Biomarkers of oxidative stress as indicators of water pollution in Nile tilapia (Oreochromis niloticus) from a water reservoir in Riyadh,Saudi Arabia

Antioxidant enzyme activities of fish (Oreochromis niloticus) were determined in order to assess the status of pollution in the Wadi Namar (WN), near Riyadh, Saudi Arabia. Activities of four antioxidant enzymes as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and concentrations of glutathione (GSH) and oxidant malondialdehyde (MDA) were selected as bioindicators. Fish (n = 14) were sampled in the month of April 2013 from WN and a control site (CS). SOD activity was increased by 37.9%, 47%, and 29% in kidney, liver, and heart, respectively, while a significant decrease (36.4%) was observed in gills of O. niloticus from WN as compared to fish from CS. CAT activity was reduced by 51%, 55%, 47%, and 35% in kidney, liver, heart, and gills of O. niloticus from WN. The GST activities in kidney, liver, and heart of O. niloticus from WN were elevated by 34%, 48%, and 32%, respectively. However, significant fall (49%) in gills of fish was noted from WN compared to fish from CS. GSH levels were increased by 44%, 36%, and 38% in kidney, liver, and heart, respectively, but decreased by 30% in gills. MDA levels of O. niloticus were significantly increased in kidney, liver, and heart in fish from WN. Data indicated that WN is polluted mainly by industrial and urban discharge of liquid waste products.     

Study of atrazine degradation in soil from Kenyan sugarcane-cultivated fields in controlled laboratory conditions

A study to compare the extent of atrazine mineralization in soils from Kenyan sugarcane-cultivated fields with and without history of atrazine use was carried out in the laboratory under controlled conditions. The study was testing the hypothesis that repeated atrazine application to soil will not result in enhanced atrazine mineralization. The study was carried out with ¹⁴C-uniformly ring-labeled atrazine in a laboratory under controlled conditions. Atrazine mineralization to ¹⁴CO₂ in soil with no history of atrazine use was negligible (0.16%) after 163 days of soil incubation. The three metabolites hydroxyatrazine, desisopropylatrazine, and desethylatrazine in the proportion of 17.7%, 1.3%, and 2.6%, respectively, were in the soil after 75 days. In the soil from the sugarcane-cultivated field with history of atrazine use, atrazine mineralization was 89.9% after 98 days. The same soil, amended with mature compost, showed a lag phase of eight days before rapid atrazine mineralization was observed.     

Methodological approach for metal pollution evaluation in sediments collected from the Taranto Gulf

The concentrations of Hg, Cd, Pb, Cu, Ni, V, and Sn were determined in marine sediments collected from Taranto Gulf (Ionian Sea, Southern Italy). The aim of this article is to study the methodological approach in order to evaluate total metal levels determined in marine sediments of a contaminated area (Taranto Gulf, Southern Italy), to identify contaminated areas and to predict adverse biological effects based on Sediment Quality Guidelines (SQGs). The results are discussed in relation to geological characteristics of sediments in order to define background levels and anthropogenic input. Experimental results were elaborated by multivariate statistical techniques and Geographical Information System (GIS) software. The geoaccumulation index I _geo and two sets of SQGs (in particular (a) the threshold effect level (TEL), the probable effect level (PEL) and (b) the effect range-low (ERL) and the effect range median (ERM)) have been used for environmental evaluation of metal concentrations. Results show that in Taranto coastal area, Mar Piccolo basin represents the most contaminated area. A comparison with results from other Mediterranean areas demonstrates that for some metals (such as Cd, Pb, and Hg) Taranto seas represent one of the most polluted areas in the Mediterranean Sea. A comparison of metal levels with SQGs also suggests an ecotoxicological risk for benthic organisms mainly in the first inlet of Mar Piccolo.     

Ecological properties of soil water and effects on forest vegetation in the Loess Plateau

In the Loess Plateau of China, soil water has three ecological properties: high infiltration capacity, high storage capacity and availability to deep plant roots. Soil desiccation is the most serious problem for forest vegetation in the Loess Plateau. Arid soils are the result of intensified soil desiccation caused by disturbances in plant succession, which constitute the ecological foundation of soil water. The negative effects of the arid soil layer on surface water infiltration for recharging underground water are discussed in terms of ecological hydrology. The arid soil layer disrupts the link between surface water and underground water and prevents vertical precipitation infiltration from supplementing underground water. Forest vegetation has a significant runoff-retaining efficiency that reduces total runoff from forest areas leading to low surface and ground runoff which affect the water cycle on a watershed scale.     

Effects of land use on water quality of two high-altitude lakes and catchments in Yunnan Province,China

SUMMARY

Reclaiming farmland from lakes in China in the 1950s damaged the water quality of many lakes. Tremendous efforts have been made since the late 1990s to restore vegetation around the damaged lakes. This paper examines water quality of Fuxian and Qilu Lakes and land-use characteristics within the two catchments in the high-altitude area of Yunnan Province, China. Landsat TM data acquired in 1989, 1994, 1999 and 2005 were used to extract land use and land cover (LULC) information. Measurements of five water quality indices (WQIs), BOD, COD, pH, TN and TP, for the same period of time were examined. The results showed that the area of residential and forest/shrub increased, whereas that of cropland and barren land decreased from 1989 to 2005 in both catchments. Qilu Lake was much more polluted than Fuxian Lake, and pollution worsened over time for both lakes. The differences in water quality between the two lakes were caused by differences in LULC composition and continued degradation in water quality was caused by intensive farming and urban sprawl. Unless the landscape is converted back to its pre-1950 composition and structure, water quality in both lakes cannot be significantly improved and will continue to threaten sustainable development in the region.     

