[Nurses and Organizational Citizenship Behavior: contribution to the Italian validation of the Podsakoff et al. scale].

PubMed

Zaghini, F; Biagioli, Valentina; Prandi, Cesarina; Fida, Roberta; Sili, A

2015-11-22

Workers engaging in Organizational Citizenship Behaviour (OCB) can benefit colleagues, organization and stakeholders. Such behavior is vital to the efficacy of health care organizations as they can have a positive effect on the quality of care and users' satisfaction. Therefore, it is important to assess such behaviour with a valid and reliable instrument. The purpose of this study was to test, from a confirmatory perspective, the dimensionality of the Italian version of the Podsakoff et al. OCB scale in a large sample of nurses, and at the same time to evaluate the differences in nurses' OCB considering socio-demographic and job characteristics. The study included 886 nurses from different health organizations in Italy. The psychometric characteristics of the Italian OCB scale were tested through confirmatory factor analysis (CFA). The differences in nurses' OCB, according to several socio-demographic and job characteristics, were evaluated through a series of correlations and analysis of variance. The CFA of the Italian OCB scale confirmed the hypothesized factor structure, consisting of three dimensions: altruism, civic virtue and conscientiousness. Nurses' gender and professional training were positively correlated with OCB, while the amount of extra work was negatively correlated. In regard to clinical work settings, palliative care nurses engaged in OCB more than nurses working in other areas. The Italian OCB scale is a valid and reliable instrument. Its use can support all individuals involved in the promotion of workers' organizational well-being in implementing processes aimed at fostering nurses' OCB.

Insights into nurses' work: Exploring relationships among work attitudes and work-related behaviors.

PubMed

Perreira, Tyrone; Berta, Whitney; Ginsburg, Liane; Barnsley, Jan; Herbert, Monique

2017-01-25

Work attitudes have been associated with work productivity. In health care, poor work attitudes have been linked to poor performance, decreased patient safety, and quality care. Hence, the importance, ascribed in the literature, of work that clearly identifies the relationships between and among work attitudes and work behaviors linked to performance. The purpose of this study is to better understand the relationships between work attitudes-perceived organizational justice, perceived organizational support (POS), affective commitment-consistently associated with a key type of performance outcome among nurses' organizational citizenship behaviors (OCBs). A survey was developed and administered to frontline nurses working in the province of Ontario, Canada. Data analysis used path analytic techniques. Direct associations were identified between interpersonal justice and POS, procedural justice and POS, and POS and affective commitment to both one's supervisor and one's co-workers. Affective commitment to patients and career was directly associated with OCBs. Affective commitment to one's co-worker was directly associated with OCBs directed toward individuals, as affective commitment to one's organization was with OCBs directed toward the organization. Finally, OCBIs and OCBs were directly associated. Examining the relationships of these constructs in a single model is novel and provides new information regarding their complexity. Findings suggest that prior approaches to studying these relationships may have been undernuanced, and conceptualizations may have led to somewhat inaccurate conclusions regarding their associations. With limited resources, knowledge of nurse work attitudes can inform human resource practices and operational policies involving training programs in employee communication, transparency, interaction, support, and performance evaluation.

A comparison of attitude, personality, and knowledge predictors of service-oriented organizational citizenship behaviors.

PubMed

Bettencourt, L A; Gwinner, K P; Meuter, M L

2001-02-01

Attitude, personality, and customer knowledge antecedents were compared in their predictive ability of 3 service-oriented forms of employee organizational citizenship behaviors (OCBs): loyalty, service delivery, and participation. For the 1st study, 236 customer-contact employees provided data concerning their OCBs and the attitude, personality, and knowledge antecedents. The 2nd investigation relied on data provided by 144 contact employees from a network of university libraries. Using hierarchical regression in both studies, the authors found that each of the 3 types of service-oriented OCBs was best predicted by different subsets of the antecedents. Job attitudes accounted for the most unique variance in loyalty OCBs, personality accounted for the most unique variance in service delivery OCBs, and customer knowledge and personality jointly were the best predictors of participation OCBs.

Chinese school teachers' organizational citizenship behavior (OCB): Predictors and outcomes.

PubMed

Li, Xia

2013-08-01

Teacher's organizational citizenship behavior (OCB) is a multifaceted construct that is critical to school effectiveness and to the education enterprise. Four hundred ninety-three teachers in eight different cities on the Chinese mainland were surveyed using the OCB scale developed by Bo Shiuan Cheng, a Taiwanese scholar. The antecedent and outcome variables of OCB were examined in this study. The results showed that the teachers' attitudinal characteristics of career satisfaction and career commitment, and the dispositional characteristic of locus of control, influenced teachers' OCB. In addition, teachers' OCB influenced their work performance as well as their career and organizational turnover intention. The implications of this study suggest a base of knowledge from which school administrators could enhance their school's organizational function and retain teachers. © 2013 The Institute of Psychology, Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

The impact of workplace spirituality dimensions on organisational citizenship behaviour among nurses with the mediating effect of affective organisational commitment.

PubMed

Kazemipour, Farahnaz; Mohd Amin, Salmiah

2012-12-01

To investigate the relationship between workplace spirituality dimensions and organisational citizenship behaviour (OCB) among nurses through the mediating effect of affective organisational commitment. Nurses' OCB has been considered recently to improve the quality of services to patients and subsequently, their performance. As an influential attitude, affective organisational commitment has been recognized to influence OCB, and ultimately, organisational performance. Meanwhile, workplace spirituality is introduced as a new organisational behaviour concept to increase affective commitment influencing employees' OCB. The cross-sectional study and the respective data were collected with a questionnaire-based survey. The questionnaires were distributed to 305 nurses employed in four public and general Iranian hospitals. To analyse the data, descriptive statistics, Pearson coefficient, simple regression, multiple regression and path analyses were also conducted. The results indicated that workplace spirituality dimensions including meaningful work, a sense of community and an alignment with organisational values have a significant positive relationship with OCB. Moreover, affective organisational commitment mediated the impact of workplace spirituality on OCB. The concept of workplace spirituality through its dimensions predicts nurses' OCB, and affective organisational commitment partially mediated the relationship between workplace spirituality and OCB. Nurses' managers should consider the potentially positive influence of workplace spirituality on OCB and affective commitment among their nurses. With any plan to increase workplace spirituality, the respective managers can improve nurses' performance and would be of considerable importance in the healthcare system. © 2012 Blackwell Publishing Ltd.

Leadership, OCB and Individual Differences: Idiocentrism and Allocentrism as Moderators of the Relationship between Transformational and Transactional Leadership and OCB

PubMed Central

Nahum-Shani, Inbal; Somech, Anit

2015-01-01

We propose and test a framework which suggests that the relationships between leadership styles and Organizational Citizenship Behaviors (OCB) are contingent upon employee cultural-based individual differences. More specifically, we examine whether followers' idiocentrism and allocentrism moderate the relationship between transformational and transactional leadership and followers' OCB. Survey data, collected from a sample of school teachers and their principals from the Israeli kibbutzim and urban sectors, support our hypotheses. We found the relationship between transformational leadership and OCB to be positive to the extent that allocentrism increases, and negative to the extent that idiocentrism increases. We also found the relationship between transactional leadership and OCB to be positive to the extent that idiocentrism increases and negative to the extent that allocentrism increases. Implications of these findings for research and practice are discussed. PMID:26893538

Individual- and organizational-level consequences of organizational citizenship behaviors: A meta-analysis.

PubMed

Podsakoff, Nathan P; Whiting, Steven W; Podsakoff, Philip M; Blume, Brian D

2009-01-01

Although one of the main reasons for the interest in organizational citizenship behaviors (OCBs) is the potential consequences of these behaviors, no study has been reported that summarizes the research regarding the relationships between OCBs and their outcomes. Therefore, the purpose of this study is to provide a meta-analytic examination of the relationships between OCBs and a variety of individual- and organizational-level outcomes. Results, based on 168 independent samples (N = 51,235 individuals), indicated that OCBs are related to a number of individual-level outcomes, including managerial ratings of employee performance, reward allocation decisions, and a variety of withdrawal-related criteria (e.g., employee turnover intentions, actual turnover, and absenteeism). In addition, OCBs were found to be related (k = 38; N = 3,611 units) to a number of organizational-level outcomes (e.g., productivity, efficiency, reduced costs, customer satisfaction, and unit-level turnover). Of interest, somewhat stronger relationships were observed between OCBs and unit-level performance measures in longitudinal studies than in cross-sectional studies, providing some evidence that OCBs are causally related to these criteria. The implications of these findings for both researchers and practitioners are discussed. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

When teachers go the extra mile: foci of organisational identification as determinants of different forms of organisational citizenship behaviour among schoolteachers.

PubMed

Christ, Oliver; van Dick, Rolf; Wagner, Ulrich; Stellmacher, Jost

2003-09-01

Psychological variables should play an important role in determining teachers' involvement in behaviours not directly or formally forced by contracts. Organisational identification as proposed from the Social Identity Approach is examined as a possible determinant of organisational citizenship behaviour (OCB) among schoolteachers. The aim of the present study was to explore the relationships between different foci of organisational identification and different forms of OCB in schools. Data sets of altogether 447 German school teachers who filled in all relevant items in a cross-sectional questionnaire are used for analyses in the present study. Standardised questionnaires measuring organisational identification and OCB were administered. Exploratory and confirmatory factor analyses revealed the proposed foci of identification (i.e., career identification, team identification, and organisational identification), as well as different forms of OCB (i.e., OCB towards the own qualification, towards the team, and towards the organisation). Structural equation modelling supports the main hypothesis that foci of identification relate differentially to forms of OCB. The results emphasise the importance of organisational identification as a determinant of OCB in schools. Practical implications are discussed.

Characteristics Shaping College Student Organizational Citizenship Behavior

ERIC Educational Resources Information Center

LeBlanc, Cary J.

2014-01-01

This study explored the concept of Organizational Citizenship Behavior (OCB) in relation to undergraduate college students. The extensive research on OCB within traditional work environments indicates that while workers who demonstrate OCB usually receive more favorable performance evaluations, those behaviors also help build community and culture…

Authentic leadership and its effect on employees' organizational citizenship behaviours.

PubMed

Edú Valsania, Sergio; Moriano León, Juan A; Molero Alonso, Fernando; Topa Cantisano, Gabriela

2012-11-01

The studies that have verified the positive association of authentic leadership with organizational citizenship behaviours (OCBs), have used global measures of both constructs. Therefore, the goal of this work is to analyze the effect of authentic leadership on employees' OCBs, specifically focusing on the relations of the four components of authentic leadership with the individual and organizational dimensions of the OCBs. The participants of this study were 220 Spanish employees (30.9% men and 69.1% women) who completed a questionnaire that included the variables of interest in this study: Authentic Leadership, OCB and Sociobiographical control variables. The results, obtained with stepwise multiple regression analysis, show that two components of authentic leadership-moral perspective and relational transparency-present significant relationships with OCB. Moreover, authentic leadership is a better predictor of employees' OCB when these behaviors are impersonal and directed towards the organization than when they are directed towards other people. These results have practical implications for human resources management in organizations, especially in selection processes and when training top executives.

Relation Between Emotional Labor and Organizational Citizenship Behavior: An Investigation Among Chinese Teaching Professionals.

PubMed

Cheung, Francis Y L; Lun, Vivian Miu-Chi

2015-01-01

This study examined the association between emotional labor and organizational citizenship behavior (OCB) and the mediation of work engagement in this relationship. A total of 264 teachers in Mainland China were recruited for this study. Bivariate correlation showed that both deep acting and the expression of naturally felt emotion were positively related to the two dimensions of OCB, namely, OCB toward the individual (OCBI) and OCB toward the organization (OCBO), whereas surface acting was not related to the OCB dimensions. Work engagement was also positively associated with both OCB dimensions. Regression results showed that work engagement partially mediated the relation between deep acting and OCBO, and that between the expression of naturally felt emotion and OCBI. Work engagement also fully mediated the association between deep acting and OCBI, and that between the expression of naturally felt emotion and OCBO. In light of these findings, strategies that encourage employees to display emotions consistent with their inner experience were discussed.

A meta-analysis of the relationship between organizational citizenship behavior and counterproductive work behavior.

PubMed

Dalal, Reeshad S

2005-11-01

Job performance is increasingly being seen to encompass constructs such as organizational citizenship behavior (OCB) and counterproductive work behavior (CWB). To clarify the OCB-CWB relationship, a meta-analysis was conducted. Results indicate a modest negative relationship (p = -0.32). The relationship strength did not increase appreciably when the target of the behavior (the organization vs. other employees) was the same. Moreover, OCB and CWB exhibited somewhat distinct patterns of relationships with antecedents. The OCB-CWB relationship was moderated by the source of the ratings, the presence of antithetical items, and the type of response options. An employee-centric perspective is proposed whereby both OCB and CWB are perceived as adaptive behavior. Implications for organizations are discussed. ((c) 2005 APA, all rights reserved).

Measurement artifacts in the assessment of counterproductive work behavior and organizational citizenship behavior: do we know what we think we know?

PubMed

Spector, Paul E; Bauer, Jeremy A; Fox, Suzy

2010-07-01

An experiment investigated whether measurement features affected observed relationships between counterproductive work behavior (CWB) and organizational citizenship behavior (OCB) and their relationships with other variables. As expected, correlations between CWB and OCB were significantly higher with ratings of agreement rather than frequency of behavior, when OCB scale content overlapped with CWB than when it did not, and with supervisor rather than self-ratings. Relationships with job satisfaction and job stressors were inconsistent across conditions. We concluded that CWB and OCB are likely unrelated and not necessarily oppositely related to other variables. Researchers should avoid overlapping content in CWB and OCB scales and should use frequency formats to assess how often individuals engage in each form of behavior.

Going the extra mile and feeling energized: An enrichment perspective of organizational citizenship behaviors.

PubMed

Lam, Chak Fu; Wan, Wylie H; Roussin, Christopher J

2016-03-01

Scholars have voiced concerns about the potential dark side of Organizational Citizenship Behavior (OCB), arguing that OCB consumes energy, which contributes to a depletion of personal resources and results in poorer well-being. Drawing from research on the meaningfulness of work, we propose a pattern opposite to depletion: that OCB enhances energy, which contributes to an enrichment of personal resources and results in better well-being. This idea was tested over the course of a workweek with 224 day-level ratings from 67 employees and 30 managers working in a service management firm. Three-level hierarchical linear modeling indicated that supervisor-rated daily OCB was positively associated with employees' vigor at the end of the workday, and multilevel structural equation modeling analyses showed that this relationship was mediated by meaningfulness of work. Moreover, we found that the association between OCB and work meaningfulness was stronger for employees with greater role ambiguity. Exploratory analyses revealed that daily in-role performance and daily OCB interacted to predict meaningfulness of work, such that the association between daily OCB and meaningfulness of work was more prominent among those who exhibited high levels of daily in-role performance. We discuss implications of these findings, limitations, and directions for future research. (c) 2016 APA, all rights reserved).

Oligoclonal bands in multiple sclerosis reactive against two herpesviruses and association with magnetic resonance imaging findings

PubMed Central

Virtanen, JO; Wohler, J; Fenton, K; Reich, DS; Jacobson, S

2016-01-01

Background Two human herpesviruses, human herpesvirus 6 (HHV-6), and Epstein-Barr virus (EBV), have been repeatedly linked to multiple sclerosis (MS). Objective The aim of this study was to investigate HHV-6 and EBV reactive oligoclonal bands (OCBs), and viral DNA in the intrathecal compartment in MS. Methods The reactivity of OCBs in cerebrospinal fluid (CSF) for EBV and HHV-6 antigens and stability of virus reactive OCBs over time were studied in a well-characterized MS patient cohort. Associations between virus reactive OCBs and viral DNA in CSF (and any clinical and/or radiological findings) were investigated. Results Of patients with MS, 38% had OCBs reactive to either one of the viruses studied, compared to none in the patients with other inflammatory neurological diseases (p=0.005). The banding pattern of virus reactive OCBs remained the same over time. Furthermore, MS patients with viral DNA in CSF had more contrast enhancing lesions (CELs). Conclusion The stable presence of herpesvirus reactive OCBs in CSF further strengthens the association of MS with these viruses. The finding that herpesviruses might be linked to the appearance of active lesions warrants investigation of new therapeutic strategies to treat these viruses in MS. PMID:23722324

The significance of HLA DRB1*1501 and oligoclonal bands in multiple sclerosis: clinical features and disability.

PubMed

Balnytė, Renata; Rastenytė, Daiva; Ulozienė, Ingrida; Mickevičienė, Dalia; Skordenienė, Erika; Vitkauskienė, Astra

2011-01-01

The aim of the present study was to determine the value of immunogenetic risk factors and to estimate their relationship with the clinical features and disability status of patients with multiple sclerosis in a Lithuanian population. This was a prospective study of 80 patients with multiple sclerosis. The diagnosis of multiple sclerosis was based on the revised McDonald criteria. Oligoclonal bands (OCBs) of immunoglobulin G (IgG) were tested using isoelectric focusing and IgG specific immunofixation. HLA DRB1 alleles were genotyped using polymerase chain reaction. Of all patients, 55% were positive for OCBs and 56% for HLA DRB1*1501. OCB-positive patients with multiple sclerosis had higher EDSS scores than their OCB-negative counterparts at onset of the disease (3.93±1.21 and 3.36±0.96 points, respectively; P=0.02) and during the last visit (4.31±2.06 and 3.09±1.98 points, respectively; P=0.009). The mean relapse rate was higher in the OCB-positive group compared with OCB-negative group (1.45±0.69 and 0.58±0.64, respectively; P=0.001). OCB-positive patients had higher IgG index compared with OCB-negative patients (P=0.0001). No relationship was found between HLA DRB1*1501 antigen status and the clinical features or EDSS score, and presence or absence of OCB in the present subset of patients with multiple sclerosis. The presence of oligoclonal bands in the cerebrospinal fluid of the patients with multiple sclerosis was associated with the greater number of exacerbations, higher degree of disability, and higher IgG index. There were no significant associations between the presence of HLA DRB1*1501 allele and the clinical symptoms, course of disease, or disability score.

Organizational citizenship behavior and social loafing: the role of personality, motives, and contextual factors.

PubMed

Tan, Hwee Hoon; Tan, Min Li

2008-01-01

The present study integrates the literature on social loafing and organizational citizenship behavior (OCB). The authors examined the roles of personality, motives, and contextual factors in influencing the work behaviors of OCB and social loafing. In a sample of 341 individuals working in project groups, with data collected over 3 time periods, the authors found that conscientiousness was negatively related to social loafing. They also found the known positive relation of OCB with conscientiousness. Felt responsibility was negatively related to social loafing. The authors found no significant relations between social loafing and OCB motives.

Relationship between workplace spirituality and organizational citizenship behavior among nurses through mediation of affective organizational commitment.

PubMed

Kazemipour, Farahnaz; Mohamad Amin, Salmiah; Pourseidi, Bahram

2012-09-01

This study aims to investigate the relationships between workplace spirituality, organizational citizenship behavior (OCB), and affective organizational commitment among nurses, and whether affective commitment mediates the relationship between workplace spirituality and OCB. In the present correlational study, a cross-sectional design was employed, and data were collected using a questionnaire-based survey. Based on the random sampling, 305 nurses were chosen and questionnaires were distributed among respondents in four public and general hospitals located in Kerman, Iran. To analyze the data descriptive statistics, Pearson coefficient, simple and multiple regression, and path analyses were also conducted. Workplace spirituality has a positive influence on nurses' OCB and affective commitment. Workplace spirituality explained 16% of the variation in OCB, while it explained 35% of the variation in affective commitment among nurses. Moreover, affective organizational commitment mediated the impact of workplace spirituality on OCB. Workplace spirituality predicts nurses' OCB and affective organizational commitment. It emphasizes benefits from the new perspective of workplace spirituality, particularly among nurses who need to be motivated in their work. This study illustrates that there are potential benefits owing to the positive influence of workplace spirituality on OCB and affective commitment among nurses. Managers of nursing services should consider workplace spirituality and its positive influence on nurses' outcomes in order to improve their performance and, subsequently, the healthcare system. © 2012 Sigma Theta Tau International.

Organizational Citizenship Behaviors in Higher Education: Examining the Relationships between Behaviors and Performance Outcomes for Individuals and Institutions

ERIC Educational Resources Information Center

Rose, Kevin

2012-01-01

Organizational citizenship behaviors (OCBs) have been described as employee behaviors that are not required by job descriptions, are not formally rewarded, and contribute positively to the organization. Previous research has shown that OCBs are related to both individual and organizational performance. Given the importance of OCBs to individual…

[Doing voluntary extra work? Organizational citizenship behavior in the hospital--a comparison between physicians and nurses].

PubMed

Boerner, S; Dütschke, E; Schwämmle, A

2005-11-01

The study compares physicians and the nursing staff of a hospital in terms of their extra-role behavior. Matters of interest include the extent of Organizational Citizenship Behavior (OCB) shown on the one hand and on the other hand which conditions stimulate the OCB of both physicians and nurses, respectively. The comparison was conducted by applying a questionnaire on n = 70 physicians and n = 112 nurses in a nursing department of a municipal hospital. The results can be summarized as follows: (1) The extra-role behavior in terms of sportsmanship, individual initiative, and conscientiousness show equally high values with respect to physicians as well as nurses. In contrast, nurses rate their own helping behavior towards colleagues higher than the physicians do. Therefore, the extent of OCB does not seem to be job-specific in the narrower sense. (2) Differences between physicians and nurses exist indeed with respect to the conditions for the occurrence of OCB: Although the extent of OCB shown by physicians and nurses is independent from age, department tenure, and organizational tenure, job experience does play a role for the degree of conscientiousness (physicians) and individual initiative (nurses). Furthermore, gender affects the sub dimension sportsmanship (nurses). (3) While job characteristics (job control and stress) play a certain role for the degree of nurses' OCB, the physicians' extra-role behavior is independent from job control and strain. Vice versa, the analyzed person-related characteristics job insecurity and strain play a role for the extra-role behavior of physicians, while the behavior of nurses remains unaffected hereof. In other words: Nurses show the same OCB at high and low levels of strain and job insecurity, while physicians lower their OCB when strain and job insecurity rise. (4) For both physicians and nurses, job satisfaction is the most important predictor for extra-role behavior. When trying to enhance the extent of OCB within a hospital, it is -- according to our results -- primarily essential to increase the job satisfaction of physicians as well as nurses. Within the nursing department, it is additionally recommended to enhance the employees' scope of action, if possible. However, for the enhancement of OCB it must be kept in mind -- according to our results -- that with rising OCB the stress (e. g. time pressure and interruptions) rise at the same time. The latter might result in higher strain for employees. In the group of physicians, on the other hand, a person-related approach seems promising: it is essential to reduce the physicians' subjectively felt strains as well as the job insecurity.

