2,4-Dichlorophenoxyacetic acid (2,4-D) sorption and degradation dynamics in three agricultural soils

The fate and transport of 2,4-dichlorophenoxyacetic acid (2,4-D) in the subsurface is affected by a complex, time-dependent interplay between sorption and mineralization processes. 2,4-D is biodegradable in soils, while adsorption/desorption is influenced by both soil organic matter content and soil pH. In order to assess the dynamic interactions between sorption and mineralization, 2,4-D mineralization experiments were carried using three different soils (clay, loam and sand) assuming different contact times. Mineralization appeared to be the main process limiting 2,4-D availability, with each soil containing its own 2,4-D decomposers. For the clay and the loamy soils, 45 and 48% of the applied dose were mineralized after 10 days. By comparison, mineralization in the sandy soil proceeded initially much slower because of longer lag times. While 2,4-D residues immediately after application were readily available (>93% was extractable), the herbicide was present in a mostly unavailable state (<2% extractable) in all three soils after incubation for 60 days. We found that the total amount of bound residue decreased between 30 and 60 incubation days. Bioaccumulation may have led to reversible immobilization, with some residues later becoming more readily available again to extraction and/or mineralization.     

Evaluation of metal mobility, plant availability and immobilization by chemical agents in a limed-silty soil

Metal-contaminated soils in the vicinity of industrial sites become of ever-increasing concern. Diagnostic criteria and ecological technologies for soil remediation should be calibrated for various soil conditions; actually, our knowledge of calcareous soil is poor. Silty soils near smelters at Evin (Pas de Calais, France) have been contaminated by non-ferrous metal fallout and regularly limed using foams. Therefore, the mobility, bioavailability, and potential phytotoxicity of Cd, Pb and Zn, were investigated using single soil extractions (i.e. water, 0.1 n Ca(NO(3))(2), and EDTA pH 7), and vegetation experiments, in parallel with a biological test based on (iso)-enzymes in leaves and roots, before and following soil treatment with chemical agents, i.e. Thomas basic slags (TBS), hydrous manganese oxide (HMO), steel shots (ST) and beringite. No visible toxicity symptoms developed on the above-ground parts of ryegrass, tobacco and bean plants grown in potted soil under controlled environmental conditions. Cd, Zn and Pb uptake resulted in high concentrations in the above-ground plant parts, but the enzyme capacities in leaves and roots, and the peroxidase pattern indicated that these metal concentrations were not phytotoxic for beans as test plants. The addition of chemical agents to the soil did not increase biomass production, but treatment with either HMO, ST or beringite markedly decreased the mobility of Cd, Zn and Pb. These agents were proven to be effective in mitigating the Cd uptake by plants. HMO and ST decreased either Pb or Zn uptake by ryegrass. TBS was effective in lowering Pb uptake by the same species. Beringite decreased Cd uptake by beans. If fallout could be restricted, the metal content of food crops in this area should be lowered by soil treatment. However, the differences in Cd uptake between plant species were not suppressed, regardless of the type of agents applied to the soil.     

Activity patterns in the terebellid polychaete <Emphasis Type="Italic">Eupolymnia nebulosa</Emphasis> assessed using a new image analysis system

The activity and surface sediment displacement by the terebellid polychaete Eupolymnia nebulosa were monitored, using new image acquisition and image analysis procedures. We used a video sensor mounted on a motorized table, to acquire adjacent images of the whole studied aquarium within about 2 s. These images were then grouped within a composite image acquired every 15 s. Consecutive composite images were compared to infer activity and surface sediment displacement. This procedure proved efficient for E. nebulosa as indicated by (1) the continuity of the tentacles within composite images, and (2) the direct comparison of images and detected activities. There were important temporal changes in the relative importance of the three main types of activity: feeding, tube-building and (both partial and total) emergence from the tube, accounting, respectively, for 75, 15 and 10% of the entire experiment duration. Activity intensity (cm² min^-1) was assessed through the surface of pixels with grey levels differing by more than 20 (on a 0–255 scale) between two consecutive images. Feeding was associated with low activity intensity, whereas tube-building and emergence from the tubes were associated with high activity intensities. Surface sediment displacement mostly resulted from tentacle activity both during feeding and tube-building and was almost zero when worms emerged from their tube. We used our experimental set up to assess spatial changes in activity intensity and particle displacements along the tentacles. Most of the activity occurred within the first 4–6 cm from the tube aperture. Particle loss during their transfer along the tentacles preferentially affected larger particles as postulated by the model of particle selection and transport in tentaculate deposit-feeders. Moreover, the speed of the particles along the tentacles correlated negatively with their size. This contributed to increase in the residence time of larger particles on the tentacles and thus, to further enhance their probability of being lost. The size distributions of particles during feeding and tube-building did not differ significantly although visual observations confirmed the preferential use of larger particles for tube-building. This suggests the existence of a sorting step occurring elsewhere than on the tentacles as already demonstrated for spionid polychaetes.     

Fate of the veterinary medicine ivermectin in soil

We investigated the fate of the drug ivermectin in the soil. We found that ivermectin was transformed solely by photos, leading to the formation of two ivermectin isomers. We indeed failed to detect any biotransformation reaction of the chemical either in the soil or in fungal liquid cultures. According to its limited water solubility, the bioavailability of ivermectin was very low in the soil solution. Here, we show that ivermectin, transferred to the soil from faeces of drug-treated cattle, could be stored for long periods in the soil.     

