Growth response of Scenedesmus to different concentrations of copper, cadmium, nickel, zinc, and lead

The fresh water alga Scenedesmus was cultured in graded concentration of Cu, Cd, Ni, Zn, and Pb to evaluate the effect of these cations on the growth response of Scenedesmus. The effective concentration of metal which depressed the Scenedesmus growth for Cu was 0.5 mg l⁻¹, for Cd 0.5 mg l⁻¹, for Ni 2 mg l⁻¹, and for Zn 2 mg l⁻¹. The alga exhibited tolerance for high Pb concentrations up to 30 mg l⁻¹. Exposure of a Scenedesmus cell to each metal revealed anatomical changes and chloroplast disruption especially at high metal concentrations.     

Phytoestrogens and mycoestrogens in surface waters — Their sources,occurrence, and potential contribution to estrogenic activity

This review discusses the potential contribution of phytoestrogens and mycoestrogens to in vitro estrogenic activities occurring in surface waters and in vivo estrogenic effects in fish. Main types, sources, and pathways of entry into aquatic environment of these detected compounds were summarized. Reviewed concentrations of phyto/mycoestrogens in surface waters were mostly undetectable or in low ng/L ranges, but exceeded tens of μg/L for the flavonoids biochanin A, daidzein and genistein at some sites. While a few phytosterols were reported to occur at relatively high concentrations in surface waters, information about their potencies in in vitro systems is very limited, and contradictory in some cases. The relative estrogenic activities of compounds (compared to standard estrogen 17β-estradiol) by various in vitro assays were included, and found to differ by orders of magnitude. These potencies were used to estimate total potential estrogenic activities based on chemical analyses of phyto/mycoestrogens. In vivo effective concentrations of waterborne phyto/mycoestrogens were available only for biochanin A, daidzein, formononetin, genistein, equol, sitosterol, and zearalenone. The lowest observable effect concentrations in vivo were reported for the mycoestrogen zearalenone. This compound and especially its metabolites also elicited the highest in vitro estrogenic potencies. Despite the limited information available, the review documents low contribution of phyto/mycoestrogens to estrogenic activity in vast majority of surface waters, but significant contribution to in vitro responses and potentially also to in vivo effects in areas with high concentrations.     

Predictors of PCP,OH-PCBs,PCBs and chlorinated pesticides in a general female Norwegian population

The aims of the current study were to assess plasma concentrations and predictors of halogenated phenolic compounds (HPCs), polychlorinated biphenyls (PCBs) and chlorinated pesticides in a representative group of postmenopausal Norwegian women (n = 311, mean age: 56 years). In addition to delivering a blood sample, the participants had also filled out a detailed questionnaire regarding their current health status, use of medication and dietary habits, etc. The association between a large number of dietary variables, lifestyle factors and plasma concentration of organic pollutants were investigated using multivariate statistics.Within the current study group, p,p′-DDE (median: 903 ng/L w.w.) and pentachlorophenol (PCP, median: 711 ng/L w.w.) were the dominating compounds on a wet weight basis and were present in considerable higher concentrations than the PCBs, the hydroxylated PCBs (OH-PCBs) and the remaining chlorinated pesticides. Of the PCBs, PCB 153 was detected in highest concentrations, whereas 4-OH-PCB187 was present in highest concentration of the selected OH-PCBs. The ratio of ΣOH-PCB to ΣPCB varied between 0.06 and 0.77 ng/L and were significantly lower in individuals with higher ΣPCB concentration. PCP did not co-vary with the other contaminants, indicating a different route of exposure. No clear food cluster was positively associated with PCP exposure; however intake of marine food was negatively linked to PCP concentration and age and being a non-smoker were positive predictors of PCP. The other investigated contaminants co-varied and were positively associated with age, plasma concentrations of marine derived omega-3 fatty acids and a traditional Norwegian fish and bread based diet. The difference in contaminant concentration between high, medium and low consumers of total marine food were however marginal for the dominating PCBs and chlorinated pesticides. The current results indicate however that marine food in itself could be a source of some of the OH-PCBs, regardless of their PCB precursors.As PCP is one of the dominating organic contaminants within the general female Norwegian population, future research on human concentrations, exposure routes and potential health effects of PCP is encouraged. Continued monitoring of human OH-PCB levels should also be performed as they could be present at levels almost as high as the PCBs and they are expected to be more toxic than their mother substances.     

