Assessment of pesticide contamination in three Mississippi Delta oxbow lakes using Hyalella azteca

Three oxbow lakes in northwestern Mississippi, USA, an area of intensive agriculture, were assessed for biological impairment from historic and current-use pesticide contamination using the amphipod, Hyalella azteca. Surface water and sediment samples from three sites in each lake were collected from Deep Hollow, Beasley, and Thighman Lakes from September 2000 to February 2001. Samples were analyzed for 17 historic and current-use pesticides and selected metabolites. Ten-day H. azteca survival and growth (as length and dry weight) were measured to determine the degree of biological impairment. Maximum number of detectable pesticides in surface water from Deep Hollow, Beasley and Thighman Lakes was 10, 11, and 17, respectively. Maximum number of detectable pesticides in lake sediments was 17, 17, and 15, respectively. Bioassay results indicated no observable survival effects on H. azteca exposed to surface water or sediment from any lake examined and no growth impairment in animals exposed to lake sediments. However, growth was significantly impaired in surface water exposures from Deep Hollow Lake (2 sites) and Beasley Lake (1 site). Statistically significant relationships between growth impairment (length) and cyanazine, methyl parathion, λ-cyhalothrin, chlorfenapyr, and pp′DDE surface water concentrations in Deep Hollow Lake as well as trifluralin, atrazine, and methyl parathion in Beasley Lake were observed. Although pesticide frequency and concentrations were typically greater in sediment than surface water, bioassay results indicated decreased availability of these pesticides in sediment due to the presence of clay and organic carbon. Growth impairment observed in surface water exposures was likely due to complex interaction of pesticide mixtures that were present.     

Desorption of PCDD/PCDF from municipal solid waste incinerator flyash under post-combustion plant conditions

The influence of temperature on the levels of PCDD and PCDF remaining in, and desorbed from, a municipal solid waste incinerator flyash was investigated by heating the ash to between 200 and 400 degrees C under a simulated flue gas for four days reaction time. Considerable desorption of PCDD/PCDF from the flyash was seen at 275 degrees C and above. Maximum desorption occurred at 350 degrees C, with the equivalent of nearly eight times the total PCDD/PCDF concentration of the original flyash being lost to the vapour phase per unit mass of initial flyash. The I-TEQ value of the desorbed PCDD/PCDF was considerable, being over fourteen times that of the original flyash at 325 degrees C. The results indicate that formation of PCDD/PCDF on flyash deposits in the post-combustion plant of incinerators can result in the release of significant amounts of PCDD/PCDF to the flue gas stream.     

Modelling of PCDD/F release from MSW bio-drying

In the present work, an experimentation was carried out to study the behaviour of PCDD/F during the process of municipal solid waste (MSW) bio-drying. This process belongs to the biological mechanical treatment (BMT) options and is aimed to the dewatering of MSW thanks to the biological exothermal reactions (thermal drying, on the contrary, needs an external heat source as methane). The result is a decrease of waste weight and an increase of lower heating value (as the energy content refers to a lower amount of waste). Of course, the overall energy availability does not increase, but the characteristics of bio-drying are interesting as a way for refuse derived fuel generation: glass, metals and inert removals are easier after bio-drying. The literature of the sector shows only few data on PCDD/F emission to air from BMT. Anyway, in the present work an original theory has been put forward in order to explain the enrichment of PCDD/F in the air exiting the biological processes. The role of the initial PCDD/F concentration in the ambient air entering the plant is obviously taken into account. The results of the developed experimentation and the following elaborations point out that PCDD/F could be freed from the volatile solids consumed during the process. The different amount of PCDD/F in the waste and the different consumption of volatile solids depending on the biological process can explain the different PCDD/F emission factors available in the literature.     

Gas chromatographic methods for monitoring of wastewater chlorophenol degradation in anaerobic reactors

Wastewater samples from an anaerobic reactor were extracted with hexane and derivatized with diazomethane (method 1) and with acetic anidride (method 2). Gas chromatography with electron-capture detection (ECD) was employed for separating the parent compound and intermediates trichlorophenols (TCP) and dichlorophenols (DCP) which originated from the penta chlorophenol (PCP) degradation process. The relations between concentrations of PCP, TCP and DCP areas were linear in the range of concentrations of 0.2 to 8 mg/L and 0.025 mg/L to 5 mg/L for methods 1 and 2, respectively. The repeatability of the extraction methods was satisfactory, with variation coefficients lower than 11%. For method 1, at the fortification level of 0.2 mg/L, recovery of PCP, TCP, and DCP was 112%, 74% and 45%, respectively. For method 2, the corresponding recovery values at the fortification level of 0.1 mg/L were 91%, 93% and 103%, respectively. Storage of the frozen samples did not alter their PCP determination properties. The chromatographic methods adapted for chlorophenol determination in wastewater were suitable with relatively simple manipulation techniques. The obtained results were reproducible and allowed identification of intermediates formed during the PCP degradation process.     