A zero-inflated Bayesian spatial model with near-locating measurements

Zero-inflated data arise in many contexts. In this paper, we develop a zero-inflated Bayesian hierarchical model which deals with spatial effects, correlation among near-locating measurements as well as excess zeros simultaneously. Inference, including the sampling from the posterior distributions, predictions at new locations, and model selection, is carried out by using computationally efficient Markov chain Monte Carlo techniques. The posterior distributions are simulated using a Gibbs sampler with the embedded ratio-of-uniform method and the slice sampling algorithm. The approach is illustrated via an application to herbaceous data collected in the Missouri Ozark Forest Ecosystem Project. The results from the proposed model are compared with those generated from a non-zero inflated model. The proposed model fully incorporates the information from data collection and provides more reliable inference. A predictive $p$ value is computed for model checking and it indicates that the proposed model fits the data well.     

Are low infidelity rates in feral horses due to infanticide?

A growing number of studies conducted on diverse taxa have shown that extra-pair/group paternity is higher than what would be predicted from behavioral observations alone. While it may be beneficial for females to mate with multiple males, this often results in offspring not sired by the behavioral father, which could influence offspring survival, especially in social mammals. Feral horses (Equus caballus) maintain stable social relationships over several years, usually with one stallion defending a harem band of unrelated mares against other males. Sneak copulations by subordinate males have been observed and mares sometimes change bands, both of which can result in foals sired by males other than the dominant band stallion. We measured female fidelity in free-ranging feral horses in 23 bands, with 51 foals over four foaling seasons and tested offspring paternity against parental behaviors. We used 12 polymorphic microsatellite loci and the program CERVUS 2.0 to determine and exclude potential sires. The majority of mares remained in the band with the sire of their foal resulting in most foals being sired by the band stallion. Most foals that were not sired by the band stallion were born in the year after a round-up and we could not determine if they were the result of band changing or sneak copulations. Foals born into a band without their sire had lower survival rates and mothers were significantly more protective of foals not sired by the band stallion. These findings suggest that band stability increases the reproductive success of mares and support the importance of infanticide risk in equid social structure.     

全氟辛烷磺酸盐(PFOS)对土壤跳虫的生态毒性

将两种跳虫(Folsomia candida和Folsomia fimetaria)暴露在全氟辛烷磺酸盐(perfluorooctane sulfonate,PFOS)污染的人工土壤中,利用跳虫存活数量、繁殖数量与回避行为来评价PFOS对跳虫的生态毒性。结果表明,PFOS对F.candida和F.fimetaria急性毒性的LC50(7d)分别为4777和2219mg·kg-1,慢性毒性的EC50(28d)分别为0.13和0.05mg·kg-1。此外,PFOS对两种跳虫回避行为影响的EC50(48h)分别为0.51mg·kg-1(F.candida)和0.31mg·kg-1(F.fimetaria)。分析比较发现,PFOS对跳虫急性死亡率影响很小,但对跳虫的回避行为和繁殖率有显著影响,可用来表征土壤中PFOS的生态毒性,且选用有性生殖的F.fimetaria及其慢性毒性实验来评价土壤中PFOS的毒性相对最灵敏。     

Process modeling and economic assessment of converting municipal solid waste into solid fuel via hydrothermal processing: a case study in Vietnam

Journal of Material Cycles and Waste Management - As with any developing country, Vietnam has faced numerous challenges in the management and treatment of municipal solid waste (MSW)....     

Flexible foraging strategies of gentoo penguins <Emphasis Type="Italic">Pygoscelis papua</Emphasis> over 5 years in the South Shetland Islands,Antarctica

Gentoo penguins Pygoscelis papua show considerable plasticity in their diet, diving, and foraging behaviors among colonies; we expected that they might exhibit similar variability over time, at a single site, since flexible foraging habits would provide a buffer against changes in prey availability. We examined interannual changes in the foraging strategies and diet of gentoo penguins in the South Shetland Islands, Antarctica, over 5 years with variable prey abundance. Antarctic krill Euphausia superba was the primary diet item, and fish the secondary, though the importance of these items varied among years. Diving behavior also varied over time: different dive depth distributions were observed among years. Nonetheless, chick-rearing success remained relatively constant, indicating that gentoo penguins were able to maintain chick provisioning by altering their foraging strategy among years. Variable abundance of krill in the region did not have observable impacts on the diet, foraging behaviors or chick-rearing success of gentoo penguins. We suggest that foraging plasticity may be one reason that gentoo penguin populations have remained stable in the region, while their congeners (P. antarctica and P. adeliae) with less flexible foraging strategies have declined.