Redistribution of organic pollutants in river sediments and alluvial soils related to major floods

Background, Aims, and Scope  More frequent occurrence of stronger floods in Europe as well as in other parts of the world in recent years raises major concern about the material damages, but also an important issue of contamination of the affected areas through flooding. The effects of major floods on levels and distribution of contamination with hydrophobic organic pollutants were examined from the continuous set of data for floodplain soils and sediments from a model industrial area in the Czech Republic where a 100-year flood occurred in 1997. The goal of this study was to evaluate the risk related to contamination associated with such extensive natural events and characterize the spatial and temporal distribution and dynamics of pollutants related to a major flooding shortly after the floods and also in the time period several years after floods. Methods  Sediments and alluvial soils from fourteen sites each were repeatedly sampled during the period from 1996 until 2005. The sampling sites represented five regions. Collected top-layer sediment and soil samples were characterized and analyzed for hydrophobic organic pollutants PCBs, OCPs and HCB using GC-ECD and PAHs using a GC-MS instrument. Spatial and temporal differences as well as the relative distribution of the pollutants were examined in detail by statistical analysis including multivariate methods with special emphases placed on the changes related to floods. Results  The organic pollutants levels in both alluvial soils and sediments exceeded the safe environmental limits at numerous sites. Pollutants concentrations and relative distribution as well as organic carbon content in both sediment and floodplain soils were significantly affected by the flooding, which resulted in a decrease of all studied contaminants in sediments and significant rise of the PAH pollution in the flooded soils. There was a unique and highly conserved PAH pattern in soils regardless of the floods and greater changes in PAH pattern in sediments related to floods. The relative distribution of individual PAHs reflected a combustion generated PAH profile. PAH levels in the river sediments rose again at the sites with continuous sources several years after floods. Discussion  The results showed different dynamics of PAHs and PCBs during the floods when PAHs were redistributed from the sediments to alluvial soils while PCBs have been washed out of the study regions. The data reveal longer contamination memory and consistent contamination pattern in soils, whereas sediments showed more dynamic changes responding strongly to the actual situation. The stable PAH pattern within the regions also indicates that a relative amount of all compounds is comparable across the samples and, thus, that the sources at different sites have similar character. Conclusions  Sediments have the potential to function as a secondary source of contamination for the aquatic ecosystem, but also for the floodplain soils and other flooded areas. The floods served as a vector of PAHs contamination from sediments to soils. The reloading of river sediments in time, namely with PAHs, due to present sources increases their risk as a potential source in the next bigger flood event both to the downstream river basin and affected alluvial soils. Recommendations and Perspectives  The results stress the importance of including the floodplain soil contamination in the risk assessment focused on flood effects. Floodplain soils have stable long-term environmental memory related to contamination levels, pattern and distribution, whereby they can provide relevant information on the overall contamination of the area. The sediments will continue to serve as a potential source of contaminants and alluvial soils as the catchment media reflecting the major flood events, especially until effective measures are taken to limit contamination sources. ESS-Submission Editor: Dr. Henner Hollert (Hollert@uni-heidelberg.de) This article is openly accessible!     

Effects of fungicides on in vitro spore germination and mycelial growth of the phytopathogens Leptosphaeria maculans and L. biglobosa (phoma stem canker of oilseed rape)

BACKGROUND: Phoma stem canker, caused by the coexisting related fungal pathogens Leptosphaeria maculans (Des.) Ces. & de Not and L. biglobosa Shoemaker & H Brun, is a major disease of winter oilseed rape in the UK. Annually, over 90% of UK crops receive at least one foliar application of fungicide, but little is known about the sensitivity of the more damaging L. maculans and the less damaging L. biglobosa to these fungicides. The effects of flusilazole, tebuconazole and Methyl Benzimidazole Carbamate (MBC) fungicides (benomyl and carbendazim) on the germination of ascospores, conidia and germ tube growth of both species were examined. Isolates collected from different oilseed rape crops in England and Wales were assessed for their mycelial growth on fungicide‐amended medium, and ED₅₀ values were calculated. RESULTS: Leptosphaeria maculans and L. biglobosa differed in their sensitivity to fungicides. Conidial germination of L. maculans was more sensitive to these fungicides than that of L. biglobosa. Isolates of L. maculans had smaller ED₅₀ values for mycelial growth for all fungicides tested than isolates of L. biglobosa. CONCLUSION: These results suggest that fungicide applications might affect the structure of L. maculans/L. biglobosa populations in UK winter oilseed rape crops. Copyright © 2009 Society of Chemical Industry     

Field leaching of pesticides at five test sites in Hawaii: study description and results