Looking good or doing good? Motivations for organisational citizenship behaviour in Turkish versus South Korean collectivists.

PubMed

Alabak, Merve; Peker, Müjde; Booth, Robert W

2016-06-01

The purpose of this article is to explore potential motivations to perform organisational citizenship behaviour (OCB) in collectivistic Turkish and South Korean societies. Although collectivism has been proposed as a predictor of OCB, previous research has not fully explored the possibility that collectivistic individuals' OCB may result from their self-oriented motives (i.e. social desirability concerns) or their future-oriented motives (i.e. long-term orientation concerns). We predicted that OCB stems from social desirability concerns among Turkish collectivists, meaning it is used for maintaining a positive image within the organisation. However, for South Korean collectivists, we predicted that OCB stems from their long-term orientation concerns, meaning it is used to make the organisation better. The results were in line with our predictions, and the findings are discussed in terms of their implications for firms in collectivistic societies. © 2015 International Union of Psychological Science.

The biogeochemistry of metal cycling

NASA Technical Reports Server (NTRS)

Nealson, Kenneth H. (Editor); Nealson, Molly (Editor); Dutcher, F. Ronald (Editor)

1990-01-01

The results of the Planetary Biology and Microbial Ecology's summer 1987 program are summarized. The purpose of the interdisciplinary PBME program is to integrate, via lectures and laboratory work, the contributions of university and NASA scientists and student interns. The 1987 program examined various aspects of the biogeochemistry of metal cycling, and included such areas as limnology, metal chemistry, metal geochemistry, microbial ecology, and interactions with metals. A particular area of focus was the use of remote sensing in the study of biogeochemistry. Abstracts and bibliographies of the lectures and reports of the laboratory projects are presented.

Intrathecal oligoclonal IgG synthesis in multiple sclerosis.

PubMed

Petzold, Axel

2013-09-15

The diagnosis of multiple sclerosis is based on dissemination in time and space. Before 2010 lack of evidence for dissemination in space could be substituted by a paraclinical test, cerebrospinal fluid (CSF) oligoclonal bands (OCBs). The present meta-analysis (13,467 patients) shows that the diagnostic specificity of OCB drops from 94% to 61% if inflammatory etiologies are considered. Importantly, this was not caused by poor laboratory practice. This review on CSF OCB further illustrates the conceptional problem of substituting dissemination in space with a biomarker. The potential prognostic value of intrathecal OCB will need to be tested prospectively. © 2013 Elsevier B.V. All rights reserved.

Production-Based Education Model for Improving Technical and Vocational Teachers Ability

NASA Astrophysics Data System (ADS)

Saputro, H.; Suharno; Widiastuti, I.; Harjanto, B.

2018-02-01

The vocational high schools (SMK) in Surakarta have applied the Production-Based Education (PBE) in order to improve the student skills. On the other hand, the implementation of PBE model is needed the professional teachers who have the skill qualifications in the production and learning. This study focuses on strengthening of teacher’s behavior related to the implementation of PBE model at vocational high schools in Surakarta, especially on teacher’s Organizational Citizenship Behavior. This research conducted based on the observational research method that employed 134 teachers of SMK Warga Surakarta as respondents. The data of teachers OCB were analyzed by using the descriptive analysis. The result showed that the PBE model had strengthened the teachers OCB at SMK Warga Surakarta. The measurements of OCB level of SMK teachers had shown the high (H) level and some of the teachers’ OCB characters show very high (VH) levels such as altruism and civic virtue. OCB or “good soldier syndrome” could be manifested by the teacher’s interaction at school such as loyalty, volunteering and helping others. Therefore, teacher’s OCB behavior became important due to the organizational effectiveness at vocational high school (SMK).

[The mediating role of organizational citizenship behavior between organizational justice and organizational effectiveness in nursing organizations].

PubMed

Park, Wall Yun; Yoon, Sook Hee

2009-04-01

This study was a secondary analysis to verify the mediating role of organizational citizenship behavior (OCB) between organizational justice (OJ) and organizational effectiveness (OE) in nursing organizations. The RN-BSNs and their colleagues in Seoul and Busan were subjects. The data was collected for 20 days between September 13 and October 2, 2004. Two hundred eighty three data sets were used for the final analysis. The fitness of models were tested using AMOS 5. The fitness of hypothetical model was moderate. Procedural Justice (PJ), Interaction Justice (IJ) and Distributive Justice (DJ) had direct effects on Job Satisfaction (JS), Organizational Commitment (OC) and Turnover Intention (TI) in OE, and indirect effects on JS, OC and TI mediated by OCB. The modified model improved with ideal fitness showed the causal relations among OE. In modified model, PJ, IJ and DJ had direct positive effects on OCB and JS and OC in OE, and indirect effects on JS and OC mediated by OCB. JS and OC in OE had a direct negative effect on TI. OCB mediated the relationship between OJ and OE, so the nursing managers should enhance OCB of the nurses in order to improve OE.

Organizational Citizenship Behavior (OCB) Display Levels of the Teachers at Secondary Schools According to the Perceptions of the School Administrators

ERIC Educational Resources Information Center

Polat, Soner

2009-01-01

The main aim of this study is to determine in what level the teachers at secondary schools display organizational citizenship behavior (OCB) according to the perceptions of the school administrators. The data of this study, which is descriptive, were collected via the "the scale of OCB" which was developed by Podsakoff, MacKenzie,…

The development of measures of organizational citizenship behaviour and changes in job behaviours related to quality management in health care.

PubMed

Irvine, D

1995-08-01

A study was conducted at two tertiary care hospitals in Canada for the purpose of developing instruments to measure organizational citizenship behaviours (OCB) and changes in job behaviours that occur as a result of participation on hospital quality improvement (CQI) teams. Semi structured interviews were conducted among 52 hospital employees in order to elicit critical incidents of OCB and changes in job behaviours related to CQI. The results of the staff interviews were used to develop a measure of OCB in the hospital setting, and a measure of changes in job behaviours related to CQI. 39 employees, who were drawn from the major departments within the two hospitals on the basis of their membership on CQI teams, participated in a test of the psychometric properties of the two research instruments. Exploratory factor analysis, employing an orthogonal rotation, yielded two factors that accounted for 30% of the variation among the OCB items. The Cronbach alpha for items loading highly on the first factor was .88. The factor was labelled 'OCB directed towards individuals within the organization'. This factor was dominated by items reflecting the kinds of extra-role job behaviours employees engage in to assist patients, family members, visitors, and other employees within the organization. The Cronbach alpha for items loading highly on the second factor was 0.71. The second factor was labelled 'organizationally directed OCB', and consisted of behaviours that reflected an impersonal form of OCB in the hospital setting. Factor analysis, employing an orthogonal rotation, yielded four factors that accounted for 48% of the variation among the items measuring changes in job behaviours related to CQI. The four factors were labelled 'problem-solving', Cronbach alpha 0.82; 'customer awareness', Cronbach alpha 0.79; 'use of CQI knowledge', Cronbach alpha 0.77; and 'organizational interests', Cronbach alpha 0.79. The two OCB factors were moderately correlated, there were no significant correlations among any of the factors measuring changes in job behaviours related to CQI, and the problem-solving job behaviours factor was moderately correlated with the two OCB factors. Directions for future research are discussed.

The nature and dimensionality of organizational citizenship behavior: a critical review and meta-analysis.

PubMed

Lepine, Jeffrey A; Erez, Amir; Johnson, Diane E

2002-02-01

This article reviews the literature on organizational citizenship behavior (OCB) and its dimensions as proposed by D. W. Organ (1988) and other scholars. Although it is assumed that the behavioral dimensions of OCB are distinct from one another, past research has not assessed this assumption beyond factor analysis. Using meta-analysis, the authors demonstrate that there are strong relationships among most of the dimensions and that the dimensions have equivalent relationships with the predictors (job satisfaction, organizational commitment, fairness, trait conscientiousness, and leader support) most often considered by OCB scholars. Implications of these results are discussed with respect to how the OCB construct should be conceptualized and measured in the future.

The mediating role of job involvement in the relationship between job characteristics and organizational citizenship behavior.

PubMed

Chen, Chien-Cheng; Chiu, Su-Fen

2009-08-01

Past researchers have found that motivating job characteristics can increase employee display of organizational citizenship behavior (OCB). In this study, the authors extended previous research by investigating the mediating process of job involvement in the relationship between job characteristics and OCB. The authors collected data from 323 employees and their supervisors from 7 companies in Taiwan. Results show that, through the mediating process of job involvement, the 3 job characteristics (i.e., task identity, task significance, and autonomy) positively influenced the display of an employee's OCB, whereas skill variety had a negative effect on OCB. The authors discuss implications of their findings, contributions, limitations, and future research directions.

Teacher organizational citizenship behaviours and job efficacy: Implications for student quality of school life.

PubMed

Jimmieson, Nerina L; Hannam, Rachel L; Yeo, Gillian B

2010-08-01

The present study investigated the impact of teachers' organizational citizenship behaviours (OCBs) on student quality of school life (SQSL) via the indirect effect of job efficacy. A measure of teacher OCBs was developed, tapping one dimension of individual-focused OCB (OCBI - student-directed behaviour) and two dimensions of organization-focused OCB (OCBO - civic virtue and professional development). In line with previous research suggesting that OCBs may enhance job efficacy, as well as studies demonstrating the positive effects of teacher efficacy on student outcomes, we expected an indirect relationship between teachers OCBs and SQSL via teachers' job efficacy. Hypotheses were tested in a multi-level design in which 170 teachers and their students (N=3,057) completed questionnaires. A significant proportion of variance in SQSL was attributable to classroom factors. Analyses revealed that the civic virtue and professional development behaviours of teachers were positively related to their job efficacy. The job efficacy of teachers also had a positive impact on all five indicators of SQSL. In regards to professional development, job efficacy acted as an indirect variable in the prediction of four student outcomes (i.e., general satisfaction, student-teacher relations, achievement, and opportunity) and fully mediated the direct negative effect on psychological distress.

A study of relationship between the organizational justice and organizational citizenship behavior among nurses in selected hospitals of Isfahan University of Medical Sciences.

PubMed

Yaghoubi, Maryam; Afshar, Mina; Javadi, Marzieh

2012-09-01

Numerous researches have been carried out to indicate that organizational justice (OJ) is a variable that anticipates many other variables in organizations, especially in hospitals. Organizational behavior (OCB) is one of the most important variables. We aimed to study the relationship between OJ and OCB of nurses in selected hospitals in Isfahan. This was a descriptive correlational study. The research was conducted among nurses of selected hospitals in Isfahan. Data were gathered using two questionnaires of OJ, and OCB. The t-test, chi-square, and Pearson correlation test were used to analyze the data through SPSS version 13. In general, the mean score (SD) of OJ among nurses was 41.2 (16.2) and the mean score of OCB was 57.7 (18). Finally, there was no significant relationship between OJ, civil virtue, and sportsmanship. There was a significant relationship between OJ, OCB, courtesy, and conscientiousness. As the scores of OCB and OJ among nurses were average in selected hospitals, the managers of the hospitals should improve the perception of justice among nurses. Today, organizations need efficient and expert workers to achieve their goals, and to grow and improve in all aspects. In fact, the efficiency and effectiveness of organizations depend on the staffs, especially in hospitals.

Critical behavior in the vicinity of nematic to smectic A (N-SmA) phase transition of two polar-polar binary liquid crystalline systems

NASA Astrophysics Data System (ADS)

Barman, Barnali; Sarkar, Sudipta Kumar; Das, Malay Kumar

2018-01-01

Phase diagram, critical behavior and order of the nematic (N)-smectic A (SmA) phase transition of two polar-polar binary systems (i) 4-n-heptyloxy-4‧-cyanobiphenyl (7OCB) and 4-n-octyloxy-4‧-cyanobiphenyl (8OCB); (ii) 4-n-octyloxy-4‧-cyanobiphenyl (8OCB) and 4-n-nonyloxy-4‧-cyanobiphenyl (9OCB) by means of a high-resolution temperature scanning measurement of birefringence have been reported in this work. A simple power law analysis has been adopted to extract the specific heat critical exponent (α‧) at N-SmA transition from birefringence data. The α‧ for N-SmA transition indicates a uniform crossover behavior and has appeared to be non-universal in nature. With increasing concentration of the higher homologues for both the binary systems, the N-SmA transition reveals a strong tendency to be driven towards the tricritical nature. The 3D-XY limit (i.e. α‧ = -0.007) for N-SmA transition reaches at the concentration x8OCB = 0.28 corresponding to the McMillan ratio 0.914, whereas the tricritical point has been found to appear near x9OCB = 1.0 corresponding to McMillan ratio 0.992.

SOC Strategies and Organizational Citizenship Behaviors toward the Benefits of Co-workers: A Multi-Source Study.

PubMed

Müller, Andreas; Weigl, Matthias

2017-01-01

Background: Individuals' behavioral strategies like selection, optimization, and compensation (SOC) contribute to efficient use of available resources. In the work context, previous studies revealed positive associations between employees' SOC use and favorable individual outcomes, like engagement and job performance. However, the social implications of self-directed behaviors like SOC that are favorable for the employee but may imply consequences for coworkers have not been investigated yet in an interpersonal work context. Objective: This study aimed to assess associations between employees' use of SOC behaviors at work and their organizational citizenship behaviors (OCB) toward the benefits of co-workers rated by their peers at work. We further sought to identify age-specific associations between SOC use and OCB. Design and Method: A cross-sectional design combining multi-source data was applied in primary school teachers (age range: 23-58 years) who frequently teach in dyads. N = 114 dyads were finally included. Teachers reported on their SOC strategies at work. Their peer colleagues evaluated teachers' OCB. Control variables were gender, workload, working hours, and perceived proximity of relationship between the dyads. Results: We observed a positive effect of loss-based selection behaviors on peer-rated OCB. Moreover, there was a significant two-way interaction effect between the use of compensation strategies and age on OCB, such that there was a positive association for older employees and a negative association for younger employees. There were no significant main and age-related interaction effects of elective selection, optimization, and of overall SOC strategies on OCB. Conclusion: Our study suggests that high use of loss-based selection and high use of compensation strategies in older employees is positively related with OCB as perceived by their colleagues. However, high use of compensation strategies in younger employees is perceived negatively related with OCB. Our findings contribute to a better understanding of the age-differentiated interpersonal effects of successful aging strategies in terms of SOC in organizations.

SOC Strategies and Organizational Citizenship Behaviors toward the Benefits of Co-workers: A Multi-Source Study

PubMed Central

Müller, Andreas; Weigl, Matthias

2017-01-01

Background: Individuals’ behavioral strategies like selection, optimization, and compensation (SOC) contribute to efficient use of available resources. In the work context, previous studies revealed positive associations between employees’ SOC use and favorable individual outcomes, like engagement and job performance. However, the social implications of self-directed behaviors like SOC that are favorable for the employee but may imply consequences for coworkers have not been investigated yet in an interpersonal work context. Objective: This study aimed to assess associations between employees’ use of SOC behaviors at work and their organizational citizenship behaviors (OCB) toward the benefits of co-workers rated by their peers at work. We further sought to identify age-specific associations between SOC use and OCB. Design and Method: A cross-sectional design combining multi-source data was applied in primary school teachers (age range: 23–58 years) who frequently teach in dyads. N = 114 dyads were finally included. Teachers reported on their SOC strategies at work. Their peer colleagues evaluated teachers’ OCB. Control variables were gender, workload, working hours, and perceived proximity of relationship between the dyads. Results: We observed a positive effect of loss-based selection behaviors on peer-rated OCB. Moreover, there was a significant two-way interaction effect between the use of compensation strategies and age on OCB, such that there was a positive association for older employees and a negative association for younger employees. There were no significant main and age-related interaction effects of elective selection, optimization, and of overall SOC strategies on OCB. Conclusion: Our study suggests that high use of loss-based selection and high use of compensation strategies in older employees is positively related with OCB as perceived by their colleagues. However, high use of compensation strategies in younger employees is perceived negatively related with OCB. Our findings contribute to a better understanding of the age-differentiated interpersonal effects of successful aging strategies in terms of SOC in organizations. PMID:29085315

Effects of service provider attitudes and employment status on citizenship behaviors and customers' attitudes and loyalty behavior.

PubMed

Payne, Stephanie C; Webber, Sheila Simsarian

2006-03-01

The relationship among job satisfaction, affective commitment, service-oriented organizational citizenship behaviors (OCBs), customer satisfaction, and customer loyalty were examined for a sample of 249 hairstylists and 1 of their corresponding customers. Employee satisfaction was positively related to service-oriented OCBs, customer satisfaction, and customer loyalty, whereas affective commitment was not related to these outcomes. The extent to which the predictor variables interacted with one another and the role of employment status on these relationships was also explored. High levels of job satisfaction or affective commitment resulted in more service-oriented OCBs for employees and self-employed workers, whereas high levels of both resulted in more service-oriented OCBs for owners.

Psychological contract and organizational citizenship behavior in China: investigating generalizability and instrumentality.

PubMed

Hui, Chun; Lee, Cynthia; Rousseau, Denise M

2004-04-01

This study examined the generalizability of psychological contract forms observed in the West (D. M. Rousseau, 2000) to China. Using 2 independent samples, results confirmed the generalizability of 3 psychological contract forms: transactional, relational, and balanced. This study also examined the nature of relationships of psychological contracts with organizational citizenship behavior (OCB). In particular, this study explored the role of instrumentality as a mediating psychological process. The authors found evidence that instrumentality mediates the relationship of relational and balanced forms with OCB; however, the transactional contract form is directly related to OCB. The authors discuss the implications of these results for the meaning of psychological contracts and OCB in China and raise issues for future research.

Importance of cerebrospinal fluid analysis in the era of McDonald 2010 criteria: a German-Austrian retrospective multicenter study in patients with a clinically isolated syndrome.

PubMed

Huss, André M; Halbgebauer, Steffen; Öckl, Patrick; Trebst, Corinna; Spreer, Annette; Borisow, Nadja; Harrer, Andrea; Brecht, Isabel; Balint, Bettina; Stich, Oliver; Schlegel, Sabine; Retzlaff, Nele; Winkelmann, Alexander; Roesler, Romy; Lauda, Florian; Yildiz, Özlem; Voß, Elke; Muche, Rainer; Rauer, Sebastian; Bergh, Florian Then; Otto, Markus; Paul, Friedemann; Wildemann, Brigitte; Kraus, Jörg; Ruprecht, Klemens; Stangel, Martin; Buttmann, Mathias; Zettl, Uwe K; Tumani, Hayrettin

2016-12-01

The majority of patients presenting with a first clinical symptom suggestive of multiple sclerosis (MS) do not fulfill the MRI criteria for dissemination in space and time according to the 2010 revision of the McDonald diagnostic criteria for MS and are thus classified as clinically isolated syndrome (CIS). To re-evaluate the utility of cerebrospinal fluid (CSF) analysis in the context of the revised McDonald criteria from 2010, we conducted a retrospective multicenter study aimed at determining the prevalence and predictive value of oligoclonal IgG bands (OCBs) in patients with CIS. Patients were recruited from ten specialized MS centers in Germany and Austria. We collected data from 406 patients; at disease onset, 44/406 (11 %) fulfilled the McDonald 2010 criteria for MS. Intrathecal IgG OCBs were detected in 310/362 (86 %) of CIS patients. Those patients were twice as likely to convert to MS according to McDonald 2010 criteria as OCB-negative individuals (hazard ratio = 2.1, p = 0.0014) and in a shorter time period of 25 months (95 % CI 21-34) compared to 47 months in OCB-negative individuals (95 % CI 36-85). In patients without brain lesions at first attack and presence of intrathecal OCBs (30/44), conversion rate to MS was 60 % (18/30), whereas it was only 21 % (3/14) in those without OCBs. Our data confirm that in patients with CIS the risk of conversion to MS substantially increases if OCBs are present at onset. CSF analysis definitely helps to evaluate the prognosis in patients who do not have MS according to the revised McDonald criteria.

Perceptions of organizational culture and organizational citizenship by faculty in U.S. colleges and schools of pharmacy.