Environmental significance of nitrogenous organic compounds in aquatic sources

The presence of nitrogenous organic compounds in raw water sources for municipal supplies is of environmental concern because many of them exert significant chlorine demand, while some produce complex stable mutagenic products upon chlorination or are precursors to haloform formation. Seven N-organic compounds have been identified in municipal water concentrates (adenine, 5-chlorouracil, cytosine, guanine, purine, thymine, and uracil) at concentrations ranging from 20 to 860 μg/L. Eight compounds (adenine, cytosine, purine, pyrrole, thymine, tryptophan, tyrosine, and uracil) have been found in filtrates from cultures of either Anabaena flos aquae or Oscillatoria tenuis. Calculated CHCl₃ levels which might have formed at pH 7 in the water supplies were well below the maximum contaminant level (MCL) of 0.1 mg/L proposed by the U.S. Environmental Protection Agency (USEPA) for total trihalogenated methanes. Calculated levels of CHCl₃ which might have been formed under more alkaline conditions, however, were more than 10% of the MCL and were therefore significant. Calculated levels of combined forms of chlorine yielding falsely positive tests for free chlorine in some samples were slightly less or exceeded the 0.5 mg/L free chlorine residual generally taken as an acceptable level of disinfection. The demonstration of a parallel increase in organic nitrogen content with population density in two laboratory grown blue-green algal cultures, and the finding of elevated organic nitrogen values in a water supply sample collected during the occurrence of a blue-green algal bloom, suggested that summer algal bloom occurrence can add considerably to the organic nitrogen content and the trihalomethane potential of water supplies.     

太湖主体湖区对梅梁湾藻类影响定量化研究

针对太湖梅梁湾独特的地理位置和富营养化严重的问题,利用太湖水量水质模型和梅梁湾藻类生长模型,在对模型进行了率定、验证的基础下,模拟了在东南风和西北风两种常见风向的条件下,太湖主体湖区对梅梁湾内营养盐浓度和藻类浓度的影响情况,并将其影响定量化。本次模拟较好地反映了太湖主体湖区在两种常见风场的条件下对梅梁湾内水质影响情况。模拟得到以下结果：在不考虑风场和流场的情况下,梅梁湾内部2001年8月藻类平均浓度为43.18 mg/m³,总氮浓度为2.48 mg/L,总磷浓度为0.248 mg/L,只考虑东南风引起流场的情况下,藻类浓度为41.92 mg/m3,总氮浓度为2.07 mg/L,总磷浓度为0.231 mg/L;考虑东南风风场和流场两个因素的情况下,藻类浓度为53.86 mg/m3,总氮浓度为2.06 mg/L,总磷浓度为0.229 mg/L;同期,只考虑西北风风场的情况下,藻类浓度为42.55 mg/m³,总氮浓度为2.19 mg/L,总磷浓度为0.232 mg/L;考虑西北风风场和流场两个因素的情况下,藻类浓度为50.71 mg/m³,总氮浓度为2.17 mg/L,总磷浓度为0.233 mg/L。结果表明,梅梁湾内部的氮、磷等营养盐浓度受到由太湖主体湖区的风场变化引起的湖流扰动的一定影响;太湖主体湖区对梅梁湾内部藻类浓度的影响主要是由藻类漂移引起的,由营养盐浓度改变而引起的藻类浓度变化非常小。     

Exposure assessment of the pharmaceutical diclofenac based on long-term measurements of the aquatic input

Although various single-concentration measurements of the pharmaceutical diclofenac are available in literature, detailed information on the mass flux in the aquatic environment is often missing. Therefore, the overall load of diclofenac was obtained by recording each concentration in nine effluents of sewage treatment plants (STP) and at three river sites located in the area of the river Main (Germany) over a time period of six weeks.In STP effluents, concentrations of up to 2200 ng/L were obtained. In combination with flow rates and connected population an average specific load per capita and day of 0.28 mg (+/? 0.11 mg) diclofenac reaches the receiving water course. This average specific load per capita is an expressive parameter to assess main diclofenac exposure to the aquatic environment avoiding uncertainties of estimated data commonly used in exposure assessment. Accordingly, predicted environmental concentrations (PEC) of 140 ng/L for a realistic worst case scenario and 2 to 52 ng/L based on water quality modeling were derived. Since concentrations of up to 140 ng/L were observed in surface water, the obtained PEC is in perfect agreement with measured concentrations. Hence, comparing the PEC with published predicted no effect concentrations (PNEC), chronic adverse effects in fish populations may occur.     

