Interaction of acetamiprid with extracellular polymeric substances (EPS) from activated sludge: A fluorescence study

Extracellular polymeric substances (EPS) are important components of activated sludge and it plays an important role in removing pollutants. The interaction between EPS and organic pollutants is still little known. In the present study, the interaction of soluble/bound EPS with acetamiprid, a neonicotinoid insecticide, was investigated using the three-dimensional excitation–emission matrix (EEM) fluorescence spectroscopy. The fluorescence spectra of EPS revealed that there were two classes of protein-like fluorophores in soluble/bound EPS and one class of fulvic acid-like fluorophore, in addition, in bound EPS. The quenching of protein-like fluorescence by acetamiprid indicated that static quenching (at peak B) and combined quenching (at peak A) occurred simultaneously. The interaction of acetamiprid with EPS was observed to have resulted in the formation of acetamiprid-EPS complexes. The binding constants of the soluble EPS for acetamiprid were greater than those of the bound EPS, indicating the soluble EPS had stronger binding capacity for acetamiprid than the bound EPS. This study confirmed that EPS (soluble/bound) play important roles in biosorption of organic pollutants by activated sludge and also indicated that they may serve as a protective barrier against toxic organic matter, for the microorganisms.Key words: Extracellular polymeric substance (EPS), activated sludge, fluorescence quenching, binding constant, acetamiprid

Analysis of Factors Influencing Carbon Emissions in the Energy Base, Xinjiang Autonomous Region, China

Analyzing the driving factors of regional carbon emissions is important for achieving emissions reduction. Based on the Kaya identity and Logarithmic Mean Divisia Index method, we analyzed the effect of population, economic development, energy intensity, renewable energy penetration, and coefficient on carbon emissions during 1990–2016. Afterwards, we analyzed the contribution rate of sectors’ energy intensity effect and sectors’ economic structure effect to the entire energy intensity. The results showed that the influencing factors have different effects on carbon emissions under different stages. During 1990–2000, economic development and population were the main factors contributing to the increase in carbon emissions, and energy intensity was an important factor to curb the carbon emissions increase. The energy intensity of industry and the economic structure of agriculture were the main factors to promote the decline of entire energy intensity. During 2001–2010, economic growth and emission coefficient were the main drivers to escalate the carbon emissions, and energy intensity was the key factor to offset the carbon emissions growth. The economic structure of transportation, and the energy intensity of industry and service were the main factors contributing to the decline of the entire energy intensity. During 2011–2016, economic growth and energy intensity were the main drivers of enhancing carbon emissions, while the coefficient was the key factor in curbing the growth of carbon emissions. The industry’s economic structure and transportation’s energy intensity were the main factors to promote the decline of the entire energy intensity. Finally, the suggestions of emissions reductions are put forward from the aspects of improving energy efficiency, optimizing energy structure and adjusting industrial structure etc. View Full-Tex

Preliminary studies on the large-scale geomorphic patterns of the complex longitudinal sand ridge zone in the Taklimakan Desert

Through analysis of satellite images from Google Earth, this article expounds the characteristics of large-scale geomorphic patterns of the complex longitudinal sand ridge zone in the Taklimakan Desert, and reduces the large-scale geomorphic patterns to six types: parallel pattern, "(sic)" character-shaped and "(sic)" character-shaped pattern, comb-shaped pattern, fork-shaped pattern, toe-shaped pattern and miscellaneous pattern. And according to the large-scale geomorphic pattern type (or composition of pattern types) as well as some other factors, the article divides the complex longitudinal sand ridge zone into 55 subzones. Lastly, aiming at the genetic problems of the large-scale geomorphic patterns, the article suggests three connective types of the sand ridges in the complex longitudinal sand ridge zone, i.e., connecting or intersecting after natural elongation, connecting in a narrow place and connecting with the aid of intermediary

Palaeoenvironment of mid- to late Holocene loess deposit of the southern margin of the Tarim Basin, NW China