PubMed

Desselle, Shane P; Raja, Leela; Andrews, Brienna; Lui, Julia

2018-04-01

(1) Describe perceptions of organizational culture and prevalence of organizational citizenship behaviors (OCBs) among faculty at United States (U.S.) colleges/schools of pharmacy; (2) determine which aspects of those phenomena are strongest and which are most problematic; (3) evaluate the psychometric properties of measures for organizational culture and OCBs in academic pharmacy; and (4) identify any relationships between organizational culture and organizational citizenship among academic pharmacy faculty. A random sample of 600 U.S. academic pharmacists acquired from the American Association of Colleges of Pharmacy were distributed an email survey through the use of Qualtrics technology. The procedures closely resembled the Total Design Method advocated to maximize survey response, including use of a pre-notification letter, reminders, and a nominal financial inducement. In addition to demographic questions, the survey employed multiple-item measures of organizational culture and OCBs described previously in the literature and derived from Delphi consensus-building procedures. The analysis plan incorporated use of factor and item analyses to evaluate psychometric properties of the measure and elicit the inherent domains comprising these phenomena, along with descriptive statistics to describe facets of organizational culture and OCBs that were most prevalent. A total of 177 responses were delivered. Factor analysis of organizational culture revealed a five-factor solution emphasizing achievement orientation, professionalism, stability, supportiveness, and reflectiveness. OCB domains were along the possibility of faculty being virtuous, disrespectful, sportsmanlike, and benevolent/malevolent. Even while multi-faceted and avoiding a simple typological descriptor, academic pharmacy cultures were reportedly healthy. Sportsmanship, while still somewhat commonly observed, was seen less frequently than other behaviors. The measures demonstrated logical, cogent factor structures and excellent internal consistency reliability. Psychometrically well-performing measures were used to assess the multi-faceted organizational culture of academic pharmacy programs and the organizational citizenship behaviors of its constituent faculty. The results can be used to measure these phenomena at individual organizations for benchmarking and to inform future inquiries that can assist with development of strategies that impact academic worklife and outcomes. Copyright © 2017 Elsevier Inc. All rights reserved.

Intrathecal immunoglobulin synthesis in patients with symptomatic epilepsy and epilepsy of unknown etiology ('cryptogenic').

PubMed

Fauser, S; Soellner, C; Bien, C G; Tumani, H

2017-09-01

To compare the frequency of intrathecal immunoglobulin (Ig) synthesis in patients with symptomatic epilepsy and epilepsy of unknown etiology ('cryptogenic'). Patients with epileptic (n = 301) and non-epileptic (n = 10) seizures were retrospectively screened for autochthonous intrathecal Ig synthesis and oligoclonal bands (OCBs) in the cerebrospinal fluid. Intrathecal IgG/OCBs were detected in 8% of patients with epilepsies of unknown etiology, 5% of patients with first seizures of unknown cause and 0-4% of patients with epilepsy due to brain tumors, cerebrovascular disease or other etiologies. Intrathecal IgG/OCBs were not seen in patients with psychogenic seizures. Identical OCBs in serum and cerebrospinal fluid were more common in all patient groups (10-40% depending on underlying etiology). Intrathecal IgG synthesis/OCBs were observed slightly more frequently in patients with 'cryptogenic' epilepsy and with first seizures of unknown etiology than in other patient groups. However, this remained an infrequent finding and thus we could not confirm humoral immunity as a leading disease mechanism in patients with epilepsy in general or with unknown etiology in particular. © 2017 EAN.

Organizational citizenship behavior in schools: validation of a questionnaire.

PubMed

Neves, Paula C; Paixão, Rui; Alarcão, Madalena; Gomes, A Duarte

2014-01-01

The present study examines the psychometric properties (including factorial validity) of an organizational citizenship behavior (OCB) scale in a school context. A total of 321 middle and high school teachers from 59 schools in urban and rural areas of central Portugal completed the OCB scale at their schools. The confirmatory factor analysis validated a hierarchical model with four latent factors on the first level (altruism, conscientiousness, civic participation and courtesy) and a second order factor (OCB). The revised model fit with the data, χ 2 /gl = 1.97; CFI = .962; GFI = .952, RMSEA = .05. The proposed scale (comportamentos de cidadania organizacional em escolas- Revista CCOE-R)- is a valid instrument to assess teacher's perceptions of OCB in their schools, allowing investigation at the organizational level of analysis.

Cerebrospinal fluid anti-Epstein-Barr virus specific oligoclonal IgM and IgG bands in patients with clinically isolated and Guillain-Barré syndrome.

PubMed

Ferraro, Diana; Galli, Veronica; Simone, Anna Maria; Bedin, Roberta; Vitetta, Francesca; Merelli, Elisa; Nichelli, Paolo Frigio; Sola, Patrizia

2017-04-01

Epstein-Barr virus (EBV) has been implicated in multiple sclerosis (MS) pathogenesis. We aimed to assess the frequency of EBV-specific IgG and IgM oligoclonal bands (OCB) in cerebrospinal fluid (CSF) of 50 patients with clinically isolated syndrome (CIS) and in 27 controls with Guillain-Barré syndrome (GBS). Furthermore, we assessed correlations between the presence of OCB and CIS patients' CSF, MRI, and clinical variables. There was no difference in the proportion of CIS and GB patients with positivity for anti-EBV-specific IgG/IgM OCB. There were no correlations between OCB and analyzed variables, nor were they predictive of a higher disability at 3 years.

Transformational Leadership and Organizational Citizenship Behavior: A Meta-Analytic Test of Underlying Mechanisms.

PubMed

Nohe, Christoph; Hertel, Guido

2017-01-01

Based on social exchange theory, we examined and contrasted attitudinal mediators (affective organizational commitment, job satisfaction) and relational mediators (trust in leader, leader-member exchange; LMX) of the positive relationship between transformational leadership and organizational citizenship behavior (OCB). Hypotheses were tested using meta-analytic path models with correlations from published meta-analyses (761 samples with 227,419 individuals overall). When testing single-mediator models, results supported our expectations that each of the mediators explained the relationship between transformational leadership and OCB. When testing a multi-mediator model, LMX was the strongest mediator. When testing a model with a latent attitudinal mechanism and a latent relational mechanism, the relational mechanism was the stronger mediator of the relationship between transformational leadership and OCB. Our findings help to better understand the underlying mechanisms of the relationship between transformational leadership and OCB.

Job satisfaction and organizational citizenship behavior of personnel at one university hospital in Thailand.

PubMed

Intaraprasong, Bhusita; Dityen, Warunee; Krugkrunjit, Peera; Subhadrabandhu, Thanya

2012-06-01

To investigate the relationship between job satisfaction and Organizational Citizenship Behavior (OCB) of the personnel at one university hospital in Thailand. This cross-sectional descriptive study was conducted on 296 respondents who worked in the Office of the Dean, 13 departments and 2 Offices of Research Center and Office of Community Medicine Center. All of them were personnel in one university hospital in Thailand. The Organizational Citizenship Behavior Questionnaire of Niehoff and Moorman using the five dimensions scale developed by Podsakoff and Mackenzie and Job Descriptive Index (JDI) were used for assessing job satisfaction. For inferential statistics, Pearson's product moment correlation coefficient was used for correlation. The percentage mean score of job satisfaction was 58.67 and subscale of job satisfaction was found that satisfaction with supervision held the highest of the mean score, while satisfaction with pay and promotion had the lowest and low of the mean score. The mean score of OCB was high and the facets of OCB was found that conscientiousness had the highest mean score and sportsmanship had the lowest. By using Pearson's Product Moment Correlation Coefficient to analyze the relationships between satisfaction and OCB, it showed that there were statistically significant low positive correlations between job satisfaction and OCB (r = 0.173, p < 0.01). The one university hospital executives should promote the pay, promotion and supervision factors which encourage personnel to be satisfied and demonstrate their OCB as their reciprocal reaction.

Autism Spectrum and Obsessive–Compulsive Disorders: OC Behaviors, Phenotypes and Genetics

PubMed Central

Jacob, Suma; Landeros-Weisenberger, Angeli; Leckman, James F.

2014-01-01

Autism spectrum disorders (ASDs) are a phenotypically and etiologically heterogeneous set of disorders that include obsessive–compulsive behaviors (OCB) that partially overlap with symptoms associated with obsessive–compulsive disorder (OCD). The OCB seen in ASD vary depending on the individual’s mental and chronological age as well as the etiology of their ASD. Although progress has been made in the measurement of the OCB associated with ASD, more work is needed including the potential identification of heritable endophenotypes. Likewise, important progress toward the understanding of genetic influences in ASD has been made by greater refinement of relevant phenotypes using a broad range of study designs, including twin and family-genetic studies, parametric and nonparametric linkage analyses, as well as candidate gene studies and the study of rare genetic variants. These genetic analyses could lead to the refinement of the OCB phenotypes as larger samples are studied and specific associations are replicated. Like ASD, OCB are likely to prove to be multidimensional and polygenic. Some of the vulnerability genes may prove to be generalist genes influencing the phenotypic expression of both ASD and OCD while others will be specific to subcomponents of the ASD phenotype. In order to discover molecular and genetic mechanisms, collaborative approaches need to generate shared samples, resources, novel genomic technologies, as well as more refined phenotypes and innovative statistical approaches. There is a growing need to identify the range of molecular pathways involved in OCB related to ASD in order to develop novel treatment interventions. PMID:20029829

The relationship between trait self-control, consideration for future consequence and organizational citizenship behavior among Chinese employees.

PubMed

Wang, Yu-Jie; Dou, Kai; Tang, Zhi-Wen

2017-01-01

Organizational citizenship behavior (OCB) is important to the development of an organization. Research into factors that foster OCB and the underlying processes are therefore substantially crucial. The current study aimed to test the association between trait self-control and OCB and the mediating role of consideration for future consequence. Four hundred and ninety-four Chinese employees (275 men, 219 women) took part in the study. Participants completed a battery of self-report measures online that assessed trait self-control, tendencies of consideration of future consequence, and organizational citizenship behavior. Path analysis was conducted and bootstrapping technique (N = 5000), a resampling method that is asymptotically more accurate than the standard intervals using sample variance and assumptions of normality, was used to judge the significance of the mediation. Results of path analysis showed that trait self-control was positively related to OCB. More importantly, the "trait self-control-OCB" link was mediated by consideration of future consequence-future, but not by consideration of future consequence-immediate. Employees with high trait self-control engage in more organizational citizenship behavior and this link can be partly explained by consideration of future consequence-future.

Antecedents of organizational citizenship behavior among Iranian nurses: a multicenter study.

PubMed

Taghinezhad, Fakhredin; Safavi, Mahboobe; Raiesifar, Afsaneh; Yahyavi, Sayed Hossein

2015-10-08

Organizational citizenship behavior (OCB) improves efficiency and employees' participation and generally provides a good ambiance. This study was conducted to determine the role of job satisfaction (JS), organizational commitment (OC) and procedural justice (PJ) in explaining OCB among nurses working in fifteen educational-treatment centers in Tehran-Iran, to provide guidelines for health care managers' further understanding of how to encourage citizenship behavior among nurses. In this multi-center descriptive-correlational study 373 nurses were evaluated through a Multi-stage cluster sampling method after obtaining approval from the Ethics Committee of Islamic Azad University, Tehran Medical Branch and Tehran University of Medical Sciences Research Deputy. Nurses who signed the informed consent and holding a bachelor or master degree, having a minimum one year of job experience and not having organizational management position during the questionnaire distribution were included in the study. In order to collect data, Demographic questionnaire, Podsakoff et al. (Leadersh Q 1(2):107-142, 1990) OCB questionnaire, OC questionnaire, Aelterman et al. (Educ Stud 33(3):285-297, 2007) JS questionnaire and PJ questionnaire were used. These questionnaires were translated into Persian and content validity was confirmed by an expert group; their reliability was calculated by the internal consistency Cronbach alpha coefficient and it was satisfied. Data were analyzed by descriptive statistics, Comparative mean tests, correlation coefficient and multiple-regression in the SPSS software version 11. The general mean and all five aspects of OCB that ranked higher than 3 were evaluated in a "quite desired" state. The mean for perceived procedural justice, the general mean for JS and the mean of general grade for OC from the nurses' was in "quite desired" state. Finding from multiple regression indicated that OC and PJ exhibit about 19 % of OCB variance totally which is statistically significant (P < 0.01). JS had no significant impact on explaining OCB. OC was the strongest predictor of nurses' OCB followed by perceived procedural justice. So, improving these factors can initiate better citizenship behavior among nurses.

CSF free light chain identification of demyelinating disease: comparison with oligoclonal banding and other CSF indexes.

PubMed

Gurtner, Kari M; Shosha, Eslam; Bryant, Sandra C; Andreguetto, Bruna D; Murray, David L; Pittock, Sean J; Willrich, Maria Alice V

2018-02-19

Cerebrospinal fluid (CSF) used in immunoglobulin gamma (IgG) index testing and oligoclonal bands (OCBs) are common laboratory tests used in the diagnosis of multiple sclerosis. The measurement of CSF free light chains (FLC) could pose as an alternative to the labor-intensive isoelectric-focusing (IEF) gels used for OCBs. A total of 325 residual paired CSF and serum specimens were obtained after physician-ordered OCB IEF testing. CSF kappa (cKFLC) and lambda FLC (cLFLC), albumin and total IgG were measured. Calculations were performed based on combinations of analytes: CSF sum of kappa and lambda ([cKFLC+cLFLC]), kappa-index (K-index) ([cKFLC/sKFLC]/[CSF albumin/serum albumin]), kappa intrathecal fraction (KFLCIF) {([cKFLC/sKFLC]-[0.9358×CSF albumin/serum albumin]^[0.6687×sKFLC]/cKFLC)} and IgG-index ([CSF IgG/CSF albumin]/[serum IgG/serum albumin]). Patients were categorized as: demyelination (n=67), autoimmunity (n=53), non-inflammatory (n=50), inflammation (n=38), degeneration (n=28), peripheral neuropathy (n=24), infection (n=13), cancer (n=11), neuromyelitis optica (n=10) and others (n=31). cKFLC measurement used alone at a cutoff of 0.0611 mg/dL showed >90% agreement to OCBs, similar or better performance than all other calculations, reducing the number of analytes and variables. When cases of demyelinating disease were reviewed, cKFLC measurements showed 86% clinical sensitivity/77% specificity. cKFLC alone demonstrates comparable performance to OCBs along with increased sensitivity for demyelinating diseases. Replacing OCB with cKFLC would alleviate the need for serum and CSF IgG and albumin and calculated conversions. cKFLC can overcome challenges associated with performance, interpretation, and cost of traditional OCBs, reducing costs and maintaining sensitivity and specificity supporting MS diagnosis.

Cerebrospinal fluid myelin basic protein is frequently ordered but has little value: a test utilization study.

PubMed

Greene, Dina N; Schmidt, Robert L; Wilson, Andrew R; Freedman, Mark S; Grenache, David G

2012-08-01

Diagnosis of multiple sclerosis (MS) is facilitated by analyzing biochemical properties of cerebrospinal fluid (CSF). Oligoclonal bands (OCBs) and immunoglobulin G (IgG) index are well-established markers for evaluating patients suspected of having MS. Myelin basic protein (MBP) is also ordered frequently, but its usefulness remains questionable. OCB, IgG index, and MBP were measured in 16,690 consecutive CSF samples. Samples were divided into 2 groups based on MS status known (n = 71) or unknown (n = 16,118). Medical charts of the MS status known group were reviewed to determine their MS status. OCBs have a stronger association to IgG index results than does MBP. Importantly, MBP does not add a statistically significant increase in diagnostic sensitivity or specificity when used in combination with OCB and/or IgG index. The data indicate that MBP is an unnecessary and overused test.

Transformational Leadership and Organizational Citizenship Behavior: A Meta-Analytic Test of Underlying Mechanisms

PubMed Central

Nohe, Christoph; Hertel, Guido

2017-01-01

Based on social exchange theory, we examined and contrasted attitudinal mediators (affective organizational commitment, job satisfaction) and relational mediators (trust in leader, leader-member exchange; LMX) of the positive relationship between transformational leadership and organizational citizenship behavior (OCB). Hypotheses were tested using meta-analytic path models with correlations from published meta-analyses (761 samples with 227,419 individuals overall). When testing single-mediator models, results supported our expectations that each of the mediators explained the relationship between transformational leadership and OCB. When testing a multi-mediator model, LMX was the strongest mediator. When testing a model with a latent attitudinal mechanism and a latent relational mechanism, the relational mechanism was the stronger mediator of the relationship between transformational leadership and OCB. Our findings help to better understand the underlying mechanisms of the relationship between transformational leadership and OCB. PMID:28848478

Oligoclonal bands in the cerebrospinal fluid of amyotrophic lateral sclerosis patients with disease-associated mutations.

PubMed

Ticozzi, Nicola; Tiloca, Cinzia; Mencacci, Niccolò E; Morelli, Claudia; Doretti, Alberto; Rusconi, Daniela; Colombrita, Claudia; Sangalli, Davide; Verde, Federico; Finelli, Palma; Messina, Stefano; Ratti, Antonia; Silani, Vincenzo

2013-01-01

In amyotrophic lateral sclerosis (ALS) cerebrospinal fluid (CSF) analysis is usually performed to exclude inflammatory processes of the central nervous system. Although in a small subset of patients an intrathecal synthesis of IgG is detectable, usually there is no clear explanation for this evidence. This study investigates the occurrence of oligoclonal bands (OCBs) in the CSF of a large series of ALS patients, attempting a correlation with genotype data. CSF was collected from 259 ALS patients. CSF parameters were measured according to standard procedures, and detection of OCBs performed by isoelectric focusing. The patients were screened for mutations in SOD1, FUS, TARDBP, ANG, OPTN, and C9ORF72. We observed the presence of OCBs in the CSF of 9/259 ALS patients (3.5 %), and of disease-associated mutations in 12 cases. OCBs were significantly more frequent in mutation carriers compared to the remaining cohort (3/12 vs 6/247; p < 0.01). Among patients with OCBs, two patients had the TARDBP p.A382T mutation (one of which in homozygous state), and one the ANG p.P-4S variant. Both patients carrying the p.A382T mutation had an atypical phenotype, one of them manifesting signs suggestive of a cerebellar involvement, and the other presenting neuroradiological findings suggestive of an inflammatory disorder of the central nervous system. Our results suggest that ALS patients with OCBs may harbor mutations in disease-causing genes. We speculate that mutations in both TARDBP and ANG genes may disrupt the blood-brain barrier (BBB), promoting local immune responses and neuroinflammation. The role of mutant TARDBP and ANG genes on BBB integrity of ALS patients warrants further investigation.

Application of κ free light chains in cerebrospinal fluid as a biomarker in multiple sclerosis diagnosis: development of a diagnosis algorithm.

PubMed

Valencia-Vera, Estefania; Martinez-Escribano Garcia-Ripoll, Ana; Enguix, Alfredo; Abalos-Garcia, Carmen; Segovia-Cuevas, Maria Jesus

2018-03-28

The determination of κ free light chains (KFLC) in cerebrospinal fluid (CSF) by nephelometry is a feasible alternative to immunoglobulin G oligoclonal bands (OCB) in the evaluation of intrathecal synthesis of immunoglobulin in multiple sclerosis (MS) and other demyelinating diseases. The aim of this study was to assess the diagnostic value of KFLC and its inclusion in a procedure algorithm along with OCB interpretation. A cross-sectional study, which included 123 patients with a CSF OCB request, was carried out. Isoelectric focusing followed by immunofixation was used to detect OCB, and nephelometry was used to analyze KFLC. The KFLC index was calculated using CSF/serum quotient of KFLC and albumin. The KFLC index was compared with MS diagnosis to find the optimal cutoff. It was obtained from the receiver operating characteristic (ROC) curves and the Youden method. The CSF KFLC median was 1.66 mg/L in the MS group, whereas in other central nervous system diseases, KFLC showed generally no or only moderate increase in CSF (median 0.10 mg/L). KFLC index showed a significant difference between groups. ROC analysis for CSF KFLC concentration, and KFLC indexes were 91.88% and 93.94%, respectively. The best cutoff for the KFLC index was 2.91 for MS diagnosis (sensitivity: 83.78%; specificity: 85.88%). The proposed algorithm showed high sensitivity (89.19%) and specificity (84.71%). KFLC determination is rapid and automatized, but it has no higher sensitivity and specificity than OCB in MS diagnosis. Nevertheless, when used in screening, it could reduce the number of manual OCB tests.

The Relationship between the Three Components of Commitment and Employee Performance in China.

ERIC Educational Resources Information Center

Chen, Zhen Xiong; Francesco, Anne Marie

2003-01-01

A three-component organizational commitment model was tested with 253 Chinese supervisor/supervisee dyads. Confirmatory factor analyses indicated that affective commitment (AC) related positively to in-role performance and organizational citizenship behavior (OCB); continuance commitment correlated negatively with OCB. Normative commitment…

Careerist Orientation and Organizational Citizenship Behavior in Expatriates and Non-Expatriates

ERIC Educational Resources Information Center

Adams, John W.; Srivastava, Abhishek; Herriot, Peter; Patterson, Fiona

2013-01-01

This study had three objectives. First, we examined the relationship between careerist orientation and organizational citizenship behavior (OCB). Second, we investigated the mediating role of life satisfaction in the relationship between careerist orientation and OCB. Third, we examined whether expatriate employees (those sent abroad on full-time…

The Strength of Accountability and Teachers' Organisational Citizenship Behaviour

ERIC Educational Resources Information Center

Elstad, Eyvind; Christophersen, Knut-Andreas; Turmo, Are

2012-01-01

Purpose: Organisational citizenship behaviour (OCB) involves discretionary behaviour advantageous to the organisation that goes beyond existing role expectations. The purpose of this paper is to explore the link between the strength of accountability and teachers' OCB within three different management systems in which teachers are working: a…

Improving environmental performance through unit-level organizational citizenship behaviors for the environment: A capability perspective.