Effects of acute γ-irradiation on community structure of the aquatic microbial microcosm

To characterise indirect effects of ionising radiation on aquatic microbial communities, effects of acute γ-irradiation were investigated in a microcosm consisting of populations of green algae (Chlorella sp. and Scenedesmus sp.) and a blue-green alga (Tolypothrix sp.) as producer; a ciliate protozoan (Cyclidium glaucoma), rotifers (Lecane sp. and Philodina sp.) and an oligochaete (Aeolosoma hemprichi) as consumer; and more than four species of bacteria as decomposers. Population changes in the constituent organisms were observed over 160 days after irradiation. Prokaryotic community structure was also examined by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA. Principle response curve analysis revealed that the populations of the microcosm as a whole were not significantly affected at 100 Gy while they were adversely affected at 500-5000 Gy in a dose-dependent manner. However, some effects on each population, including each bacterial population detected by DGGE, did not depend on radiation doses, and some populations in the irradiated microcosm were larger than those of the control. These unexpected results are regarded as indirect effects through interspecies interactions, and possible mechanisms are proposed originating from population changes in other organisms co-existing in the microcosm. For example, some indirect effects on consumers and decomposers likely arose from interspecies competition within each trophic level. It is also likely that prey-predator relationships between producers and consumers caused some indirect effects on producers.     

Effect of Nile River water quality on algal distribution at Cairo,Egypt

Changes of phytoplankton density and their relation to physicochemical characteristics along the Nile River have been noted in the Cairo district between 1976 and 1982. Three major phytoplankton groups were found to dominate the river Nile: green algae, blue-green algae, and diatoms. Diatoms represent the most dominant group and comprised from 42% to 96% of the phytoplankton community during the investigated period. Blue-green algae comprised from 0.7% to 48% of total cell number. Green algae represent the low percentage group, which ranges from 0.2% to 41% of Nile water algae. High species diversity (H′) was detected in green algae (1.22) followed by diatoms (0.84); the lowest diversity was in blue-green algae (0.45). The density of total phytoplankton count fluctuated between 10⁶ and 10⁷ organism/L. The concentration of chlorophyll-a ranged from 5 to 37 mg/m³. Primary production rates in the Nile River ranged from 8.5 to 52 mg O₂/m³h. Statistical analysis revealed significant positive correlations between chlorophyll-a content, and concentrations of phosphoruss and nitrate. Phytoplankton diversity, primary production, ammonia, and nitrite content revealed that there is no indication of pollution in the Nile.     

Alteration of DNA,RNA and collagen synthesis in lung organ cultures exposed to mercury ions

We have examined the effect of Hg²⁺ ions on DNA, RNA and collagen synthesis in organ cultures of neo-natal rat lungs. These cultures exhibit many biochemical characteristics of lung in vivo and they continue to synthesize macromolecules at increasing rates up to 6 days. When these cultures were exposed to 1.0μM HgC1₂, the synthesis of DNA was stimulated nearly 3-fold after 72 hr of exposure followed by a decline at 120 hr reflecting cumulative cytotoxicity. Higher concentrations were inhibitory at all times. A nearly 3-fold increase in RNA synthesis occurred after 24 hr exposure to 1.0 μM HgC1₂ and at 72 hr the cultures continued to synthesize RNA at rates comparable to control. There was a decrease in RNA synthesis at 120 hr. Increased collagen synthesis was observed at concentrations up to 10 μM and at all times. The maximal increase, 2–3 fold, occurred at 120 hr in cultures exposed to 0.1 M. These studies suggest that Hg²⁺-induced cell injury in lung organ cultures elicits a reparative response characterized by increased collagen synthesis. This is similar to chemically induced tissue-injury in lungs in vivo. The relevance of these data to the mechanism of induced pulmonary fibrosis is discussed. These studies also point to the usefulness of organ cultures for studying pulmonary toxicity of environmental agents.     

