Use of experimental ecosystems in regulatory decision making

Tiered testing for the effects of chemicals on aquatic ecosystems has begun to include tests at the ecosystem level as a component in pesticide regristration. Because such tests are expensive, regulators and industry need to know what additional information they can gain from such tests relative to the costs of the simpler single-species toxicity bioassays. Requirements for ecosystem-level testing have developed because resource managers have not fully understood the implications of potential damage to resources without having evaluations of the predicted impacts under field conditions. We review approaches taken in the use of experimental ecosystems, discuss benefits and limitations of small- and large-scale ecosystem tests, and point to correlative approaches between laboratory and field toxicity testing.Laboratory experimental ecosystems (microcosms) have been successfully used to measure contaminant bioavailability, to determine routes of uptake in moderately complex aquatic systems, and to isolate factors modifying contaminant uptake into the biota. Such factors cannot be as readily studied in outdoor experimental ecosystems because direct cause-and-effect relations are often confounded and difficult to isolate. However, laboratory tests can be designed to quantify the relations among three variables: known concentrations of Stressors; specific sublethal behavioral, biochemical, and physiological effects displayed by organisms; and responses that have been observed in ecosystem-level analyses. For regulatory purposes, the specificity of test results determines how widely they can be applied. Ecotoxicological research should be directed at attempts to identify instances where single-species testing would be the appropriate level of analysis for identifying critical ecological endpoints and for clarifying relationships between ecosystem structure and function, and where it would be inadequate for a given level of analysis.     

Volatile organic compounds produced during the aerobic biological processing of municipal solid waste in a pilot plant

The volatile organic carbon (VOC) and odours emitted during the aerobic biological processing of municipal solid waste (MSW) was studied in a pilot-scale reactor. VOCs were detected by different techniques on solid waste samples and the outlet air stream, before and after a biofilter. Organic compounds (alpha-pinene, beta-myrcene, D-limonene) were also measured in condensate water and leachate from the process. Results showed uniformity in the composition of the air in the solid waste samples, air sampled during the process and condensed water, indicating a matrix-derived origin of these compounds. Leachates, however, contained substances with a quite different molecular structure from the compounds identified in the gaseous fraction. Most of the substances in the gaseous effluent had a hydrocarbon-like structure, mainly terpenoids. The odour produced and detected through olfactometry agreed with GC-MS analyses. This was true above all for terpenes.     

Sterols in sediment samples from Venice Lagoon, Italy

Sterols of different origin were analysed in sediment samples collected in the Venice Lagoon. The purpose of the study was to investigate the degree of sewage contamination within the Lagoon using fecal sterols (coprostanol, epicoprostanol and coprostanone) and to analyse the pattern of the sterols to plot the origin of the organic matter.

Sedimentary coprostanol at Canal Grande within the city of Venice was more than one order of magnitude higher than other stations in the Lagoon and two orders higher than in a sediment sample collected in the open sea. The cholesterol/coprostanol ratio, like the percentage of coprostanol in total sterols at this sample site was very similar to values in sewage sludge. The different pattern of sterols at station 2 which had the largest amount of total sterol indicates a difference in the origin of the organic material. Nevertheless the sterols used as tracer of terrestrial vascular plants did not show any particular trend at this station, receiving fresh water inputs. (3-Sitosterol and cholestanol reached the highest levels at the station within the Chioggia basin.     

Multimetric Assessment of Nutrient Enrichment in Impounded Rivers Based on Benthic Macroinvertebrates

In this investigation we evaluated the performance of multiple metrics, based on benthic macroinvertebrates, to assess nutrient enrichment in impounded rivers. Field studies were conducted in the upper reaches of four impounded mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks. Two sampling sites, upstream and downstream from the reservoir, were established in stony riffles of each impounded river. We used a total of 34 metrics, representing five different metric groups: measures of abundance and richness, percentages of taxonomic groups, percentages of functional feeding groups, measures of dominance and diversity, and biotic indices. Evaluation of different metrics was mainly based on correlation analyses between concentrations of nutrients (NO3-N, NH4-N, PO4-P) and values of individual metrics. Deep releases from the reservoirs were the primary cause responsible for the nutrient enrichment at downstream sampling sites. Chironomidae density, Gastropoda density, % Chironomidae, % Gastropoda, % collector-gatherers and scrapers, proportion of the two most dominant taxa, and Camargo's dominance index exhibited the highest positive correlation coefficients. Conversely, Plecoptera density, Trichoptera density, EPT richness, % Plecoptera, % Trichoptera, % collector-filterers, % predators, % shredders, Simpson's and Camargo's diversity indices, and the average BMWQ score (biotic index) exhibited the highest negative correlation coefficients. Overall it is concluded that the multimetric approach may be a useful technique for the biological assessment of nutrient enrichment in fluvial ecosystems, particularly in upper reaches of siliceous rivers.     

Statistical control of hygienic quality of bathing water

In Denmark the hygienic quality of the bathing water has been controlled, based on general guidelines since 1978. Today more than 1100 control sites in marine areas have been established to ensure safe bathing water quality. According to EEC directives and Danish tradition, the control is usually performed by measuring the content of the indicator bacteria Escherichia coli (E. coli) in 5 to 20 test samples each bathing season.In Denmark, control programmes and data are evaluated using basic statistical quality control principles. This paper presents general guidelines for bacterial control, their statistical background and practical application. Furthermore, the evaluation and application of a specific programme for control of Staphylococcus aureus (S. aureus) are presented. This programme was used in a Danish bay where the authorities prescribe direct control of these potentially harmful bacteria.     

