot waterdischarges from a thermoelectric plant. Thetemperature in the sampling area ranged from 23.5 to36 °C with differences between the coldest andthe hottest station from 5.3 to 9.2 °C.Photosynthetically active radiation (PAR) were reducedin the discharge area water column, due to turbulence.One hundred and one different taxa were identifiedwith a strong predominance of Diatoms. The chlorophylla concentration ranged from 0.3 to 6.1 μgL^-1, with highest values of thephaeophytin:chlorophyll ratio found at the hottest station.The community structure did not show significativedifferences among sampling stations with respect totemperature variations. However, in the algalassemblages influenced by thermal discharges, it waspossible to observe alterations in the photosynthesisbehaviour. Phytoplankton response to short termphotosynthesis experiments was segregated according tocomposition and origin of microalgal assemblages.Samples with larger heterogeneous composition had moreconsistent oxygen production responses. Algalcommunities exposed to hot effluent showed differentdegrees of photosynthesis rate reduction,higher light requirements (>500 μE m² s^-1)and lower temperature (25 °C) to achieve Pmaxthan algae sampled in sites without such exposure.     

Uptake Kinetics of As, Hg, Sb, and Se in the Aquatic Moss Fontinalis antipyretica Hedw

Laboratory experiments were carried out to study the uptake kinetics of selected metals and metalloids in the aquatic moss Fontinalis antipyretica. For this purpose, moss specimens from a clean site were exposed to concentrations of As, Hg, Sb, and Se ranging from 0.1 to 10,000???g?l^?1, for incubation times of between 1 and 22?days, and the tissue concentrations of the metals in the moss specimens were then measured. Uptake kinetics followed different patterns in relation to exposure time, although the most common was Michaelis?CMenten kinetics. On the contrary, the contamination factors followed very similar patterns in relation to the exposure concentrations in all cases, with a good fit to logarithmic equations. The bioconcentration factors tended to decrease as exposure concentration increased. The bioconcentration factors for Hg were extremely high, even at the lowest concentration in water and for the shortest incubation time, which implies that F. antipyretica has a high capacity to magnify Hg levels in water, which is an important characteristic in a good biomonitor. According to the time to reach equilibrium, the minimum exposure time recommended for use in active biomonitoring by means of transplants is very variable, although high levels of the elements, except Sb, were found in the moss tissues within a few days. We do not recommend the use of this moss species to biomonitor low concentrations of Sb in water. The differences in maximum contamination factors and lowest bioconcentration factors suggest that As and Se were the most toxic of the elements under study.