BACKGROUND: Following the discovery of pesticides in wells, the Hawaii Department of Agriculture (HDOA) supported research to evaluate the likelihood of pesticide leaching to the groundwater in Hawaii. The aim of this study was to evaluate the relative leaching pattern of five pesticides at five different sites on three islands and to compare their leaching behavior with bromide and a reference chemical (atrazine) that is known to leach in Hawaiian conditions. Laboratory measurements of sorption and degradation of the pesticides were made. RESULTS: Most of the applied mass of pesticides was still present in the top 80 cm after the 16 week study period. The aggregated oxisol at Kunia showed the most intensive leaching among the five sites. The revised attenuation factor screening approach used by the HDOA indicated that all chemicals, with the exception of trifloxystrobin, had the potential to leach. Similarly, the groundwater ubiquity score ranked trifloxystrobin as a non‐leacher. The field leaching data, however, suggested that trifloxystrobin was the most mobile compound among the pesticides tested. CONCLUSION: Although the results were variable among the sites, the field and laboratory experiments provided useful information for regulating use of these pesticides in Hawaii. Copyright © 2010 Society of Chemical Industry     

Canopy reduction as a possible measure for adaptation of young Scots pine stand to insufficient precipitation in Central Europe

Climate change towards a warmer and dryer vegetation period may negatively impact growing conditions for Scots pine monocultures situated on dry, sandy soils in Central Europe. The purpose of the study was to evaluate the effect of thinning on precipitation throughfall in young Scots pine stands on typical pine sites. In 1992, observation of precipitation and throughfall started at the Tyniště research site (lowland of Eastern Bohemia) in a 7-year-old pine stand planted in rows at a stocking of ca 10,000 trees ha⁻¹. Throughfall was measured at weekly intervals during the growing season (April-September) by gauges randomly located in two treatments - variant 1C - Control without thinning and variant 2T - Thinned - and compared to precipitation at an open space outside of the canopy. The results demonstrated the positive effects of heavy low thinning (removal of 47% of the total number of trees and 31% of total pre-treatment basal area) on the water supply of young Scots pine stands. On the Thinned treatment, throughfall increased by 2-8% compared to Control plot. This positive effect persisted for six years after the first canopy reduction and the differences were significant for the first four years after thinning. After the second treatment (high thinning), throughfall on the Thinned treatment showed a nominal, but statistically insignificant increase. The likely reason for this result is that the application of a different type of thinning increased the variability of the canopy and, consequently, the effect of released crowns could not be detected.     

Spatial patterns and temporal changes of heavy metal distributions in river sediments in a region with multiple pollution sources

Purpose

The main purpose of this study was to evaluate temporal and regional variability of contamination by heavy metals (HMs) in river sediments using their enrichment factors (EFs) and benchmarking according to sediment quality guidelines (SQGs). The Zlin region in the Czech Republic (Morava and Drevnice River basins) represents a model area where several regionally specific ecological risk assessment studies have recently been conducted with a focus on organic pollution, eco-toxicity, geological, and geochemical characteristics.

Materials and methods

Four consecutive sediment sampling campaigns were undertaken in spring and autumn 2005–2006. Aqua-regia leachable content of Cd, Co, Cr, Cu, Ni, Pb, Sb, V, and Zn in surface sediments from 14 sites was analyzed using ICP-MS, and Hg content was analyzed using AMA-254 analyzer. EFs were calculated to identify the human impact on pollution in the area. Comparisons to SGQs were conducted to identify the areas and HMs of greatest risk.

Results and discussion

Calculation of EFs contributed to the effective clustering of HMs. Median EFs of Co, Ni, and V ranged from 0.9 to 1.4 at all sites indicating concentrations very close to natural geological background levels. There was greater enrichment at locally polluted sites, the highest in the cases of Cd, Sb, Hg, and Cr. Widespread influence of diffuse HM sources (traffic, agriculture, and urban wastes) was apparent from elevated concentrations of Pb, Cu, and Zn at all sites. EF values also helped to identify the greatest temporal changes and shifts in HMs contamination between adjacent sites caused by 50-year recurrence interval floods in early spring 2006. The impact was most apparent in downstream sites; namely directly below the confluence of the two major rivers.

Conclusions

The overall contamination of HMs in the region was classified as low-to-moderate with significantly contaminated sub-areas. The study showed relatively stable spatial distributions of HMs, indicating potential sources of pollution. Cu was identified as the HM of greatest risk. The study emphasizes the necessity of considering both environmental circumstances and background HM occurrence to prevent misinterpretation of the pollution situation. The use of EFs which include grain size proxy normalization and HM background levels, along with the comparison of the detected concentrations to SQGs, proved an efficient way to identify hazardous contamination from anthropogenic sources.     

