Leaf litter breakdown in streams receiving treated and untreated metal mine drainage

Rates of alder leaf decomposition were used as an ecosystem-level measure of effects of untreated and treated acid mine drainage on two Colorado mountain streams. Untreated mine effluents had low pH and high concentrations of metals, particularly iron. Deposition of ferric hydroxide on leaf surfaces inhibited colonization by decomposers, such as fungi and aquatic insects, and thus little leaf breakdown occurred. Treated effluents had improved water quality (basic pH, low metal concentrations), but suspended flocs released by the treatment process buried leaves and reduced consumer activity. The rate of leaf breakdown was not significantly different from the rate with untreated effluents; thus improvement in water quality alone was insufficient to restore this important pathway of energy flow in headwater streams.     

The behavioral component in the meaning of places

How do people think about the physical setting in the world around them? Part of the answer to this question may be in terms of the behaviors that occur there. To explore people's knowledge of behavior—place associations, twenty places (shown via color photographs) were assessed in five ways: (a) ratings of the place's suitability for each of eleven behaviors, (b) ratings of the expected frequency of occurrence of the eleven behaviors, (c) free listings of reasons for going to each place, (d) free listings of activities-while-there and (e) free listings of activities associated with the place. Results showed that people can distinguish places on the basis of behaviors, that the behavioral component of place meaning is composed of distinct aspects, and that knowledge of behavior is related to a global, overall representation of a place.     

Evaluating colloidal phosphorus delivery to surface waters from diffuse agricultural sources

Colloid-facilitated phosphorus (P) delivery from agricultural soils in different hydrological pathways was investigated using a series of laboratory and field experiments. A soil colloidal P test was developed that yields information on the propensity of different soils to release P attached to soil colloids. The relationship between turbidity of soil extracts and total phosphorus (TP) was significant (r2 = 0.996, p < 0.001) across a range of agricultural soils, and a strong positive relationship (r2 = 0.86, p < 0.001) was found between "colloidal P" (H2O-CaCl2 extracts) and turbidity. Linear regression of the proportion of fine clay (<2 microm) for each soil type evaluated against the (H2O-CaCl2) colloidal P fraction gave a weak but positive relationship (r2 = 0.38, p = 0.082). The relative contribution of different particle-size fractions in transporting P in agricultural runoff from grassland soils was evaluated using a randomized plot experiment. A significant difference (p = 0.05) in both TP and reactive phosphorus (RP) in subsurface flow was recorded for different particle-size fractions, with most TP transferred either in association with the 2-microm fraction or with the 0.001-microm or smaller fractions. Total P concentrations in runoff were higher from plots receiving P amendments compared with the zero-P plots; however, these differences were only significant for the >0.45-microm particle-size fractions (p = 0.05), and may be evidence of surface applications of organic and inorganic fertilizers being transferred through the soil either as intact organic colloids or attached to mineral particles. Our results highlight the potential for drainage water to mobilize colloids and associated P during rainfall events.     

Records of atmospheric delivery of pyrolysis-derived pollutants in recent mountain lake sediments of the Julian Alps (NW Slovenia)

The historical record of the input of pyrolysis-derived pollutants via the atmosphere, i.e. black carbon (BC), polycyclic aromatic hydrocarbons (PAH) and spheroidal carbonaceous particles (SCP) was measured in the sediments of three remote alpine lakes situated in the Julian Alps, northwest Slovenia. Parallel sedimentary trends for BC, PAH and SCP were observed across the Julian Alps and relationships among these contaminants are discussed. Inputs of these pyrolytic-contaminants to sediments of remote lakes started to rise at the end of the 19th century, while their peak inputs were observed in the mid-20th century, amounting up to 6.0 gm(-2) yr(-1) for BC, 5200 x 10(4) m(-2) yr(-1) for SCP and 2900 microg m(-2) yr(-1) for PAH. In the last two to three decades, inputs decreased substantially, by a factor of up to 3 for BC, 7 for SCP and at least 3 for PAH.     