PubMed

Alt, Elisa; Spitzeck, Heiko

2016-11-01

Organizational citizenship behaviors for the environment (OCBEs) are increasingly advocated as a means of complementing formal practices in improving environmental performance. Adopting a capability perspective, we propose that a firm's employee involvement capability translates into environmental performance through the manifestation of unit-level OCBEs, and that this relationship is amplified by a shared vision capability. In a cross-country and multi-industry sample of 170 firms, we find support for our hypotheses, shedding light on contextual determinants of OCBEs, and on how firms may engender a positive relationship between top-down environmental initiatives and bottom-up behaviors. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Moderated Mediation Model of the Relationship between Organizational Citizenship Behaviors and Job Performance

ERIC Educational Resources Information Center

Ozer, Muammer

2011-01-01

Addressing numerous calls for future research on understanding the theoretical mechanisms that explain the relationship between organizational citizenship behaviors (OCBs) and job performance, this study focused on how an employee's relationships with coworkers mediate the relationship between his or her OCBs and his or her job performance. It…

Promoting Organizational Citizenship Behavior in Schools: The Impact of Individual and Organizational Characteristics

ERIC Educational Resources Information Center

Somech, Anit; Ron, Ifat

2007-01-01

Purpose: The success of schools fundamentally depends on teachers' willingness to go above and beyond the call of duty, namely, to exhibit organizational citizenship behaviors (OCBs). Attempts to understand the causes of OCB frequently focus on individual characteristics; only recently have researchers begun to direct their attention to more…

Organizational Citizenship Behavior: Its Importance in Academics

ERIC Educational Resources Information Center

Kernodle, Thomas A.; Noble, Deborah

2013-01-01

The purpose of this paper is to support Organizational Citizenship Behavior (OCB) as an essential area of study in the field of business education that is often neglected. OCB has been defined as individual behavior that is discretionary, not directly or explicitly recognized by the formal reward system, and that in the aggregate promotes the…

Impact of Satisfaction and Commitment on Teachers' Organizational Citizenship

ERIC Educational Resources Information Center

Sesen, Harun; Basim, Nejat H.

2012-01-01

This study examined the impact of job satisfaction and organizational commitment on teachers' organizational citizenship behavior (OCB) in a structural equation model. The study was employed to a group of teachers and their supervisors. The results indicated that job satisfaction and commitment to the school had an impact on OCBs of the teachers…

Organizational Citizenship Behavior in Teaching: The Consequences for Teachers, Pupils, and the School

ERIC Educational Resources Information Center

Oplatka, Izhar

2009-01-01

Purpose: Professionals and employees have been documented to perform a wide variety of extra-role activities (also called organizational citizenship behaviors (OCB)) for which they are neither paid, nor obliged to accomplish by superiors. The paper aims to obtain greater understanding of the consequences of teacher OCB to the teachers who perform…

An Analysis of Studies on Organizational Citizenship Behaviors in Turkey: 2000-2015

ERIC Educational Resources Information Center

Yaylaci, Ali Faruk

2016-01-01

In recent years, the number of studies on the organizational citizenship behaviors (OCBs) that reflect the mainstream tendencies has dramatically increased especially in the field of business and educational sciences in Turkey. On the other hand, there is a need for a new conceptualization of the OCBs better suited to educational organizations. An…

Transformational Leadership and Organizational Citizenship Behavior in the Arab Educational System in Israel: The Impact of Trust and Job Satisfaction

ERIC Educational Resources Information Center

Nasra, Muhammed Abu; Heilbrunn, Sibylle

2016-01-01

The present study aims to extend and integrate previous research on the mediating effects of trust in supervisor and job satisfaction on the relationship between transformational leadership style and organizational citizenship behavior (OCB). Drawing on previous research, we argue that transformational leadership impacts OCB directly and…

Organizational Citizenship Behaviors in American and Portuguese Public Schools: Measuring the Construct across Cultures

ERIC Educational Resources Information Center

DiPaola, Michael F.; da Costa Neves, Paula Maria Mendes

2009-01-01

Purpose: Organizational citizenship behaviors (OCB) have been studied in both private and public sector organizations in countries around the globe. The purpose of this study is to compare the perceptions of the OCB construct between American and Portuguese public secondary school teachers and test an operational measure of the construct for…

Investigating Relationships between Sense of Belonging and Organizational Citizenship Behavior among Adjunct Faculty

ERIC Educational Resources Information Center

Edgren, Gerald R., Jr.

2012-01-01

Organizational citizenship behavior (OCB) is a social science construct defined by Organ (1988) as employee actions that are discretionary, not formally recognized or rewarded, and that are helpful to the effectiveness of the organization. This study explored part-time work as a base of OCB by investigating the relationship between this construct…

An Integrative Model for Understanding Team Organizational Citizenship Behavior: Its Antecedents and Consequences for Educational Teams

ERIC Educational Resources Information Center

Somech, Anit; Khotaba, Soha

2017-01-01

Purpose: The purpose of this paper is to use a model to broaden the understanding of the organizational citizenship behavior (OCB) phenomenon in educational teams and examines team OCB's mediating role in the relation of the contextual variables of team justice climate (distributive justice, procedural justice, interpersonal justice) to team…

Climate Profile and OCBs of Teachers in Public and Private Schools of India

ERIC Educational Resources Information Center

Garg, Pooja; Rastogi, Renu

2006-01-01

Purpose: This research aims to assess the significant differences in the climate profile and organizational citizenship behaviors (OCBs) of teachers working in public and private schools of India. Design/methodology/approach: The sample comprised of 100 teachers, out of which 50 teachers were from public school and 50 teachers were from private…

Group-Level Organizational Citizenship Behavior in the Education System: A Scale Reconstruction and Validation

ERIC Educational Resources Information Center

Vigoda-Gadot, Eran; Beeri, Itai; Birman-Shemesh, Taly; Somech, Anit

2007-01-01

Purpose: Most writings on Organizational Citizenship Behavior (OCB) to date have focused on analysis at the individual level and paid less attention to other analytical frameworks at the group level (i.e., team, unit, or organization). This article approaches OCB from the less conventional perspective of group-level activities and uses it to…

Job insecurity and organizational citizenship behavior: exploring curvilinear and moderated relationships.

PubMed

Lam, Chak Fu; Liang, Jian; Ashford, Susan J; Lee, Cynthia

2015-03-01

This article examined a curvilinear relationship between job insecurity and organizational citizenship behavior (OCB). Drawing from social exchange theory and research on personal control, we developed and tested an explanation for employees' reactions to job insecurity based on their conceptualization of their social exchange relationship with the organization at different levels of job insecurity. Using data from 244 Chinese employees and 102 supervisory ratings of OCB, we found support for a U-shaped relationship between job insecurity and OCB. Moreover, 2 factors--psychological capital and subordinate-supervisor guanxi--moderated the curvilinear relationship, such that the curvilinear relationship is more pronounced among those with lower psychological capital or less positive subordinate-supervisor guanxi. PsycINFO Database Record (c) 2015 APA, all rights reserved.

An integrative model linking feedback environment and organizational citizenship behavior.

PubMed

Peng, Jei-Chen; Chiu, Su-Fen

2010-01-01

Past empirical evidence has suggested that a positive supervisor feedback environment may enhance employees' organizational citizenship behavior (OCB). In this study, we aim to extend previous research by proposing and testing an integrative model that examines the mediating processes underlying the relationship between supervisor feedback environment and employee OCB. Data were collected from 259 subordinate-supervisor dyads across a variety of organizations in Taiwan. We used structural equation modeling to test our hypotheses. The results demonstrated that supervisor feedback environment influenced employees' OCB indirectly through (1) both positive affective-cognition and positive attitude (i.e., person-organization fit and organizational commitment), and (2) both negative affective-cognition and negative attitude (i.e., role stressors and job burnout). Theoretical and practical implications are discussed.

Compulsory citizenship behavior and organizational citizenship behavior: the role of organizational identification and perceived interactional justice.

PubMed

Zhao, Hongdan; Peng, Zhenglong; Chen, Hsiu-Kuei

2014-01-01

This article examines the psychological mechanism underlying the relationship between compulsory citizenship behavior (CCB) and organizational citizenship behavior (OCB) by developing a moderated mediation model. The model focuses on the mediating role of organizational identification and the moderating role of interactional justice in influencing the mediation. Using a time-lagged research design, the authors collected two waves of data from 388 supervisor-subordinate dyads in 67 teams to test the moderated mediation model. Results revealed that CCB negatively influenced OCB via impairing organizational identification. Moreover, interactional justice moderated the strength of the indirect effect of CCB on OCB (through organizational identification), such that the mediated relationship was stronger under low interactional justice than under high interactional justice.

Psychological contract breach and outcomes: Combining meta-analysis and structural equation models.

PubMed

Topa Cantisano, Gabriela; Morales Domínguez, J Francisco; Depolo, Marco

2008-08-01

In this study, meta-analytic procedures were used to examine the relationships between psychological contract perceived breach and certain outcome variables, such as organizational commitment, job satisfaction and organizational citizenship behaviours (OCB). Our review of the literature generated 41 independent samples in which perceived breach was used as a predictor of these personal and organizational outcomes. A medium effect size (ES) for desirable outcomes (job satisfaction, organizational commitment, organizational trust, OCB and performance) was obtained (r=-.35). For undesirable outcomes (neglect in role duties and intention to leave), ES were also medium (r=.31). When comparing attitudinal (job satisfaction, organizational commitment, organizational trust) and behavioural outcomes (OCB, neglect in role duties and performance), a stronger ES was found for attitudinal (r=-.24) than for behavioural outcomes (r=-.11). Potential moderator variables were examined, and it was found that they explained only a percentage of variability of primary studies. Structural equation analysis of the pooled meta-analytical correlation matrix indicated that the relationships of perceived breach with satisfaction, OCB, intention to leave and performance are fully mediated by organizational trust and commitment. Results are discussed in order to suggest theoretical and empirical implications.

Socialization and organizational citizenship behavior among Turkish primary and secondary school teachers.

PubMed

Çavuş, Mustafa Fedai

2012-01-01

The aim of the present study is to investigate the effects of organizational socialization levels of employees on organizational citizenship behavior (OCB). A total of 185 (70 female, 115 male) teachers were sampled at 27 primary and secondary schools. Their ages ranged from 23 to 55 years, with a mean (SD) of 36 (5.1). In this sample, 100 (54.1%) worked in primary schools, and 85 (45.9%) worked in secondary schools. A three-part questionnaire was designed for the study. The research scales were self-report measures of organizational socialization, OCB, and demographic variables. The hypothesized model was tested using Pearson correlation analyses and multiple regression analyses. The teachers demonstrated high level socialization (Mean 4.2, SD 0.7) and OCB (Mean 4.0, SD 0.54). Understanding, coworker support, and performance proficiency explained significant variance in organizational citizenship behavior; however, there was no relationship (p=0.286) between the organizational goals and values and OCB. The findings contribute to our understanding of the relationship between the level of organizational socialization and organizational citizenship behavior in educational settings. These findings suggest that high level organizational socialization supports organizational citizenship behavior in primary and secondary school teachers.

The Cost of Going the Extra Mile: The Relationship between Teachers' Organizational Citizenship Behavior, Role Stressors, and Strain with the Buffering Effect of Job Autonomy

ERIC Educational Resources Information Center

Somech, Anit

2016-01-01

Organizational citizenship behavior (OCB) is defined as performance that supports the social and psychological environment in which a task is conducted. Teachers' OCB can be directed toward particular individuals (OCBI) and/or toward the organization (OCBO). Despite their beneficial impact on school, these could entail personal costs for the…

Associations of HLA DRB1 alleles with IgG oligoclonal bands and their influence on multiple sclerosis course and disability status.

PubMed

Balnytė, Renata; Rastenytė, Daiva; Vaitkus, Antanas; Skrodenienė, Erika; Vitkauskienė, Astra; Ulozienė, Ingrida

2016-01-01

Oligoclonal bands (OCB) may be associated with the genes of HLA complex, which allows to consider the possible interaction of genetic and immunological factors and its importance in the development and progression of multiple sclerosis (MS). The aim of this study was to evaluate the associations between HLA DRB1 alleles and oligoclonal bands (OCBs) in the disease course and disability of multiple sclerosis (MS) patients. This was a prospective study of 120 patients with MS. HLA DRB1 alleles were genotyped using the polymerase chain reaction. Matched cerebrospinal fluid (CSF) and plasma samples were analyzed using isoelectric focusing and IgG specific immunofixation to test for the presence of intrathecal specific OCB. HLA DRB1*08 allele was related to a lower degree of disability. Oligoclonal bands were an independent and significant factor that influenced disability status irrespective of HLA DRB1* 04, *07, *08, *13, *15 and *16 alleles. Age at the onset and duration of the disease were independent and significant factors for MS progression in all logistic regression models with each newly added HLA DRB1 allele. HLA DRB1*08 allele was related to 75% lower odds that relapsing remitting (RR) MS will change to a progressive course MS irrespective of the other factors investigated. Detection of OCBs in the CSF was associated with the higher possibility of RR MS progression in all cases, except when the *08 allele was present. OCBs had an influence on disability status, while HLA DRB1*08 allele was significantly associated with lower possibility that RR MS will change to progressive course MS. Copyright © 2016 The Lithuanian University of Health Sciences. Production and hosting by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Got political skill? The impact of justice on the importance of political skill for job performance.

PubMed

Andrews, Martha C; Kacmar, K Michele; Harris, Kenneth J

2009-11-01

The present study examined the moderating effects of procedural and distributive justice on the relationships between political skill and task performance and organizational citizenship behavior (OCB) among 175 supervisor-subordinate dyads of a government organization. Using Mischel's (1968) situationist perspective, high justice conditions were considered "strong situations," whereas low justice conditions were construed as "weak situations." We found that when both procedural and distributive justice were low, political skill was positively related to performance. Under conditions of both high procedural and high distributive justice, political skill was negatively related to performance. Finally, under conditions of low distributive justice, political skill was positively related to OCB, whereas under conditions of high distributive justice, political skill had little effect on OCB. These results highlight the importance of possessing political skill in weak but not strong situations.

A multilevel study on the relationships between work characteristics, self-efficacy, collective efficacy, and organizational citizenship behavior: the case of Taiwanese police duty-executing organizations.

PubMed

Chen, Chun-Hsi Vivian; Kao, Rui-Hsin

2011-01-01

Public security, traffic management, and service for the people are the 3 major functions of policing in Taiwan. This definition encompasses not only the traditional job characteristics, but also the level of contextual characteristics and social characteristics because of police work's characteristics and its frequent interaction with the public. Thus, the present study conducted a multilevel model analysis by taking self-efficacy and collective efficacy as the mediating variables. The purpose was to investigate the influences of motivational work characteristics (knowledge-oriented) and social work characteristics (socially and contextually oriented) of work-design model on the police officers' organizational citizenship behavior (OCB), by using first-line police officers in Taiwan as the research objects. The study showed not only that knowledge characteristics will influence the self-efficacy of a police officer and that self-efficacy can in turn influence individual police officers' OCB, but also the contextual effect of social characteristics, contextual characteristics, and collective efficacy on self-efficacy and individuals' OCB. Additionally, there was a crosslevel moderating effect from contextual characteristics on the relationship between knowledge characteristics and self-efficacy and the relationship between self-efficacy and the individuals' OCB. The authors conclude the article with research implications.

Effect of emotional dissonance on organizational citizenship behavior: testing the stressor-strain-outcome model.

PubMed

Cheung, Francis Yue-Lok; Cheung, Ray Yu-Hin

2013-01-01

In this study, the stressor-strain-outcome (SSO) model developed by Koeske and Koeske was adopted to examine the mediating effect of burnout between emotional dissonance and organizational citizenship behavior (OCB). The study involved 264 full-time Chinese school teachers (82 men, 16 women, and 22 individuals whose genders were not specified; mean age = 34.4 years and SD = 8.09 years). Correlation analysis showed that emotional dissonance is positively related to all three burnout dimensions (i.e., emotional exhaustion, depersonalization, and lack of personal accomplishment). Emotional dissonance is also negatively related to OCB toward individuals. Results from structural equation modeling support the SSO model, which states that emotional dissonance first leads to burnout and then to lower OCB. The limitations and implications to the school management, such as provision of emotional regulation training and strengthening of the social network system, were also discussed.

The personal costs of citizenship behavior: the relationship between individual initiative and role overload, job stress, and work-family conflict.

PubMed

Bolino, Mark C; Turnley, William H

2005-07-01

By and large, prior research has focused on the positive aspects of organizational citizenship behavior (OCB). D. W. Organ and K. Ryan (1995), though, suggest that individuals who engage in high levels of OCB may become overloaded. This research explores the relationship between a specific type of OCB--namely, individual initiative--and role overload, job stress, and work-family conflict. Results from a sample of 98 couples indicate that higher levels of individual initiative (as assessed by the spouse or significant other) are associated with higher levels of employee role overload, job stress, and work-family conflict. The findings also suggest that the relationship between individual initiative and work-family conflict is moderated by gender, such that the relationship is stronger among women than among men. Some implications of this work and directions for future research are discussed as well. Copyright 2005 APA, all rights reserved.

Tic disorders and obsessive compulsive disorder: where is the link?

PubMed

Roessner, V; Becker, A; Banaschewski, T; Rothenberger, A

2005-01-01

Over the last years evidence on the overlap between tic-disorders (TD) and obsessive compulsive behavior/disorder (OCB/OCD) has increased. The main focus of research have been the phenomenological and epidemiological similarities and differences in samples of different age, primary diagnosis (TD vs. OCD) including the co-occurrence of both. Unfortunately, only a minority of studies included all three groups (TD, TD + OCD, OCD). Nevertheless, new insight concerning possible subtypes for both TD and OCD has been gained. While some authors concentrated on OCD with/without tics we will summarize the field of TD and OCB/OCD from the viewpoint of tics, since OCB plays an important role in patients with TD. Thereby we will not only sharpen the clinicans' awareness of known differences in phenomenology, epidemiology, genetics and neurobiology, aimed to improve their diagnoses and treatment but also highlight the gaps of knowledge and discuss possibilities for further research in this field.

Organizational learning capability and organizational citizenship behaviour in the health sector: examining the role of happiness at work from a gender perspective.

PubMed

Salas-Vallina, Andrés; Alegre, Joaquin; Fernández, Rafael

2017-04-01

Both researchers and managers are interested in finding the factors that raise organizational citizenship behaviour (OCB), particularly in the health sector. In this complex context, characterized by a high workload, it becomes essential that physicians voluntarily contribute beyond their official job description. Our research aims to evidence the working conditions that promote OCB, considering the role of organizational learning capability through happiness at work. Our research was based on a sample of 167 allergists at Spanish public hospitals, and by means of structural equation models, interesting results were found. We offer to hospital managers both a tool and an explanation for the fostering of OCB. Physicians that progress through learning, under positive attitudes at work, may indeed behave more civically, going beyond their job description. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The impact of education on caregiver burden on two inpatient oncology units.

PubMed

Creedle, Crista; Leak, Ashley; Deal, Allison M; Walton, Ann Marie; Talbert, Gayl; Riff, Barbara; Hornback, Ann

2012-06-01

Providing standardized education can alleviate the burden felt by the caregiver and improve health outcomes for both the patient and caregiver. Four disease groups were included in this study that represent a significantly longer hospital stay than other cancers: acute myelogenous leukemia, acute lymphoblastic leukemia, lymphoma, or those undergoing blood marrow transplant. The complexity of care is significantly higher, necessitating greater caregiver burden following hospitalization. Eligible patients and their caregivers received post-hospitalization care education through an Oncology CarePartner Program addressing the patient's physical and emotional needs. The impact of the CarePartners program on caregiver burden was evaluated by the Oberst Caregiving Burden Scale (OCBS) and Bakas Caregiving Outcomes Scale (BCOS) on two oncology units (medical/oncology (n = 17) and blood marrow transplant (n = 21)) at three times: within 5 days of admission (T1), patient discharge from the hospital (T2), and 30 days post-discharge (T3). There were significant increases seen from T1-T2 (median = 4, p = 0.0007) and T1-T3 (median = 5.5, p = 0.003) in the BCOS. No significant changes in OCBS (time or difficulty) were seen. Standardized patient education helped improve caregivers' overall well-being but lacked in impacting the time spent and difficulty with caregiving tasks. Educational changes to address these specific areas or evaluation by different scales are both worth further investigation.

Health worker performance in rural health organizations in low- and middle-income countries: do organizational factors predict non-task performance?

PubMed

Jayasuriya, Rohan; Jayasinghe, Upali W; Wang, Qian

2014-07-01

Health worker (HW) performance is a critical issue facing many low- and middle-income countries (LMICs). The aim of this study was to test the effects of factors in the work environment, such as organizational culture and climate, on HW non-task performance in rural health work settings in a LMIC. The data for the study is from a sample of 963 HWs from rural health centres (HCs) in 16 of the 20 provinces in Papua New Guinea. The reliability and validity of measures for organizational citizenship behaviour (OCB), counterproductive work behaviour (CWB) and work climate (WC) were tested. Multilevel linear regression models were used to test the relationship of individual and HC level factors with non-task performance. The survey found that 62 per cent of HCs practised OCB "often to always" and 5 percent practised CWB "often to always". Multilevel analysis revealed that WC had a positive effect on organizational citizenship behaviour (OCB) and a negative effect on CWB. The mediation analyses provided evidence that the relationship between WC and OCB was mediated through CWB. Human resource policies that improve WC in rural health settings would increase positive non-task behaviour and improve the motivation and performance of HWs in rural settings in LMICs. Copyright © 2014 Elsevier Ltd. All rights reserved.

78 FR 8128 - Request for Nominations of Experts to the EPA Office of Research and Development's Board of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-05

... Program; Homeland Security Research Program; Human Health Risk Assessment Research Program; Safe and... --atmospheric physics Biology --biogeochemistry --cell biology --endocrinology (endocrine disruptors... analysis --uncertainty analysis Nanotechnology Public Health --children's health --community health...

Comparison of the development of performance skills in ultrasound-guided regional anesthesia simulations with different phantom models.

