scholarly journals The role of organic matter and clay content in sediments for bioavailability of pyrene

2017 ◽  
Vol 77 (2) ◽  
pp. 439-447 ◽  
Author(s):  
Jelena Spasojević ◽  
Snežana Maletić ◽  
Srđan Rončević ◽  
Marko Grgić ◽  
Dejan Krčmar ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Contaminants ◽  
Strong Association ◽  
Great Influence ◽  
Clay Content ◽  
A Value ◽  
Bioavailable Fraction ◽  
Polycyclic Aromatic

Abstract Evaluation of the bioavailable fractions of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) is extremely important for assessing their risk to the environment. This available fraction, which can be solubilised and/or easily extracted, is believed to be the most accessible for bioaccumulation, biosorption and/or transformation. Sediment organic matter (OM) and clay play an important role in the biodegradation and bioavailability of PAHs. The strong association of PAHs with OM and clay in sediments has a great influence not only on their distribution but also on their long-term environmental impact. This paper investigates correlations between bioavailability and the clay and OM contents in sediments. The results show that OM is a better sorbent for pyrene (chosen as a model PAH) and that increasing the OM content reduces the bioavailable fraction. A mathematical model was used to predict the kinetic desorption, and these results showed that the sediment with the lowest content of OM had an Ffast value of 24%, whereas sediment with 20% OM gave a value of 9%. In the experiments with sediments with different clay contents, no clear dependence between clay and rate constants of the fast desorbing fractions was observed, which can be explained by the numerous possible interactions at the molecular level.

The Role of Cement in the Long Term Performance and Premature Failure of Charnley Low Friction Arthroplasties

1986 ◽  
Vol 15 (1) ◽  
pp. 19-22 ◽  
Author(s):  
G H Isaac ◽  
J R Atkinson ◽  
D Dowson ◽  
B M Wroblewski
Keyword(s):  
Premature Failure ◽  
Hip Prostheses ◽  
Acrylic Cement ◽  
A Value ◽  
Articulating Surface ◽  
Long Term Performance ◽  
Term Performance

A number of polyethylene acetabular cups (59) and femoral stems (38) of Charnley hip prostheses were obtained following revision surgery and examined by scanning electron microscopy. In many cases, acrylic cement particles were embedded in the articulating surface of the cups. These particles caused surface pitting. The appearance of the articulating surfaces suggested that some cement had been present from the time of arthroplasty. In other cups there was evidence of cement ingress during the service life. Failure to use sufficient cement at arthroplasty resulted in cavities on the backs of the cups. Many femoral heads had become scratched in vivo, the surface roughness increasing from an initial value less than 0.02 μm Ra to a value on removal of 0.07 μm Ra. The increased roughness increases the amount of wear in the polyethylene sockets. Laboratory tests show that retrieved acrylic cement particles will scratch stainless steel, and it is our conclusion that entrapped cement will damage both components of the prosthesis and may cause premature failure.

The Role of Condensed Organic Matter in the Nonlinear Sorption of Hydrophobic Organic Contaminants by a Peat and Sediments

2002 ◽  
Vol 31 (6) ◽  
pp. 1953-1962 ◽  
Author(s):  
Yong Ran ◽  
Weilin Huang ◽  
P. S. C. Rao ◽  
Dehan Liu ◽  
Guoying Sheng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Contaminants ◽  
Hydrophobic Organic Contaminants ◽  
Nonlinear Sorption

scholarly journals Bioremediation of Heavy Metals and Organic Toxicants by Composting

2002 ◽  
Vol 2 ◽  
pp. 407-420 ◽  
Author(s):  
Allen V. Barker ◽  
Gretchen M. Bryson
Keyword(s):  
Organic Matter ◽  
Aromatic Hydrocarbons ◽  
Organic Contaminants ◽  
Contaminated Soils ◽  
Native Plants ◽  
Organic Complexes ◽  
Soils And Sediments ◽  
Polycyclic Aromatic ◽  
By Products ◽  
Metallic Pollutants

