Duration of paternal care in pine engraver beetles: why do larger males care less?

Male pine engravers, Ips pini (Coleoptera: Scolytidae), assist their mates during reproduction by removing the debris that accumulates while females excavate oviposition tunnels in the phloem tissue of host tree bark. Although duration of paternal care and male reproductive success are positively correlated, large males leave their mates and brood sooner than small males. We address two hypotheses to explain the earlier departure of larger males from their breeding galleries: (1) females oviposit most rapidly when paired with large males, thereby reducing the length of time that paternal care increases male reproductive success, (2) larger males have better prospects for future reproduction, and thus leave their galleries in search of new breeding opportunities sooner than smaller males. Contrary to the first hypothesis, when females were paired either with large or small males, there was no effect of male size on their rate of oviposition. Consistent with the second hypothesis, males that initiated breeding galleries were larger than males from the general population. In addition, large males flew farther and faster on flight mills than small males, which may indicate that large males have an advantage in locating suitable breeding sites. Thus, we suggest that large male pine engravers leave their galleries earlier than small males because large individuals have better prospects for future reproduction. Received: 30 November 1997 / Accepted after revision: 23 May 1998     

Do tubificid worms influence organic matter processing and fate of pollutants in stormwater sediments deposited at the surface of infiltration systems?

The purpose of this study was to quantify the influences of tubificid worms on the biogeochemical functioning of an infiltration system impacted by a stormwater sediment deposit. Effects of worms with stormwater sediment deposit were compared with effects of worms with two other natural sediment deposits (one low and one rich-particulate organic matter deposits). We measured the effects of invertebrates on sediment reworking, organic matter processing, solute fluxes, microbial characteristics, and pollutant release from stormwater deposit to water. Our results showed that tubificid worms had slight effects on microbial activities in presence of the stormwater deposit whereas they significantly stimulated microbial activities in columns impacted by the other two deposits. High contents of labile organic matter contained in stormwater sediments probably led to very strong microbial activities that could not be easily stimulated by worm activities. In our experimental conditions, no significant influence of tubificid worms on the fate of pollutants (heavy metals and PAHs) contained in the stormwater deposit was measured. In conclusion, our study demonstrated that the organic matter characteristics of the stormwater sediments limited the efficiency of tubificid worms to stimulate organic matter mineralization in infiltration systems.     

Bacteriological safety assessment,hygienic habits and cross-contamination risks in a Nigerian urban sample of household kitchen environment

Urban household kitchen environment was assessed for safety by determining their levels of indicator bacteria, hygienic habits and risk of cross-contamination. Household kitchens (60) were selected in Warri Town, Nigeria, by the multi-stage sampling technique. Contact surfaces, water and indoor kitchen air were analysed for aerobic plate counts, total and faecal coliforms using Nutrient and McConkey media by swab/rinse method, membrane filtration and sedimentation methods, respectively. Hygienic habits and risk of cross-contamination were assessed with structured questionnaire which included socio-demographic variables. On the basis of median counts, the prevalence of high counts (log cfu/cm²/m³/100 mL) of aerobic plate counts (>3.0), total coliforms (>1.0) and faecal coliforms (>0) on contact surfaces and air was high (58.0–92.0%), but low in water (30.0–40.0%). Pots, plates and cutleries were the contact surfaces with low counts. Prevalence of poor hygienic habits and high risk of cross-contamination was 38.6 and 67.5%, respectively. Education, occupation and kitchen type were associated with cross-contamination risk (P = 0.002–0.022), while only education was associated with hygienic habits (P = 0.03). Cross-contamination risk was related (P = 0.01–0.05) to aerobic plate counts (OR 2.30; CL 1.30–3.17), total coliforms (OR 5.63; CL 2.76–8.25) and faecal coliforms (OR 4.24; CL 2.87–6.24), while hygienic habit was not. It can be concluded that urban household kitchens in the Nigerian setting are vulnerable to pathogens likely to cause food-borne infections.     

Social network characteristics and resource access among formerly displaced households in Lira,Uganda

In rural African communities, the support of extended family, friends, and neighbours is essential in borrowing or leveraging land, labour, food, and money, especially at times of social and financial turmoil. Little is known, though, about the nature of the networks and the conditions under which they may generate greater support in post‐conflict communities. This study, conducted in the Lira district of northern Uganda, examined the composition, proximity, and size of the networks that households utilise to gain access to resources during and after resettlement. Network structures with more kin and co‐resident ties were found to offer greater resource access to households in post‐conflict settings. Furthermore, there was a lack of meaningful linkages outside of a person's own village, especially with regard to households whose head has no or a low level of education. These findings enhance understanding of the specific role of relationships in social support for resource access among households in post‐conflict communities.     

