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31.
Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids 总被引:3,自引:0,他引:3
V. Dwarakanath K. Kostarelos Gary A. Pope Doug Shotts William H. Wade 《Journal of contaminant hydrology》1999,38(4):1109
A variety of column experiments have been completed for the purpose of selecting and evaluating suitable surfactants for remediation of nonaqueous phase liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense nonaqueous phase liquid from a site at Hill Air Force Base, UT. Both Ottawa sand and Hill field soil were used in these experiments. Surfactant candidates were first screened using phase behavior experiments and only the best ones were selected for the subsequent column experiments. Surfactants which showed high contaminant solubilization, fast coalescence times, and the absence of liquid crystal phases and gels during the phase behavior experiments were tested in soil column experiments. The primary objective of the soil column experiments was to identify surfactants that recovered at least 99% of the contaminant. The secondary objective was to identify surfactants that show low adsorption and little or no loss of hydraulic conductivity during the column experiments. Results demonstrated that up to 99.9% of the contaminants were removed as a result of surfactant flooding of the soil columns. The addition of xanthan gum polymer to the surfactant solution was shown to increase remediation efficiency as a lower volume of surfactant was required for recovering a given volume of NAPL. Based on these experimental results, guidelines for designing highly efficient and robust surfactant floods have been developed and applied to a field demonstration. 相似文献
32.
Is selenium affecting body condition and reproduction in boreal breeding scaup, scoters, and ring-necked ducks? 总被引:1,自引:0,他引:1
DeVink JM Clark RG Slattery SM Wayland M 《Environmental pollution (Barking, Essex : 1987)》2008,152(1):116-122
Elevated levels of selenium (Se) have been detected in wintering and spring-staging lesser scaup. Here, we compared spring scaup Se and mercury (Hg) levels to those of ring-necked ducks and white-winged scoters, species exhibiting increasing and decreasing boreal populations, respectively. Mercury concentrations were low in all three species. Geometric mean (95%CI) liver Se concentrations were 6.2 (5.5-7.0), 4.6 (4.0-5.4), and 32.6 (28.4-37.3)mg/kg dry weight (dw) in scaup, ringnecks and scoters, respectively. Only scoter livers (66%) were above 33 mg/kgdw Se. Scaup and ringneck Se levels were unrelated to breeding status or lipid and protein levels; breeding scoters and females with greater lipid mass had higher Se than non-breeders. Egg and follicle concentrations in scaup and scoters were normal (mean [95%CI]=2.3 [1.9-2.6] and 2.4 [2.1-2.7]mg/kgdw, respectively). Overall, we found no support for a relationship between selenium and boreal scaup and scoter declines, and discuss current Se threshold concentrations. 相似文献
33.
Comparison of naphthalene bioavailability determined by whole-cell biosensing and availability determined by extraction with Tenax 总被引:1,自引:0,他引:1
Kohlmeier S Mancuso M Deepthike U Tecon R van der Meer JR Harms H Wells M 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):803-808
A rapid biological method for the determination of the bioavailability of naphthalene was developed and its value as an alternative to extraction-based chemical approaches demonstrated. Genetically engineered whole-cell biosensors are used to determine bioavailable naphthalene and their responses compared with results from Tenax extraction and chemical analysis. Results show a 1:1 correlation between biosensor results and chemical analyses for naphthalene-contaminated model materials and sediments, but the biosensor assay is much faster. This work demonstrates that biosensor technology can perform as well as standard chemical methods, though with some advantages including the inherent biological relevance of the response, rapid response time, and potential for field deployment. A survey of results from this work and the literature shows that bioavailability under non-equilibrium conditions nonetheless correlates well with Koc or Kd. A rationale is provided wherein chemical resistance is speculated to be operative. 相似文献
34.
Johnson LL Ylitalo GM Arkoosh MR Kagley AN Stafford C Bolton JL Buzitis J Anulacion BF Collier TK 《Environmental monitoring and assessment》2007,124(1-3):167-194
To better understand the dynamics of contaminant uptake in outmigrant juvenile salmon in the Pacific Northwest, concentrations
of polychlorinated biphenyls (PCBs), DDTs, polycylic aromatic hydrocarbons (PAHs) and organochlorine pesticides were measured
in tissues and prey of juvenile chinook and coho salmon from several estuaries and hatcheries in the US Pacific Northwest.