Hazardous organic and metallic residues or by-products can enter into plants, soils, and sediments from processes associated with domestic, municipal, agricultural, industrial, and military activities. Handling, ingestion, application to land or other distributions of the contaminated materials into the environment might render harm to humans, livestock, wildlife, crops, or native plants. Considerable remediation of the hazardous wastes or contaminated plants, soils, and sediments can be accomplished by composting. High microbial diversity and activity during composting, due to the abundance of substrates in feedstocks, promotes degradation of xenobiotic organic compounds, such as pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). For composting of contaminated soils, noncontaminated organic matter should be cocomposted with the soils. Metallic pollutants are not degraded during composting but may be converted into organic combinations that have less bioavailability than mineral combinations of the metals. Degradation of organic contaminants in soils is facilitated by addition of composted or raw organic matter, thereby increasing the substrate levels for cometabolism of the contaminants. Similar to the composting of soils in vessels or piles, the on-site addition of organic matter to soils (sheet composting) accelerates degradation of organic pollutants and binds metallic pollutants. Recalcitrant materials, such as organochlorines, may not undergo degradation in composts or in soils, and the effects of forming organic complexes with metallic pollutants may be nonpermanent or short lived. The general conclusion is, however, that composting degrades or binds pollutants to innocuous levels or into innocuous compounds in the finished product.

scholarly journals The role of sideration in the accumulation of organic matter

2021 ◽  
Vol 3 (45) ◽  
pp. 17-17
Author(s):  
Alexander Saakian ◽  
◽  
Keyword(s):  
Organic Matter ◽  
Crop Rotation ◽  
Podzolic Soil ◽  
Organic Fertilizer ◽  
Crop Productivity ◽  
Organic Fertilizers ◽  
White Mustard ◽  
Central Regions

Data on the effect of long-term (18 years) use of crop sideration (white mustard), both separately and in combination with straw fertilizer, on the content of organic matter in sod-podzolic soil and crop productivity are presented. In the conditions of an acute shortage of organic fertilizers in agriculture in the central regions of the non-Chernozem zone, a promising and economically profitable form of organic fertilizer is crop crops of sideral crops from the cruciferous family (white mustard, etc.) Keywords: SOD-PODZOLIC SOIL, CROP ROTATION, WHITE MUSTARD, ORGANIC MATTER

PENGARUH PENAMBAHAN SERBUK BATA MERAH TERHADAP NILAI CBR

2020 ◽  
Vol 14 (2) ◽  
pp. 47
Author(s):  
Muhammad Rayhan Agustian Arif ◽  
A'isyah Salimah ◽  
Putera Agung Maha Agung
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Soft Soil ◽  
Soil Conditions ◽  
Soil Functions ◽  
A Value ◽  
Brick Powder ◽  
Cbr Test ◽  
Loose Sediments

Abstract Soil is a collection of minerals, organic matter and relatively loose sediments that are located above the bedrock. Based on the particle size, it is divided into four types, namely gravel, sand, silt and clay. The role of soil is very important in a construction because the soil functions as a support for the loads that are above it, so that the soil is expected to have a good bearing capacity. In this study, the soil taken is soft soil in Hambalang, Bogor where the soil conditions in the area are hard in the dry season and soft in the rainy season, so it is necessary to review the CBR (California Bearing Ratio) value. In this study, using waste from red brick as an additive to soft soil. CBR testing is appropriate (SNI 1744: 2012), with the CBR Laboratory test soaked and unsoaked. Along with the addition of% red brick powder, the CBR values of soaked and unsoaked (top and bottom) have increased, so that the addition of% content of red brick powder is 15% respectively got a value of 4.55% and 4.9% (soaked) and 17.94% and 19.70 (unsoaked). So, from this CBR test, it was found that the effect of adding red brick powder increases CBR tilapia soaked and unsoaked soft soil of Hambalang. Keywords: Soft Soil, Red Brick Powder,CBR soaked, CBR unsoaked

Effect of anaerobic digestion at 35, 55 and 60 °C on pharmaceuticals and organic contaminants

