Human exposure to dioxins through diet in Italy

We have measured the content of polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans (together defined as “dioxins”) in 269 samples of food of animal origin collected through the regional veterinary services, covering the national territory. Quantification of the dioxins was accomplished by isotope dilution method, and toxic equivalents (TEQ) were calculated. The average daily food intake was obtained from two main sources: national data collected by the National Institute of Nutrition, and data from an ongoing cohort study on diet and cancer including 40, 000 Italian subjects.

The mean value of dioxins measured in food of animal origin was 0.144 ± 0.266 pg-TEQ/g (range: 0.003–1.655 pg-TEQ/g). Fish was the item with the highest content. The estimated intake of dioxins with main food items of animal origin is presented. The major contribution to dioxins intake with food comes from cow milk and fish consumption. These results are in agreement with what observed in studies conducted in other countries, such as Germany, Finland, Japan, Spain, and are below the limits set by the European legislation.     

硫酸锰废渣的浸出毒性及处理研究

研究了硫酸锰废渣的主要金属元素组成及浸出毒性,并采用锰渣加石灰混合的方法进行无害化处理,研究结果表明,硫酸锰废渣浸出液中Mn、Cd超标,锰渣加石灰混合处理的方法能有效降低废渣的浸出毒性,锰渣与石灰的重量比为25:2最佳.     

Relating cadmium concentrations in three macrophyte-associated freshwater invertebrates to those in macrophytes,water and sediments

We found that Cd concentrations in three species of macrophyte-associated invertebrates (the gastropods Bithynia tentaculata and Physa gyrina, and the amphipod Gammarus fasciatus) collected at twenty sites along the St. Lawrence River were correlated with Cd concentrations in their main food source, i.e. macrophytes and associated periphyton. Cd in these invertebrates was not significantly correlated with Cd concentrations in the sediments (even when corrections for iron oxide or organic carbon content were applied) or to calculated free-cadmium concentrations in the water. Cd levels in juveniles of B. tentaculata were very tightly linked to Cd concentrations in macrophytes, which is consistent with the close relationship that these organisms have developed with macrophytes. Linear models predicting Cd levels in juveniles of B. tentaculata from Cd levels in different macrophyte species were strong (R2 = 0.69-0.90). Analysis of covariance on these models showed no statistical difference of slope or intercept for any of the macrophyte species, except Vallisneria americana. We suggest that the macrophyte-periphyton complex is a key link in the transfer of cadmium to some aquatic invertebrates in the littoral zone of the St. Lawrence River and that macrophytes and their associated epiphytes should also be used as biomonitors.     

湿法回收砷碱渣中锑的工艺研究

本研究先以水浸实现砷碱渣中的砷锑分离,再对水浸渣进行盐酸浸出,得到了可作为工业原料氯化锑溶液.研究结果表明,在液固比为6∶1,温度40℃,浸出时间40 min的条件下,可使水浸过程中锑的浸出率低于3%,砷的浸出率达到99%;盐酸浸出中,控制酸浓度为1∶1,液固比10∶1,温度60℃,浸出时间30 min,能使锑的浸出率达到88%以上.经过水浸和盐酸浸出,锑的直接回收率为85.36%.     

化工制药工艺残渣燃烧过程固氯研究

采用管式固定床反应器对化工制药工艺残渣的燃烧分解进行了实验研究,进一步通过加入氧化钙/碳酸钙来防止燃烧过程残渣中氯的释放.实验结果表明,残渣在燃烧时氯主要以氯化氢形式排出,加入固氯剂后能有效地抑制氯化氢的生成,且固氯效果随着钙化物投加量的增加而明显提高.当氧化钙/残渣比(质量比)达到0.8时,固氯率可达97%以上;当碳酸钙/残渣比(质量比)提高到2.0时,固氯率为76%.与此对应的Ca/Cl摩尔比分别为30和40.继续增加钙投加量,固氯效果基本不变.同时发现添加一定量的木屑在助燃的同时有助于提高固氯效果.     

头孢噻肟钠生产废渣的综合利用

从头孢噻肟钠生产废渣中回收２－硫醇基苯并噻唑合成二硫化二苯并噻唑,ＤＭ的收率达２３．８％,产品质量达到ＨＧＢ２－１５８－６１标准,小试表明,方法可行,操作稳定,简便,既减轻了废渣生成的污染,又回收和用途广泛的化工原料,有一定的环境效益和经济效益。     

Food-dependent benefits of hatching asynchrony in American kestrels Falco sparverius

