Pesticide contamination of the upper Elbe River and an adjacent floodplain area

Journal of Soils and Sediments - Pesticide contamination of river waters is a global problem, and therefore, authorities regularly monitor the water quality status. Especially, flood events might...     

Microbial community changes during humification of 14C-labelled maize straw in heat-treated and native Orthic Luvisol

The microbial communities in agricultural soils are responsible for nutrient cycling and thus for maintaining soil fertility. However, there is still a considerable lack of knowledge on anthropogenic impacts on soils, their microflora, and the associated nutrient cycles. In this microcosm study, microorganisms involved in the conversion of crop residues were investigated by means of classical microbiological and molecular methods such as denaturing gradient gel electrophoresis (DGGE) of PCR (polymerase chain reaction) amplified 16S rRNA genes. ¹⁴C‐labelled maize straw was humified by the naturally occurring microflora in native and in ashed soils, from which organic carbon was removed by heating at 600°C. The humic acids synthesized in the microcosms served as indicators of the humification process and were analysed by ¹³C‐NMR spectroscopy. Ashed, autoclaved and native soil exhibited similar microbial and physicochemical dynamics after inoculation with a soil suspension. Bacterial counts and DGGE analyses showed that in the first few weeks a small number of rapidly growing r‐strategists were principally responsible for the conversion of maize straw. As the incubation continued, the bacterial diversity increased as well as the fungal biomass. ¹³C‐NMR spectroscopy of 26‐week old soil extracts revealed that structures typical of humic substances also evolved from the plant material.     

Food habits and physical activity patterns among Palestinian adolescents: findings from the national study of Palestinian schoolchildren (HBSC-WBG2004)

OBJECTIVE: To describe the food habits and physical (in)activity patterns and to investigate the relationship with sociodemographic factors among Palestinian adolescents. DESIGN AND SUBJECTS: The Palestinian Health Behaviour in School-aged Children (HBSC) is a cross-sectional survey of grades 6, 8, 10 and 12. Students completed a modified version of the international HBSC questionnaire. A total of 8885 students were included in this analysis; 53% were from the West Bank and 47% from the Gaza Strip. RESULTS: Adolescents in the West Bank consume more fruit, meat, chicken, sweets and soft drinks, but less vegetables than adolescents in Gaza (P<0.01). Girls reported more daily consumption of fruit, vegetables and sweets than boys (P<0.001), and less consumption of soft drinks, milk, meat and chicken (P<0.01). Boys were physically more active than girls (P<0.01), whereas girls reported doing more homework (P<0.001). Both boys and girls reported less physical activity with increasing age (P<0.001). Consumption of fruit and milk was positively associated with both parents' education, while consumption of meat, chicken and soft drinks was positively associated with mother's education only. Having breakfast on schooldays was positively associated with the father's education. Physical activity and television viewing were associated with the mother's education (P<0.01). The parents' level of education had no effect on vegetable consumption and dieting status. CONCLUSION: This study indicated that there are problems with Palestinian adolescents' eating, dieting and physical activity. Regional, gender and parental socio-economic status differences should be taken into account in developing interventions. More detailed studies are needed with more elaborate instruments about food habits and physical activity of adolescents.     

Degradation and humification of maize straw in soil microcosms inoculated with simple and complex microbial communities

Microbial communities are responsible for soil organic matter cycling and thus for maintaining soil fertility. A typical Orthic Luvisol was freed from organic carbon by thermal destruction at 600°C. Then the degradation and humification of ¹⁴C‐labelled maize straw by defined microbial communities was analysed. To study the role of microbial diversity on the humification of plant material, microcosms containing sterilized soil were inoculated with a natural microbial community or with microbial consortia consisting of bacterial and fungal soil isolates. Within 6 weeks, 41 ± 4% of applied ¹⁴C‐labelled maize straw was mineralized in the soil microcosms containing complex communities derived from a soil suspension, whilst the most efficient communities composed of soil isolates mineralized less than 35%. The humification products were analysed by solution state ¹³C‐NMR‐spectroscopy and gel permeation chromatography (GPC). The analyses of humic acids extracts by solution state ¹³C‐NMR‐spectroscopy revealed no difference in the development of typical chemical functional groups for humic substances during incubation. However, the increase in specific molecular size fractions of the extracted humic acids occurred only after inoculation with complex communities, but not with defined isolates. While it seems to be true that redundancy in soil microbial communities contributes to the resilience of soils, specific soil functions may no longer be performed if a microbial community is harshly affected in its diversity or growth conditions.     

家禽肠道螺旋体病

家禽肠道螺旋体病Avain Intestinal spirochaetosis，AIS）被普遍认为是家禽生产中一个越来越严重的疾病。本病由多种螺旋体引起。螺旋体为一类外形呈螺旋状的细菌，它们主要定殖在大多数哺乳动物和家禽（包括猪、人类和家禽）的大肠中。     

Effect of pesticide fate parameters and their uncertainty on the selection of 'worst-case' scenarios of pesticide leaching to groundwater