PubMed

Liu, Yang; Glass, Nancy L; Glover, Chris D; Power, Robert W; Watcha, Mehernoor F

2013-12-01

Ultrasound-guided regional anesthesia (UGRA) skills are traditionally obtained by supervised performance on patients, but practice on phantom models improves success. Currently available models are expensive or use perishable products, for example, olive-in-chicken breasts (OCB). We constructed 2 inexpensive phantom (transparent and opaque) models with readily available nonperishable products and compared the process of learning UGRA skills by novice practitioners on these models with the OCB model. Three experts first established criteria for a satisfactory completion of the simulated UGRA task in the 3 models. Thirty-six novice trainees (<20 previous UGRA experience) were randomly assigned to perform a UGRA task on 1 of 3 models-the transparent, opaque, and OCB models, where the hyperechoic target was identified, a needle was advanced to it under ultrasound guidance, fluid was injected, and images were saved. We recorded the errors during task completion, number of attempts and needle passes, and the time for target identification and needle placement until the predetermined benchmark of 3 consecutive successful UGRA simulations was accomplished. The number of errors, needle passes, and time for task completion per attempt progressively decreased in all 3 groups. However, failure to identify the target and to visualize the needle on the ultrasound image occurred more frequently with the OCB model. The time to complete simulator training was shortest with the transparent model, owing to shorter target identification times. However, trainees were less likely to agree strongly that this model was realistic for teaching UGRA skills. Training on inexpensive synthetic simulation models with no perishable products permits learning of UGRA skills by novices. The OCB model has disadvantages of containing potentially infective material, requires refrigeration, cannot be used after multiple needle punctures, and is associated with more failures during simulated UGRA. Direct visualization of the target in the transparent model allows the trainee to focus on needle insertion skills, but the opaque model may be more realistic for learning target identification skills required when UGRA is performed on real patients in the operating room.

Trace element geochemistry and mineralogy of coal from Samaleswari open cast coal block (S-OCB), Eastern India

NASA Astrophysics Data System (ADS)

Saha, Debasree; Chatterjee, Debashis; Chakravarty, Sanchita; Mazumder, Madhurina

2018-04-01

Coal samples of Samaleswari open cast coal block (S-OCB) are high ash (Aad, mean value 35.43%) and low sulphur content (St, on dry basis, mean value 0.91% < 1%) in quality. The stratigraphic variation of volatile matter and fixed carbon (dry ash-free) reflect a progress of coal metamorphism with depth that accordance to the coal rank variation from lignite to high volatile bituminous in the studied borehole. The younger coal seams have greater detrital minerals (quartz, illite, rutile) influence whereas older coal seams have greater authigenic mineral (kaolinite, dolomite, siderite, apatite) contribution that are possibly due to subsidence and sediment transportation. In S-OCB coal trace elements affinities in-between mineral and organic fraction are identified with statistical hierarchical cluster analysis. The work is further supported by the use of chemical fractionation experiment that reveals the multi mode of occurrence of several environmentally concern and interested trace elements (Sb, As, Be, Cd, Cr, Co, Cu, Pb, Mn, Ni, Zn). Among the analysed trace elements Co, Mn and Zn have major silicate association along with significant carbonate/oxide/monosulfide association. Whereas As, Cd, Cu, Pb and Ni have dominant pyritic association with notable silicate and carbonate/oxide/monosulfide association. The rest three elements (Sb, Be, Cr) have principally organic association with minor silicate and carbonate/oxide/monosulfide association. The stratigraphic variation of organo-mineral matrix content and detrital-authigenic mineral ratio are primarily related to coal rank. Geochemical character of coal also reflects a light towards proper utilisation of S-OCB coal from technical and environmental view point.

The contextualized self: how team-member exchange leads to coworker identification and helping OCB.

PubMed

Farmer, Steven M; Van Dyne, Linn; Kamdar, Dishan

2015-03-01

This article develops the argument that team-member exchange (TMX) relationships operate at both between- and within-group levels of analysis to influence an employee's sense of identification with coworkers in the group and their helping organizational citizenship behavior (OCB) directed at coworkers. Specifically, we propose that relatively higher quality TMX relationships of an employee as compared with other members of the group influence an employee's sense of positive uniqueness, whereas higher average level of TMX quality in the group creates a greater sense of belonging. Multilevel modeling analysis of field data from 236 bank managers and their subordinates supports the hypotheses and demonstrates 3 key findings. First, team members identify more with their coworkers when they have high relative TMX quality compared with other group members and are also embedded in groups with higher average TMX. Second, identification with coworkers is positively related to helping OCB directed toward team members. Finally, identification with coworkers mediates the interactive effect of relative TMX quality and group average TMX quality on helping. When TMX group relations allow individuals to feel a valued part of the group, but still unique, they engage in higher levels of helping. Overall moderated mediation analysis demonstrates that the mediated relationship linking relative TMX quality with helping OCB via identification with coworkers is stronger when group average TMX is high, but not present when group average TMX is low. We discuss theoretical and practical implications and recommend future research on multilevel conceptualizations of TMX. PsycINFO Database Record (c) 2015 APA, all rights reserved.

The efficacy of an opportunistic cognitive behavioral intervention package (OCB) on substance use and comorbid suicide risk: a multisite randomized controlled trial.

PubMed

Morley, Kirsten C; Sitharthan, Gomathi; Haber, Paul S; Tucker, Peter; Sitharthan, Thiagarajan

2014-02-01

People with substance use disorders who present with suicidal behavior are at high risk of subsequent suicide. There are few effective treatments specifically tailored for this population that diminish this risk. We aimed to assess the impact of an opportunistic cognitive behavioral intervention package (OCB) among adult outpatients with a substance use and comorbid suicide risk. A randomized controlled trial was conducted across 2 sites in which 185 patients presenting with suicide risk and concurrent substance use received either OCB (8 sessions plus group therapy) or treatment as usual (TAU) over a 6-month period. Primary outcomes were suicidal behavior (suicide attempts, suicidal intent and presence of suicide ideation) and level of drug and alcohol consumption. Secondary outcomes were changes in psychological measures of suicide ideation, depression, anxiety, and self-efficacy. There were no completed suicides, and only 2 participants reported suicide attempts at follow-up. Suicide ideation, alcohol consumption, and cannabis use fell over time but no significant Treatment × Time differences were found. There were also no differences between OCB and TAU over time on psychological measures of depression, anxiety, or self-efficacy. Suicide ideation at 6-month follow-up was predicted by cannabis use and higher scores on the Brief Psychiatric Rating Scale at baseline. The opportunistic cognitive behavioral intervention package did not appear to be beneficial in reducing suicide ideation, drug and alcohol consumption, or depression relative to treatment as usual. PsycINFO Database Record (c) 2014 APA, all rights reserved.

The influence of time management skill on the curvilinear relationship between organizational citizenship behavior and task performance.

PubMed

Rapp, Adam A; Bachrach, Daniel G; Rapp, Tammy L

2013-07-01

In this research we integrate resource allocation and social exchange perspectives to build and test theory focusing on the moderating role of time management skill in the nonmonotonic relationship between organizational citizenship behavior (OCB) and task performance. Results from matching survey data collected from 212 employees and 41 supervisors and from task performance metrics collected several months later indicate that the curvilinear association between OCB and task performance is significantly moderated by employees' time management skill. Implications for theory and practice are discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Status of the Polar Engineering Development Center's (PEDC) Open-Closed Boundary Synoptic Nowcast

NASA Astrophysics Data System (ADS)

Gerrard, A. J.; Kim, H.

2017-12-01

We present the most recent Polar Engineering Development Center (PEDC) developments, specifically the first magnetic-field open-closed boundary (OCB) determination scheme. This scheme is implemented in "near real time" and utilizes data from an array of fluxgate magnetometers that are distributed across the high Antarctic plateau, as per Urban et al. [2012]. This OCB determination enables a high-latitude, synoptic measure of space weather variability that provides for more regional determinations of particle precipitation and related impacts. This methodology therefore supplements exciting "index-based" or empically-based space weather nowcasts currently in use.

Carbamazepine but not valproate induces CYP2A6 activity in smokers with mental illness

PubMed Central

Williams, Jill M; Gandhi, Kunal K; Benowitz, Neal L

2010-01-01

BACKGROUND Anti-epileptic drugs (AED) are increasingly used in the management of serious mental illness yet their effects on nicotine metabolism have not been studied. METHODS This study investigated the effects of 3 AED (carbamazepine, CBZ; oxcarbazepine, OCB or valproic acid, VPA) on nicotine and nicotine metabolite levels in 149 smokers with schizophrenia and bipolar disorder who participated in an afternoon blood draw for nicotine, cotinine, and 3’-hydroxycotinine (3HC). The ratio of 3HC to cotinine was calculated as a marker of CYP2A6 metabolic activity. Eight smokers were taking CBZ, six were taking OCB and 40 were taking VPA. RESULTS The 3HC/cotinine ratio was significantly higher in individuals taking CBZ or OCB (combined, n=14) vs. those not taking it (mean 0.993 vs. 0.503; p< 0.001). The cotinine/cigarette per day ratio was significantly lower in individuals taking CBZ or OCB. The 3HC/cotinine ratios were also significantly higher in the subgroup of individuals taking CBZ (n=8) vs. those not taking it. There were no significant differences in nicotine or cotinine levels or 3HC/cotinine ratios in individuals taking VPA vs. those not taking it. We conducted backward stepwise linear regression models to identify predictors of the log transformed 3HC/cotinine ratios. Taking CBZ and number of cigarettes smoked per day were significant determinants of log 3HC/Cotinine. CONCLUSIONS CBZ likely induces hepatic metabolism via CYP2A6 and is associated with increased 3HC/Cotinine ratios. IMPACT Increased nicotine metabolism in individuals using AED has implications for increased smoking behavior and exposure to more tobacco toxins that warrants further study. PMID:20719908

Glucose and Applied Voltage Accelerated p-Nitrophenol Reduction in Biocathode of Bioelectrochemical Systems

PubMed Central

Wang, Xinyu; Xing, Defeng; Mei, Xiaoxue; Liu, Bingfeng; Ren, Nanqi

2018-01-01

p-Nitrophenol (PNP) is common in the wastewater from many chemical industries. In this study, we investigated the effect of initial concentrations of PNP and glucose and applied voltage on PNP reduction in biocathode BESs and open-circuit biocathode BESs (OC-BES). The PNP degradation efficiency of a biocathode BES with 0.5 V (Bioc-0.5) reached 99.5 ± 0.8%, which was higher than the degradation efficiency of the BES with 0 V (Bioc-0) (62.4 ± 4.5%) and the OC-BES (59.2 ± 12.5%). The PNP degradation rate constant (kPNP) of Bioc-0.5 was 0.13 ± 0.01 h-1, which was higher than the kPNP of Bioc-0 (0.024 ± 0.002 h-1) and OC-BES (0.013 ± 0.0005 h-1). PNP degradation depended on the initial concentrations of glucose and PNP. A glucose concentration of 0.5 g L-1 was best for PNP degradation. The initial PNP increased from 50 to 130 mg L-1 and the kPNP decreased from 0.093 ± 0.008 to 0.027 ± 0.001 h-1. High-throughput sequencing of 16S rRNA gene amplicons indicated differences in microbial community structure between BESs with different voltages and the OC-BES. The predominant populations were affiliated with Streptococcus (42.7%) and Citrobacter (54.1%) in biocathode biofilms of BESs, and Dysgonomonas were the predominant microorganisms in biocathode biofilms of OC-BESs. The predominant populations were different among the cathode biofilms and the suspensions. These results demonstrated that applied voltage and biocathode biofilms play important roles in PNP degradation. PMID:29636747

The correspondence between dayside long-period geomagnetic pulsations and the open-closed field line boundary

NASA Astrophysics Data System (ADS)

Pilipenko, V. A.; Kozyreva, O. V.; Lorentzen, D. A.; Baddeley, L. J.

2018-05-01

Long-period pulsations in the nominal Pc5-6 band (periods about 3-15 min) have been known to be a persistent feature of dayside high latitudes. A mixture of broadband Irregular Pulsations at Cusp Latitudes (IPCL) and narrowband P≿5 waves is often observed. The mechanism and origin of IPCL have not been firmly established yet. Magnetopause surface eigenmodes were suggested as a potential source of high-latitude ULF waves with frequencies less than 2 mHz. A ground response to these modes is expected to be beneath the ionospheric projection of the open-closed field line boundary (OCB). To unambiguously resolve a possible association of IPCL with the magnetopause surface modes, multi-instrument observation data from Svalbard have been analyzed. We examine the latitudinal structure of high-latitude pulsations in the Pc5-6 band recorded by magnetometers covering near-cusp latitudes. This structure is compared with an instant location of the equatorward boundary of the cusp aurora, assumed to be a proxy of the OCB. The optical OCB latitude has been identified by an automatic algorithm, using data from the meridian scanning photometer at Longyearbyen, Svalbard. The comparison has shown that the latitudinal maximum of the broadband IPCL maximizes about 2°-3° deeper in the magnetosphere than the OCB optical proxy. Therefore, these pulsations cannot be associated with the ground image of the magnetopause surface modes. It is likely that an essentially non-dipole geometry of field lines and a high variability of the magnetopause region may suppress the excitation efficiency. The obtained result imposes important limitations on possible mechanisms of high-latitude dayside ULF variations.

Interdependence and organizational citizenship behavior: exploring the mediating effect of group cohesion in multilevel analysis.

PubMed

Chen, Chun-Hsi Vivian; Tang, Ya-Yun; Wang, Shih-Jon

2009-12-01

The authors investigated the mechanism of group cohesion in the relationship between (a) task interdependence and goal interdependence and (b) individuals' organizational citizenship behavior (OCB). The authors adopted a multilevel perspective to facilitate understanding of the complex relations among variables. They collected data from 53 supervisors and 270 employees from R&D departments in Taiwan. The authors found that group cohesion fully mediated the effects of task interdependence and goal interdependence on employees' OCB. In addition, task interdependence had a greater effect on group cohesion than did goal interdependence. The authors discuss implications and suggestions for future research.

SuperDARN observations of an unusually contracted ionospheric convection pattern during the recent deep solar minimum

NASA Astrophysics Data System (ADS)

Imber, S. M.; Milan, S. E.; Lester, M.

2012-04-01

We present a long term study, from 1995 - 2011, of the latitude of the Heppner-Maynard Boundary (HMB) determined using the northern hemisphere SuperDARN radars. The HMB represents the equatorward extent of ionospheric convection. We find that the average latitude of the HMB at midnight is 61° magnetic latitude during the solar maximum of 2003, but it moves significantly poleward during solar minimum, averaging 64° latitude during 1996, and 68° during 2010. This poleward motion is observed despite the increasing number of low latitude radars built in recent years as part of the StormDARN network, and so is not an artefact of data coverage. We believe that the recent extreme solar minimum lead to an average HMB location that was further poleward than previous solar cycles. We also calculated the open-closed field line boundary (OCB) from auroral images during the years 2000-2002 and find that on average the HMB is located equatorward of the OCB by ~6°. We suggest that the HMB may be a useful proxy for the OCB when global auroral images are not available.

Viruses and Multiple Sclerosis

PubMed Central

Owens, Gregory P.; Gilden, Don; Burgoon, Mark P.; Yu, Xiaoli; Bennett, Jeffrey L.

2012-01-01

Multiple sclerosis (MS) is a chronic demyelinating disorder of unknown etiology, possibly caused by a virus or virus-triggered immunopathology. The virus might reactivate after years of latency and lyse oligodendrocytes, as in progressive multifocal leukoencephalopathy, or initiate immunopathological demyelination, as in animals infected with Theiler’s murine encephalomyelitis virus or coronaviruses. The argument for a viral cause of MS is supported by epidemiological analyses and studies of MS in identical twins, indicating that disease is acquired. However, the most important evidence is the presence of bands of oligoclonal IgG (OCBs) in MS brain and CSF that persist throughout the lifetime of the patient. OCBs are found almost exclusively in infectious CNS disorders, and antigenic targets of OCBs represent the agent that causes disease. Here, the authors review past attempts to identify an infectious agent in MS brain cells and discuss the promise of using recombinant antibodies generated from clonally expanded plasma cells in brain and CSF to identify disease-relevant antigens. They show how this strategy has been used successfully to analyze antigen specificity in subacute sclerosing panencephalitis, a chronic encephalitis caused by measles virus, and in neuromyelitis optica, a chronic autoimmune demyelinating disease produced by antibodies directed against the aquaporin-4 water channel. PMID:22130640

Contralateral Dpoae Suppression in Humans at Very Low Sound Intensities

NASA Astrophysics Data System (ADS)

Janssen, T.; Gehr, D. D.; Kevanishvili, Z.

2003-02-01

Different functions are attributed to the olivo-cochlear bundle system (OCBS) such as protecting the ear from acoustic injury, improving signal detection in noise, and mediating selective attention. OCBS reflex strength can be evaluated, in animals as well as in humans, by measuring the degree of suppression of an ipsilateral DPOAE by a contralateral sound. The purpose of the study was to evaluate OCBS reflex strength depending on ipsilateral stimulus level, especially at threshold, by means of extrapolated DPOAE I/O-functions. Additionally, DPOAE was measured at near-to-threshold contralateral stimulus levels when using low-level ipsilateral stimulation for investigating possible enhancement of outer hair cell motion in the presence of low-level contralateral sound. The recording of the 2f1-f2 DPOAE in the presence or absence of contralateral sound was performed in normally hearing human subjects at f2 = 2 kHz. DPOAE I/O-functions were measured in a primary tone level range from L2 = 20 to L2 = 65 dB SPL (L1 = 0.4L2 + 39, f2/f1=1.2). Broad-band noise (BBN), narrow-band noise from 1720 to 2320 Hz (NBN), and pure tones (PT) at f2, 2f1-f2, geometric mean of f1 and f2, and 0.1oct + f2 were used for contralateral stimulation. The contralateral stimulus level (Ls) was decreased from 70 down to 10 dB SPL in 10 dB steps. DPOAE suppression was highest at the lowest primary tone level and was more pronounced for BBN and NBN than for pure tones, suggesting a more diffuse than a strong tonotopic organisation of the OCBS. The contralateral stimulus level at which significant DPOAE suppression occurred (p < 0.05) was different for the different stimuli being 20, 40, and 70 dB SPL for BBN, NBN, and pure-tone (f2), respectively. Significant DPOAE suppression to BBN and NBN occurred at Ls well below audiological middle-ear reflex threshold. DPOAE time course was different for Ls below and above middle-ear reflex threshold. Thus, middle-ear muscle contraction is suggested not to be involved in DPOAE suppression at low Ls. No enhancement of DPOAE could be found. The findings suggest the OCBS to be functioning in a more protective way than for improving signal detection in noise.

Investigating gas hydrate as a factor in accretionary margin frontal ridge slope failures and cold seep biogeochemistry

USGS Publications Warehouse

Enkin, R.; Esteban, L.; Haacke, R.; Hamilton, T.S.; Hogg, M.; Lapham, L.; Middleton, G.; Neelands, P.; Pohlman, John W.; Riedel, M; Rose, K.; Schlesinger, A.; Standen, G.; Stephenson, A.; Taylor, S.; Waite, W.; Wang, X.

2008-01-01

During August 2008, a research expedition (2008-007-PGC) was carried out offshore Vancouver Island on the northern Cascadia Margin (Figure 1) to study the role of gas hydrate in slope stability and cold seep biogeochemistry. The cruise was organized by the Geological Survey of Canada (GSC) as part of the Earth Science Sector, Natural Gas Hydrate Program, Natural Resources Canada (NRCan). This international collaboration included McGill University, University of Victoria, the U.S. Geological Survey, Florida State University, and the U.S. Department of Energy.

Organizational citizenship behavior and the quantity and quality of work group performance.

PubMed

Podsakoff, P M; Ahearne, M; MacKenzie, S B

1997-04-01

Despite the widespread interest in the topic of organizational citizenship behaviors (OCBs), little empirical research has tested the fundamental assumption that these forms of behavior improve the effectiveness of work groups or organizations in which they are exhibited. In the present study, the effects of OCBs on the quantity and quality of the performance of 218 people working in 40 machine crews in a paper mill located in the Northeastern United States were examined. The results indicate that helping behavior and sportsmanship had significant effects on performance quantity and that helping behavior had a significant impact on performance quality. However, civic virtue had no effect on either performance measure.

Towards Real-Time Maneuver Detection: Automatic State and Dynamics Estimation with the Adaptive Optimal Control Based Estimator

NASA Astrophysics Data System (ADS)

Lubey, D.; Scheeres, D.

Tracking objects in Earth orbit is fraught with complications. This is due to the large population of orbiting spacecraft and debris that continues to grow, passive (i.e. no direct communication) and data-sparse observations, and the presence of maneuvers and dynamics mismodeling. Accurate orbit determination in this environment requires an algorithm to capture both a system's state and its state dynamics in order to account for mismodelings. Previous studies by the authors yielded an algorithm called the Optimal Control Based Estimator (OCBE) - an algorithm that simultaneously estimates a system's state and optimal control policies that represent dynamic mismodeling in the system for an arbitrary orbit-observer setup. The stochastic properties of these estimated controls are then used to determine the presence of mismodelings (maneuver detection), as well as characterize and reconstruct the mismodelings. The purpose of this paper is to develop the OCBE into an accurate real-time orbit tracking and maneuver detection algorithm by automating the algorithm and removing its linear assumptions. This results in a nonlinear adaptive estimator. In its original form the OCBE had a parameter called the assumed dynamic uncertainty, which is selected by the user with each new measurement to reflect the level of dynamic mismodeling in the system. This human-in-the-loop approach precludes real-time application to orbit tracking problems due to their complexity. This paper focuses on the Adaptive OCBE, a version of the estimator where the assumed dynamic uncertainty is chosen automatically with each new measurement using maneuver detection results to ensure that state uncertainties are properly adjusted to account for all dynamic mismodelings. The paper also focuses on a nonlinear implementation of the estimator. Originally, the OCBE was derived from a nonlinear cost function then linearized about a nominal trajectory, which is assumed to be ballistic (i.e. the nominal optimal control policy is zero for all times). In this paper, we relax this assumption on the nominal trajectory in order to allow for controlled nominal trajectories. This allows the estimator to be iterated to obtain a more accurate nonlinear solution for both the state and control estimates. Beyond these developments to the estimator, this paper also introduces a modified distance metric for maneuver detection. The original metric used in the OCBE only accounted for the estimated control and its uncertainty. This new metric accounts for measurement deviation and a priori state deviations, such that it accounts for all three major forms of uncertainty in orbit determination. This allows the user to understand the contributions of each source of uncertainty toward the total system mismodeling so that the user can properly account for them. Together these developments create an accurate orbit determination algorithm that is automated, robust to mismodeling, and capable of detecting and reconstructing the presence of mismodeling. These qualities make this algorithm a good foundation from which to approach the problem of real-time maneuver detection and reconstruction for Space Situational Awareness applications. This is further strengthened by the algorithm's general formulation that allows it to be applied to problems with an arbitrary target and observer.