An interlaboratory comparison of nanosilver characterisation and hazard identification: Harmonising techniques for high quality data

Within the FP7 EU project NanoValid a consortium of six partners jointly investigated the hazard of silver nanoparticles (AgNPs) paying special attention to methodical aspects that are important for providing high-quality ecotoxicity data. Laboratories were supplied with the same original stock dispersion of AgNPs. All partners applied a harmonised procedure for storage and preparation of toxicity test suspensions. Altogether ten different toxicity assays with a range of environmentally relevant test species from different trophic levels were conducted in parallel to AgNP characterisation in the respective test media. The paper presents a comprehensive dataset of toxicity values and AgNP characteristics like hydrodynamic sizes of AgNP agglomerates and the share (%) of Ag⁺-species (the concentration of Ag⁺-species in relation to the total measured concentration of Ag). The studied AgNP preparation (20.4 ± 6.8 nm primary size, mean total Ag concentration 41.14 mg/L, 46–68% of soluble Ag⁺-species in stock, 123.8 ± 12.2 nm mean z-average value in dH₂O) showed extreme toxicity to crustaceans Daphnia magna, algae Pseudokirchneriella subcapitata and zebrafish Danio rerio embryos (EC50 < 0.01 mg total Ag/L), was very toxic in the in vitro assay with rainbow trout Oncorhynchus mykiss gut cells (EC50: 0.01–1 mg total Ag/L); toxic to bacteria Vibrio fischeri, protozoa Tetrahymena thermophila (EC50: 1–10 mg total Ag/L) and harmful to marine crustaceans Artemia franciscana (EC50: 10–100 mg total Ag/L). Along with AgNPs, also the toxicity of AgNO₃ was analyzed. The toxicity data revealed the same hazard ranking for AgNPs and AgNO₃ (i.e. the EC50 values were in the same order of magnitude) proving the importance of soluble Ag⁺-species analysis for predicting the hazard of AgNPs. The study clearly points to the need for harmonised procedures for the characterisation of NMs. Harmonised procedures should consider: (i) measuring the AgNP properties like hydrodynamic size and metal ions species in each toxicity test medium at a range of concentrations, and (ii) including soluble metal salt control both in toxicity testing as well as in Ag⁺-species measurements. The present study is among the first nanomaterial interlaboratory comparison studies with the aim to improve the hazard identification testing protocols.     

Toxicokinetics of dioxins and other organochlorine compounds in Japanese people: Association with hepatic CYP1A2 expression levels

Concentrations of persistent organochlorine compounds (OCs) including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in the liver and adipose tissue of Japanese cadavers were measured, and their toxicokinetics were examined in association with hepatic cytochrome P450 (CYP) 1A protein expression levels. Total 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) were 66 ± 74 and 65 ± 57 pg/g lipid weight (mean ± S.D.) in the liver and adipose tissue, respectively. Total PCBs (sum of 62 congeners targeted), p,p′-dichlorodiphenyl-dichloroethylene (p,p′-DDE) and β-hexachlorocyclohexane (β-HCH) were detected at concentrations over 1 μg/g lipid in both tissues of some specimens. For most of the dioxin-like congeners, total PCBs, p,p′-DDE, oxychlordane, α- and β-HCH, hexachlorobenzene (HCB), and tris(4-chlorophenyl)methane (TCPMe), age-dependent increases in concentrations were found in the adipose tissue of males. No such age-dependent trend was observed in the liver, suggesting that there are different mechanisms underlying the hepatic concentrations of OCs. Immunoblot analyses indicated detectable expression of hepatic CYP1A2 protein, whereas no CYP1A1 protein was detected. The CYP1A2 expression levels were positively correlated with concentrations (on wet weight basis) of 2,3,4,7,8-P₅CDF, the dominant TEQ-contributed congeners in the liver, indicating the induction of this CYP. Hepatic CYP1A2 protein levels were strongly correlated with the liver to adipose concentration (L/A) ratios of PCDD/F congeners with more than 5 chlorine atoms. Together with higher concentrations of the congeners in the liver than in the adipose tissue, the observation on L/A ratios of highly chlorinated PCDD/Fs suggests that induced hepatic CYP1A2 protein is involved in their sequestration in this human population, as observed in model animals (rodents). Nonetheless, the magnitude of hepatic sequestration (L/A ratio) of PCDD/Fs in this human population was lower than in other mammals and birds, reported previously. This study emphasizes the fact that toxicokinetics of some OCs can be affected at least partly by CYP1A2 protein levels in humans. For the extrapolation of their toxicokinetics from model animals to humans, knowledge on the induction and sequestration potencies of CYP1A is necessary.     

