Assessing dimethoate contamination in temperate and tropical climates: potential use of biomarkers in bioassays with two chironomid species

This study was conducted to investigate the potential use of biomarkers in bioassays with chironomids to assess contamination by pesticides in temperate and tropical climates. Two species of midge were studied, the widespread Chironomus riparius and the tropical Kiefferulus calligaster (Kieffer, 1911). Preliminary studies included investigations of the effects of temperature on larval development and the influence of larval age on normal variability of cholinesterase (ChE) and glutathione S-transferase (GST) activities and protein content. In the second phase, the influence of two abiotic factors particularly important in tropical conditions (temperature and oxygen concentration) and of the organophosphorous (OP) insecticide dimethoate on biochemical and conventional endpoints was investigated. Results showed that K. calligaster is morphologically and physiologically similar to C. riparius and for both, the time of larval development decreases with the increase of temperature. Moreover, 3rd and 4th instars appeared to be the most suitable for biomarkers determinations. ChE activity seems to be valuable biomarker regarding temperature and dissolved oxygen (DO) variations, while some caution should be taken when using GST as an environmental biomarker, since it shows some dependence of these parameters. C. riparius was more sensitive to dimethoate than K. calligaster suggesting that the use of bioassays with the former species in tropical conditions may overestimate the toxicity of OP pesticides to autochthonous species. When testing sub-lethal effects of dimethoate to C. riparius, ChE activity showed to be a very sensitive parameter detecting significant effects at the lowest concentration that caused emergence delay of larvae, suggesting that it is an ecologically relevant parameter.     

Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes

There is growing interest in the development of more cost-effective and retrofit technologies for the upgrade and expansion of existing wastewater treatment plants with extreme space constraints. A free-floating sponge media (BioCube) process, using a 24L lab scale reactor, was operated to study the nitrification profiles and microbial community. The COD removal efficiencies were maintained, at an average of 95%, with the mixed liquor suspended solids (MLSS) inside the BioCube sponge media maintained at 12,688mg/L. The nitrification removal efficiencies were between 92% and 100%, with an average value of 99%. From the results of microelectrode measurements, the ammonium ion concentration was found to rapidly decrease from the surface of the BioCube sponge media to a depth of 2mm due to chemical reactions carried out by ammonia oxidizing bacteria (AOB) species. Multi-fluorescence in situ hybridization (FISH) has been used to investigate the spatial distributions of various microbial activities within reactors. Microbial communities were targeted using different oligonucleotide probes specific to AOB and nitrite oxidizing bacteria (NOB). There were a large number of AOB populations, but these were not uniformly distributed in the biofilm compared to the NOB populations.     

Effect of metal and glycol on mechanochemical dechlorination of polychlorinated biphenyls (PCBs)

This paper assesses the potential of mechanochemical method with fine metal powder, glycol and alkali for polychlorinated biphenyls (PCBs) removal from waste insulating oil. The effects of relevant parameters, such as kinds of chemicals, rate and time of milling were examined. After each run, the total PCBs content in waste insulating oil was measured. Polyethylene glycol 200, long chain-glycol was more effective than triethylene glycol and ethylene glycol, short chain-glycol as hydrogen donor in mechanochemical dechlorination of PCBs. A maximum of 99.9% PCBs removal (below 2ppm) and 94% total chlorine removal were achieved with the mechanochemical process for 2h.     

Assessment of tap water quality and corrosion scales from the selected distribution systems in northern Pakistan

Corrosion deposits formed within drinking water distribution systems deteriorate drinking water quality and resultantly cause public health consequences. In the present study, an attempt was made to investigate the concurrent conditions of corrosion scales and the drinking water quality in selected water supply schemes (WSS) in districts Chitral, Peshawar, and Abbottabad, northern Pakistan. Characterization analyses of the corrosion by-products revealed the presence of α-FeOOH, γ-FeOOH, Fe₃O₄, and SiO₂ as major constituents with different proportions. The constituents of all the representative XRD peaks of Peshawar WSS were found insignificant as compared to other WSS, and the reason could be the variation of source water quality. Well-crystallized particles in SEM images indicated the formation of dense oxide layer on corrosion by-products. A wider asymmetric vibration peak of SiO₂ appeared only in Chitral and Abbottabad WSS, which demonstrated higher siltation in the water source. One-way ANOVA analysis showed significant variations in pH, turbidity, TDS, K, Mg, PO₄, Cl, and SO₄ values, which revealed that these parameters differently contributed to the source water quality. Findings from this study suggested the implementation of proper corrosion prevention measures and the establishment of international collaboration for best corrosion practices, expertise, and developing standards.     