Effect of coumaphos on cholinesterase activity, hematology, and biochemical blood parameters of bovines in tropical regions of Mexico

To assess the effect of coumaphos [O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) O,O-diethyl phosphorothioate] exposure on physiological responses during bovine production, acetylcolinesterase (AChE) and butyrylcholinesterase (BuChE) activities were measured in whole blood, erythrocytes, and plasma of healthy male steers (Bos Taurus x Bos indicus) sprayed with coumaphos at a non-lethal dose of 1 mg kg(- 1) body weight per day once every 14 (in vivo group) or 21 days (southern and central groups). Coumaphos topically administered at 1 mg/kg body weight per day to cattle under normal management practices in tropical areas produced a significant inhibition in erythrocyte (RBC) AChE and BuAChE activities when compared to baseline levels. RBC-AChE activity for the in vivo group decreased 71.3% (P < 0.05) and BuChE activity 59.1% (P < 0.05); RBC-AChE activity decreased 55.1% (P < 0.05) (southern group) and 43.4% (P < 0.05) (central group). Compared to the control specimens, steers from in vivo, southern, and central groups after 150 days of exposure had lower (P < 0.05) leukocyte count, absolute lymphocyte, erythrocyte, and platelet counts. Decreases in RBC-AChE activities correlated with decreased lymphocyte (r = 1.000, p = 0.01), erythrocyte (r = 1.000, p = 0.003), and platelet counts (r = 0.841, p = 0.036). Significantly increased BUN levels (P < 0.05) correlated with the decrease in RBC-AChE activities (r = - 0.997, p = 0.047) and with the decrease in absolute red blood cell (r = - 0.883, p = 0.020) and lymphocyte (r = - 0.825, p = 0.043) counts; increased (P < 0.05) total plasma protein levels correlated with the decrease in RBC-AChE activities (r = -0.998, p = 0.043), absolute red blood cell (r = - 0.998, p = 0.040), lymphocyte (r = - 0.893, p = 0.017), and platelet (r = -0.855, p = 0.030) counts. The physiological responses correlated with the erythrocyte acetylcholinesterase inhibition could be considered as early indicators or warning responses of bovine exposures to organophosphorus pesticides (OPs).     

Contaminant exposure in terrestrial vertebrates

Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research.     

A fluorescence-based bioassay for aquatic macrophytes and its suitability for effect analysis of non-photosystem II inhibitors

Background, Goals and Scope During the last years the miniaturization of toxicity test systems for rapid and parallel measurements of large quantities of samples has often been discussed. For unicellular algae as well as for aquatic macrophytes, fluorescence-based miniaturized test systems have been introduced to analyze photosystem II (PSII) inhibitors. Nevertheless, high-throughput screening should also guarantee the effect detection of a broad range of toxicants in order to ensure routinely applicable, high-throughput measuring device experiments which can cover a broad range of toxicants and modes of action others than PSII inhibition. Thus, the aim of this study was to establish a fast and reproducible measuring system for non-PSII inhibitors for aquatic macrophyte species to overcome major limitations for use. Methods A newly developed imaging pulse-amplitude-modulated chlorophyll fluorometer (I-PAM) was applied as an effect detector in short-term bioassays with the aquatic macrophyte species Lemna minor. This multiwell-plate based measuring device enabled the incubation and measurement of up to 24 samples in parallel. The chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides, polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals and personal care products (PPCPs), which are often detected in the aquatic environment. The I-PAM was used (i) to establish and validate the sensitivity of the test system to the three non-PSII inhibitors, (ii) to compare the test systems with standardized and established biotests for aquatic macrophytes, and (iii) to define necessary time scales in aquatic macrophyte testing. For validation of the fluorescence-based assay, the standard growth test with L. minor (ISO/DIS 20079) was performed in parallel for each chemical. Results The results revealed that fluorescence-based measurements with the I-PAM allow rapid and parallel analysis of large amounts of aquatic macrophyte samples. The I-PAM enabled the recording of concentration-effect-curves with L. minor samples on a 24-well plate with single measurements. Fluorescence-based concentration-effect-curves could be detected for all three chemicals after only 1 h of incubation. After 4–5 h incubation time, the maximum inhibition of fluorescence showed an 80–100% effect for the chemicals tested. The EC50 after 24 h incubation were estimated to be 0.06 mg/L, 0.84 mg/L and 1.69 mg/L for paraquatdichloride, alizarine and triclosan, respectively. Discussion The results obtained with the I-PAM after 24 h for the herbicide paraquat-dichloride and the polycyclic aromatic hydrocarbon alizarine were in good accordance with median effective concentrations (EC50s) obtained by the standardized growth test for L. minor after 7 d incubation (0.09 mg/L and 0.79 mg/L for paraquat-dichloride and alizarine, respectively). Those results were in accordance with literature findings for the two chemicals. In contrast, fluorescence-based EC50 of the antimicrobial agent triclosan proved to be two orders of magnitude greater when compared to the standard growth test with 7 d incubation time (0.026 mg/L) as well as with literature findings. Conclusion Typically, aquatic macrophyte testing is very time consuming and relies on laborious experimental set-ups. The I-PAM measuring device enabled fast effect screening for the three chemicals tested. While established test systems for aquatic macrophytes need incubation times of ≥ 7 d, the I-PAM can detect inhibitory effects much earlier (24 h), even if inhibition of chemicals is not specifically associated with PSII. Thus, the fluorescence-based bioassay with the I-PAM offers a promising approach for the miniaturization and high-throughput testing of chemicals with aquatic macrophytes. For the chemical triclosan, however, the short-term effect prediction with the I-PAM has been shown to be less sensitive than with long-term bioassays, which might be due to physicochemical substance properties such as lipophilicity. Recommendations and Perspectives The results of this study show that the I-PAM represents a promising tool for decreasing the incubation times of aquatic macrophyte toxicity testing to about 24 h as a supplement to existing test batteries. The applicability of this I-PAM bioassay on emergent and submerged aquatic macrophyte species should be investigated in further studies. Regarding considerations that physicochemical properties of the tested substances might play an important role in microplate bioassays, the I-PAM bioassay should either be accompanied by evaluating physicochemical properties modeled from structural information prior to an experimental investigation, or by intensified chemical analyses to identify and determine nominal concentrations of the toxicants tested. The chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides, PAHs and PPCPs which are often detected in the aquatic environment. Nevertheless, in order to ensure a routinely applicable measuring device, experiments with a broader range of toxicants and samples of surface and/or waste waters are necessary. ESS-Submission Editor: Dr. Markus Hecker (MHecker@Entrix.com)     