Information privacy in organizations: empowering creative and extrarole performance.

PubMed

Alge, Bradley J; Ballinger, Gary A; Tangirala, Subrahmaniam; Oakley, James L

2006-01-01

This article examines the relationship of employee perceptions of information privacy in their work organizations and important psychological and behavioral outcomes. A model is presented in which information privacy predicts psychological empowerment, which in turn predicts discretionary behaviors on the job, including creative performance and organizational citizenship behavior (OCB). Results from 2 studies (Study 1: single organization, N=310; Study 2: multiple organizations, N=303) confirm that information privacy entails judgments of information gathering control, information handling control, and legitimacy. Moreover, a model linking information privacy to empowerment and empowerment to creative performance and OCBs was supported. Findings are discussed in light of organizational attempts to control employees through the gathering and handling of their personal information. (c) 2006 APA, all rights reserved.

Intrathecal oligoclonal IgG bands are infrequently found in neuro-Behçet's disease.

PubMed

Saruhan-Direskeneli, Guher; Yentür, S P; Mutlu, Melike; Shugaiv, E; Yesilot, Nilufer; Kürtüncü, M; Akman-Demir, Gulsen

2013-01-01

Oligoclonal bands (OCB) of immunoglobulins (IgG) in the cerebrospinal fluid (CSF) provides an evidence for the humoral response and have been screened in the CSF and serum of patients revealing 5 different patterns. In this study, patients with Behçet's disease (BD) are screened in a larger sample to potentially provide information about the possible role of CSF oligoclonal immunoglobulins in the diagnosis of this disease. Paired CSF and serum samples from 121 consecutive BD patients with neurological complaints (43 women and 78 men) were included in this study. Parenchymal NBD was diagnosed in 74 patients, and 22 patients had cerebral venous sinus thrombosis (CVST); of the remaining patients, 18 had primary headache disorders not directly associated with BD, and 7 had a cerebrovascular event. OCB of IgG were detected by isoelectric focusing on agarose and immunoblotting of matched serum and CSF sample pairs. Intrathecal production of IgG only is considered positive (Pattern 2 or 3). In the whole group, only 8 patients had OCB in the CSF showing pattern 2. All these positive cases had parenchymal neuro-BD (10.8% positive and 78.4% negative in parenchymal neuro-BD group). All other groups were negative. The rare presence of oligoclonal IgG bands in CSF can be utilized as another laboratory finding in the diagnosis of NBD.

8OCB and 8CB Liquid Crystals Confined in Nanoporous Alumina: Effect of Confinement on the Structure and Dynamics.

PubMed

Selevou, Aristoula; Papamokos, George; Steinhart, Martin; Floudas, George

2017-08-03

The effect of oxygen substitution is studied in two homologous compounds of n-cyanobiphenyls with n = 8 in the bulk and under confinement within self-ordered nanoporous alumina (AAO). Oxygen substitution in 8OCB increases the dipole moment and stabilizes the crystalline, smectic, and nematic phases to higher temperatures relative to 8CB. Within their smectic- A (SmA) phase both 8CB and 8OCB behave as weak viscoelastic solids with low shear moduli reflecting the underlying supramolecular defect structure. Dielectric spectroscopy assisted by DFT calculations identified strong dipolar associations within the isotropic phases characterized by a Kirkwood-Fröhlich interaction parameter, g ∼ 0.36. Dielectric spectroscopy further identified a slow process (∼ kHz) of low dielectric strength. The proximity of this process to the rheology time scale suggests as common origin a cooperative relaxation of the defect structure. Confinement alters the phase diagram by stabilizing certain crystalline phases and by reducing the N-I transition temperature in agreement with surface tension effects. However, the N-I transition seems to retain its first order character. Surface treatment with n-decyltrichlorosilane results in destabilization of the SmA phase at the expense of the N phase. This is consistent with a picture of surface anchored LC molecules at the pore walls that stabilize the nematic phase.

Organizational citizenship behavior and work experience.

PubMed

Kegans, Loyd; McCamey, Randy B; Hammond, Honor

2012-01-01

The authors compared the relationship of elements of the Organizational Citizenship Behavior (OCB) and years of work experience of registered nurses in the state of Texas. Work experience research has shown a relationship between OCB and work experience through mediating roles of various work related characteristics does exist. Work experience is described as the overall length of time in an occupation or workforce. Civic virtue was the only element of organizational citizenship behavior to have a statistically significant correlation with years of work experience in this study. Other elements were found to have no statistically significant correlation with years of work experience. Further research should be undertaken to determine if correlations between these two constructs holds up when the population under study is further refined by job classification, such as management and staff, or industry segment.

NIGHTHAWK - A Program for Modeling Saturated Batch and Column Experiments Incorporating Equilibrium and Kinetic Biogeochemistry

EPA Science Inventory

NIGHTHAWK simulates the fate and transport of biogeochemically reactive contaminants in the saturated subsurface. Version 1.2 supports batch and one- dimensional advective-dispersive-reactive transport involving a number of biogeochemical processes, including: microbially-mediate...

Global Ocean Carbon and Biogeochemistry Coordination

NASA Astrophysics Data System (ADS)

Telszewski, Maciej; Tanhua, Toste; Palacz, Artur

2016-04-01

The complexity of the marine carbon cycle and its numerous connections to carbon's atmospheric and terrestrial pathways means that a wide range of approaches have to be used in order to establish it's qualitative and quantitative role in the global climate system. Ocean carbon and biogeochemistry research, observations, and modelling are conducted at national, regional, and global levels to quantify the global ocean uptake of atmospheric CO2 and to understand controls of this process, the variability of uptake and vulnerability of carbon fluxes into the ocean. These science activities require support by a sustained, international effort that provides a central communication forum and coordination services to facilitate the compatibility and comparability of results from individual efforts and development of the ocean carbon data products that can be integrated with the terrestrial, atmospheric and human dimensions components of the global carbon cycle. The International Ocean Carbon Coordination Project (IOCCP) was created in 2005 by the IOC of UNESCO and the Scientific Committee on Oceanic Research. IOCCP provides an international, program-independent forum for global coordination of ocean carbon and biogeochemistry observations and integration with global carbon cycle science programs. The IOCCP coordinates an ever-increasing set of observations-related activities in the following domains: underway observations of biogeochemical water properties, ocean interior observations, ship-based time-series observations, large-scale ocean acidification monitoring, inorganic nutrients observations, biogeochemical instruments and autonomous sensors and data and information creation. Our contribution is through the facilitation of the development of globally acceptable strategies, methodologies, practices and standards homogenizing efforts of the research community and scientific advisory groups as well as integrating the ocean biogeochemistry observations with the multidisciplinary global ocean observing system. Over the past 4-5 years IOCCP's long standing experience in coordinating biogeochemical observations and data flows globally, resulted in assuming a leadership role during the design and implementation of the biogeochemistry portion of the Framework for Ocean Observing (FOO, 2012). To optimize and enhance the global ocean observing system IOCCP started to implement major elements of the system's approach outlined in the FOO. Starting by setting of ocean observing requirements representing the needs of societal and scientific stakeholders, followed by development of a set of essential ocean variables (EOVs) with spatial and temporal resolution specifications to best meet current demands for data and information services given current and potential national capabilities. The IOCCP works directly with projects and programs programmatically connected to GOOS as well as the WMO-IOC JCOMM to integrate ocean carbon and biogeochemistry observation information into the plans of the Global Climate Observing System in support of the United Nations Framework Convention on Climate Change, the World Summit on Sustainable Development, the Group on Earth Observations, and other international and intergovernmental strategies. We would like to update our partners across disciplines and domains on our short- and long-term strategies as well as learn from their combined experience and knowledge so that our individual activities align more with those undertaken by our counterparts in biological and physical oceanography as well as in terrestrial and atmospheric domains.

Surgery for Conditions of Infectious Etiology in Resource-Limited Countries Affected by Crisis: The Médecins Sans Frontières Operations Centre Brussels Experience

PubMed Central

Sharma, Davina; Hayman, Kate; Dominguez, Lynette; Trelles, Miguel; Saqeb, Sanaulhaq; Kasonga, Cheride; Hangi, Theophile Kubuya; Mupenda, Jerome; Naseer, Aamer; Wong, Evan; Kushner, Adam L.

2015-01-01

Abstract Background: Surgery for infection represents a substantial, although undefined, disease burden in low- and middle-income countries (LMICs). Médecins Sans Frontières–Operations Centre Brussels (MSF-OCB) provides surgical care in LMICs and collects data useful for describing operative epidemiology of surgical need otherwise unmet by national health services. This study aimed to describe the experience of MSF-OCB operations for infections in LMICs. By doing so, the results might aid effective resource allocation and preparation of future humanitarian staff. Methods: Procedures performed in operating rooms at facilities run by MSF-OCB from July 2008 through June 2014 were reviewed. Projects providing specialty care only were excluded. Procedures for infection were described and related to demographics and reason for humanitarian response. Results: A total of 96,239 operations were performed at 27 MSF-OCB sites in 15 countries between 2008 and 2014. Of the 61,177 general operations, 7,762 (13%) were for infections. Operations for skin and soft tissue infections were the most common (64%), followed by intra-abdominal (26%), orthopedic (6%), and tropical infections (3%). The proportion of operations for skin and soft tissue infections was highest during natural disaster missions (p<0.001), intra-abdominal infections during hospital support missions (p<0.001) and orthopedic infections during conflict missions (p<0.001). Conclusion: Surgical infections are common causes for operation in LMICs, particularly during crisis. This study found that infections require greater than expected surgical input given frequent need for serial operations to overcome contextual challenges and those associated with limited resources in other areas (e.g., ward care). Furthermore, these results demonstrate that the pattern of operations for infections is related to nature of the crisis. Incorporating training into humanitarian preparation (e.g., surgical sepsis care, ultrasound-guided drainage procedures) and ensuring adequate resources for the care of surgical infections are necessary components for providing essential surgical care during crisis. PMID:26230672

Investigation of thermal and optical properties of some quartet mixed hydrogen-bonded liquid crystals

NASA Astrophysics Data System (ADS)

Okumuş, Mustafa

2017-11-01

In this study, the thermal and optical properties of quartet mixtures formed at different weight ratios (1:1:1:1 and 1.5:1:1:1) from liquid crystals 4-octyloxy-4‧-cyanobiphenyl (8OCB), 4-hexylbenzoic acid, 4-(octyloxy)benzoic acid and 4-(decyloxy)benzoic acid were investigated by differential scanning calorimeter (DSC) and polarized optic microscopy (POM). The phase transition temperatures of the novel quartet mixtures measured in the DSC experiments are in line with the POM experiments. The experimental results clearly show that the novel liquid crystal mixtures have displayed pure liquid crystalline properties. According to the phase diagram drawn from DSC results, the nematic range of the novel mixture at the eutectic point is larger than the nematic ranges of the components. The mesomorphic structures of produced homolog complex mixtures are found to be smectic and nematic phases. But the smectic phase cannot be observed in the novel complex 1.5:1:1:1 mixture during continuous cooling. The nematic range of the novel complex 1.5:1:1:1 mixture is bigger than the nematic range of the novel complex 1:1:1:1 mixture with increasing 8OCB. Also, the nematic-to-isotropic phase transition temperature decreases with increasing the weight ratio of 8OCB in the complex quartet mixture. Another interesting result is that the produced mixtures are to be like a medical cream at room temperatures. Furthermore, order parameter and thermal stability factor of the transitions are also calculated.

Surgery for children in low-income countries affected by humanitarian emergencies from 2008 to 2014: The Médecins Sans Frontières Operations Centre Brussels experience☆,☆☆,★,★★

PubMed Central

Flynn-O’Brien, Katherine T.; Trelles, Miguel; Dominguez, Lynette; Hassani, Ghulam Hiadar; Akemani, Clemence; Naseer, Aamer; Ntawukiruwabo, Innocent Bagura; Kushner, Adam L.; Rothstein, David H.; Stewart, Barclay T.

2018-01-01

Purpose Pediatric surgical care is deficient in developing countries disrupted by crisis. We aimed to describe pediatric surgical care at Médecins Sans Frontières-Brussels (MSF-OCB) projects to inform resource allocation and define the pediatric-specific skillset necessary for humanitarian surgical teams. Methods Procedures performed by MSF-OCB from July 2008 to December 2014 were reviewed. Project characteristics, patient demographics and clinical data were described. Multivariable logistic regression was performed to determine predictors of perioperative death. Results Of 109,828 procedures, 26,284 were performed for 24,576 children (22% of all procedures). The most common pediatric operative indication was trauma (13,984; 57%). Nine percent of all surgical indications were due to violence (e.g., land mines, firearms, gender-based violence, etc.). The majority of procedures (19,582; 75%) were general surgical, followed by orthopedic (4350; 17%), and obstetric/gynecologic/urologic (2135; 8%). Perioperative death was low (42; 0.17%); independent predictors of death included age <1 year, use of general anesthesia with a definitive airway, and operation during conflict. Conclusion Surgical care for children comprised nearly a quarter of all procedures performed by MSF-OCB between 2008 and 2014. Attention to trauma surgery and infant perioperative care is particularly needed. These findings are important when resourcing projects and training surgical staff for humanitarian missions. PMID:26454469

Surgery for children in low-income countries affected by humanitarian emergencies from 2008 to 2014: The Médecins Sans Frontières Operations Centre Brussels experience.

PubMed

Flynn-O'Brien, Katherine T; Trelles, Miguel; Dominguez, Lynette; Hassani, Ghulam Hiadar; Akemani, Clemence; Naseer, Aamer; Ntawukiruwabo, Innocent Bagura; Kushner, Adam L; Rothstein, David H; Stewart, Barclay T

2016-04-01

Pediatric surgical care is deficient in developing countries disrupted by crisis. We aimed to describe pediatric surgical care at Médecins Sans Frontières-Brussels (MSF-OCB) projects to inform resource allocation and define the pediatric-specific skillset necessary for humanitarian surgical teams. Procedures performed by MSF-OCB from July 2008 to December 2014 were reviewed. Project characteristics, patient demographics and clinical data were described. Multivariable logistic regression was performed to determine predictors of perioperative death. Of 109,828 procedures, 26,284 were performed for 24,576 children (22% of all procedures). The most common pediatric operative indication was trauma (13,984; 57%). Nine percent of all surgical indications were due to violence (e.g., land mines, firearms, gender-based violence, etc.). The majority of procedures (19,582; 75%) were general surgical, followed by orthopedic (4350; 17%), and obstetric/gynecologic/urologic (2135; 8%). Perioperative death was low (42; 0.17%); independent predictors of death included age <1year, use of general anesthesia with a definitive airway, and operation during conflict. Surgical care for children comprised nearly a quarter of all procedures performed by MSF-OCB between 2008 and 2014. Attention to trauma surgery and infant perioperative care is particularly needed. These findings are important when resourcing projects and training surgical staff for humanitarian missions. Copyright © 2016 Elsevier Inc. All rights reserved.

The Effects of Transformational Leadership and Mediating Factors on the Organizational Success Using Structural Equation Modeling: A Case Study.

PubMed

Ravangard, Ramin; Karimi, Sakine; Farhadi, Payam; Sajjadnia, Zahra; Shokrpour, Nasrin

This study was undertaken to determine the effects of transformational leadership (TL) and mediating factors on organizational success (OS) from the administrative, financial, and support employees' perspective in teaching hospitals affiliated with Shiraz University of Medical Sciences using structural equation modeling. Three hundred administrative and financial employees were selected, using stratified sampling proportional to size and simple random sampling. Data were collected using 5 questionnaires and analyzed using SPSS 21.0 and Lisrel 8.5 through Pearson correlation coefficient and path analysis and confirmatory factor analysis methods. Results showed that TL had significant positive effects on the 3 mediating factors, including organizational culture (t = 15.31), organizational citizenship behavior (OCB) (t = 10.06), and social capital (t = 10.25). Also, the organizational culture (t = 2.26), OCB (t = 3.48), and social capital (t = 7.41) had significant positive effects on OS. According to the results, TL had an indirect effect on OS. Therefore, organizations can achieve more success by strengthening organizational culture, OCB, and social capital through using transformational leadership style. Therefore, in order to increase OS, the following recommendations are made: supporting and encouraging new ideas in the organization, promoting teamwork, strengthening intergroup and intragroup relationships, planning to strengthen and enrich the social and organizational culture, considering the promotion of social capital in the employee training, establishing a system to give rewards to the employees performing extra-role activities, providing a suitable environment for creative employees, and so on.

Gendered Help at the Workplace: Implications for Organizational Power Relations.

PubMed

Chernyak-Hai, Lily; Waismel-Manor, Ronit

2018-01-01

One of the most thoroughly studied aspects of prosocial workplace behavior is organizational citizenship behavior (OCB). Yet, the definition of OCB seems to overlook the fact that help-giving acts may be of different types with different consequences for both giver and recipient. The present research explores workplace help-giving behavior by investigating the importance of gender as a factor that facilitates or inhibits specific types of help that empower and disempower independent coping: autonomy- and dependency-oriented help, respectively. A pilot and two following studies were conducted. The pilot study empirically assessed which acts would be clearly perceived by participants as representing both types of help. Then, using the descriptions of these acts, Study 1 examined which type of help would be perceived as most likely to be given by a male or female employee to a male or female colleague in a sample of 226 participants (78% women). Study 2 explored which type of help participants perceived as one they would rather receive from a male or female helper in a sample of 170 participants (65% women). Our findings indicate that male and female respondents who rated men giving help were more likely to expect them to give autonomy-oriented help, especially to women. There were no significant differences in dependency-oriented help. Further, women preferred to receive more autonomy-oriented help than men did, regardless of the help-giver's gender; no significant results were found for men. Implications for OCB and workplace power relations are discussed.

Paying you back or paying me forward: understanding rewarded and unrewarded organizational citizenship behavior.

PubMed

Korsgaard, M Audrey; Meglino, Bruce M; Lester, Scott W; Jeong, Sophia S

2010-03-01

The definition of organizational citizenship behavior (OCB) has evolved from one in which the behavior is unrewarded to one in which rewards play a significant role. As a result, little is known about mechanisms that sustain unrewarded OCB. We used the theory of other orientation to examine 2 mechanisms based on the norm of reciprocity: the obligation to reciprocate the benefits already received from another ("paying you back") and the expected reciprocity that one's actions will stimulate future benefits from another ("paying me forward"). We propose that these mechanisms are more or less influential depending on one's motivational orientation. In 3 experiments using both trait and state indicators of other orientation, we found that the prosocial behavior of individuals higher in other orientation was more strongly influenced by the obligation to reciprocate and less affected by the expectation of reciprocity. 2010 APA, all rights reserved

A simulation study on terahertz absorption of liquid crystal mixture E7

NASA Astrophysics Data System (ADS)

Dong, Jian-qi; Cheng, Wen-qi; Li, Meng-ge; Wang, Kai-li; Chen, Ze-zhang; Ma, Heng

2017-09-01

A simulation work on a broad THz absorption of liquid crystal mixture E7 consisting of 5CB, 7CB, 8OCB and 5CT is reported. Based on the density functional theory, the molecular structures of the monomers were optimized and calculated using the Gaussian package with base set B3LYP and 6-311g. The results indicate that the simulation of the characteristic absorption spectra is accurate compared to the experimental and literature report in the infrared band. By analyzing contribution of the benzene ring, C-O and alkyl bonds on THz absorption, it is found that there are no significant effects from the cyano group and the alkyl radical. The addition of a benzene ring leads to an increase in absorption intensity and redshift. By discussing the atomic mass distribution and the structural symmetry of the monomers, a reason for the strong THz absorption of 8OCB is proposed.

Hydrology and Nitrogen Biogeochemistry in the Hyporheic Zone of a Geomorphically Degraded Urban Stream

EPA Science Inventory

Few studies have investigated the relationship between hydrology and nitrogen biogeochemistry in hyporheic zones of degraded urban streams despite significant national efforts to restore such streams. We examined relationships between hydrology and biogeochemistry in Minebank Ru...

Nursing work stress: the impacts of social network structure and organizational citizenship behavior.