BACKGROUND: For the registration of pesticides in the European Union, model simulations for worst‐case scenarios are used to demonstrate that leaching concentrations to groundwater do not exceed a critical threshold. A worst‐case scenario is a combination of soil and climate properties for which predicted leaching concentrations are higher than a certain percentile of the spatial concentration distribution within a region. The derivation of scenarios is complicated by uncertainty about soil and pesticide fate parameters. As the ranking of climate and soil property combinations according to predicted leaching concentrations is different for different pesticides, the worst‐case scenario for one pesticide may misrepresent the worst case for another pesticide, which leads to ‘scenario uncertainty’. RESULTS: Pesticide fate parameter uncertainty led to higher concentrations in the higher percentiles of spatial concentration distributions, especially for distributions in smaller and more homogeneous regions. The effect of pesticide fate parameter uncertainty on the spatial concentration distribution was small when compared with the uncertainty of local concentration predictions and with the scenario uncertainty. CONCLUSION: Uncertainty in pesticide fate parameters and scenario uncertainty can be accounted for using higher percentiles of spatial concentration distributions and considering a range of pesticides for the scenario selection. Copyright © 2010 Society of Chemical Industry     

Television viewing behaviour and associations with food habits in different countries

OBJECTIVE: Several environmental factors influence adolescents' food habits and television (TV) viewing is thought to be one of these factors. The purpose of the present study was to describe sociodemographic differences in TV viewing and to examine associations of TV viewing with the consumption of sweets, soft drinks, fruit and vegetables in different countries. METHODS: Data were collected from 162,305 young people completing the 2001/02 Health Behaviour in School-Aged Children survey, a World Health Organization cross-national study on health and health behaviours among 11-, 13- and 15-year-old school pupils. Analyses of variance were used to examine sociodemographic differences in TV viewing and logistic regression analyses to examine associations between TV viewing and food habits. RESULTS: Large differences were found between countries in reported daily TV viewing time, from an average of 2.0 h in Switzerland to 3.7 h in Ukraine. The results indicate that those most likely to watch TV are boys, 13-year-olds and pupils of lower socio-economic status. Those who watched more TV were more likely to consume sweets and soft drinks on a daily basis and less likely to consume fruit and vegetables daily, although the latter associations were not so apparent among Central and Eastern European countries. CONCLUSIONS: Given the high TV viewing rates among adolescents and the association with less healthy food options, many young people are at increased risk of overweight or obesity. Interventions to modify TV viewing behaviour are needed. The findings underscore the importance of tackling socio-economic differences.     

Effects of mineral surface iron on the CPMAS 13C-NMR spectroscopic detection of organic matter from soil fractions in an agricultural topsoil with different amendments

The decrease of NMR visibility of the C signal in soil samples due to the association between organic carbon (OC) and the topsoil mineral surface was investigated. CPMAS ¹³C‐NMR spectra were obtained for soil particle‐size fractions (< 2 μm, 2–20 μm, > 20 μm) and bulk soils from an agricultural topsoil (Chernozem) that had received three different amendments (no fertilization, mineral fertilization (NPK), mineral (NPK) and organic (cattle manure) fertilizations) at Bad Lauchstädt, Germany. The soil organic carbon content of the three soils depended on the degree of soil fertilization. There was no constant relationship between the total NMR signal intensity and the total amount of organic carbon (TOC) for all size fractions. Indeed, a key role played in the C signal intensity by the paramagnetic ferric ion from the clay content in soil fractions and bulk soils was confirmed. Thus, we describe the variations of C signal intensity by taking into account the distribution of clay‐associated OC and non‐associated OC pools. Depending on the amendment, the C signal visibility was weakened by a factor of 2–4 for the clay‐associated OC. This estimation was rendered possible by combining mineral specific surface area (SSA) measurements with the N₂ gas adsorption method (BET method) and determination of TOC and iron concentrations. This approach contributes to the quantitative evaluation of the CPMAS ¹³C‐NMR detection.     

Simulating decomposition of 14C‐labelled fresh organic matter in bulk soil and soil particle fractions at various temperatures and moisture contents

¹⁴C‐labelled fresh organic matter (FOM) was homogeneously incorporated into an agricultural topsoil of small total organic carbon (TOC) content in order to perform decomposition batch experiments at temperatures (T) ranging from 5 to 45°C and soil gravimetric water contents (w) ranging from 7 to 35%. After 4–6‐month incubation (t_end), the residual ¹⁴C (D_end) was measured in bulk soil (0–2000 µm) and soil particle size fractions of 0–53, 53–200 and 200–2000 µm by chemical dispersion and sieving. The ¹⁴C‐FOM decomposition kinetics from soil were fitted either by a single first‐order reaction (rate constant, k_0–2000) assuming only a one‐pool model in the bulk soil or by consecutive first‐order reactions (rate constants, k_0–53 and k_53–2000) assuming a two‐pool model in the bulk soil aggregate structure. In the latter case, a two‐step reaction mechanism involving a FOM particle‐size decrease along the soil fractions was considered where k_0–53 was assumed to be a limiting rate constant. The ¹⁴C‐FOM decomposition kinetics was described for the experimental temperature and water ranges by Arrhenius and Michaelis‐Menten relationships, respectively. Additionally, the results obtained by the adapted Arrhenius physicochemical relationship were compared with the function proposed by Kirschbaum (1995) . Scaling functions T_m and w_m were established and can be used to simulate FOM decomposition rates under different temperature and moisture level conditions. Modelling based on consecutive first‐order reactions supported the hypothesis that the circulation (inflow and outflow) of C into the soil particle small‐size fractions (<53 µm) controls the total C mineralization.