Holocene environmental history in the Tarim Basin and the Taklimakan Desert is known mainly froth isolated eolian and lacustrine deposits and remain puzzling. Here we present an adequately preserved loess section, covering the past 5000 years, at a highland (2,850 m a.s.l) on the northern slope of Kunlun Mountains. Pollen preserved in the section reveal a drying trend with significant moisture fluctuations around 3000-2600 cal yr BP and 1800 cal yr BP at the study site. Comparing the pollen, grain size from the same section provides a different scene occurred in the Tarim basin and the Taklimakan desert. Comparison of grain size to A/C ration of pollen suggests that active sand southward shifting in south margin of the desert is coincident with increasing moisture condition at the section locality, implying a casual link. This moisture pattern occurred at the upper and lower elevation of the slope is best explained by the vertical variation of local precipitation along the slope

Toxic effects of antimony on photosystem II of Synechocystis sp as probed by in vivo chlorophyll fluorescence

It has been demonstrated that antimony (Sb) at concentrations ranging from 1.0 to 10.0 mg L-1 inhibits O-2 evolution. Deeper insight into the influence of Sb on PSII was obtained with measurements of in vivo chlorophyll fluorescence. The donor and the acceptor sides of PSII were shown to be the target of Sb. Sb treatment induces inhibition of electron transport from Q (A) (-) to Q(B)/Q (B) (-) and accumulation of P (680) (+) . S-2(Q(A)Q(B))(-) charge recombination and oxidation by PQ9 molecules became more important in Q (A) (-) reoxidation as the electron transfer in PSII was inhibited. Sb exposure caused a steady increase in the proportion of PSIIX and PSII beta. These changes resulted in increased fluxes of dissipated energy and decreased index of photosynthesis performance, of maximum quantum yield, and of the overall photosynthetic driving force of PSII

Characterizing variations in soil particle size distribution in oasis farmlands-A case study of the Cele Oasis

Characterizing soil particle size distributions (PSD) and their variation is an important issue in environmental research. In this study, fractal theory was used to analyse the soil PSD and its variations in the Cele Oasis, which is located at the southern margin of the Tarim Basin. The characteristics of the soil PSD were then evaluated to identify the primary factors that influence soil PSD. The results showed that the fractal dimension (D) values ranged from 2.11 to 2.27, and that there were significant differences among groups. Furthermore, the D values showed a significant positive correlation with fine particles (<50 mu m) and soil organic matter contents. According to a comparative analysis of D values, the utilization years of farmlands had a significant influence on PSD, while the difference in the spatial distribution of farmlands did not. These results indicated that long-term and effective tillage management of the farmlands will be beneficial to keeping and improving the states of the soil PSD and other soil properties. (C) 2009 Elsevier Ltd. All rights reserved

Ordination as a tool to characterize soil particle size distribution, applied to an elevation gradient at the north slope of the Middle Kunlun Mountains

Soil particle-size distribution (PSD) is one of the most fundamental physical attributes of soil due to its strong influence on other soil properties related to water movement, productivity, and soil erosion. Characterizing variation of PSD in soils is an important issue in environmental research. Using ordination methods to characterize particle size distributions (PSDs) on a small-scale is very limited. In this paper, we selected the Cele River Basin on the north slope of the Middle Kunlun Mountains as a study area and investigated vegetation and soil conditions from 1960 to 4070 m a.s.l. Soil particle-size distributions obtained by laser diffractometry were used as a source data matrix. The Canonical Correspondence Analysis (CCA) ordination was applied to analyse the variation characteristics of PSDs and the relationships between PSDs and environmental factors. Moreover, single fractal dimensions were calculated to support the interpretation of the ordination results. Our results indicate that a differentiation of 16 particle fractions can sufficiently characterize the PSDs in CCA biplots. Elevation has the greatest effect on PSDs: the soil fine fractions increase gradually with increasing elevation. In addition, soil pH, water and total salt content are significantly correlated with PSDs. CCA ordination biplots show that soil and vegetation patterns correspond with one another, indicating a tight link between soil PSDs and plant communities on a small scale in arid regions. The results of fractal dimensions analysis were rather similar to CCA ordination results, but they yielded less detailed information about PSDs. Our study shows that ordination methods can be beneficially used in research into PSDs and, combined with fractal measures, can provide comprehensive information about PSDs. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved

Effects of levofloxacin hydrochlordie on photosystem II activity and heterogeneity of Synechocystis sp.