PCBs, DDTs, and PAHs were found in tissues (whole bodies or bile) and stomach contents of chinook and coho salmon sampled
from all estuaries, as well as in chinook salmon from hatcheries. Organochlorine pesticides were detected less frequently.
Of the two species sampled, chinook salmon had the highest whole body contaminant concentrations, typically 2--5 times higher
than coho salmon from the same sites. In comparison to estuarine chinook salmon, body burdens of PCBs and DDTs in hatchery
chinook were relatively high, in part because of the high lipid content of the hatchery fish. Concentrations of PCBs were
highest in chinook salmon from the Duwamish Estuary, the Columbia River and Yaquina Bay, exceeding the NOAA Fisheries' estimated
threshold for adverse health effects of 2400 ng/g lipid. Concentrations of DDTs were especially high in juvenile chinook salmon
from the Columbia River and Nisqually Estuary; concentrations of PAH metabolites in bile were highest in chinook salmon from
the Duwamish Estuary and Grays Harbor. Juvenile chinook salmon are likely absorbing some contaminants during estuarine residence
through their prey, as PCBs, PAHs, and DDTs were consistently present in stomach contents, at concentrations significantly
correlated with contaminant body burdens in fish from the same sites. 相似文献
35.
At the new Marais des Cygnes National Wildlife Refuge in Linn County, Kansas, and Bates County, Missouri, USA, we evaluated
long-lived contaminants before acquisition of the land for the refuge. We sampled sediments at 16 locations and fish at seven
locations. The samples were analyzed for metals and for chlorinated hydrocarbon compounds. Selected sediment samples also
were analyzed for aliphatic hydrocarbons. Arsenic concentrations in sediment samples from six locations were elevated compared
to US norms, but arsenic was not detected in any fish composite. Mercury concentrations in largemouth bass from two locations
were comparable to the 85th percentile concentrations in nationwide fish collections. Most sediment concentrations of other
metals were unlikely to have detrimental effects on biota. No chlorinated hydrocarbons were detected in any sediment sample.
Chlordane compound concentrations in fish composites from two sites at the eastern end of the sampling area were 0.127 and
0.228 μg/g wet weight, respectively, which are high enough to cause concern. Most aliphatic hydrocarbons detected were found
at low concentrations and probably were natural in origin. We concluded that there are no serious contaminants concerns within
the project area, but past use of arsenical pesticides may mean a legacy of elevated soil arsenic levels in parts of the area
and some use of banned pesticides such as chlordane and DDT likely is still occurring near the refuge. 相似文献
36.
Nowadays, trends in wastewater treatment by zero-valent iron (ZVI) were turned to use bimetallic NZVI particles by planting another metal onto the ZVI surface to increase its reactivity. Nano size zero-valent iron/copper (NZVI/Cu0) bimetallic particles were synthesized in order to examine its toxicity effects on the wastewater microbial life, kinetics of phosphorus, ammonia stripping and the reduction of chemical oxygen demand (COD). Various concentrations of NZVI/Cu0 and operation conditions both aerobic and anaerobic were investigated and compared with pure NZVI experiment. The results showed that addition 10 mg/L of NZVI/Cu0 significantly increased the numbers of bacteria colonies under anaerobic condition, conversely it inhibited bacteria activity with the presence of oxygen. Furthermore, the impact of nanoparticles on ammonia stripping and phosphorus removal was also linked to the emitted iron ions electrons. It was found that dosing high concentration of bimetallic NZVI/Cu0 has a negative effect on ammonia stripping regardless of the aeration condition. In comparison to control, dosing only 10 mg/L NZVI/Cu0, the phosphorus removal increased sharply both under aerobic and anaerobic conditions, these outcomes were obtained as a result of complete dissolution of bimetallic nanoparticles which formed copper-iron oxides components that are attributed to increasing the phosphorus adsorption rate. 相似文献
37.
The biological effects of contaminants in British estuaries and coastal waters have been studied for over 100 years. Until the 1970s. the major pollution impact on estuarine organisms was probably caused by poorly treated sewage which led to severe oxygen deficits and consequent asphyxiation of many water-breathers. However, since the introduction of improved sewage treatment in the last 30 years, a number of continuing impacts have come to light which represent true toxic effects of micro-contaminants. Sublethal changes observed in various bioassays and biomarkers are widespread in both fish and invertebrates, and in the most urbanised and industrialised estuaries, these effects are probably having impacts at the population and community levels. For example, there is good evidence to show that tributyltin from some antifouling paints has not only affected the sexuality and reproductive success of individual estuarine and coastal molluscs, but has also damaged some benthic communities of which molluscs are but a part. Although there are data to show that some contaminant concentrations are now declining, we do not yet have enough data in most cases to decide whether organisms have also begun to recover. This paper reviews the entire field of contaminant effects in UK estuarine and marine waters, focusing especially on the years 1985-2000, and makes some recommendations for future research and monitoring programmes. 相似文献
38.