Food supply and hatching asynchrony were manipulated for 90 broods of American kestrels (Falco sparverius) during 1989–1991. We measured the growth and mortality of nestlings within four treatment groups (asynchronous, synchronous, food-supplemented, unsupplemented) to test the brood reduction hypothesis of Lack (1947, 1954). Fledging success did not differ between synchronous and asynchronous broods when food was poor but consistent with the brood reduction hypothesis, nestlings died at a younger age in asynchronous broods. When food was supplemented, mortality did not occur in the synchronous broods but youngest nestlings still died in asynchronous nests despite apparently adequate food for the brood. Oldest nestlings in asynchronous broods fledged with a greater mass than their younger siblings, also consistent with Lack's hypothesis. Average nestling quality in synchronous broods was very dependent on food levels. Synchronous young that were supplemented were, on average, the heaviest of any treatment group but young from unsupplemented synchronous broods were the lightest. Overall, patterns of mortality and growth for kestrels support the brood reduction hypothesis when food is limited, but not when it is abundant. This food-dependent benefit of asynchrony in the nestling period is a prerequisite for facultatively adjusted hatching spans during laying.     

Effect of food location and quality on recruitment sounds and success in two stingless bees,<Emphasis Type="Italic"> Melipona mandacaia</Emphasis> and<Emphasis Type="Italic"> Melipona bicolor</Emphasis>

It is unclear whether stingless bees in the genus Melipona (Hymenoptera, Apidae, Meliponini) can reliably encode the distance to a food source through recruitment sounds produced inside the nest, in part because the sound features correlated with distance also vary with food quality. We therefore trained marked foragers of two species, Melipona mandacaia and M. bicolor, to feeders at different distances and to different sucrose concentrations at the same distance. In both species, foragers successfully recruited to a rich 2.5-m food source and produced pulsed recruitment sounds in which pulse duration was significantly and positively correlated with distance to the rich food source. When returning from poorer food sources (0.6–1.5 m), foragers of both species decreased sound production, producing shorter sound pulses and longer sound interpulses than they did for 2.5 m food located at the same distance. Thus the temporal structure of M. mandacaia and M. bicolor recruitment sounds varies with distance and food quality. However, nestmates were not recruited by performances for poorer food sources (0.6–1.5 m), whose sucrose concentration was sufficiently low to affect recruitment sounds. Surprisingly, the interphase (the time between behavioral phases that communicate location) also increases with decreasing food quality in the closely related honeybees (Apis), suggesting a potential homology in the effect of food quality on the recruitment systems of Apis and Melipona. We explore the evolutionary implications of these similarities.Communicated by M. Giurfa     

Ontogeny of provisioning in two populations of wild golden lion tamarins (Leontopithecus rosalia)

Provisioning weaned young is an important part of the cooperative rearing system of marmosets and tamarins (family: Callitrichidae). Juvenile callitrichids receive a substantial proportion of their diet from all adult group members, whereas juveniles of most other primate species only receive food from the mother infrequently via scrounging. We conducted a longitudinal study of provisioning to 21 young wild golden lion tamarins through their first year of life in two Brazilian reserves. Juveniles were predicted to experience higher provisioning rates at the site with mature forest (the presumed ancestral habitat) and in territories that contained a higher proportion of preferred habitat within the mature forest reserve. Key measures of provisioning did not differ substantially between habitat types. The rates at which juveniles begged for food were very similar across habitats, while the influence of habitat on the rates at which juveniles received food was small and varied across age groups. The most pronounced differences between the reserves were: adult resistance to food-transfer attempts was less frequent, food-offering calls before food transfer were more frequent, and the proportion of prey provisioned was higher in the reserve in which earlier successional-stage forest predominated. Within the mature forest reserve, begging success of young juveniles covaried positively with preferred habitat. Rather than overt caretaker–offspring conflict, an information–feedback loop between juveniles and adults appears to drive provisioning changes as juveniles mature. Direct measures of resource abundance are needed to help clarify the mechanisms by which forest successional stage influences provisioning.     

Food abundance and parental care in yellow warblers (Dendroica petechia)

Emlen and Oring (1977) suggested that monogamy in birds is maintained because of the need for strict biparental care. A corollary of their suggestion is that paternal care should decrease under conditions of high food abundance. An alternative is that paternal care would increase if males take advantage of the higher food abundance by trying to reduce the length of the nestling feeding period. We tested these two ideas using yellow warblers (Dendroica petechia) by providing some pairs with supplemental food, thereby reducing the importance of biparental care. However, the extra food did not decrease paternal effort, nor did it increase it (Fig. 2). Early in the nestling period experimental females brooded more but visited their nestlings less than did control females, but later, when brooding times decreased, experimental females fed their nestlings more than did control females (Fig. 3). There were no significant differences in nestling survival (Fig. 5), but nestlings in the control treatment were larger and heavier up to 6 days old (Fig. 6). The main effect of supplemental food was on maternal, not paternal behaviour. Models of biparental care assume interdependence between the parental effort of both parents. In this species, however, males and females provide for their brood independently from each other.