Buffer capacity of heterogeneous chemical equilibria in natural waters

2012 ◽  
Vol 90 (4) ◽  
pp. 395-402 ◽  
Author(s):  
Igor Povar ◽  
Vasile Rusu
Keyword(s):  
Natural Waters ◽  
Buffer Capacity ◽  
Chemical Equilibria ◽  
Mineral Equilibria ◽  
Proportional Relation ◽  
Heterogeneous Chemical ◽  
Metal Levels ◽  
Two Phases ◽  
Buffer Capacities

A novel ion–molecular buffer approach for estimating buffer capacities for natural water – mineral equilibria has been developed. Using this approach, the buffer capacity for any component of the heterogeneous system can be assessed. A proportional relation between different capacities in relation to ions of the compound distributed between two phases has been found. The influence of major thermodynamic parameters, such as temperature, pH, and the main chemical component concentrations of natural waters upon system buffer capacities has been investigated. It is expected that this type of approach will help to predict long-term diminishing effects in natural waters as a remediation alternative. The obtained results are intended to provide users with a compulsory tool to set reliable limits of ion (including metal) levels in environmental systems.

Buffer Properties of Heterogeneous Mixtures “Mineral – Natural Waters”

2020 ◽  
pp. 164-196
Author(s):  
Igor Povar ◽  
Oxana Spinu
Keyword(s):  
Aquatic Ecosystems ◽  
Plant Nutrition ◽  
Natural Waters ◽  
Stoichiometric Composition ◽  
Heterogeneous Systems ◽  
Chemical Equilibria ◽  
Natural Remediation ◽  
Buffer Capacities

The provision of plants is generally assessed by the potential buffering capacity of soils in relation to the elements of plant nutrition. The main focus in this chapter is to review the developed earlier buffer theory and show how to use the for assessing and predicting the long-term phenomena of attenuation and natural remediation of ionic pollutants in contaminated aquatic ecosystems. The buffer theory is based on the rigorous thermodynamic analysis of complex chemical equilibria under environmental conditions in aquatic ecosystems, developed in the previous chapter. It has been proved that both homogeneous and heterogeneous systems manifest a buffer action towards all their components. It has been established that the buffer capacities of components are mutually proportional, whereas for heterogeneous systems these relationships depend on the stoichiometric composition of solid phases. The use of the developed buffer approach yields deeper understanding of the processes that control the concentrations of various components.

scholarly journals When Housing and Communities Were Delivered: A Case Study of Post-Wenchuan Earthquake Rural Reconstruction and Recovery

2021 ◽  
Vol 13 (14) ◽  
pp. 7629
Author(s):  
Haorui Wu
Keyword(s):  
Built Environment ◽  
Wenchuan Earthquake ◽  
Place Making ◽  
Sustainable Rural Development ◽  
Residential Communities ◽  
Social Settings ◽  
Disaster Survivors ◽  
Two Phases

This study contributes to an in-depth examination of how Wenchuan earthquake disaster survivors utilize intensive built environment reconstruction outcomes (housing and infrastructural systems) to facilitate their long-term social and economic recovery and sustainable rural development. Post-disaster recovery administered via top-down disaster management systems usually consists of two phases: a short-term, government-led reconstruction (STGLR) of the built environment and a long-term, survivor-led recovery (LTSLR) of human and social settings. However, current studies have been inadequate in examining how rural disaster survivors have adapted to their new government-provided housing or how communities conducted their long-term recovery efforts. This qualitative case study invited sixty rural disaster survivors to examine their place-making activities utilizing government-delivered, urban-style residential communities to support their long-term recovery. This study discovered that rural residents’ recovery activities successfully perpetuated their original rural lives and rebuilt social connections and networks both individually and collectively. However, they were only able to manage their agriculture-based livelihood recovery temporarily. This research suggests that engaging rural inhabitants’ place-making expertise and providing opportunities to improve their housing and communities would advance the long-term grassroots recovery of lives and livelihoods, achieving sustainable development.