Modeling Past and Future Acidification of Swedish Lakes

Decades of acid deposition have caused acidification of lakes in Sweden. Here we use data for 3000 lakes to run the acidification model MAGIC and estimate historical and future acidification. The results indicate that beginning in about 1920 a progressively larger number of lakes in Sweden fell into the category of “not naturally acidified” (∆pH > 0.4). The peak in acidification was reached about 1985; since then many lakes have recovered in response to lower levels of acid deposition. Further recovery from acidification will occur by the year 2030 given implementation of agreed legislation for emissions of sulphur (S) and nitrogen (N) in Europe. But the number of catchments with soils being depleted in base cations will increase slightly. MAGIC-reconstructed history of acidification of lakes in Sweden agrees well with information on fish populations. Future acidification of Swedish lakes can be influenced by climate change as well as changes in forest harvest practices.     

Quantification of bisphenol A, 353-nonylphenol and their chlorinated derivatives in drinking water treatment plants

Bisphenol A (BPA) and nonylphenols (NP) are of major concern to public health due to their high potential for human exposure and to their demonstrated toxicity (endocrine disruptor effect). A limited number of studies have shown that BPA and NP are present in drinking water. The chlorinated derivatives that may be formed during the chlorination step in drinking water treatment plants (DWTP) exhibit a higher level of estrogenic activity than their parent compounds. The aim of this study was to investigate BPA, 353NP, and their chlorinated derivative concentrations using an accurate and reproducible method of quantification. This method was applied to both surface and treated water samples from eight French DWTPs producing from surface water. Solid-phase extraction followed by liquid chromatography?Ctandem mass spectrometry was developed in order to quantify target compounds from water samples. The limits of detection ranged from 0.3 to 2.3?ng/L for BPA and chlorinated BPA and from 1.4 to 63.0?ng/L for 353NP and chlorinated 353NP. BPA and 353NP were found in most analyzed water samples, at a level ranging from 2.0 to 29.7?ng/L and from 0 to 124.9?ng/L, respectively. In most of DWTPs a decrease of BPA and 353NP was observed between surface water and treated water (36.6 to 78.9?% and 2.2 to 100.0?% for BPA and 353NP, respectively). Neither chlorinated BPA nor chlorinated 353NP was detected. Even though BPA and 353NP have been largely removed in the DWTPs studied, they have not been completely eliminated, and drinking water may consequently remain a source of human exposure.     

Comparison of specific versus literature species sensitivity distributions for herbicides risk assessment

Species sensitivity distributions (SSDs) are an important predictive tool in risk assessment. Usually, literature data are used to build SSDs that are mostly based on planktonic species. But, to get adequate protective thresholds for environmental communities, one could argue that SSD should be built on ecotoxicological data obtained from species found in the ecosystem that should be protected. This is particularly true when benthic algae are of concern. Due to the lack of literature data, building SSD on benthic microalgae is difficult. This paper aims in comparing SSDs, and thus protective thresholds (hazardous concentration that affects 5 % of the species of a community, HC₅), built on ecotoxicological data obtained (1) from literature and (2) with specific bioassays on benthic diatoms from a lake. Thresholds were derived for protection against four herbicides separately and for a mixture of them. Sensitivity data obtained from literature were statistically lower than the specific data for all herbicides: Species tested in the literature were usually more sensitive (mainly chlorophytes), leading to more protective lower HC₅. The HC₅ thresholds (literature or specific) derived for protection against the mixture were also compared to the observed sensitivity of an assemblage of benthic diatom species exposed to an increasing range of herbicide mixture concentrations. We observed that one species within the assemblage (Fragilaria rumpens) was affected at a concentration below both the literature and the specific HC₅ thresholds.     

Control of Claus Plant Sulfur Compound Emissions

The body of information of this paper is directed to those individuals charged with selecting a process to control atmospheric sulfur emissions from Claus plants serving refineries, gas processing installations, and chemical plants. The TGT process developed by the French Petroleum Institute (IFP) is an extension of the Claus reaction itself in the liquid phase. Mixed H₂S and SO₂ in tail gas from Claus units is fed to a packed tower in which a solution of proprietary catalyst in a high BP polyglycol circulates countercurrent to the gas flow. The mixed gases react with the catalyst to form a complex, which in turn reacts with more gases to produce elemental sulfur. Reaction temperature keeps the sulfur above its melting point. Product accumulates in the boot of the tower and is drawn off continuously through a seal leg.

The IFP TGT process is simple in design and units have simple construction, characterized by use of low carbon steel and the use of very few pieces of equipment. Of all processes used today to take effluent sulfur values down to 1000 ppm SO₂ after incineration, the IFP TGT process requires the least capital investment and the lowest operating costs. Twenty-six full scale plants are operating or under design or construction: nine each in the U.S. and Japan, five in the U.S.S.R. and Poland, two in western Europe and one in Canada. Capacities of the Claus plants served range from 45 to 800 Lt/d sulfur.