Social synchronization of circadian rhythms in deer mice (Peromyscus maniculatus)

Summary Deer mice (Peromyscus maniculatus), kept in individual cages under constant dim-light conditions, displayed steady free-running rhythms of activity, the period of which varied between individuals.When two previously isolated mice with different rhythms were placed in a common enclosure, under the same constant light conditions, they soon displayed a mutual synchronization of their activity rhythms. When separated again, the mice lost mutual synchronization (Figs. 1 and 2)The process by which mutual synchronization was attained in the common enclosure is typical of entrainment by an external synchronizer (Zeitgeber). Our results suggest that the activity rhythm of the dominant mouse entrains the activity rhythm of the subordinate, and is thus a social Zeitgeber.     

Multiple sexual advertisements honestly reflect health status in peacocks (Pavo cristatus)

The evolution of multiple sexual traits remains controversial and poorly understood in evolutionary biology. In many bird species, males exhibit complex courtships involving feather ornaments and behavioral display. Multiple traits may convey information on the genetic and phenotypic quality of males. In particular, fixed characters, such as feather ornaments (produced once a year during the annual molt in many bird species) might convey information about past male condition (at the time of trait development); whereas flexible traits such as behavioral displays should be sensitive to present condition. Here we show that both flexible behavioral displays and fixed feather ornaments of peacocks, used by females to choose a mate, honestly reflect health status. Correlative data showed that peacocks with high display rate (the number of behavioral displays per hour) and a large number of tail eyespots had low levels of circulating heterophils, suggesting better health status. Experimental activation of the immune system, through LPS injection, significantly reduced display rate compared to a control group. However, the sensitivity of a male display rate to the immune challenge was dependent on the number of tail eyespots: males with higher number of tail eyespots were better able to cope with the experimental immune challenge, and maintained their display rate at levels closer to the levels performed before the immune activation. These results are consistent with the idea that multiple signaling might enhance information reliability.     

Development of a new masters program for occupational physicians in Flanders

Background: discussions with occupational physicians and a postal survey identified the shortcomings of previous programs, mainly found in the fields of occupational hygiene, ergonomics, environmental health and management.Objectives of the new program: basic knowledge (see content), the development of problem solving skills, scientific and social attitudes.Content: first year: occupational health practice, occupational hygiene, epidemiology, work physiology, toxicokinetics and dynamics and in service training (4 weeks). Second year: occupational pathology, environmental health, ergonomics, social legislation, safety, management and in service training (4 weeks). The total study load is estimated at about 1600 hours per year.Methods: interactivity is stimulated by the introduction of interdisciplinary seminars, project work in groups and Socratic dialogue. The objectives, contents and teaching and student-evaluation methods of the separate items were defined before selecting teachers.Finality of the program: a masters title sufficient to practice occupational medicine in Belgium. A subsequent postacademic training of 2 years, while at work, will be required for the title of specialist in occupational medicine, valid at European Union (EU) level. It will include preparing and publically defending a thesis.Statement: The collaboration of ex-students working in the field is essential in the development and quality assessment of adequate teaching programs.     

Emergency braking is affected by the use of cruise control

Objective: We compared the differences in the braking response to vehicle collision between an active human emergency braking (control condition) and cruise control (CC) or adaptive cruise control (ACC).

Methods: In 11 male subjects, age 22 to 67 years, we measured the active emergency braking response during manual driving using the accelerator pedal (control condition) or in condition mimicking CC or ACC. In both conditions, we measured the brake reaction time (BRT), delay to produce the peak braking force (PBD), total emergency braking response (BRT + PBD), and peak braking force (PBF). Electromyograms of leg and thigh muscles were recorded during braking. The tonic vibratory response (TVR), Hoffman reflex (HR), and M-waves were recorded in leg muscles to explore the change in sensorimotor control.

Results: No difference in PBF, TVR amplitude, HR latency, and H_max/M_max ratio were found between the control and CC/ACC conditions. On the other hand, BRT and PBD were significantly lengthened in the CC/ACC condition (240 ± 13 ms and 704 ± 70 ms, respectively) compared to control (183 ± 7 ms and 568 ± 36 ms, respectively). BRT increased with the age of participants and the driving experience shortened PBD and increased PBF.

Conclusions: In male subjects, driving in a CC/ACC condition significantly delays the active emergency braking response to vehicle collision. This could result from higher amplitude of leg motion in the CC/ACC condition and/or by the age-related changes in motor control. Car and truck drivers must take account of the significant increase in the braking distance in a CC/ACC condition.     

天津市非道路移动源污染物排放清单开发

基于天津市非道路移动源污染管控需求,根据调研收集到的2015年非道路移动源活动水平数据,采用环保部《非道路移动污染源排放清单编制技术指南(试行)》推荐的核算方法,建立较为完整的天津市非道路移动源排放清单,分析污染物的时空分布.2015年,天津市非道路移动源排放CO 6.15×10~3t、HC 2.45×10~3t、NO_x2.90×10~4t、PM 1.45×10~3t、SO_21.37×10~4t.船舶污染物排放占比最高,为所有非道路移动源污染物排放总量的73.66%,主要分布于天津港区;其次是非道路移动机械,占21.66%,主要分布于市郊种植业和养殖业区县、城市建设和人群活动较为密集的城区;民航飞机和铁路机车占比较小,分别为3.55%和1.13%,主要分布于机场和铁路沿线.总体上,非道路移动源从3月开始排放量逐渐升高,而年底和年初(冬季)排放量相对较低.