scholarly journals Voices We Forget—Danish Students Experience of Returning to School Following Parental Bereavement

2016 ◽  
Vol 78 (1) ◽  
pp. 24-42 ◽  
Author(s):  
Martin Lytje
Keyword(s):  
Focus Group ◽  
Data Collection ◽  
Return To School ◽  
Parental Bereavement ◽  
Focus Group Interviews ◽  
Academic Challenges ◽  
Two Phases ◽  
Group Interviews ◽  
Returning To School

This study explores how Danish students experience returning to school following parental bereavement. Eighteen focus group interviews with 39 participants aged 9 to 17 years were conducted. All participants had experienced the loss of a primary caregiver. Data collection was divided into two phases. In Phase I, 22 participants from four grief groups were interviewed 4 times over the course of a year. During Phase II, confirmatory focus groups were undertaken with the 17 participants. This article explores findings related to the four themes of initial school response, long-term support, challenges within the class, and academic challenges. The study found that (a) students struggle to reconnect with classmates following the return to school and often feel alone, (b) schools fail to have guidelines in place for what they are allowed to do if becoming sad the class, and (c) schools seem to forget their loss as time passes.

scholarly journals Long-Term River Water Quality Trends and Pollution Source Apportionment in Taiwan

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1394 ◽  
Author(s):  
Marsha Putri ◽  
Chao-Hsun Lou ◽  
Mat Syai’in ◽  
Shang-Hsin Ou ◽  
Yu-Chun Wang
Keyword(s):  
Water Pollution ◽  
Water Quality ◽  
Heavy Metal ◽  
Cluster Analysis ◽  
River Water ◽  
Principal Component ◽  
Pollution Level ◽  
Metal Levels ◽  
Metal Monitoring

The application of multivariate statistical techniques including cluster analysis and principal component analysis-multiple linear regression (PCA-MLR) was successfully used to classify the river pollution level in Taiwan and identify possible pollution sources. Water quality and heavy metal monitoring data from the Taiwan Environmental Protection Administration (EPA) was evaluated for 14 major rivers in four regions of Taiwan with the Erren River classified as the most polluted river in the country. Biochemical oxygen demand (6.1 ± 2.38), ammonia (3.48 ± 3.23), and total phosphate (0.65 ± 0.38) mg/L concentration in this river was the highest of the 14 rivers evaluated. In addition, heavy metal levels in the following rivers exceeded the Taiwan EPA standard limit (lead: 0.01, copper: 0.03, and manganese: 0.03) mg/L concentration: lead-in the Dongshan (0.02 ± 0.09), Jhuoshuei (0.03 ± 0.03), and Xinhuwei Rivers (0.02 ± 0.02) mg/L; copper: in the Dahan (0.036 ± 0.097), Laojie (0.06 ± 1.77), and Erren Rivers are (0.05 ± 0.158) mg/L; manganese: in all rivers. A total 72% of the water pollution in the Erren River was estimated to originate from industrial sources, 16% from domestic black water, and 12% from natural sources and runoff from other tributaries. Our research demonstrated that applying PCA-MLR and cluster analysis on long-term monitoring water quality would provide integrated information for river water pollution management and future policy making.

scholarly journals Hematopoietic recovery after transplantation is primarily derived from the stochastic contribution of hematopoietic stem cells

2021 ◽  
Author(s):  
Stefan Radtke ◽  
Mark Enstrom ◽  
Dnyanada P. Pande ◽  
Margaret L. Cui ◽  
Ravishankar Madhu ◽  
...  
Keyword(s):  
Clonal Diversity ◽  
Enhanced Sampling ◽  
Primate Model ◽  
Hematopoietic Stem ◽  
Neutrophil Recovery ◽  
Hematopoietic Recovery ◽  
Hematopoietic Reconstitution ◽  
Initial Recovery ◽  
Two Phases