Frequent Detection and Genetic Diversity of Human Bocavirus in Urban Sewage Samples

The prevalence and genetic diversity of human bocaviruses (HBoVs) in sewage water samples are largely unknown. In this study, 134 raw sewage samples from 25 wastewater treatment plants (WTPs) in Italy were analyzed by nested PCR and sequencing using species-specific primer pairs and broad-range primer pairs targeting the capsid proteins VP1/VP2. A large number of samples (106, 79.1 %) were positive for HBoV. Out of these, 49 were classified as HBoV species 2, and 27 as species 3. For the remaining 30 samples, sequencing results showed mixed electropherograms. By cloning PCR amplicons and sequencing, we confirmed the copresence of species 2 and 3 in 29 samples and species 2 and 4 in only one sample. A real-time PCR assay was also performed, using a newly designed TaqMan assay, for quantification of HBoVs in sewage water samples. Viral load quantification ranged from 5.51E+03 to 1.84E+05 GC/L (mean value 4.70E+04 GC/L) for bocavirus 2 and from 1.89E+03 to 1.02E+05 GC/L (mean value 2.27E+04 GC/L) for bocavirus 3. The wide distribution of HBoV in sewages suggests that this virus is common in the population, and the most prevalent are the species 2 and 3. HBoV-4 was also found, representing the first detection of this species in Italy. Although there is no indication of waterborne transmission for HBoV, the significant presence in sewage waters suggests that HBoV may spread to other water environments, and therefore, a potential role of water in the HBoV transmission should not be neglected.     

Effects of zinc oxide nanoparticles on growth and antioxidant enzymes of Capsicum chinense

Abstract

The effects of suspensions of zinc oxide nanoparticles at concentrations between 100 and 500?mg L^?1 on germination of Capsicum chinense seeds and vigor of plants were evaluated using a randomized complete design with four replications, resulting in increased germination and improved development of lengths of plumule and radicle. The activities of peroxidase, catalase and ascorbate peroxidase were determined, showing that at all concentrations the activities of the former two enzymes were increased, whereas the activity of the latter was reduced at 500?mg L^?1. Pretreatments of seeds with ZnO nanoparticles can improve germination and development of seedlings and the activities of antioxidant enzymes.     

Localising the global food system

Agricultural systems have become increasingly industrialized and mechanized, relying on machinery and chemical inputs, rather than people and natural processes, to increase yields of food. The trend towards an increasingly globalised food system encourages unsustainable transportation of food around the world. Agricultural intensification and the globalisation of the agrofood chain has resulted in adverse environmental, social and economic consequences impeding moves towards sustainability. Organic farming can overcome many of the environmental problems associated with agricultural intensification. However, it does not have the potential to fully address the social and economic problems caused by the globalisation of the food system. Organic farming must be combined with local and regional sourcing of food products, for instance through forms of direct marketing of organic produce. Direct marketing schemes such as farmers' markets, food box delivery schemes and community-supported agriculture are all projects which, if managed with sustainability as the prime objective, have the potential to move towards a more socially, environmentally and economically sustainable agrofood system.     

Assessment of opium-based farming systems: a case study in the Nahom area,Oudomxay Province in Northern Laos

SUMMARY

An interdisciplinary team of 10 completed an exploratory one-month survey of villages in Nahom, Oudomxay Province, Laos, an area representative of upland farming systems based on opium and shifting cultivation. The study included investigation of the physical and socioeconomic environments and assessment of the farming systems. Due to the relatively low population density, there is enough land for villagers to practice shifting cultivation with a one year cultivation cycle, followed by 10–12 years of fallow. The soil degradation commonly caused by shifting cultivation was not significant in this area and the soil fertility is still relatively high. However, most of the original forests had been cut down and used for shifting cultivation and some degradation of the vegetation has occurred, showing that the ecological sustainability has been threatened by prevailing practices. Thirty-six percent of the households had food supply problems for more than three months of each year. The extremely low return for labour from upland rice cultivation, only 5.64 kg per labour-day, was the critical factor that caused the food shortage. Because of poor technique, rice yield from paddy fields was also low, thus shifting cultivators have no enthusiasm to expand their paddy fields. Income from opium provided 80.5% of household income. Opium was extremely tempting to local people due to the very high return for labour, 5700 kip (US$6) per labour-day, low investment, and good labour availability (mostly during the off-season of rice cultivation). However, opium was also a ‘two-edged sword’. It did not bring real wealth, health and happiness but instead brings poverty, poor health and disappointment.     

Photodegradation of the pure and formulated alpha-cypermethrin insecticide gives different products

Alpha-cypermethrin is a broad-spectrum insecticide widely used in the treatment of rice crops, mainly commercialized as a CONTEST^® formulation. The photodegradation of alpha-cypermethrin and of the commercial formulation has not yet been systematically investigated in paddy water under natural conditions. Here, paddy water solutions of alpha-cypermethrin and CONTEST^® formulation at 5.0 mg L^?1 were irradiated under simulated sunlight for 10 days. Hydrolysis experiments were carried out on the same solutions preserved in the dark. Analysis by ultra-high-performance liquid chromatography–tandem mass spectrometry was developed for the identification of photodegradation products. Results show that degradation of pure alpha-cypermethrin and the formulation counterpart produces both common and different photodegradation products. Five out eleven photodegradation products were identified for the first time, in particular three in the alpha-cypermethrin paddy water solution and four in the formulation. Our findings underline the importance of carrying out photodegradation experiments directly on the commercial formulation, since degradation products could be different from the pure insecticide.