A two-generational reproductive toxicity study of zinc in rats

A two-generation reproductive toxicity study of zinc chloride (ZnCl(2)) was conducted in rats. F(o) male and female rats were administered 0.00 (control), 7.50 (low), 15.00 (mid) and 30.00 (high) mg/kg/day of ZnCl(2). Selected F(1) male and female rats were exposed to the same doses received by their parents (F(o)). Exposure of F(0) parental rats to ZnCl(2) showed significant reduction in fertility, viability (days 0 and 4), and the body weight of F(1) pups from the high-dose group but caused no effects on litter size, weaning index, and sex ratio. Similarly, the continued exposure of F(1) parental rats to ZnCl(2) also reduced fertility, liter size, viability (day 0), and the body weight of F(2) pups within the high-dose group but caused no effects on weaning index and sex ratio. Exposure of ZnCl(2) to F(0) and F(1) parental males resulted in a significant reduction in their body weights, and the F(0) and F(1) parental females did not show any significant difference in their body weights compared to their control groups. However, the postpartum dam weights of both F(0) and F(1) female rats were significantly reduced compared to their controls. Exposure of ZnCl(2) to F(o) and F(1) generation parental rats did not produce any significant change of their clinical signs as well as their clinical pathology parameters, except the alkaline phosphotase (ALK) level, which showed an upward trend in both sexes of both generations. Exposure of ZnCl(2) to F(0) rats resulted in a reduction of brain, liver, kidney, spleen and seminal vesicles weights of males and in the spleen and uterus of females. Similarly, exposure of F(1) rats to ZnCl(2) also resulted in reduction of brain, liver, kidney, adrenal, spleen, prostate and seminal vesicles weights of males and in spleen and uterus of females. ZnCl(2) exposure resulted in grossly observed gastro-intestianla (GI) tract, lymphoreticular/hematopoietic, and reproductive tract lesions in parental rats in both generations. Reduced body fat was also recorded in F(1) parental rats.     

The Distribution and Sources of Polycyclic Aromatic Hydrocarbons in Surface Sediments Along the Egyptian Mediterranean Coast

Coastal marine sediment samples were collected from 31 sampling stations along the Egyptian Mediterranean Sea coast. All sediment samples were analyzed to determine aliphatic and polycyclic aromatic hydrocarbons (PAHs) as well as total organic carbon (TOC) contents and grain size analysis. Total concentrations of 16 EPA-PAHs in the sediments were varied from 88 to 6338 ng g⁻¹ with an average value of 154 ng g⁻¹ (dry weight). However, the concentrations of total aliphatic were varied from 1.3 to 69.9 ng g⁻¹ with an average value of 15.6 ng g⁻¹ (dry weight). The highest contents of PAHs were found in the Eastern harbor (6338 ng g⁻¹), Manzala (5206 ng g⁻¹) and El-Jamil East (4895 ng g⁻¹) locations. Good correlations observed between a certain numbers of PAH concentrations allowed to identify its origin. The average total organic carbon (TOC) percent was varied from 0.91 to 4.54%. Higher concentration of total pyrolytic hydrocarbons (∑COMB) than total fossil hydrocarbons (∑PHE) declared that atmospheric fall-out is the significant source of PAHs to marine sediments of the Egyptian Mediterranean coast. The selected marked compounds, a principal component analysis (PCA) and special PAHs compound ratios (phenanthrene/anthracene vs fluoranthene/pyrene; ∑COMB/∑EPA-PAHs) suggest the pyrogenic origins, especially traffic exhausts, are the dominant sources of PAHs in most locations. Interferences of rather petrogenic and pyrolytic PAH contaminations were noticed in the harbors due to petroleum products deliveries and fuel combustion emissions from the ships staying alongside the quays.