Reconstitution after hematopoietic stem cell (HSC) transplantation is assumed to occur in two distinct phases: initial recovery mediated by short-term progenitors and long-term repopulation by multipotent HSCs which do not contribute to hematopoietic reconstitution during the first 6-9 months. We have previously reported the transplantation and exclusive engraftment of the HSC-enriched CD34+CD45RA-CD90+ phenotype in a nonhuman primate model. Here, we closely followed the clonal diversity and kinetics in these animals. Enhanced sampling and high density clonal tracking within the first 3 month revealed that multipotent HSCs actively contributed to the early phases of neutrophil recovery and became the dominant source for blood cells as early as 50 days after transplant. Longitudinal changes in clonal diversity supported a stochastic engraftment of HSCs with the majority of HSCs clones vanishing early during neutrophil recovery and a smaller fraction of HSC clones expanding into bigger pools to support long-term hematopoiesis. In contrast to the bi-phasic model, we propose that hematopoietic recovery after myeloablation and transplantation is primarily derived from HSCs in a stochastic manner rather than in two phases by independent cell populations.

Characterization of Atrazine Accumulation by Excised Velvetleaf (Abutilon theophrasti) Roots

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 14-19 ◽  
Author(s):  
Thomas P. Price ◽  
Nelson E. Balke
Keyword(s):  
Initial Phase ◽  
External Solution ◽  
Abutilon Theophrasti ◽  
Linear Phase ◽  
Rapid Absorption ◽  
Two Temperatures ◽  
Two Phases ◽  
Excised Tissue

Long-term absorption of14C-atrazine [2-chloro-4 - (ethylamino) - 6 - (isopropylamino) -s- triazine] by excised velvetleaf (Abutilon theophrastiMedic.) roots was investigated. A rapid, initial phase of absorption was followed by a long-term, linear phase of absorption, which resulted in atrazine accumulation in the tissue to concentrations above the external solution. This accumulation did not result from metabolism of the atrazine. Aging of the excised tissue appeared to be responsible for the accumulation. Dinitrophenol, but not cyanide, inhibited accumulation. Atrazine accumulation decreased as the temperature during absorption was decreased. The Q10the absorption rate was ca. 2.5 between 15 and 25 C. Efflux of atrazine from the tissue occurred in two phases. At 25 C, loss of 80% of the atrazine occurred in 20 min. At 4C, the rate of this efflux was slower and the phase lasted longer. At both 4 and 25 C a second, slower phase of efflux occurred through at least 6 h and resulted in loss of equal amounts of atrazine at the two temperatures. These experiments show that, in addition to rapid absorption of atrazine to a passive equilibrium, excised velvetleaf roots accumulate atrazine by a metabolically dependent process over long periods of time.

scholarly journals Spatial and Temporal Dynamics of Electrical and Photosynthetic Activity and the Content of Phytohormones Induced by Local Stimulation of Pea Plants

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1364
Author(s):  
Maria Ladeynova ◽  
Maxim Mudrilov ◽  
Ekaterina Berezina ◽  
Dmitry Kior ◽  
Marina Grinberg ◽  
...  
Keyword(s):  
Photosynthetic Activity ◽  
Temporal Dynamics ◽  
Response Analysis ◽  
Vascular Bundles ◽  
Variation Potential ◽  
Spatial And Temporal Dynamics ◽  
Two Phases ◽  
Local Stimulation ◽  
Transpiration Suppression

A local leaf burning causes variation potential (VP) propagation, a decrease in photosynthesis activity, and changes in the content of phytohormones in unstimulated leaves in pea plants. The VP-induced photosynthesis response develops in two phases: fast inactivation and long-term inactivation. Along with a decrease in photosynthetic activity, there is a transpiration suppression in unstimulated pea leaves, which corresponds to the long-term phase of photosynthesis response. Phytohormone level analysis showed an increase in the concentration of jasmonic acid (JA) preceding a transpiration suppression and a long-term phase of the photosynthesis response. Analysis of the spatial and temporal dynamics of electrical signals, phytohormone levels, photosynthesis, and transpiration activity showed the most pronounced changes in the more distant leaf from the area of local stimulation. The established features are related to the architecture of the vascular bundles in the pea stem.

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