Effects of LH on photosynthesis of Synechocystis sp. were investigated by a variety of in vivo chlorophyll fluorescence. O-2 evolution and the photosystem II (PSII) activity were clearly inhibited by LH. Exposure to LH increased the proportion of PSII beta and this weakened the connectivity between PS11 units and hindered excitation energy-transfer between PSII units. LH decreased the density of the active photosynthetic reaction centers, inhibited electron transport, and increased the dissipated energy flux per reaction center. The inhibitory effect of LH on Q(A)(-) reoxidation process could be divided into several stages. LH first inhibited the electron transfer from Q(A)(-) to Q(B) by weakening the connectivity between Q(A)(-) and Q(B), and PQ binding began taking part in Q(A)(-) reoxidation. At the second stage, the connectivity between Q(A)(-) and PQ pool was broken and inhibition on PQ binding occurred. At this stage, some Q(A)(-) began to be oxidized by S-2(Q(A)Q(B))(-). Finally, when the connectivity between Q(A)(-) and Q(B) and PQ was completely broken, all Q(A)(-) was oxidized through charge recombination. (C) 2009 Elsevier Ltd. All rights reserved

Paleoenvironment and Migration of rivers,delta and lakes in the lowest reaches of Heihe River

Migration of rivers and lakes in the lowest reaches of Heihe River during the last 8000 years, was investigated mainly by field observation, micro-fossil and chemical analyses of sediments, AMS datings and satellite images, in relation to the shift of delta and sand dunes. The results are summarized as follows.From 7500 to 1700 years BP, giant Old Juyan Lake was existed just faced on the Juyan Delta. The extension of Old Juyan Lake in the past was reconstructed by the former shorelines (gravel bars) and those ages were determined by AMS method using molluscan fossils from the bar deposits. The main part of the Juyan Delta is covered with sand dunes, but traces of braided channels still preserved. Around the Green City and western half of Juyan Delta, human occupation including irrigation channels and agricultural land was dominated at least in Han Dynasty.After AD250, the Old Juyan Lake was dried up or became very small lakes, because no former shorelines were found. At this moment a river began to enter into Sogo Nur. Sand dune formation was activated and disturbed the river course.Around AD1200, Heihe channels migrated to northward, commenced to form Ejina Delta. Frequent flooding deposits are distributed and the river water reached to Gashun Nur. In Xixia and Yuan Dynasties, they used still irrigation channels for agriculture around Black City and in the western part of Juyan Delta.During the Little Ice Age, pollen and diatom analyses indicate that Gashun Nur environment alternated between water coverage and desiccation. AD 1450 - 1550, irrigation channels were covered with Tamarix cones, suggesting abandonment of the human occupation under such arid environments in the lower reaches of Heih

Grain size characteristics of the sand silt layers in the ancient delta of the dried Lop Nur lake (east Tarim Basin) and their environmental implications

Grain size characteristics of sediments are an effective index for the depositional environment. However, whether grain size is an accurate indicator for the formation environment is still obscure. In this study, two main types of lithology can be found in the yardang sediments from the Loulan area (Lop Nur): sand-silt layers and clay-silt layers. These two types are common in arid northwestern China. The clay-silt layers were primarily composed of lacustrine-swamp deposits, whereas the sand silt layers were formed under fluvial conditions based on geomorphic and stratigraphic lithologic evidence. However, grain size characteristics of the sand-silt layers, such as grain size distribution, C-M diagram, and grain size parameters, were consistent with that of the aeolian deposits. The study of the field deposition environment indicated that the sand-silt layers were fluvial sediments of materials originating from the aeolian sediments transported over a short distance and deposited by floods. As a result, the fluvial sediments exhibited the grain size characteristics of aeolian sediments. This indicates that some sediments may retain different depositional environment information, having undergone transportation and deposition processes. Therefore, when using grain size characteristics to determine the depositional environment, field deposition environment investigation should be combined with other environmental proxy indicators