Landscape ecological security assessment based on projection pursuit in Pearl River Delta

Regional landscape ecological security is an important issue for ecological security, and has a great influence on national security and social sustainable development. The Pearl River Delta (PRD) in southern China has experienced rapid economic development and intensive human activities in recent years. This study, based on landscape analysis, provides a method to discover the alteration of character among different landscape types and to understand the landscape ecological security status. Based on remotely sensed products of the Landsat 5 TM images in 1990 and the Landsat 7 ETM+ images in 2005, landscape classification maps of nine cities in the PRD were compiled by implementing Remote Sensing and Geographic Information System technology. Several indices, including aggregation, crush index, landscape shape index, Shannon’s diversity index, landscape fragile index, and landscape security adjacent index, were applied to analyze spatial–temporal characteristics of landscape patterns in the PRD. A landscape ecological security index based on these outcomes was calculated by projection pursuit using genetic algorithm. The landscape ecological security of nine cities in the PRD was thus evaluated. The main results of this research are listed as follows: (1) from 1990 to 2005, the aggregation index, crush index, landscape shape index, and Shannon’s diversity index of nine cities changed little in the PRD, while the landscape fragile index and landscape security adjacent index changed obviously. The landscape fragile index of nine cities showed a decreasing trend; however, the landscape security adjacent index has been increasing; (2) from 1990 to 2005, landscape ecology of the cities of Zhuhai and Huizhou maintained a good security situation. However, there was a relatively low value of ecological security in the cities of Dongguan and Foshan. Except for Foshan and Guangzhou, whose landscape ecological security situation were slightly improved, the cities had reduced values in landscape ecological security, with the most decreased number 0.52 in Zhaoqing. Results of this study offer important information for regional eco-construction and natural resource exploitation.     

Bird on the wire: Landscape planning considering costs and benefits for bird populations coexisting with power lines

Power-line grids are increasingly expanding worldwide, as well as their negative impacts on avifauna, namely the direct mortality through collision and electrocution, the reduction of breeding performance, and the barrier effect. On the other hand, some bird species can apparently benefit from the presence of power lines, for example perching for hunting purposes or nesting on electricity towers. In this perspective essay, we reviewed the scientific literature on both costs and benefits for avifauna coexisting with power lines. Overall, we detected a generalized lack of studies focusing on these costs or benefits at a population level. We suggest that a switch in research approach to a larger spatio-temporal scale would greatly improve our knowledge about the actual effects of power lines on bird populations. This research approach would facilitate suitable landscape planning encompassing both mitigation of costs and promotion of benefits for bird populations coexisting with power lines. For example, the strategic route planning of electricity infrastructures would limit collision risk or barrier effects for threatened bird populations. Concurrently, this strategic route planning would promote the range expansion of threatened populations of other bird species, by providing nesting structures in treeless but potentially suitable landscapes. We suggest establishing a collaborative dialogue among the scientific community, governments, and electricity companies, with the aim to produce a win–win scenario in which both biodiversity conservation and infrastructure development are integrated in a common strategy.     

From vineyards to feedlots: a fund-flow scanning of sociometabolic transition in the Vallès County (Catalonia) 1860–1956–1999

Regional Environmental Change - We analyse the changes to agricultural metabolism in four municipalities of Vallès County (Catalonia, Iberia) by accounting for their agroecosystem funds and...     

Assessment and potential sources of metals in the surface sediments of the Yellow River Delta,Eastern China

The Yellow River Delta is the most intact estuary wetland in China and suffers from great pressure of metals. Seventy-seven surface sediment samples were collected in the delta, and contents of Cu, Pb, Cd, Cr, Zn, Ni, and Mn were analyzed by inductively coupled plasma spectrometry and those of Hg and As by atomic fluorescence spectrometry. The results showed that means of metal contents (ppm, dry weight) were as follows: Hg, 0.04; Cr, 61.72; Cu, 20.97; Zn, 60.73; As, 9.47; Pb, 21.91; Cd, 0.12; Ni, 27.24; and Mn, 540.48. 43.8% of Hg and 14.3% of Cd were from the allogenic source while others from the authigenic source. The results of the geoaccumulation indexes appeared that 6.5% of sites from the estuarine and the Gudao areas were moderately polluted by Hg. All ecological risk index values of Hg and 37.7% of Cd were more than 40, which were the main factors of strongly and moderately potential ecological risks of 37.7% of sites in the delta. High Cd contents may be due to the alkaline conditions of the delta and the unreasonable management of the farmland, while the abnormal distribution of Hg to the wet or dry deposition and the erosion of the seawater. It was suggested to monitor Hg content in the atmosphere of the Yellow River Delta. The results were expected to update the pollution status of metals in the delta and created awareness of preserving the sound condition of the Yellow River Delta.     

Genetic diversity and population structure of the invasive plant <Emphasis Type="Italic">Solanum rostratum</Emphasis> in China

The level of genetic diversity of 13 Chinese populations of S. rostratum was investigated using nine microsatellite loci. The genetic diversity of the Weisanlu population in Hebei province was the highest and the Hohhot population was the lowest. The genetic differentiation among the populations was highly significant (P < 0.001). A total of 68.54% of the total genetic variation of population was within populations, and the genetic variation between populations accounted for 31.46%. The long-distance dispersal of its seeds by human transport mainly resulted in the rapid dispersal of S. rostratum in China.