Phenolic xenoestrogens in surface water, sediments, and sewage sludge from Baden-Württemberg, south-west Germany.

Nine structurally different phenolic chemicals, which have been reported to mimic estrogen effects, were determined in various aquatic environmental compartments. Twenty-three water samples from five streams and rivers showed levels up to 458 ng/l for 4-nonylphenol (4NP), 189 ng/l for 4-t-octylphenol (4tOP), 272 ng/l for bisphenol A (BPA) and 47 ng/l for 2-hydroxybiphenyl (2OHBiP). Elevated levels of these compounds in a stream with a high load of effluents of sewage treatment plants (STPs), compared to a brook free of sewage, identified STPs as major sources. With a similar order, 4NP (10-259 micrograms/kg dry matter), 4tOP (< 0.5-8 micrograms/kg), BPA (< 0.5-15 micrograms/kg), and 2OHBiP (2-69 micrograms/kg) were also detected regularly in riverine sediment (n = 11). Levels in sewage sludge were one order of magnitude higher than in sediments. 4-Hydroxybiphenyl and 4-chloro-3-methylphenol were found predominantly in sludge and sediment in the lower ppb range.     

No evidence for the work-conflict hypothesis in the eusocial naked mole-rat (Heterocephalus glaber )

The work-conflict hypothesis (Reeve 1992) postulates that in eusocial naked mole-rat (Heterocephalus glaber) colonies there is potential conflict between the breeding female and her non-breeding colony mates over how much aid they provide in support of her reproduction. Non-breeders may withhold aid either because they are hopeful reproductives and/or because they have less to gain in terms of inclusive fitness. Breeding females should, therefore, preferentially direct aggression in the form of shoving (prolonged pushes usually involving nose-to-nose contact) towards large (hopeful reproductives) and less related non-breeders to incite them to provide aid. This study tested the following predictions of the work-conflict hypotheses. (1) There is kin bias in the shove rate of breeding females and work rates of non-breeders; (2) Shoving activates work in non-breeders. We found no evidence to suggest that the breeding female shove rate and the amount of colony maintenance activities performed by non-breeders is influenced by relatedness. Body size was a better predictor of work rate and shove rate; large animals were shoved more and worked less. Furthermore, shoving did not affect the work rate of non-breeders and rarely incited activity in inactive mole-rats. Individual mole-rats were also more likely to be shoved when already active than when resting in the nest. These results suggest that shoving by the breeding female may have functions other than the incitement of activity, such as the reproductive suppression of non-breeders. Received: 17 January 1996 / Accepted after revision: 21 September 1996     

Sustainability: definition and five core principles,a systems perspective

A systems perspective is used to discuss the concept of sustainability. From this perspective, it is argued, sustainability can be regarded as a system state that is mediated by specific structures. This is fundamentally different from regarding sustainability merely as a normative goal, as it is presently regarded by most. Insight into the kinds of structures which mediate a system’s state open the door to proactive design of new structures and mechanisms, which are necessary for yielding effective change: in this case, promoting the sustainability agenda. The kind of change required to transform the prevailing trajectory of human affairs is presented as a second order change: a change that requires a major shift, and a complete transformation of the system itself, not only in a few aspects of its behavior. A new definition of sustainability is offered, anchored in the interaction of a population and the carrying capacity of its environment. From this definition, five core sustainability principles are derived, along with their respective policy and operational implications. Together, these principles prescribe the conditions that must be met to attain sustainability as an enduring state. The principles themselves form an integrated, systemic set, which requires them to be acted on simultaneously. A piecemeal approach—focusing on one aspect while neglecting others—is not likely to yield effective results for the whole.     

Amazonian freshwater habitats experiencing environmental and socioeconomic threats affecting subsistence fisheries

Matching the trend seen among the major large rivers of the globe, the Amazon River and its tributaries are facing aquatic ecosystem disruption that is affecting freshwater habitats and their associated biodiversity, including trends for decline in fishery resources. The Amazon’s aquatic ecosystems, linked natural resources, and human communities that depend on them are increasingly at risk from a number of identified threats, including expansion of agriculture; cattle pastures; infrastructure such as hydroelectric dams, logging, mining; and overfishing. The forest, which regulates the hydrological pulse, guaranteeing the distribution of rainfall and stabilizing seasonal flooding, has been affected by deforestation. Flooding dynamics of the Amazon Rivers are a major factor in regulating the intensity and timing of aquatic organisms. This study’s objective was to identify threats to the integrity of freshwater ecosystems, and to seek instruments for conservation and sustainable use, taking principally fish diversity and fisheries as factors for analysis.     

IMPACTS OF AGRICULTURAL DRAINAGE WELL CLOSURE ON CROP PRODUCTION: A WATERSHED CASE STUDY1

ABSTRACT: Much of north-central Iowa is characterized by flat topography, shallow depressions, and poor natural surface drainage. Land drainage systems comprising of tile drains and agricultural drainage wells (ADWs) are used as outlets for subsurface drainage of cropland under corn and soybean production. Studies have shown that these drainage systems, mainly the ADWs, are potential routes for agricultural chemicals to underground aquifers. To protect the region's vital groundwater resource, researchers are evaluating alternative outlets ranging from complete closure of existing ADWs (and creation of wetlands) to continued use of ADWs and chemical management in a comprehensive policy framework. This paper presents the results of a study designed to provide government jurisdictions, farmers, and land managers information for assessing the impact of closing ADWs on crop production. The study couples a geographic information systems database for a 471-hectare watershed in Humboldt County, Iowa, with a groundwater flow model (MODFLOW) and an empirical crop yield loss model to predict long-term effects of complete closure of ADWs on crop production. The cropland areas inundated and the relative crop yield loss due to ADW closure are determined as a function of long-term climatic data. The results indicate that elimination of drainage outlets in the watershed could result in ponding of low-lying areas and poorly drained soils, making them unsuitable for crop production. Such wetness also decreases the efficiency of production in the no-ponding areas by isolating fields, and the crop yield loss can be reduced by an annual average of about 18 percent.     

Organochlorines in deep-sea fish from the Nordfjord

Hepatic levels of OCs (Organochlorines) were analysed in deep-sea fish from the Nordfjord in Norway. Levels of PCBs in the present study exceed background levels in fish from Norwegian water by a factor of 1.5 to 50, and DDTs by one to two orders of magnitude. DDTs in fish from the Nordfjord have previously been attributed to DDT use in fruit orchards. The present levels of DDTs show that the decline usually found in biota in Scandinavia since the 1970s is not found in the deep-sea fish in Nordfjord. There is no known local PCB source that can explain the elevated levels in the present study. This indicates that the fjord efficiently accumulates atmospheric contaminants. Chlordanes and HCB were less important, and HCHs were not detected.     

Characterization and COD fractionation of domestic wastewaters

Results of a comprehensive study are reported for wastewater characterization in relation to modelling and design of biological nutrient removal systems for the Metropolitan Area of Istanbul. Domestic sewage quality was experimentally assessed in terms of major polluting parameters. Size distribution and calculation of significant ratios such as BOD5:COD and COD:N were used to evaluate the merit of candidate physical, chemical and biological treatment alternatives. COD fractionation was effected to assess biological treatability and to yield the necessary process components to the recent modelling approaches.