PubMed

Tsang, Seng-Su; Chen, Tzu-Yin; Wang, Shih-Fong; Tai, Hsin-Ling

2012-03-01

The nursing workplace imposes significantly more stress on its employees than other workplace settings. Organizational resources, both physical and psychological, have been recognized in prior studies as important alleviators of nursing workplace stress. Whereas physical resources are less difficult to manipulate because of their tangibility, psychological resources, particularly psychological support from colleagues, are typically not deployed to greatest effect. This article investigated the alleviation of nursing work stress using resources already extant in coworker social networks. Researchers conducted a survey in a dialysis department at a medical center located in Taipei City, Taiwan. This survey measured nurse work stress, satisfaction, organizational citizenship behavior (OCB) and social network structures. Researchers employed UCINET to analyze the network structure data, which were in dyadic matrix format to estimate nurse network centralities and used partial least squares analysis to estimate research construct path coefficients and test extrapolated hypotheses. The level of OCB induced by nurse social ties was satisfactory and did not only directly increased work satisfaction but also alleviated work stress, which indirectly boosted work satisfaction. Findings suggest that managers may be able to use social network analysis to identify persons appropriate to conduct the distribution of organizational resources. Choosing those with multiple social connections can help distribute resources effectively and induce higher OCB levels within the organization. In addition, staff with strong friendship network connections may provide appropriate psychological resources (support) to coworkers. If those with high friendship network centrality receive proper counseling training, they should be in a good position to provide assistance when needed.

Prognostic value of free light chains lambda and kappa in early multiple sclerosis.

PubMed

Voortman, Margarete M; Stojakovic, Tatjana; Pirpamer, Lukas; Jehna, Margit; Langkammer, Christian; Scharnagl, Hubert; Reindl, Markus; Ropele, Stefan; Seifert-Held, Thomas; Archelos, Juan-Jose; Fuchs, Siegrid; Enzinger, Christian; Fazekas, Franz; Khalil, Michael

2017-10-01

Cerebrospinal fluid (CSF) immunoglobulin free light chains (FLC) have been suggested as quantitative alternative to oligoclonal bands (OCB) in the diagnosis of multiple sclerosis (MS). However, little is known on their role in predicting clinical and paraclinical disease progression, particularly in early stages. To assess the prognostic value of FLC in OCB-positive patients with clinically isolated syndrome (CIS) suggestive of MS and early MS. We determined FLC kappa (KFLC) and lambda (LFLC) in CSF and serum by nephelometry in 61 patients (CIS ( n = 48), relapsing-remitting multiple sclerosis ( n = 13)) and 60 non-inflammatory neurological controls. Median clinical follow-up time in CIS was 4.8 years (interquartile range (IQR), 1.5-6.5 years). Patients underwent 3T magnetic resonance imaging (MRI) at baseline and follow-up (median time interval, 2.2 years; IQR, 1.0-3.7 years) to determine T2 lesion load (T2LL) and percent brain volume change (PBVC). CSF FLC were significantly increased in CIS/MS compared to controls (all p < 0.001). A lower KFLC/LFLC CSF ratio was associated with CIS-clinically definite multiple sclerosis (CDMS) conversion (hazard ratio (HR) = 2.89; 95% confidence interval (CI) = 1.17-7.14; p < 0.05). No correlations were found for FLC variables with T2LL or PBVC. Our study confirms increased intrathecal synthesis of FLC in CIS/MS which supports their diagnostic contribution. The KFLC/LFLC CSF ratio appears to have a prognostic value in CIS beyond OCB.

Impacts of mangrove density on surface sediment accretion, belowground biomass and biogeochemistry in Puttalam Lagoon, Sri Lanka

USGS Publications Warehouse

Phillips, D.H.; Kumara, M.P.; Jayatissa, L.P.; Krauss, Ken W.; Huxham, M.

2017-01-01

Understanding the effects of seedling density on sediment accretion, biogeochemistry and belowground biomass in mangrove systems can help explain ecological functioning and inform appropriate planting densities during restoration or climate change mitigation programs. The objectives of this study were to examine: 1) impacts of mangrove seedling density on surface sediment accretion, texture, belowground biomass and biogeochemistry, and 2) origins of the carbon (C) supplied to the mangroves in Palakuda, Puttalam Lagoon, Sri Lanka. Rhizophora mucronata propagules were planted at densities of 6.96, 3.26, 1.93 and 0.95 seedlings m−2along with an unplanted control (0 seedlings m−2). The highest seedling density generally had higher sediment accretion rates, finer sediments, higher belowground biomass, greatest number of fine roots and highest concentrations of C and nitrogen (N) (and the lowest C/N ratio). Sediment accretion rates, belowground biomass (over 1370 days), and C and N concentrations differed significantly between seedling densities. Fine roots were significantly greater compared to medium and coarse roots across all plantation densities. Sulphur and carbon stable isotopes did not vary significantly between different density treatments. Isotope signatures suggest surface sediment C (to a depth of 1 cm) is not derived predominantly from the trees, but from seagrass adjacent to the site.

Effective Management of Ocean Biogeochemistry and Ecological Data: the BCO-DMO Story

NASA Astrophysics Data System (ADS)

Chandler, C. L.; Groman, R. C.; Allison, M. D.; Wiebe, P. H.; Glover, D. M.; Gegg, S. R.

2012-04-01

Data availability expectations of the research community, environmental management decision makers, and funding agency representatives are changing. Consequently, data management practices in many science communities are changing as well. In an effort to improve access to data generated by ocean biogeochemistry and ecological researchers funded by the United States (US) National Science Foundation (NSF) Division of Ocean Sciences (OCE), the Biological and Chemical Oceanography Data Management Office (BCO-DMO) was created in late 2006. Currently, the main BCO-DMO objective is to ensure availability of data resulting from select OCE and Office of Polar Programs (OPP) research awards granted by the US NSF. An important requirement for the BCO-DMO data management system is that it provides open access to data that are supported by sufficient metadata to enable data discovery and accurate reuse. The office manages and serves all types of oceanographic data (in situ, experimental, model results) generated during the research process and contributed by the originating investigators from large national programs and medium-sized collaborative research projects, as well as researchers with single investigator awards. BCO-DMO staff members have made strategic use of standards and use of terms from controlled vocabularies while balancing the need to maintain flexible data ingest systems that accommodate the heterogeneous nature of ocean biogeochemistry and ecological research data. Many of the discrete ocean biogeochemistry data sets managed by BCO-DMO are still acquired manually, often with prototype sensor systems. Data sets such as these that are not "born-digital" present a significant management challenge. Use of multiple levels of term-mappings and development of an ontology has enabled BCO-DMO to incorporate a semantically enabled faceted search into the data access system that will improve data access through enhanced data discovery. BCO-DMO involves an ongoing collaboration between data managers and marine scientists funded by the US NSF. BCO-DMO staff members work with investigators throughout the data life cycle, beginning with the data management plan that is part of the original proposal, during cruise planning and experimental design, through data reporting to meet funding agency requirements and finally to submission of final data sets for publication and final archive in a permanent data center. It is important to note that support from and continued active involvement of the NSF program managers has been a significant contributor to the success of this developing system. URL: http://bco-dmo.org/

Surgical Burn Care by Médecins Sans Frontières-Operations Center Brussels: 2008 to 2014.

PubMed

Stewart, Barclay T; Trelles, Miguel; Dominguez, Lynette; Wong, Evan; Fiozounam, Hervé Tribunal; Hassani, Ghulam Hiadar; Akemani, Clemence; Naseer, Aemer; Ntawukiruwabo, Innocent Bagura; Kushner, Adam L

Humanitarian organizations care for burns during crisis and while supporting healthcare facilities in low-income and middle-income countries. This study aimed to define the epidemiology of burn-related procedures to aid humanitarian response. In addition, operational data collected from humanitarian organizations are useful for describing surgical need otherwise unmet by national health systems. Procedures performed in operating theatres run by Médecins Sans Frontières-Operations Centre Brussels (MSF-OCB) from July 2008 through June 2014 were reviewed. Surgical specialist missions were excluded. Burn procedures were quantified, related to demographics and reason for humanitarian response, and described. A total of 96,239 operations were performed at 27 MSF-OCB projects in 15 countries between 2008 and 2014. Of the 33,947 general surgical operations, 4,280 (11%) were for burns. This proportion steadily increased from 3% in 2008 to 24% in 2014. People receiving surgical care from conflict relief missions had nearly twice the odds of having a burn operation compared with people requiring surgery in communities affected by natural disaster (adjusted odds ratio, 1.94; 95% confidence interval, 1.46-2.58). Nearly 70% of burn procedures were planned serial visits to the theatre. A diverse skill set was required. Unmet humanitarian assistance needs increased US$400 million dollars in 2013 in the face of an increasing number of individuals affected by crisis and a growing surgical burden. Given the high volume of burn procedures performed at MSF-OCB projects and the resource intensive nature of burn management, requisite planning and reliable funding are necessary to ensure quality for burn care in humanitarian settings.

Molecular Approach to Targeted Therapy for Multiple Sclerosis.

PubMed

Sherbet, Gajanan V

2016-01-01

The development and evolution of targeted therapy to any disease require the identification of targets amenable to treatment of patients. Here the pathogenetic signalling systems involved in multiple sclerosis are scrutinised to locate nodes of deregulation and dysfunction in order to devise strategies of drug development for targeted intervention. Oliogoclonal bands (OCB) are isoelectric focusing profiles of immunoglobulins synthesised in the central nervous system. OCBs enable the diagnosis of multiple sclerosis with high sensitivity and specificity and are related to the course of the disease and progression. The OCB patterns can be linked with the expression of angiogenic molecular species. Angiogenic signalling which has also been implicated in demyelination provides the option of using angiogenesis inhibitors in disease control. The PI3K (phosphoinositide 3-kinase)/Akt axis has emerged with a key role in myelination with its demonstrable links with mTOR mediated transcription of downstream target genes. Inflammatory signals and innate and acquired immunity from the activation of NF-κB (nuclear factor κB) responsive genes are considered. NF-κB signalling could be implicated in myelination. The transcription factor STAT (signal transducers and activators of transcription) and the EBV (Epstein- Barr virus) transcription factor BZLF1 contributing significantly to the disease process are a major environmental factor linked to MS. EBV can activate TGF (transforming growth factor) and VEGF (vascular endothelial growth factor) signalling. EBV microRNAs are reviewed as signalling mediators of pathogenesis. Stem cell transplantation therapy has lately gained much credence, so the current status of mesenchymal and hematopoietic stem cell therapy is reviewed with emphasis on the differential expression immune-related genes and operation of signalling systems.

The Relationship between Multiple Commitments and Organizational Citizenship Behavior in Arab and Jewish Culture

ERIC Educational Resources Information Center

Cohen, Aaron

2006-01-01

This study examined the relation between multiple commitments (organizational commitment, occupational commitment, job involvement, and group commitment), ethnicity, and cultural values (individualism/collectivism, power distance, uncertainty avoidance, and masculinity/femininity) with organizational citizenship behaviors (OCB) and in-role…

The newfoundland basin - Ocean-continent boundary and Mesozoic seafloor spreading history

NASA Technical Reports Server (NTRS)

Sullivan, K. D.

1983-01-01

It is pointed out that over the past 15 years there has been considerable progress in the refinement of predrift fits and seafloor spreading models of the North Atlantic. With the widespread acceptance of these basic models has come increasing interest in resolution of specific paleogeographic and kinematic problems. Two such problems are the initial position of Iberia with respect to North America and the geometry and chronology of early (pre-80 m.y.) relative motions between these two plates. The present investigation is concerned with geophysical data from numerous Bedford Institute/Dalhousie University cruises to the Newfoundland Basin which were undrtaken to determine the location of the ocean-continent boundary (OCB) and the Mesozoic spreading history on the western side. From the examination of magnetic data in the Newfoundland Basin, the OCB east of the Grand Banks is defined as the seaward limit of the 'smooth' magnetic domain which characterizes the surrounding continental shelves. A substantial improvement in Iberia-North America paleographic reconstructions is achieved.

Leading by Example: The Case of Leader OCB

ERIC Educational Resources Information Center

Yaffe, Tal; Kark, Ronit

2011-01-01

The importance of leading by personal example or role modeling for effective leadership has been recognized in many leadership theories. However, leaders' ability to influence group behavior through exemplary behavior has received little attention in empirical work. This study explores leading by example through theoretical development and…

The NASA planetary biology internship experience

NASA Technical Reports Server (NTRS)

Hinkle, G.; Margulis, L.

1991-01-01

By providing students from around the world with the opportunity to work with established scientists in the fields of biogeochemistry, remote sensing, and origins of life, among others, the NASA Planetary Biology Internship (PBI) Program has successfully launched many scientific careers. Each year approximately ten interns participate in research related to planetary biology at NASA Centers, NASA-sponsored research in university laboratories, and private institutions. The PBI program also sponsors three students every year in both the Microbiology and Marine Ecology summer courses at the Marine Biological Laboratory. Other information about the PBI Program is presented including application procedure.

Criterion-Focused Approach to Reducing Adverse Impact in College Admissions

ERIC Educational Resources Information Center

Sinha, Ruchi; Oswald, Frederick; Imus, Anna; Schmitt, Neal

2011-01-01

The current study examines how using a multidimensional battery of predictors (high-school grade point average (GPA), SAT/ACT, and biodata), and weighting the predictors based on the different values institutions place on various student performance dimensions (college GPA, organizational citizenship behaviors (OCBs), and behaviorally anchored…

Work Ethic and Academic Performance: Predicting Citizenship and Counterproductive Behavior

ERIC Educational Resources Information Center

Meriac, John P.

2012-01-01

In this study, work ethic was examined as a predictor of academic performance, compared with standardized test scores and high school grade point average (GPA). Academic performance was expanded to include student organizational citizenship behavior (OCB) and student counterproductive behavior, comprised of cheating and disengagement, in addition…

Effects of Organizational Citizenship Behaviors on Selection Decisions in Employment Interviews

ERIC Educational Resources Information Center

Podsakoff, Nathan P.; Whiting, Steven W.; Podsakoff, Philip M.; Mishra, Paresh

2011-01-01

This article reports on an experiment examining the effects of job candidates' propensity to exhibit organizational citizenship behaviors (OCBs) on selection decisions made in the context of a job interview. We developed videos that manipulated candidate responses to interview questions tapping task performance and citizenship behavior content in…

Relationships among Servant Leadership, Organizational Citizenship Behavior, and School Climate in Alabama High Schools

ERIC Educational Resources Information Center

Dixon, David L.

2013-01-01

This study examined the relationship between servant leadership of the principal with Organizational Citizenship Behavior (OCB) and school climate. Servant leadership, a leadership behavior that emphasizes personal growth of followers, has a useful research history in business but limited exposure in public schools. Organizational Citizenship…

Transformational Leadership and Knowledge Sharing: Mediating Roles of Employee's Empowerment, Commitment, and Citizenship Behaviors

ERIC Educational Resources Information Center

Han, Seung Hyun; Seo, Gaeun; Yoon, Seung Won; Yoon, Dong-Yeol

2016-01-01

Purpose: The purpose of this paper is to empirically examine the fundamental process through which transformational leaders play a significant role in employees' knowledge sharing by investigating mediating roles of individual affects, particularly psychological empowerment, organizational commitment and organizational citizenship behavior (OCB).…

The Components and Determinants of Preschool Teacher Organisational Citizenship Behaviour

ERIC Educational Resources Information Center

Oplatka, Izhar; Stundi, Masada

2011-01-01

Purpose: The purpose of this paper is to explore the components and determinants of preschool teacher organisational citizenship behaviours (OCB), i.e. role behaviours that are discretionary, unrewarded and beyond formal-role expectations. Design/methodology/approach: A total of 12 Israeli kindergarten teachers and four supervisors participated in…

Academic Optimism, Organizational Citizenship Behaviors, and Student Achievement at Charter Schools

ERIC Educational Resources Information Center

Guvercin, Mustafa

2013-01-01

The purpose of this study was to examine the relationship among academic optimism, Organizational Citizenship Behaviors (OCBs), and student achievement in college preparatory charter schools. A purposeful sample of elementary school teachers from college preparatory charter schools (N = 226) in southeast Texas was solicited to complete the…

Soil C and N storage and microbial biomass in US southern pine forests: Influence of forest management

Treesearch

J.A. Foote; T.W. Boutton; D.A. Scott

2015-01-01

Land management practices have strong potential to modify the biogeochemistry of forest soils, with implications for the long-term sustainability and productivity of forestlands. The Long-Term Soil Productivity (LTSP) program, a network of 62 sites across the USA and Canada, was initiated to address concerns over possible losses of soil productivity due to soil...

Interactions among hydrogeomorphology, vegetation, and nutrient biogeochemistry in floodplain ecosystems

USGS Publications Warehouse

Noe, G.B.; Shroder, John F.

2013-01-01

Hydrogeomorphic, vegetative, and biogeochemical processes interact in floodplains resulting in great complexity that provides opportunities to better understand linkages among physical and biological processes in ecosystems. Floodplains and their associated river systems are structured by four-dimensional gradients of hydrogeomorphology: longitudinal, lateral, vertical, and temporal components. These four dimensions create dynamic hydrologic and geomorphologic mosaics that have a large imprint on the vegetation and nutrient biogeochemistry of floodplains. Plant physiology, population dynamics, community structure, and productivity are all very responsive to floodplain hydrogeomorphology. The strength of this relationship between vegetation and hydrogeomorphology is evident in the use of vegetation as an indicator of hydrogeomorphic processes. However, vegetation also influences hydrogeomorphology by modifying hydraulics and sediment entrainment and deposition that typically stabilize geomorphic patterns. Nitrogen and phosphorus biogeochemistry commonly influence plant productivity and community composition, although productivity is not limited by nutrient availability in all floodplains. Conversely, vegetation influences nutrient biogeochemistry through direct uptake and storage as well as production of organic matter that regulates microbial biogeochemical processes. The biogeochemistries of nitrogen and phosphorus cycling are very sensitive to spatial and temporal variation in hydrogeomorphology, in particular floodplain wetness and sedimentation. The least-studied interaction is the direct effect of biogeochemistry on hydrogeomorphology, but the control of nutrient availability over organic matter decomposition and thus soil permeability and elevation is likely important. Biogeochemistry also has the more documented but indirect control of hydrogeomorphology through regulation of plant biomass. In summary, the defining characteristics of floodplain ecosystems are determined by the many interactions among physical and biological processes. Conservation and restoration of the valuable ecosystem services that floodplains provide depend on improved understanding and predictive models of interactive system controls and behavior.

Effects of Nonnative Ungulate Removal on Plant Communities and Soil Biogeochemistry in Tropical Forests

NASA Astrophysics Data System (ADS)

Cole, R. J.; Litton, C. M.; Giardina, C. P.; Sparks, J. P.

2014-12-01

Non-native ungulates have substantial impacts on native ecosystems globally, altering both plant communities and soil biogeochemistry. Across tropical and temperate ecosystems, land managers fence and remove non-native ungulates to conserve native biodiversity, a costly management action, yet long-term outcomes are not well quantified. Specifically, knowledge gaps include: (i) the magnitude and time frame of plant community recovery; (ii) the response of non-native invasive plants; and (iii) changes to soil biogeochemistry. In 2010, we established a series of paired ungulate presence vs. removal plots that span a 20 yr. chronosequence in tropical montane wet forests on the Island of Hawaii to quantify the impacts and temporal legacy of feral pig removal on plant communities and soil biogeochemistry. We also compared soil biogeochemistry in targeted areas of low and high feral pig impact. Our work shows that both native and non-native vegetation respond positively to release from top-down control following removal of feral pigs, but species of high conservation concern recover only if initially present at the time of non-native ungulate removal. Feral pig impacts on soil biogeochemistry appear to last for at least 20 years following ungulate removal. We observed that both soil physical and chemical properties changed with feral pig removal. Soil bulk density and volumetric water content decreased while extractable base cations and inorganic N increased in low vs. high feral pig impact areas. We hypothesize that altered soil biogeochemistry facilitates continued invasions by non-native plants, even decades after non-native ungulate removal. Future work will concentrate on comparisons between wet and dry forest ecosystems and test whether manipulation of soil nutrients can be used to favor native vs. non-native plant establishment.

Interactions among hydrogeomorphology, vegetation, and nutrient biogeochemistry in floodplain ecosystems

USGS Publications Warehouse

Noe, G.B.

2013-01-01

Hydrogeomorphic, vegetative, and biogeochemical processes interact in floodplains resulting in great complexity that provides opportunities to better understand linkages among physical and biological processes in ecosystems. Floodplains and their associated river systems are structured by four dimensional gradients of hydrogeomorphology: longitudinal, lateral, vertical, and temporal components. These four dimensions create dynamic hydrologic and geomorphologic mosaics that have a large imprint on the vegetation and nutrient biogeochemistry of floodplains. Plant physiology, population dynamics, community structure, and productivity are all very responsive to floodplain hydrogeomorphology. The strength of this relationship between vegetation and hydrogeomorphology is evident in the use of vegetation as an indicator of hydrogeomorphic processes. However, vegetation also influences hydrogeomorphology by modifying hydraulics and sediment entrainment and deposition that typically stabilize geomorphic patterns. Nitrogen and phosphorus biogeochemistry commonly influence plant productivity and community composition, although productivity is not limited by nutrient availability in all floodplains. Conversely, vegetation influences nutrient biogeochemistry through direct uptake and storage as well as production of organic matter that regulates microbial biogeochemical processes. The biogeochemistries of nitrogen and phosphorus cycling are very sensitive to spatial and temporal variation in hydrogeomorphology, in particular floodplain wetness and sedimentation. The least studied interaction is the direct effect of biogeochemistry on hydrogeomorphology, but the control of nutrient availability over organic matter decomposition and thus soil permeability and elevation is likely important. Biogeochemistry also has the more documented but indirect control of hydrogeomorphology through regulation of plant biomass. In summary, the defining characteristics of floodplain ecosystems are determined by the many interactions among physical and biological processes. Conservation and restoration of the valuable ecosystem services that floodplains provide depends on improved understanding and predictive models of interactive system controls and behavior.

Understanding the health impacts of urbanization in China: A living laboratory for urban biogeochemistry research

NASA Astrophysics Data System (ADS)

Zhu, Y. G.