2014 ◽  
Vol 69 (6) ◽  
pp. 1282-1288 ◽  
Author(s):  
Å. Davidsson ◽  
H. Kjerstadius ◽  
S. Haghighatafshar ◽  
J. Fick ◽  
M. Olsson ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Organic Contaminants ◽  
Wastewater Treatment Plants ◽  
Pharmaceutical Compounds ◽  
Commercial Fertilizer ◽  
Low Concentrations ◽  
Treated Sewage ◽  
Polycyclic Aromatic ◽  
Individual Pahs

The application of treated sewage sludge on farmland is a suggested method for recycling nutrients and reducing demand for commercial fertilizer. However, sludge needs to be safe from possible contaminants which can cause acute and long-term health and environmental problems. Residual pharmaceuticals and organic contaminants are mentioned as emerging threats since wastewater treatment plants are not designed to degrade these substances. The aim of this study was to screen and evaluate the presence, and reduction, of pharmaceuticals and polycyclic aromatic hydrocarbons (PAHs) during anaerobic digestion of mixed primary and waste-activated sludge at 35, 55 and 60 °C and during pasteurization at 70 °C. The study showed the difficulty of analysing pharmaceutical compounds in low concentrations in the sludge matrix. No general reduction of these compounds was seen during treatment, but for individual substances some reduction occured. The PAHs were generally not reduced during digestion or pasteurization, but for three substances (indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene (analysed together) and benzo[g,h,i]perylene) reduction (up to 60%) during digestion was seen. Digestion at 35 and 55 °C resulted in about the same order of reduction of the three individual PAHs, which was higher than for digestion at 60 °C.

Humus acids as reserve of water-soluble organic matter in irrigated chernozems of Near-Ob are

2020 ◽  
pp. 28-32
Author(s):  
Boris Klenov
Keyword(s):  
Organic Matter ◽  
Water Soluble ◽  
Organic Fertilizers ◽  
Relative Role ◽  
Weakly Alkaline ◽  
Soil Medium ◽  
Humus Composition ◽  
Humus Acids

It has been shown the role of carbon of dissolved organic matter (C DOM) in humus composition of irrigated chernozems as well as participation of humus substances proper in the formation of DOM. It has been found out that in chernozem long-term irrigated with weakly alkaline water the yield of C DOM is reliably higher than in nonirrigated soil when used even ordinary water extraction. It accounts for 53 and 40 mg l–1 respectively. It is attributed to the fact that because of influence of irrigative water the pH range became wider to some extent and alkalinity of soil medium became stronger and consequently the solubility of DOM increased. It has been noted that that the same tendency that is decrease is observed in depthwise distribution of humus and C DOM. As it should be expected, in irrigated soil processed with irrigative water the content of C DOM is somewhat higher (by 7–10 mg l–1) in the studied part of the profile as a whole. At the same time the relative role of C DOM in humus composition increases with increasing pH, up to 3 % of total organic soil carbon. It has been examined the interaction of irrigative water free of DOM with preparations of humus acids extracted from soil. Drown coloration of irrigative water is evidence of separation of DOM from humus acids. Moreover, the yield of C DOM proved to be three times higher in case of irrigative water than distilled one and accounted 120 and 350 mg l–1 respectively. This comparative experiment is an evidence of the fact that humus acids can be served as a source of DOM, especially in the event if more accessible organic matter is not available. Thus, long-term irrigation of chernozems in case of unsatisfactory application of organic fertilizers leads not only to biological and irrigational humus losses but also humus losses by way of transformation of humus acids into DOM

Prediction of preterm birth: the role cervical assessment by ultrasound and cervico-vaginal biomarkers

2020 ◽  
Author(s):  
Giuseppe Rizzo ◽  
Ilenia Mappa Mappa ◽  
Victoria Bitsadze ◽  
Jamilya Khizroeva ◽  
Alexander Makatsariya
Keyword(s):  
Preterm Birth ◽  
Neonatal Morbidity ◽  
Cervical Length ◽  
Fetal Fibronectin ◽  
Neonatal Deaths ◽  
A Value ◽  
Increased Risk ◽  
Asymptomatic Women

