An evaluation of in situ microcosms for validating aquatic fate and transport models

The fates of two compounds, 2,4 Dichlorophenoxy Acetic Acid Butoxyethyl Ester (2,4-DBEE) and 1,4 Dichlorobenzene (1,4-DCB), were examined in in situ microcosms placed in a pond and compared with the fates in the pond itself. Results also were compared with predictions of an aquatic fate and transport model (EXAMS). Decay rates of 2,4-DBEE were not significantly different among the microcosms, pond and model predictions. The decay rate of 1,4-DCB in the microcosms was significantly lower than the rate for the pond, and lower than the rate predicted by the model. The low volatility of 1,4-DCB in the microcosms is attributed primarily to lack of water surface turbulence in the microcosms.     

Implication of two in-stream processes in the fate of nutrients discharged by sewage system into a temporary river

The aim of this study was to better understand the fate of nutrients discharged by sewage treatment plants into an intermittent Mediterranean river, during a low-flow period. Many pollutants stored in the riverbed during the low-flow period can be transferred to the downstream environments during flood events. The study focused on two processes that affect the fate and the transport of nutrients, a physical process (retention in the riverbed sediments) and a biological process (denitrification). A spatial campaign was carried out during a low-flow period to characterize the nutrient contents of both water and sediments in the Vène River. The results showed high nutrient concentrations in the water column downstream of the treated wastewater disposal (up to 13,315 μg N/L for ammonium and 2,901 μg P/L for total phosphorus). Nutrient concentrations decreased rapidly downstream of the disposal whereas nutrient contents in the sediments increased (up to 1,898 and 784 μg/g for total phosphorus and Kjeldahl nitrogen, respectively). According to an in situ experiment using sediment boxes placed in the riverbed for 85 days, we estimated that the proportion of nutrients trapped in the sediments represents 25% (respectively 10%) of phosphorus (respectively nitrogen) loads lost from the water column. In parallel, laboratory tests indicated that denitrification occurred in the Vène River, and we estimated that denitrification likely coupled to nitrification processes during the 85 days of the experiment was significantly involved in the removal of nitrogen loads (up to 38%) from the water column and was greater than accumulation processes.     

Status of Aquatic Bioassessment in U.S. EPA Region IX

U.S. EPA Region IX is supporting bioassessment programs in Arizona, California, Hawaii and Nevada using biocriteria program and Regional Environmental Monitoring and Assessment Program (R-EMAP) resources. These programs are designed to improve the state, tribal and regional ability to determine the status of water quality. Biocriteria program funds were used to coordinate with Arizona, California and Hawaii which resulted in these states establishing reference conditions and in developing biological indices. U.S. EPA Region IX has initiated R-EMAP projects in California and Nevada. These U.S. EPA Region IX sponsored programs have provided an opportunity to interact with the States and provide them with technical and management support. In Arizona, several projects are being conducted to develop the State's bioassessment program. These include the development of a rotational random monitoring program; a regional reference approach for macroinvertebrate bioassessments; ecoregion approach to testing and adoption of an alternate regional classification system; and development of warm-water and cold-water indices of biological integrity. The indices are projected to be used in the Arizona Department of Environmental Quality (ADEQ) 2000 water quality assessment report. In California, an Index of Biological Integrity (IBI) has been developed for the Russian River Watershed using resources from U.S. EPA's Non-point Source (NPS) Program grants. A regional IBI is under development for certain water bodies in the San Diego Regional Water Quality Control Board. Resources from the U.S. EPA Biocriteria program are being used to support the California Aquatic Bioassessment Workgroup (CABW) in conjunction with the California Department of Fish & Game (CDFG), and to support the Hawaii Department of Health (DoH) Bioassessment Program to refine biological metrics. In Nevada, R-EMAP resources are being used to create a baseline of aquatic information for the Humboldt River watershed. U.S. EPA Region IX is presently working with the Nevada Division of Environmental Protection (NDEP) to establish a Nevada Aquatic Bioassessment Workgroup. Future R-EMAP studies will occur in the Calleguas Creek watershed in Southern California, and in the Muddy and Virgin River watersheds in southern Nevada, and the Walker River watershed in eastern California and west-central Nevada.     