Sediments in the Port Jackson estuary are polluted by a wide range of toxicants and concentrations are among the highest reported
for any major harbor in the world. Sediment quality guidelines (SQGs), developed by the National Oceanographic and Atmospheric
Administration (NOAA) in the United States are used to estimate possible adverse biological effects of sedimentary contaminants
in Port Jackson to benthic animals. The NOAA guidelines indicate that Pb, Zn, DDD, and DDE are the most likely contaminants
to cause adverse biological effects in Port Jackson. On an individual chemical basis, the detrimental effects due to these
toxicants may occur over extensive areas of the harbor, i.e., about 40%, 30%, 15% and 50%, respectively. The NOAA SQGs can
also be used to estimate the probability of sediment toxicity for contaminant mixtures by determining the number of contaminants
exceeding an upper guideline value (effects range medium, or ERM), which predicts probable adverse biological effects. The
exceedence approach is used in the current study to estimate the probability of sediment toxicity and to prioritize the harbour
in terms of possible adverse effects on sediment-dwelling animals. Approximately 1% of the harbor is mantled with sediment
containing more than ten contaminants exceeding their respective ERM concentrations and, based on NOAA data, these sediments
have an 80% probability of being toxic. Sediment with six to ten contaminants exceeding their respective ERM guidelines extend
over approximately 4% of the harbor and have a 57% probability of toxicity. These areas are located in the landward reaches
of embayments in the upper and central harbor in proximity to the most industrialised and urbanized part of the catchment.
Sediment in a further 17% of the harbor has between one and five exceedences and has a 32% probability of being toxic. The
application of SQGs developed by NOAA has not been tested outside North America, and the validity of using them in Port Jackson
has yet to be demonstrated. The screening approach adopted here is to use SQGs to identify contaminants of concern and to
determine areas of environmental risk. The practical application and management implications of the results of this investigation
are discussed. 相似文献
39.
Pesticides and trace elements in cannabis: Analytical and environmental challenges and opportunities
Caley B. Craven Nicholas Wawryk Ping Jiang Zhongshan Liu Xing-Fang Li 《环境科学学报(英文版)》2019,31(11):82-93
Cannabis is increasingly used for both medicinal and recreational purposes with an estimate of over 180 million users annually. Canada has recently legalized cannabis use in October 2018, joining several states in the United States of America (e.g., Colorado, California, and Oregon) and a few other countries. A variety of cannabis products including dry flowers, edibles, and oil products are widely consumed. With high demand for cannabis products worldwide, the quality of cannabis and its related products has become a major concern for consumer safety. Various guidelines have been set by different countries to ensure the quality, safety, and efficacy of cannabis products. In general, these guidelines require control of contaminants including pesticides, toxic elements, mycotoxins, and pathogens, as well as residual solvents in regard to cannabis oil. Accordingly, appropriate analytical methods are required to determine these contaminants in cannabis products for quality control. In this review, we focus on the current analytical challenges and method development for detection of pesticides and toxic elements in cannabis to meet various guidelines. 相似文献
40.
A simulation model was developed to describe linkages among fish food web, nutrient cycling, and contaminant processes in
the southern basin of Lake Michigan. The model was used to examine possible effects of management actions and an exotic zooplankter
(Bythotrephes) on Lake Michigan food web and contaminant dynamics. The model predicts that contaminant concentrations in salmonines will
decrease by nearly 20% ifBythotrephes successfully establishes itself in the lake. The model suggests that this decrease will result from lowered transfer efficiencies
within the food web and increased flux of contaminants to the hypolimnion. The model also indicates that phosphorus management
will have little effect on contaminant concentrations in salmonines. The modeling exercise helped identify weaknesses in the
data base (e.g., incomplete information on contaminant loadings and on the biomass, production, and ecological efficiencies
of dominant organisms) that should be corrected in order to make reliable management decisions. 相似文献