Phosphorus retention in constructed wetlands enhanced by zeolite- and clinopyroxene-dominated lava sand

Constructed wetlands (CWs) are engineered systems for treating wastewater by sequestering nutrients and contaminants. Our aim was to assess the main phosphorus (P) binding states in operating CWs to assess P saturation and indications on P recycling potential of filter materials, which might be necessary under future peak P scenarios. The investigated vertical flow CWs (operation time up to 16 years) are based on either fluviatile (Fluv) sand or zeolite- (Ze-LS) and clinopyroxene (Cl-LS)-dominated lava sand. Organic and inorganic P accumulated in all CWs independent of filter materials and showed a considerable increase with operation time. Concentrations of P decreased sharply with depth in the Fluv-CWs compared to only a slight decrease in the lava sand CWs, with P concentrations of deeper horizons approximating the relatively P enriched original lava sand substrates. Orthophosphate was the dominant pool in all CWs, while the sum of organic fractions ranged between 11% and 33%. Sequential extraction indicated that P was mainly associated with Fe and Al (hydr)oxides for Fluv-CWs and Ze-LS-CWs, while Ca and Mg bound mineral phosphates dominated in Cl-LS-CWs. Oxalate extractions pointed to a clear dominance of P fractions associated with poorly crystalline Fe- and Al-(oxy)hydroxides. Solution ³¹P NMR analyses revealed that inositol hexakisphosphates were a major pool of organic P in surface layers of CWs, which increased with operation time. With a maximum of 0.5% P content, filter sands do not appear to be a suitable fertilizer for direct application to agricultural fields. The dominance of inorganic, poorly crystalline P species point to potentially high desorption capacity which might be investigated further, to assess recycling potential of P or usage of filter materials as soil amendments with relatively high plant available P. The latter might become feasible and economically attractive under future P scarcity. Simultaneously, P saturation indexes (DPS) did not indicate an imminent P saturation of filters, since P accumulation was not restricted by binding to Al and Fe minerals.     

Bioavailability and Interaction of Si and P in a Coastal Saline Soil Amended with Pig Slurry

The effects of widely applied organic waste amendment on soil Si and P bioavailability and their interaction have rarely been investigated. The study examined bioavailability and interaction of Si and P in response to pig slurry (PS) amendment in a coastal saline (CS) soil. The final purposes of the study are to assess fertilizer Si and P needs and to ensure environmental quality. The results show that PS amendment can cause accumulation of bioavailable Si in surface soil (0–20 cm), and significantly improve both soil bioavailable P content and soil P lability through PS‐Si and P input, and by the input of PS‐organic matter (OM) and enhancing the complexation of OM with soil Si and P. As a result of the Si‐P competitive sorption, Si shows a more rapid increase in bioavailability than P at the preliminary stage of PS amendment. However, under the weakly alkaline conditions as a result of relatively long term PS amendment, the fixation capacity of Si by soil solid components increases causing a rapider decline of Si bioavailability than that of P.     

Using GIS and a digital elevation model to assess the effectiveness of variable grade flow diversion terraces in reducing soil erosion in northwestern New Brunswick,Canada

Flow diversion terraces (FDT) are commonly used beneficial management practice (BMP) for soil conservation on sloped terrain susceptible to water erosion. A simple GIS‐based soil erosion model was designed to assess the effectiveness of the FDT system under different climatic, topographic, and soil conditions at a sub‐basin level. The model was used to estimate the soil conservation support practice factor (P‐factor), which inherently considered two major outcomes with its implementation, namely (1) reduced slope length, and (2) sediment deposition in terraced channels. A benchmark site, the agriculture‐dominated watershed in northwestern New Brunswick (NB), was selected to test the performance of the model and estimated P‐factors. The estimated P‐factors ranged from 0·38–1·0 for soil conservation planning objectives and ranged from 0·001 to 0·45 in sediment yield calculations for water‐quality assessment. The model estimated that the average annual sediment yield was 773 kg ha^?1 yr ^?1 compared with a measured value of 641 kg ha^?1 yr^?1. The P‐factors estimated in this study were comparable with predicted values obtained with the revised universal soil loss equation (RUSLE2). The P‐factors from this study have the potential to be directly used as input in hydrological models, such as the soil and water assessment tool (SWAT), or in soil conservation planning where only conventional digital elevation models (DEMs) are available. Copyright © 2009 John Wiley & Sons, Ltd.     