Occurrence of perfluorosulfonates and other perfluorochemicals in dust from selected homes in the city of Ottawa, Canada

A series of perfluorinated compounds (PFCs) including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been recently measured in a variety of environmental samples and biological matrices. In order to better understand the human exposure routes of these chemicals, levels of PFOS, PFOA, perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHS) and perfluorooctane sulfonamide (PFOSA) in house dust samples were investigated. The data revealed a correlation between the concentrations of PFCs and the percentage of carpeting in the house; older houses tended to have less carpeting, hence lower levels of these perfluorinated compounds in their dust.     

水环境中藻毒素污染监测与评价

水质富营养化污染的频繁发生,使藻毒素污染成为突出的环境问题,对人类身体健康产生严重的威胁.文章介绍了目前常见的藻毒素的产生及其对人体健康的危害,提出应根据不同的监测对象,在不同的时期采用不同的监测方法,对藻毒素污染进行有效的监测和评价,对其污染的发生和危害进行有效监控.     

The fate and persistence of polychlorinated biphenyls in soil

The fate and persistence of PCBs 28, 52, 101, 138, and 180 artificially introduced into three soils was studied under a variety of field conditions for up to 415 d following initial contamination. A relationship was detected between ln Koa (octanol/air partition coefficient) and the experimentally observed first-order loss rate constant that was statistically significant at at least the 90% level in all but one instance. In nearly all experiments, PCB persistence was greater in soils of higher organic carbon content. Soil temperature and moisture content were also indicated as important influences on persistence. Significantly longer half-lives were observed in a soil in which initial PCB contamination had occurred ca. 1 year previously. A mass balance showed the most likely mechanism of loss to be volatilisation. Losses attributable to aerobic biodegradation could not be ruled out, but those due to leaching, uptake by biota, and soil erosion were demonstrated to be negligible. First-order rate constants (Kv) were determined for volatilisation of the same congeners from soil under a variety of controlled laboratory scenarios. Multiple linear regression analysis (MLRA) showed the most important influences on kv to be ln Koa (adjusted for soil temperature) and soil organic carbon content. Limited evidence was observed for a relationship between kv and soil moisture content, but not water flux. When tested against field measurements, the MLRA-derived relationship between kv and independent variables predicted to within a factor of 2.5, the persistence of PCBs 28, 52, and 101, However, it did not account for the influence of the age of contaminant association with the soil, soil moisture content or water flux, and failed to function for soils of high organic content, or where ln Koa exceeds ca. 23.     

Transportation and fate of cationic surfactant in river water

The degradation, sorption, transportation and material balance of cationic surfactants discharged from domestic waste into river water was studied. Ion-pair solid-phase extraction behavior showed that the sorption of cationic surfactants as an ion-pair with anionic surfactant onto river sediment was so strong that little cationic surfactant was found in the bulk water. Cationic surfactant was found in river sediment at more than 500 times higher concentration than that in the bulk water. The degradation of the cationic surfactant was very slow in river water and much slower in the sediment. A material balance of cationic surfactant was estimated for a river running through Toyama City by measuring the flow rate and the concentration of cationic surfactant in the water at several points. It was found that more than 30% of cationic surfactant introduced to the river was lost during the river running through ca. 3 km in 3 h. This reduction probably comes from a quick transfer of the cationic surfactant from river water to sediment and water weed by means of adsorption or precipitation with suspending solids.     

Performance evaluation of oil spill software systems in early fate and trajectory of oil spill: comparison analysis of OILMAP and PISCES 2 in Mersin bay spill

The aim of this study is to evaluate the performance level of two advanced oil spill software systems in early transport and fate of oil spill through algorithms accepted in oil spill literature. To do this, the performance level of software systems mostly used in real cases have been compared. OILMAP (the oil spill prediction modeling system) and PISCES 2 (potential incident simulation, control and evaluation system) have been used for spill trajectory in the light of four spill scenarios. The findings reveal that the OILMAP has predicted a relatively larger area of spill. In addition, OILMAP has achieved closer results to the calculations of approaches adopted in the literature for evaporation calculations. Besides, OILMAP software has provided highly reliable results in the evaporation rates of oil compared to the calculations of PISCES 2. On the other hand, as for the determination of the risky area, both software systems have yielded results with high reliability values, which could be used in taking precautions against oil spill in such areas.     