Strategies of adaptation to heavy metal pollution in Deschampsia caespitosa and Lychnis flos-cuculi: Analysis based on dose-response relationship

The response to copper pollution was studied in the vegetative progeny of tufted hair grass (Deschampsia caespitosa (L.) Beauv.) and ragged robin (Lychnis flos-cuculi L.) plants growing together in chronically polluted areas around the Middle Ural Copper Smelter or in background areas. The root elongation test was used, with copper sulfate (0.006–0.51 mg Cu/L) being added directly to the nutrient medium. Using multimodel inference, dose-response curves were plotted for each of 85 maternal plants, and their parameters (effective Cu concentrations and curve slope in the linear segment) were evaluated. The pattern of transformation in dose dependence of root increment upon transition from background to impact populations proved to be basically different in the two species. The curves for L. flos-cuculi showed a parallel shift, with their shape remaining generally unchanged. In D. caespitosa, this transition was accompanied by a decrease in sensitivity to Cu, but tolerance to this metal was found to increase only at the highest concentration range. These results provide evidence for different strategies of adaptation to heavy metal pollution, which are discussed by comparing the physiological and ecological properties of the two species.     

Toxicities and tolerances of Cd, Cu, Pb and Zn in a primary producer (Isochrysis galbana) and in a primary consumer (Perna viridis)

Studies on toxicities and tolerances of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in the brown alga Isochrysis galbana and in the green-lipped mussel Perna viridis were conducted by short-term bioassays using endpoints growth production and mortality, respectively. The 5-day EC(50) and 24-h LC(50) of these heavy metals were determined in the brown alga and mussel, respectively. The EC(50) values calculated for the alga were 0.74 mg/l for Cd, 0.91 mg/l for Cu, 1.40 mg/l for Pb and 0.60 mg/l for Zn. The LC(50) values for the mussels were 1.53 mg/l for Cd, 0.25 mg/l for Cu, 4.12 mg/l for Pb and 3.20 mg/l for Zn. These LC(50) values were within the concentration ranges as reported by other authors who used P. viridis as the test organism. Based on these EC(50) and LC(50) values, the alga was most sensitive to Zn, followed by Cd, Cu and Pb while the mussel was most sensitive to Cu, followed by Cd, Zn and Pb. Differences in the trophic levels, metal handling strategies, biology and ecology of the primary producer (brown alga) and the primary consumer (mussel) are believed to be the plausible causes for the different toxicities and tolerances of the metals studied.     

Sulfide production during anaerobic lagoon treatment of tapioca wastewater

Laboratory-scale experiments on anaerobic lagoon treatment of tapioca wastewater were conducted under ambient, tropical conditions. The objectives of this study were to investigate factors that affect hydrogen sulfide production and to propose means to control the formation of hydrogen sulfide in lagoon effluents. The concentrations of sulfides were found to increase with increasing organic loading from 2.76 to 5.77 kg COD/m³.d, decreasing hydraulic retention time; and increasing pH from 3 to 7. The maximum total sulfide concentration of 18.8 mg/L occurred at the organic loading of 5.77 kg COD/ m³.d and neutral pH. the maximum H₂S concentration was calculated to be 13.3 mg/L which occurred in the laggoon operated at an organic loading of 5.77 kg COD/m³.d and a pH of 5. The control of odour problems due to the H₂S formation should be possible by raising pH of the lagoon water to be more than 8 or operating the lagoon at low organic loadings.     