Preterm delivery (PTB) is one of the most common and serious complications of pregnancy. PTB accounts for approximately 70% of neonatal deaths and is a major cause of neonatal morbidity including respiratory distress syndrome, necrotising enterocolitis and long-term neurological disabilities. Prevention of PTB and its complications include identification among symptomatic women those at high risk of immediate delivery requiring prenatal corticosteroids administration. Transvaginal ultrasonographic evaluation of the cervical length (CL) is predictive of PTB and a value 15 mm identifies among symptomatic women approximately 70% of women who will deliver within one week. In the range of CL within 15 and 30 mm biomarkers n cervical-vaginal fluids (fetal fibronectin, phosphorylated insulin-like growth factor protein-1, placental alpha-microglobulin-, cytokines) and other ultrasonographic cervical variables (posterior cervical angle, elastography) improve the identification of women at risk, In asymptomatic women CL can be applied as screening and has been proposed as a universal screening during the second trimester in singleton gestations. The finding of a CL25mm is associated with an increased risk of subsequent PTB with a sensitivity between 30 and 60% that is improved with the combination of biomarkers. Asymptomatic women with a CL 25mm should be offered vaginal progesterone treatment for the prevention of preterm birth and neonatal morbidity. The role of cerclage and pessary is still controversial. In this review we discuss the evidence-based role of ultrasonographic cervical assessment and cervicovaginal biomarkers in the prediction of PTB in symptomatic and asymptomatic women

Long-term soil water content and exchangeable Ca interact to stabilize organic matter

2020 ◽  
Author(s):  
Itamar Shabtai ◽  
Srabani Das ◽  
Thiago Inagaki ◽  
Ingrid Kogel-Knabner ◽  
Johannes Lehmann
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Microbial Respiration ◽  
Plant Litter ◽  
Exchangeable Ca

<p>Organo-mineral interactions stabilize soil organic matter (SOM) by protecting from microbial enzymatic attack. Soil water content affects aggregation, mineral weathering, and microbial respiration, thus influencing the relative importance of SOM stabilization mechanisms. While the response of microbial respiration to momentary changes in water content is well established, it is unclear how microbial activity will impact stabilization mechanisms under different long-term moisture contents.</p><p>To understand how long-term soil moisture affects SOM stabilization mechanisms we studied fallow soils from upstate New York situated on a naturally occurring water content gradient. Wetter (but not saturated) soils contained more exchangeable Ca and had more strongly stabilized SOM, resulting in SOM accumulation. But it was not clear whether Ca-driven surface interactions or occlusion in micro-aggregates was more important, and if interactions with Fe and Al played a role in the Ca-poor soils. Also, the role of biotic drivers in SOM stabilization at different water contents was unknown.</p><p>We tested which mechanisms governed SOM stabilization by determining C and N contents and natural isotope abundances in particulate and mineral-associated organic matter fractions. We also extracted the C bound to Ca and to reactive Fe+Al phases. Wetter, Ca-rich soils had higher oPOM content, and in the heavy mineral fraction, higher relative concentrations of Ca-bound C, lower C:N values, and more oxidized C forms. In addition, wetter soils had greater microbial biomass. Together, these results showed that high long-term soil moisture increased microbial SOM cycling, and that processed SOM was better stabilized, in agreement with the recent notion that stable SOM consists of processed labile C. Additionally, higher soil moisture augmented the role of Ca in SOM stabilization over that of Al+Fe phases. We then manipulated the exchangeable Ca content and incubated soils with <sup>13</sup>C<sup>15</sup>N labeled plant litter. Ca-amended soils emitted less CO<sub>2 </sub>while incubated with litter, confirming that Ca is instrumental in SOM stabilization. Tracing the labeled isotopes in the gaseous phase and soil fractions will allow us to gain a clearer understanding of how water content and soil Ca interact to stabilize SOM.  </p>

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