液相色谱/质谱用于饮用水和地下水中的苯脲及三嗪草类除草剂的确认分析

本文介绍了液相色谱／大气压化学电离-质谱联用技术作为确认方法，检测饮用水和地下水中苯脲及三嗪草类除草剂的残留。共分析了16种除草剂，同时对分析方法进行了验证，其中标准偏差、离散度等结果均能满足饮用水的标准方法指南。     

A simulation model of rhizome networks for Fallopia japonica (Japanese knotweed) in the United Kingdom

Fallopia japonica (Japanese knotweed) is an aggressively invasive herbaceous perennial that causes substantial economic and environmental damage in the United Kingdom (UK). As such, it is of considerable concern to councils, environmental groups, private landowners and property developers. We construct a 3D correlated random walk model of the development of the subterranean rhizome network for a single stand of F. japonica. The formulation of this model uses detailed knowledge of the morphology and physiology of the plant, both of which differ in the UK to that of its native habitat due to factors including a lack of predation and competition, longer growth seasons and favourable environmental conditions in the UK. Field data obtained as a part of this study are discussed and used in the model for parameterisation and validation. The simulation captures the field data well and predicts, for example, quadratic growth in time for the stand area. Furthermore, the role of a selection of parameters on long-term stand development are discussed, highlighting some key factors affecting vegetative spread rates.     

Predatory behavior and chemical communication in two Metapone species (Hymenoptera:Formicidae)

Summary. Colonies of two species of Metapone (M. madagascarica, M. new species.) were collected in Madagascar and established in laboratory nests. It could be demonstrated that both species are specialist predators of termites (Cryptotermes kirbyi). During hunting the ants sting the termites and thereby paralyze and preserve the prey alive. In this way prey can be stored in the ant nest for extended periods. During foraging and colony emigrations the ants lay chemical trails with poison gland secretions. Among the seven compounds identified in the venom only methyl pyrrole-2-carboxylate elicits trail following behavior in both Metapone species. Received 11 February 2002, accepted 23 February 2002.     

Studies on the sublittoral free-living nematodes of Liverpool Bay. I. The structure and distribution of the nematode populations

Data collected from a survey of the benthic fauna of Liverpool Bay (UK) have been used to study the distribution and structure, in terms of percent age dominance and percent age frequency, of the nematode populations. Cluster analysis of the faunistic data from individual stations has shown that the populations are not sharply delimited. The relative proportions of their characteristic genera are extremely variable, and apparently influenced by small differences in sediment composition. It is, thus, considered more logical to think in terms of a number of different habitats, each with certain characteristic genera, rather than in terms of a series of discrete associations. Six types of habitat are distinguished on the basis of sediment granulometry: (1) mud and sandy mud; (2) very muddy sand; (3) muddy sand; (4) muddy sand-gravel mixtures; (5) clean sand-gravel mixtures; (6) clean sand. Habitats 1, 2 and 3 were dominated by Sabatieria spp., the degree of dominance apparently being related to the percentage of silt-clay. Habitat 4 was dominated by Neochromadora sp. and Sabatieria spp. and Habitats 5 and 6 by Desmodora sp. Both generic and dominance diversity were very much lower for Habitats 1 and 2 than elsewhere.     

<Emphasis Type="Italic">Oithona similis</Emphasis> in a high latitude ecosystem: abundance,distribution and temperature limitation of fecundity rates in a sac spawning copepod

In this study we report the abundance, fecundity and an index of the relative survival of Oithona similis (nauplii to copepodites) across a large latitudinal and temperature range within the Southern Ocean. The abundance of O. similis was strongly related to temperature and to depth-integrated (0–100 m) chlorophyll a, abundance increasing with increasing temperature (and therefore decreasing latitude) and Chl a. In situ egg production rates and fecundity per female were also significantly and positively related to temperature and Chl a. Egg hatch times rapidly lengthen as temperature decreases and in sac spawning species the next batch of eggs cannot be produced until the previous clutch hatch. Consequently, we predict that in O. similis, fecundity must decline rapidly at low temperatures, especially below 5°C. A model comparing maximum rates of fecundity with in situ data suggested production rates were strongly food limited across our study region. However, the relationship of in situ and maximum rates to temperature were similar, confirming the importance of temperature. Further, as time taken to develop from egg to adult also rapidly extends with declining temperature, it is increasingly unlikely that O. similis will be able to maintain its population against mortality. Our findings have broad implications for the cold temperature (and hence geographic) limits of O. similis, but also for the distribution of other sac spawning copepods and planktonic species generally.