Identification of candidate miRNAs and expression profile of yak oocytes before and after in vitro maturation by high‐throughput sequencing

Small RNA represents several unique non‐coding RNA classes that have important function in a wide range of biological processes including development of germ cells and early embryonic, cell differentiation, cell proliferation and apoptosis in diverse organisms. However, little is known about their expression profiles and effects in yak oocytes maturation and early development. To investigate the function of small RNAs in the maturation process of yak oocyte and early development, two small RNA libraries of oocytes were constructed from germinal vesicle stage (GV) and maturation in vitro to metaphase II‐arrested stage (M II) and then sequenced using small RNA high‐throughput sequencing technology. A total of 9,742,592 and 12,168,523 clean reads were obtained from GV and M II oocytes, respectively. In total, 801 and 1,018 known miRNAs were acquired from GV and M II oocytes, and 75 miRNAs were found to be significantly differentially expressed: 47 miRNAs were upregulated and 28 miRNAs were downregulated in the M II oocytes compared to the GV stage. Among the upregulated miRNAs, miR‐342 has the largest fold change (9.25‐fold). Six highly expressed miRNAs (let‐7i, miR‐10b, miR‐10c, miR‐143, miR‐146b and miR‐148) were validated by real‐time quantitative PCR (RT‐qPCR) and consistent with the sequencing results. Furthermore, the expression patterns of two miRNAs and their potential targets were analysed in different developmental stages of oocytes and early embryos. This study provides the first miRNA profile in the mature process of yak oocyte. Seventy‐five miRNAs are expressed differentially in GV and M II oocytes as well as among different development stages of early embryos, suggesting miRNAs involved in regulating oocyte maturation and early development of yak. These results showed specific miRNAs in yak oocytes had dynamic changes during meiosis. Further functional and mechanistic studies on the miRNAs during meiosis may beneficial to understanding the role of miRNAs on meiotic division.     

Application of an ELISA Milk Pregnancy Test in Beef Cows

Pregnancy‐associated glycoproteins (PAG) are secreted by the binucleate giant cells of the ruminant placenta and enter maternal circulation at the time of placental attachment. The IDEXX Milk Pregnancy Test (IDEXX, Westbrook, ME) detects a subset of PAG in milk. Although designed as a management tool for dairy cows, there is potential for using the milk PAG test in beef cows. Our objective was to compare the performance of the milk PAG ELISA with a gold standard method for pregnancy diagnosis and determine the agreement between milk and serum PAG analysis in lactating beef cows. Angus and Angus‐crossed cows (n = 332) from two Michigan beef herds were enrolled in this study. Cows were subjected either to timed artificial insemination followed by exposure to a bull or exclusively exposed to a bull. The bulls and cows were separated 30 days prior to examination. Serum and milk samples were collected and submitted within 24 h of collection to a commercial laboratory for PAG analysis using the IDEXX Milk Pregnancy Assay (milk) and the IDEXX Bovine Pregnancy Assay (serum). Concurrently with milk and serum collection, each cow was examined transrectally by palpation or ultrasonography. When compared to transrectal examination, the performance (and 95% confidence intervals) of the milk PAG ELISA was sensitivity of 99.7% (99.0–100.0%) and specificity of 80.8% (65.6–95.9%). The lower specificity is likely due to the low prevalence (9.9%) of open cows (n = 30) in the herds examined. Of the 332 cows examined, 1.8% (n = 6) were classified as rechecks using the milk PAG ELISA. Results of the milk and serum PAG ELISA were in high agreement (kappa coefficient = 0.91). The milk PAG ELISA was accurate in predicting pregnancy status using milk collected from beef cattle between days 37 and 125 post‐insemination and may be useful for aiding management decisions in beef herds.     

Temperature-induced momentum-dependent spectral weight transfer in Bi2Sr2CaCu2O8+delta

Angle-resolved photoemission data from the cuprate superconductor Bi2Sr2CaCu2O8+delta above and below the superconducting transition temperature Tc reveal momentum-dependent changes that extend up to an energy of about 0.3 electron volt, or 40kTc (where k is the Boltzmann constant). The data suggest an anomalous transfer of spectral weight from one momentum to another, involving a sizable momentum transfer Q approximately (0.45pi, 0). The observed Q is intriguingly near the charge-order periodicity required if fluctuating charge stripes are present.     

The effect of the age of stallions and mares on their fertility

The study was based on the documentation of the Napajedla Stud Farm of the English Thoroughbred horse for 1888-1972. Evaluating the effect of the age of stallions on their fertility (leaving aside the variability of the age of their mothers), such an effect was found to be significant only in four out of the 26 studs evaluated. In 65% of the selected stallions, the correlation coefficients were found to be negative, but without statistical significance. However, the objective of the study was to evaluate stallions and mares parallelly as to their age variability and fertility. The relationships of the effect of the age of the stallion and of the mare on fertility were evaluated by different modificatons of the value chi2. The prerequisite for the analyses of the effect of different stallion age at a constant age of mares was the calculation of the global chi2 used jointly for the evaluation of the variable age of stallions and mares. The result are varied and report on the individuality of the effect of stallions, giving no clear basis for generalizing any fertility-decreasing tendency with the higher age of the parents. The problem is analyzed from the physiological viewpoint.