Monitoring of fate and effects of oil in the marine environment

Examples are presented of different techniques which are in use, or could be used, to monitor the fate and effects of oil pollution in Dutch marine waters by oil spills and chronic contamination by rivers, processing water from the oil industry, etc.A number of techniques are presented to quantify the fate of oil in water, sediments and biota, and some readily available methods to monitor possible effects in the ecosystem.In Dutch coastal waters much effort is being given to airborne detection of oil at the sea surface in order to reduce pollution and to take rapid measures in cases of severe pollution. Oil concentrations in sediments and selected organisms can be monitored as a general quality control measure, and to check the functioning of licensed installations. If concentrations above background levels are found, research on possible effects should be initiated. In this context short term studies on stress-indicators are very useful. Laboratory based investigations, for example in model ecosystems, can be carried out to test hypotheses from such studies. Elevated oil concentrations and indications for ecological effects may result in changes in the management of the marine area in question. Monitoring of population dynamics and species composition, notably of benthic macrofauna, should be carried out to verify long-term effects on the ecosystem.     

Tracing the fate of PCBs in forest ecosystems

Forests were shown to play an important role in influencing atmospheric concentrations and transport of persistent organic pollutants (POPs) in the environment. World forests cover more than 4 billion hectares and contain up to 80% of the above ground organic carbon. Given the lipophilic nature of POPs, this suggests that forests can influence the environmental fate of POPs at a global scale. POP accumulation in forest canopies still presents points of concern given the complexity of these ecosystems. In particular, the role of ecological parameters such as LAI (leaf area index) and SLA (specific leaf area) and their dynamics during the growing season was not sufficiently investigated yet. This paper reviews, compares and interprets a unique case study in which air and leaf concentrations and deposition fluxes for selected polychlorinated biphenyls (PCBs) were measured in three different forest types exposed to the same air masses. In order to trace the air-leaf-soil path of these compounds, a dynamic model of POP accumulation into forest canopy was applied. The dynamics of the canopy biomass strongly affected the trend of leaf concentration with time. Growth dilution effect can prevent the more chlorinated compounds from reaching the partitioning equilibrium before litter fall, while the more volatile compounds can approach equilibrium in the range of few weeks. An amount of up to 60 ng of PCBs per square metre of ground surface was predicted to be stored in each of the selected forests at fully developed canopy. Dry gaseous deposition fluxes to forest canopy were estimated to reach a maximum value of about 0.5-1.5 ng m(-2) d(-1) during the spring period.     

The fate of fipronil in modular estuarine mesocosms

The degradation and corresponding product manifold for the pesticide fipronil was determined in three replicate estuarine mesocosms. Aqueous fipronil concentrations rapidly decreased over the 672 h timescale of the experiment (95% removal). Loss was apparently first-order in fipronil, although there appeared to be a change in the removal mechanism after 96 h that corresponded to a dramatic slowdown in its disappearance. The reduction product of fipronil, fipronil sulfide, was not detected in the water column; however, it formed rapidly in sediments and was identified as the major product of fipronil degradation in the system (20% yield at 672 h, with respect to initial fipronil concentration). Fipronil sulfone is thought to form primarily via biological oxidation; and, although it was generated rapidly in the water column (10% yield), only trace amounts were detected in the sediment (1% yield). The direct photolysis product of fipronil, fipronil desulfinyl, was present in all samples; it formed rapidly in the water column (4% yield) and partitioned into the sediment phase (7% yield) over the course of the experiment. The mass balance on fipronil and associated products was 42% at 672 h.     