Indoor air pollution due to organic gases and vapours of solvents in building materials

The emission of organic gases and vapours of solvent type from 42 commonly used building materials was measured under standard atmospheric conditions. An average of 22 compounds was found in the air around each building material, and the total concentration of gases and vapours was from 0.01 to 1410 mg/m³. The average arithmetic emission rate was 9.5 mg/m² h, and 52 different compounds were identified. A mathematical model was established for the indoor air concentrations of pollutants originating from building materials. The model was tested on three model rooms constructed from the materials investigated. The calculated total air concentrations of gases and vapours in the three rooms ranged from 1.6 to 23.6 mg/m³, and the number of compounds in the air from 23 to 32. These concentrations and number of compounds did not differ from those found in actual rooms similar in size and construction to the model rooms. The risks of health effects due to the compounds identified from the building materials were investigated, and criteria for future air quality standards are discussed. It is concluded that the possibility of negative health effects cannot be neglected, especially not for the more sensitive minority of the general population.     

Soil mutagenicity as a strategy to evaluate environmental and health risks in a contaminated area

Soil can be a storage place and source of pollutants for interfacial environments. This study looked at a site contaminated with wood preservatives as a source of mutagens, defined routes and extent of the dispersion of these contaminants by particle remobilization and atmospheric deposition, considering an evaluation of risk to human health by quantifying mutagenic risk. Soil sampling sites were chosen at gradually increasing distances (150, 500 and 1700 m) from SI (industrial area pool) and indoor dust (pool in an area at risk at 385 m and at 1700 m). Mutagenesis was evaluated in the Salmonella/microsome assay, TA98, TA97a and TA100 strains with and without S9 mix, YGs strains 1041, 1042 and 1024 for nitrocompounds. Acid extracts were analyzed to define the effects of metals and organics for polycyclic aromatic hydrocarbons (PAHs) and nitroderivates, besides concentrations of these compounds and pentachlorophenol (PCP). Risk to human health was obtained from the relation between the quantified potential of mutagenic risk and estimated soil ingestion for children according to USEPA. Metal concentrations showed a gradient of responses with As, Cr and Cu (total metal) or Cr and Cu (fraction available) higher for SI. However, mutagenic effects of the mixtures did not show this grading. Site SR1700, without a response, was characterized as a reference. In organic extracts, the mutagenesis responses showed the mobility of these compounds from the source. In the surrounding area, a smaller pattern similar to SI was observed at SR150, and at the other sites elevated values of direct mutagenesis at SR500 and diminished effects at SR1700. Tests with YG strains indicated that nitrated compounds have a significant effect on the direct mutagenesis found, except SR500. The investigation of indoor dust in the surrounding area enabled confirmation of the particle resuspension route and atmospheric deposition, showing responses in mutagenicity biomarkers, PAH concentrations and PCP dosage similar to SI. The range of values obtained, considering the soil masses needed to induce mutagenicity was 0.02 to 0.33 g, indicating a high risk associated with human populations exposed, since these values found surpass the standard estimate of 200 mg/day of rate of soil ingestion for children according to USEPA. The study showed that it is essential to evaluate the extent of contamination from the soil to delimit remedial measures and avoid damage to the ecological balance and to human health.     

Development of extraction method of pharmaceuticals and their occurrences found in Japanese wastewater treatment plants

In this study, occurrence of 66 PPCPs (pharmaceuticals and personal care products) in liquid and solid phases of sewage sludge was elucidated. The extraction methods for the PPCPs from sludge were newly developed employing Pressurized Liquid Extraction (PLE) and Ultrasonic Solvent Extraction (USE). As an appropriate method, PLE using water (pH2), PLE using methanol (pH4), and USE using mixture of methanol and water (1/9,v/v, pH11) was found most effective because total recovery of most of the PPCPs indicated 40 to 130%. The developed extraction method with previously developed method for liquid phase analysis was applied to field survey at wastewater treatment plants (WWTPs) in Japan. 56 compounds were detected from the primary sludge and 61 compounds were detected from the excess sludge. The concentration was ranged between several ng/g and several μg/g. Solid-water distribution coefficient (Log K_d) ranged between 0.9 L/kg (Caffeine) and 3.7 L/kg (Levofloxacin) for primary sludge and between 1.4 L/kg (Sulpirid) and 4.3 L/kg (Mefenamic acid) for excess sludge.     