P_5含量对滑坡体砾质土的力学性质影响试验研究

粗粒含量对滑坡体砾质土的力学性质具有重要意义。针对乌东德水电站金坪子滑坡体砾质土拟合了5条不同P5含量的试验级配,分别进行饱和状态与非饱和状态的固结排水剪切试验。试验表明,两种试验条件下的变形参数和强度参数均较高,变形参数k值与kb总体上随P5含量的增大而增大;P5含量越高粗颗粒的骨架作用越强,试样的模量越大。砾质土饱和状态的内摩擦角和变形参数低于非饱和状态,说明试样浸水饱和会使强度模量降低,降雨将降低滑坡体的稳定性。     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （August 2006～September 2006）

Illustration All the data in this catalog are chosen from the ″Preliminary Seismological Report of Chinese Seismic Stations″ (Its abbreviation is ″Monthly Report″). The catalog includes the events of M≥4.7 in and near China and M≥6 all over the world. The ″Monthly Report″ is monthly compiled by the Ninth Section of Institute of Geophysics, China Earthquake Administration.     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （December 2006-January 2007）

Illustration All the data in this catalog are chosen from the ″Preliminary Seismological Report of Chi-nese Seismic Stations″ (Its abbreviation is ″Monthly Report″). The catalog includes the events of M≥4.7 in and near China and M≥6 all over the world. The ″Monthly Report″ is monthly compiled     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （April 2007～May 2007）

Illustration All the data in this catalog are chosen from the ″Preliminary Seismological Report of Chi-     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （June 2007-July 2007）

Illustration All the data in this catalog are chosen from the ″Preliminary Seismological Report of Chi-nese Seismic Stations″ (Its abbreviation is ″Monthly Report″). The catalog includes the events of     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （October, 2005-November, 2005）

Illustration All the data in this catalog are chosen from the ＂Preliminary Seismological Report of Chinese Seismic Stations＂ （Its abbreviation is ＂Monthly Report＂）. The catalog includes the events of M≥4.7 in and near China and M≥6 all over the world. The ＂Monthly Report＂ is monthly compiled by the Ninth Section of Institute of Geophysics, China Earthquake Administration.     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （December 2005～January 2006）

Illustration All the data in this catalog are chosen from the ＂Preliminary Seismological Report of Chinese Seismic Stations＂ （Its abbreviation is ＂Monthly Report＂）. The catalog includes the events of M≥4.7 in and near China and M≥6 all over the world. The ＂Monthly Report＂ is monthly compiled by the Ninth Section of Institute of Geophysics, China Earthquake Administration.     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （June, 2006-July, 2006）

Illustration All the data in this catalog are chosen from the ＂Preliminary Seismological Report of Chinese Seismic Stations＂ （Its abbreviation is ＂Monthly Report＂）. The catalog includes the events of M≥4.7 in and near China and M≥6 all over the world. The ＂Monthly Report＂ is monthly compiled by the Ninth Section of Institute of Geophysics, China Earthquake Administration.     

Assessments of Potential Spatial‐temporal Variations in Phosphorus Distribution and Fractionation in River Bed Sediments

Sediment characteristics influence the distribution and bioavailability of phosphorus (P) in river sediments. In this study, we analyzed different P fractions in the sediments of the Bronx River, New York City, NY, using sequential extraction. The results showed that the average P pool rank order was HCl?P > NaOH?P > NaHCO₃?P > residue?P, and their relative proportions were 3.7: 2.0: 1.4: 1 in sediments collected in 2006, while HCl?P > NaOH?P > residue?P > NaHCO₃?P, with their relative proportions of 27.8:6.2:2.7:1 in the sediments obtained in 2007. The strong correlation between microbial P and organic P (OP), along with the changes in microbial P over time indicate that most of the OP in the river bed sediments is potentially bioavailable. The sediment transport, deposition, assimilation, the exchange of P between sediments and water columns, the land use changes, raw sewer discharge, gas spill, construction, fertilizer application, etc., as well as the hydro‐climatic changes could result in the spatial and temporal variations in P bioavailability in the river bed sediments. The estimations of P pools and their bioavailability in river bed sediments could help determine the spatial and temporal variations in P transport and impacts of land use on water quality, in turn, help regulate P in the river's watershed.     

Strong earthquake activity all over the world and strong moderate earthquake ac—tivity within and near China（Dec.,2002～Jan.,2003）

Illustration All the data in this catalog are chosen from the Preliminary Seismological Report of Chinese Seismic Stations (abbreviated to Monthly Report). The catalog includes the events of M(4.7 in and near China and M(6 all over the world. The Monthly Report is monthly compiled by the Ninth Section of Institute of Geophysics, CSB.     

Strong earthquake activity all over the world and strong-moderate earthquake activity within and near China （February 2007-March 2007）

Illustration All the data in this catalog are chosen from the ″Preliminary Seismological Report of Chinese Seismic Stations″ (Its abbreviation is ″Monthly Report″). The catalog includes the events of M≥4.7 in and near China and M≥6 all over the world. The ″Monthly Report″ is monthly compiled by the Ninth Section of Institute of Geophysics, China Earthquake Administration.