Evaluation of environmental fate of acetamiprid in the laboratory

The acetamiprid, a nenicotinoid insecticide, is a popular crop protection agent used in fields as well as in protected cultivation. A laboratory experiment was conditions to study the effect of light, moisture, and pH on the persistence of acetamiprid in water and soil. Dissipation half-lives of acetamiprid in water at pH 4, 7, and 9 were 6.2, 7.3, and 5.1 days, respectively, and 4.3 days under UV and sunlight conditions. Half-life in soil at three concentrations, 0.1, 1.0, and 10 μg g^?1 under different moisture regimes varied from 21.5–22.8, 15.6–22.4, 10.0–15.8 days, respectively, indicating that acetamiprid dissipated faster in submerged soil as compared to field capacity moisture and dry conditions. The leaching study showed that the possibility for leaching of acetamiprid to ground water is extremely low under normal condition of average rainfall due to compact nature soil in the field. Acetamiprid poses low risks to the ecosystem because of their rapid dissipation and low-bound residues in the environment.     

Sources and fate of Salmonella and fecal indicator bacteria in an urban creek

This research aimed to understand the sources and fate of Salmonella and fecal bacteria in urban surface waters. An urban creek (San Pedro Creek, California, USA) that had unusually high levels of Salmonella and fecal bacteria relative to other nearby waterbodies was chosen as a model field site. State of the art microbiological methods were used in concert with modeling to investigate Salmonella and fecal bacteria sources, and determine field-relevant dark inactivation and photoinactivation rates. Three along-creek surveys that spanned reaches adjacent to both urban and forested land covers were conducted to measure Salmonella, enterococci, Escherichia coli, and horse- and human-specific Bacteroidales. Salmonella were detected adjacent to and downstream of urban land cover, but not adjacent to forested land cover. No human or horse-specific Bacteroidales fecal markers were detected implicating other urban animal sources of bacteria. Two locations along the creek where Salmonella was consistently detected were sampled hourly for 25 hours and a mass-balance model was applied to determine field-relevant light and dark inactivation rates for Salmonella, enterococci, and E. coli. Sunlight inactivation did not appear to be important in modulating concentrations of Salmonella, but was important in modulating both enterococci and E. coli concentrations. Dark inactivation was important for all three organisms. This is the first study to quantitatively examine the fate of Salmonella within an urban surface water. Although the work is carried out at a single site, the methodologies are extendable to source tracking in other waterbodies. Additionally, the rate constants determined through the modeling will be useful for modeling these organisms in other surface waters, and represent useful benchmarks for comparison to laboratory-derived inactivation rates.     

Occurrence and fate of pharmaceuticals and personal care products in drinking water in southern China

Occurrence and fate of pharmaceuticals and personal care products (PPCPs) in drinking water was investigated in southern China. Fifteen and twelve PPCPs were detected with concentrations of 0-36 ng L(-1) in source water and of 0-20 ng L(-1) in treated water, respectively. Four PPCPs were detected with concentrations of approximately 1 ng L(-1) in drinking water of distribution network. Conventional water treatment processes removed the types and average concentrations of PPCPs by 30% and above 50%, respectively. Advanced water treatment processes were more efficient in the removal of most PPCPs, with the types and concentrations reduced by 50% and approximately 90%, respectively. Molecular properties of PPCPs had an important influence on their behaviors during water treatment. pK(a) (acidity coefficient) and K(oc) (organic carbon partition coefficient) of PPCPs appeared to have a combined effect on PPCPs removal during coagulation and oxidation. Adsorption and biodegradation were two possible mechanisms responsible for PPCPs removal during sand filtration.     

Implications of Atmospheric Change for Biodiversity of Aquatic Ecosystems in Canada

Overall, the greatest threats to Canadian and global biodiversity are associated with conversions of natural ecosystems to anthropogenic ones, and over-exploitation of biological resources. This circumstance does not, however, trivialize the importance of atmospheric influences. Although scientific understanding of the risks is incomplete, it is nevertheless clear that anthropogenic changes in atmospheric stressors are potentially damaging to biodiversity and other ecological values over medium- and longer-term scales. It is important that greater investments be made in support of longer-term monitoring and research designed to understand the effects of atmospheric and other environmental stressors on the biodiversity and structure and function of Canadian ecosystems.