Acute toxicity of two insecticides to tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri

Acute toxicity and presumable harmless concentration of two commercial insecticides, Furadan 3G and Malataf 50E were reported for tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri. L. hoffmeisteri were found more susceptible to both the insecticides; the Furadan was found to be more toxic than Malataf to tubificid worms. Analysis of variants showed a significant difference between safe concentrations of the same insecticide to different species.     

Novel exposure biomarkers of N,N-diethyl-m-toluamide (DEET): Data from the 2007–2010 National Health and Nutrition Examination Survey

BackgroundN,N-diethyl-m-toluamide (DEET) is a widely used insect repellent in the United States.ObjectivesTo assess exposure to DEET in a representative sample of persons 6 years and older in the U.S. general population from the 2007–2010 National Health and Nutrition Examination Survey.MethodsWe analyzed 5348 urine samples by using online solid-phase extraction coupled to isotope dilution-high-performance liquid chromatography-tandem mass spectrometry. We used regression models to examine associations of various demographic parameters with urinary concentrations of DEET biomarkers.ResultsWe detected DEET in ~ 3% of samples and at concentration ranges (> 0.08 μg/L–45.1 μg/L) much lower than those of 3-(diethylcarbamoyl)benzoic acid (DCBA) (> 0.48 μg/L–30,400 μg/L) and N,N-diethyl-3-hydroxymethylbenzamide (DHMB) (> 0.09 μg/L–332 μg/L). DCBA was the most frequently detected metabolite (~ 84%). Regardless of survey cycle and the person's race/ethnicity or income, adjusted geometric mean concentrations of DCBA were higher in May–Sep than in Oct–Apr. Furthermore, non-Hispanic whites in the warm season were more likely than in the colder months [adjusted odds ratio (OR) = 10.83; 95% confidence interval (CI), 3.28–35.79] and more likely than non-Hispanic blacks (OR = 3.45; 95% CI, 1.51–7.87) to have DCBA concentrations above the 95th percentile.ConclusionsThe general U.S. population, including school-age children, is exposed to DEET. However, reliance on DEET as the sole urinary biomarker would likely underestimate the prevalence of exposure. Instead, oxidative metabolites of DEET are the most adequate exposure biomarkers. Differences by season of the year based on demographic variables including race/ethnicity likely reflect different lifestyle uses of DEET-containing products.     

博落回植物与肥料复合的杀螺效应及对水稻生长影响

探索一种杀螺施肥双效作用的新型杀螺剂。将博落回植物粉末分别与氮、磷、钾肥复合制成植物3种单肥复合杀螺剂(简称MPF)，与3种肥料混合配成植物混合肥复合杀螺剂(简称MCF)。采用浸杀法进行杀螺试验, 同时检验该复合杀螺剂对水稻萌发及生长的影响。结果显示，3种MPF(博落回植物分别与氮、磷、钾肥复合杀螺剂)处理钉螺，48 h钉螺死亡率分别为100%、533%、667%；作用于水稻，能明显促进种子萌发和幼苗生长，如3种MPF使水稻种子萌发率分别为100%、80%和53%，分别比对照（40%）提高了60%、40%和13%；水稻幼苗分别增长了1268%、707%和605%。MCF随处理浓度增加及处理时间延长，钉螺死亡率上升，较低浓度（200 mg/L）处理48 h 和72 h,钉螺死亡率分别为733%和867%；较高浓度（400 mg/L）复合处理48 h和72 h，钉螺死亡率分别为833%、100%。然而，低浓度（200 mg/L）MCF对水稻萌发和生长有促进作用，如水稻幼苗比对照增长了876%，但高浓度（400 mg/L）则有一定抑制作用。因此，MPF对钉螺具有较好的杀螺活性，同时能促进水稻萌发和生长，其中植物氮肥复合杀螺剂效果最佳；MCF对钉螺均有杀螺活性，但低浓度对水稻有促进作用，而高浓度则有抑制作用