2015-12-01

China has the largest population in the world, and by 2011, more than 50% of its population are now living in cities. This ongoing societal change has profound impacts on environmental quality and population health. In addition to intensive discharges of waste, urbanization is not only changing the land use and land cover, but also inducing fundamental changes in biogeochemical processes. Unlike biogeochemistry in non-urban environment, the biological component of urban biogeochemistry is dominated by direct human activities, such as air pollution derived from transport, wastewater treatment, garbage disposal and increase in impervious surface etc. Managing urban biogeochemistry will include source control over waste discharge, eco-infrastructure (such as green space and eco-drainage), resource recovery from urban waste stream, and integration with peri-urban ecosystem, particularly with food production system. The overall goal of managing urban biogeochemistry is for human health and wellbeing, which is a global challenge. In this paper, the current status of urban biogeochemistry research in China will be briefly reviewed, and then it will focus on nutrient recycling and waste management, as these are the major driving forces of environmental quality changes in urban areas. This paper will take a holistic view on waste management, covering urban metabolism analysis, technological innovation and integration for resource recovery from urban waste stream, and risk management related to waste recycling and recovery.

The Mediating Role of Affective Commitment in the Relation of the Feedback Environment to Work Outcomes

ERIC Educational Resources Information Center

Norris-Watts, Christina; Levy, Paul E.

2004-01-01

The Feedback Environment, as opposed to the formal performance appraisal process, is comprised of the daily interactions between members of an organization (Steelman, Levy, & Snell, in press). Relations between the feedback environment and work outcome variables such as Organizational Citizenship Behavior (OCB) were examined through the mediating…

Organizational Citizenship of Faculty and Achievement of High School Students

ERIC Educational Resources Information Center

DiPaola, Michael F.; Hoy, Wayne K.

2005-01-01

All successful organizations, including successful high schools, have employees who go beyond their formal job responsibilities and freely give of their time and energy to succeed. Organ was the first to use the phrase "organizational citizenship behavior" (OCB) to denote organizationally beneficial behavior of workers that was not prescribed but…

Leadership, Absenteeism Acceptance, and Ethical Climate as Predictors of Teachers' Absence and Citizenship Behaviors

ERIC Educational Resources Information Center

Shapira-Lishchinsky, Orly; Raftar-Ozery, Tehila

2018-01-01

The goal of this study was to explore the mediating role of 'absenteeism acceptance' between different leadership styles and school ethical climate (SEC) on organizational citizenship behaviors (OCB) and voluntary absence among Israeli teachers. 304 teachers were randomly selected from 304 different mainstream and special-education schools. The…

Returning the Favor: Positive Employee Responses to Supervisor and Peer Support for Training Transfer

ERIC Educational Resources Information Center

Wei Tian, Amy; Cordery, John; Gamble, Jos

2016-01-01

Drawing on social exchange theory and associated notions of reciprocity, we argue that interpersonal support for training transfer in the workplace is associated with increased employee task performance and organizational citizenship behavior (OCB) and reduced turnover intention. We test our hypotheses using survey data from 786 Chinese retail…

Can Heterosexism Harm Organizations? Predicting the Perceived Organizational Citizenship Behaviors of Gay and Lesbian Employees

ERIC Educational Resources Information Center

Brenner, Bradley R.; Lyons, Heather Z.; Fassinger, Ruth E.

2010-01-01

An initial test and validation of a model predicting perceived organizational citizenship behaviors (OCBs) of lesbian and gay employees were conducted using structural equation modeling. The proposed structural model demonstrated acceptable goodness of ft and structural invariance across 2 samples (ns = 311 and 295), which suggested that…

Linking Teacher Competences to Organizational Citizenship Behaviour: The Role of Empowerment

ERIC Educational Resources Information Center

Kasekende, Francis; Munene, John C.; Otengei, Samson Omuudu; Ntayi, Joseph Mpeera

2016-01-01

Purpose: The purpose of this paper is to examine relationship between teacher competences and organizational citizenship behavior (OCB) with empowerment as a mediating factor. Design/methodology/approach: The study took a cross-sectional descriptive and analytical design. Using cluster and random sampling procedures, data were obtained from 383…

Influence of Teacher Empowerment on Teachers' Organizational Commitment, Professional Commitment and Organizational Citizenship Behavior in Schools

ERIC Educational Resources Information Center

Bogler, Ronit; Somech, Anit

2004-01-01

The present study focuses on the relationship between teacher empowerment and teachers' organizational commitment, professional commitment (PC) and organizational citizenship behavior (OCB). It examines which subscales of teacher empowerment can best predict these outcomes. The data were collected through a questionnaire returned by a sample of…

Communication Satisfaction, Organizational Citizenship Behavior and the Relationship to Student Achievement in High Schools

ERIC Educational Resources Information Center

Blanchard, Gayle A.

2012-01-01

This study used a correlational design that allowed the researcher to examine the relationship among communication satisfaction, organizational citizenship behaviors (OCB) and student achievement. High school teachers were surveyed from a convenience sample of 12 school districts in Arizona. Established instruments were used to survey teachers'…

Fairness, Teachers' Non-Task Behavior and Alumni Satisfaction: The Influence of Group Commitment

ERIC Educational Resources Information Center

de Lara, Pablo Zoghbi Manrique

2008-01-01

Purpose--The purpose of this study is to examine the relationship between interactional justice, as a type of organizational justice that reflects the teachers' perceived fairness of supervisor treatment, and their non-task behavior in terms of organizational citizenship behavior (OCB) and deviant workplace behavior (DWB).…

The Effects of Values, Work Centrality, and Organizational Commitment on Organizational Citizenship Behaviors: Evidence from Turkish SMEs

ERIC Educational Resources Information Center

Ucanok, Basak; Karabati, Serdar

2013-01-01

Organizational citizenship behaviors (OCBs) are voluntary contributions of employees not explicitly recognized by the formal reward system and are ultimately critical for sustaining organizational effectiveness (Organ, 1988). The current study aims to investigate the effects of values, work centrality, and organizational commitment on…

Affective Organizational Commitment and Citizenship Behavior: Linear and Non-linear Moderating Effects of Organizational Tenure

ERIC Educational Resources Information Center

Ng, Thomas W. H.; Feldman, Daniel C.

2011-01-01

Utilizing a meta-analytical approach for testing moderating effects, the current study investigated organizational tenure as a moderator in the relation between affective organizational commitment and organizational citizenship behavior (OCB). We observed that, across 40 studies (N = 11,416 respondents), the effect size for the relation between…

Psychological Empowerment as a Mediator between Teachers' Perceptions of Authentic Leadership and Their Withdrawal and Citizenship Behaviors

ERIC Educational Resources Information Center

Shapira-Lishchinsky, Orly; Tsemach, Sigalit

2014-01-01

Purpose: This study explores the mediating role of psychological empowerment on authentic leadership, organizational citizenship behaviors (OCB), and a variety of withdrawal behaviors among teachers, using the psychological model of perceptions-attitudes-behaviors. Research Design: A total of 366 teachers from 23 randomly selected Israeli schools…

Oligoclonal bands predict multiple sclerosis in children with optic neuritis.

PubMed

Heussinger, Nicole; Kontopantelis, Evangelos; Gburek-Augustat, Janina; Jenke, Andreas; Vollrath, Gesa; Korinthenberg, Rudolf; Hofstetter, Peter; Meyer, Sascha; Brecht, Isabel; Kornek, Barbara; Herkenrath, Peter; Schimmel, Mareike; Wenner, Kirsten; Häusler, Martin; Lutz, Soeren; Karenfort, Michael; Blaschek, Astrid; Smitka, Martin; Karch, Stephanie; Piepkorn, Martin; Rostasy, Kevin; Lücke, Thomas; Weber, Peter; Trollmann, Regina; Klepper, Jörg; Häussler, Martin; Hofmann, Regina; Weissert, Robert; Merkenschlager, Andreas; Buttmann, Mathias

2015-06-01

We retrospectively evaluated predictors of conversion to multiple sclerosis (MS) in 357 children with isolated optic neuritis (ON) as a first demyelinating event who had a median follow-up of 4.0 years. Multiple Cox proportional-hazards regressions revealed abnormal cranial magnet resonance imaging (cMRI; hazard ratio [HR] = 5.94, 95% confidence interval [CI] = 3.39-10.39, p < 0.001), presence of cerebrospinal fluid immunoglobulin G oligoclonal bands (OCB; HR = 3.69, 95% CI = 2.32-5.86, p < 0.001), and age (HR = 1.08 per year of age, 95% CI = 1.02-1.13, p = 0.003) as independent predictors of conversion, whereas sex and laterality (unilateral vs bilateral) had no influence. Combined cMRI and OCB positivity indicated a 26.84-fold higher HR for developing MS compared to double negativity (95% CI = 12.26-58.74, p < 0.001). Accordingly, cerebrospinal fluid analysis may supplement cMRI to determine the risk of MS in children with isolated ON. © 2015 American Neurological Association.

Planetary Biology and Microbial Ecology: Molecular Ecology and the Global Nitrogen cycle

NASA Technical Reports Server (NTRS)

Nealson, Molly Stone (Editor); Nealson, Kenneth H. (Editor)

1993-01-01

This report summarizes the results of the Planetary Biology and Molecular Ecology's summer 1991 program, which was held at the Marine Biological Laboratory in Woods Hole, Massachusetts. The purpose of the interdisciplinary PBME program is to integrate, via lectures and laboratory work, the contributions of university and NASA scientists and student interns. The goals of the 1991 program were to examine several aspects of the biogeochemistry of the nitrogen cycle and to teach the application of modern methods of molecular genetics to field studies of organisms. Descriptions of the laboratory projects and protocols and abstracts and references of the lectures are presented.

Subsurface Microbiology and Biogeochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fredrickson, Jim K.; Fletcher, Madilyn

2001-05-01

Jim contributed a chapter to this book, in addition to co-editing it with Madilyn Fletcher. Fredrickson, J. K., and M. Fletcher. (eds.) 2001 Subsurface Microbiology and Biogeochemistry. Wiley-Liss, Inc., New York.

Genetic Regulation of Guanylate-Binding Proteins 2b and 5 during Leishmaniasis in Mice

PubMed Central

Sohrabi, Yahya; Volkova, Valeryia; Kobets, Tatyana; Havelková, Helena; Krayem, Imtissal; Slapničková, Martina; Demant, Peter; Lipoldová, Marie

2018-01-01

Interferon-induced GTPases [guanylate-binding proteins (GBPs)] play an important role in inflammasome activation and mediate innate resistance to many intracellular pathogens, but little is known about their role in leishmaniasis. We therefore studied expression of Gbp2b/Gbp1 and Gbp5 mRNA in skin, inguinal lymph nodes, spleen, and liver after Leishmania major infection and in uninfected controls. We used two different groups of related mouse strains: BALB/c, STS, and CcS-5, CcS-16, and CcS-20 that carry different combinations of BALB/c and STS genomes, and strains O20, C57BL/10 (B10) and B10.O20, OcB-9, and OcB-43 carrying different combinations of O20 and B10 genomes. The strains were classified on the basis of size and number of infection-induced skin lesions as highly susceptible (BALB/c, CcS-16), susceptible (B10.O20), intermediate (CcS-20), and resistant (STS, O20, B10, OcB-9, OcB-43). Some uninfected strains differed in expression of Gbp2b/Gbp1 and Gbp5, especially of Gbp2b/Gbp1 in skin. Uninfected BALB/c and STS did not differ in their expression, but in CcS-5, CcS-16, and CcS-20, which all carry BALB/c-derived Gbp gene-cluster, expression of Gbp2b/Gbp1 exceeds that of both parents. These data indicate trans-regulation of Gbps. Infection resulted in approximately 10× upregulation of Gbp2b/Gbp1 and Gbp5 mRNAs in organs of both susceptible and resistant strains, which was most pronounced in skin. CcS-20 expressed higher level of Gbp2b/Gbp1 than both parental strains in skin, whereas CcS-16 expressed higher level of Gbp2b/Gbp1 than both parental strains in skin and liver. This indicates a trans-regulation present in infected mice CcS-16 and CcS-20. Immunostaining of skin of five strains revealed in resistant and intermediate strains STS, CcS-5, O20, and CcS-20 tight co-localization of Gbp2b/Gbp1 protein with most L. major parasites, whereas in the highly susceptible strain, BALB/c most parasites did not associate with Gbp2b/Gbp1. In conclusion, expression of Gbp2b/Gbp1 and Gbp5 was increased even in organs of clinically asymptomatic resistant mice. It suggests a hidden inflammation, which might contribute to control of persisting parasites. This is supported by the co-localization of Gbpb2/Gbp1 protein and L. major parasites in skin of resistant and intermediate but not highly susceptible mice. PMID:29467757

Long-term monitoring sites and trends at the Marcell Experimental Forest. Chapter 2.

Treesearch

Stephen D. Sebestyen; Carrie Dorrance; Donna M. Olson; Elon S. Verry; Randall K. Kolka; Art E. Elling; Richard Kyllander

2011-01-01

The MEF is one of few long-term research programs on the hydrology and ecology of undrained peatlands in boreal forests. No other site in the Experimental Forest and Range Network of the Forest Service and few sites around the globe have studied the hydrology and biogeochemistry of peatland watersheds with the intensity or longevity as on the MEF. In this chapter, we...

Environmental controls of C, N and P biogeochemistry in peatland pools.

PubMed

Arsenault, Julien; Talbot, Julie; Moore, Tim R

2018-08-01

Pools are common in northern peatlands but studies have seldom focused on their nutrient biogeochemistry, especially in relation to their morphological characteristics and through seasons. We determined the environmental characteristics controlling carbon (C), nitrogen (N) and phosphorus (P) biogeochemistry in pools and assessed their evolution over the course of the 2016 growing season in a subboreal ombrotrophic peatland of eastern Canada. We showed that water chemistry variations in 62 pools were significantly explained by depth (81.9%) and the surrounding vegetation type (14.8%), but not by pool area or shape. Shallow pools had larger dissolved organic carbon (DOC) and total nitrogen (TN) concentrations and lower pH than deep pools, while pools surrounded by coniferous trees had more recalcitrant DOC than pools where vegetation was dominated by mosses. The influence of depth on pool biogeochemistry was confirmed by the seasonal survey of pools of different sizes with 47.1% of the variation in pool water chemistry over time significantly explained. Of this, 67.3% was explained by the interaction between time and pool size and 32.7% by pool size alone. P concentrations were small in all pools all summer long and combined with high N:P ratios, are indicative of P-limitation. Our results show that pool biogeochemistry is influenced by internal processes and highlight the spatial and temporal heterogeneity of nutrient biogeochemistry in ombrotrophic peatlands. Copyright © 2018 Elsevier B.V. All rights reserved.

The Separate, Relative, and Joint Effects of Employee Job Performance Domains on Supervisors' Willingness to Mentor

ERIC Educational Resources Information Center

Lapierre, Laurent M.; Bonaccio, Silvia; Allen, Tammy D.

2009-01-01

The purpose of our study was to further elucidate how employees should behave at work to increase their chances of being mentored by their immediate supervisor. To that end, we experimentally tested how three domains of employee performance [task performance (TP), organizational citizenship behavior (OCB) targeting the supervisor, and…

Job Satisfaction through Organizational Citizenship Behaviour: A Case of University Teachers of Pakistan

ERIC Educational Resources Information Center

Abdullah, Nauman; Akhtar, Mahr Muhammad Saeed

2016-01-01

Teachers' job satisfaction leads to job continuity, which in turn affects teacher performance as well as the effectiveness of their institutions. The purpose of this study was to identify if there was a relationship between the Organizational Citizenship Behavior (OCB) and Job Satisfaction (JS) of teachers since discretionary behaviours have a…

The Principal's Role in Promoting Teachers' Extra-Role Behaviors: Some Insights from Road-Safety Education

ERIC Educational Resources Information Center

Oplatka, Izhar

2013-01-01

The current study aimed to understand the principal's role in promoting or inhibiting the appearance of teacher organizational citizenship behaviors (OCB) in safety education. Based on semistructured interviews with 30 teachers and 10 principals working in the Israeli State Education System, it was found that the principal influences teacher OCB…

ENANTIOSELECTIVE REDUCTIVE TRANSFORMATION OF CHIRAL POLYCHLORINATED BIPHENYLS IN LAKE SEDIMENT MICROCOSMS

EPA Science Inventory

The transformation rates and enantiomeric ratios of two chiral poylchlorinated biphenyls (PCBs), 2,2',3,4',5',6-hexachlorobiphenyl (2,2',3,4',5',6-HCB) and 2,2',3,3',4,4',5,6-octachlorobiphenyl (2,2',3,3',4,4',5,6-OCB), were determined in anaerobic lake sediment microcosms (25oC)...

The Relationship between Spiritual Leadership and Organizational Citizenship Behaviors: A Research on School Principals' Behaviors

ERIC Educational Resources Information Center

Kaya, Ahmet

2015-01-01

This study aimed to examine the relationship between Spiritual Leadership and the dimensions of Organizational Citizenship Behaviors (OCB) of school principals from the perspectives of primary school teachers. A quantitative survey was performed on a sample of teachers (N = 383) from primary schools to study the influence of spiritual leadership…

Investigation of Motivators for Organizational Citizenship Behaviors of Tenured Faculty in California Community Colleges

ERIC Educational Resources Information Center

Phipps, Charmaine

2013-01-01

Purpose: The purpose of this study was to identify which of the motivators of organizational citizenship behavior (OCB) present in the literature are reported as applicable to community college faculty and to examine the nature of those motivators. Methodology: A mixed-methods design was selected for this study. Emphasis was on the qualitative…

Distance in Schools: The Influence of Psychological and Structural Distance from Management on Teachers' Trust in Management, Organisational Commitment, and Organisational Citizenship Behaviour

ERIC Educational Resources Information Center

Thomsen, Maren; Karsten, Sjoerd; Oort, Frans J.

2016-01-01

This study aimed to examine the relationship between teachers' perceived psychological distance and structural distance from management and teachers' affective organisational commitment (AOC) and organisational citizenship behaviour (OCB). Teachers' trust in management was expected to mediate these relationships. Furthermore, the adequacy and…

Slow science: the value of long ocean biogeochemistry records.

PubMed

Henson, Stephanie A

2014-09-28

Sustained observations (SOs) have provided invaluable information on the ocean's biology and biogeochemistry for over 50 years. They continue to play a vital role in elucidating the functioning of the marine ecosystem, particularly in the light of ongoing climate change. Repeated, consistent observations have provided the opportunity to resolve temporal and/or spatial variability in ocean biogeochemistry, which has driven exploration of the factors controlling biological parameters and processes. Here, I highlight some of the key breakthroughs in biological oceanography that have been enabled by SOs, which include areas such as trophic dynamics, understanding variability, improved biogeochemical models and the role of ocean biology in the global carbon cycle. In the near future, SOs are poised to make progress on several fronts, including detecting climate change effects on ocean biogeochemistry, high-resolution observations of physical-biological interactions and greater observational capability in both the mesopelagic zone and harsh environments, such as the Arctic. We are now entering a new era for biological SOs, one in which our motivations have evolved from the need to acquire basic understanding of the ocean's state and variability, to a need to understand ocean biogeochemistry in the context of increasing pressure in the form of climate change, overfishing and eutrophication.

Spectrometry of Pasture Condition and Biogeochemistry in the Central Amazon

NASA Technical Reports Server (NTRS)

Asner, Gregory P.; Townsend, Alan R.; Bustamante, Mercedes M. C.

1999-01-01

Regional analyses of Amazon cattle pasture biogeochemistry are difficult due to the complexity of human, edaphic, biotic and climatic factors and persistent cloud cover in satellite observations. We developed a method to estimate key biophysical properties of Amazon pastures using hyperspectral reflectance data and photon transport inverse modeling. Remote estimates of live and senescent biomass were strongly correlated with plant-available forms of soil phosphorus and calcium. These results provide a basis for monitoring pasture condition and biogeochemistry in the Amazon Basin using spaceborne hyperspectral sensors.

Understanding the Relationship among Leadership Effectiveness, Leader-Member Interactions and Organizational Citizenship Behaviour in Higher Institutions of Learning in Ghana

ERIC Educational Resources Information Center

Alabi, Goski

2012-01-01

The study ascertained the relationship between Quality of Leader-Member-Exchanges (QLMX) and Leadership Effectiveness (LE) with Organizational Citizenship Behaviour (OCB) as an intervening variable for LE in public higher Institutions of learning in Ghana. The study was based on a quantitative cross-sectional design and a regression analysis…

A Quantitative Study of the Relationship between Distributed Leadership and Organizational Citizenship Behavior: Perceptions of Turkish Primary School Teachers

ERIC Educational Resources Information Center

Kilinç, Ali Çagatay

2014-01-01

The purpose of this study was to determine the relationship between primary school teachers' perceptions on distributed leadership and organizational citizenship behaviors (OCBs). A total of 258 teachers employed in 14 primary schools located in Kastamonu, Turkey participated in this study. Data of the study was collected through "Distributed…

Job insecurity and discretionary behaviors: Social exchange perspective versus group value model.

PubMed

Piccoli, Beatrice; De Witte, Hans; Reisel, William D

2017-02-01

This study examines the relationship between job insecurity and discretionary behaviors, that is, organizational citizenship behaviors (OCB) and counterproductive work behaviors (CWB), with the purpose to extend knowledge on the theoretical explanations for these outcomes. Considering the employment relationship with the organization, two different perspectives are suggested and compared in a multiple mediator model, in order to understand the reasons for discretionary behaviors. We draw upon social exchange theory as the basis of psychological contract perceptions and we rely on the group value model to explain organizational justice evaluations. A total of 570 blue-collar workers in Italy participated in our survey. The results show that job insecurity is indirectly related to OCB and CWB through psychological contract breach and organizational injustice. Both mediational mechanisms have equivalent strength in explaining the relationships, namely, they are complementary processes in accounting for both behaviors. These findings suggest that employees' behaviors in job insecure contexts are driven not only by concerns related to the exchange of resources with the organization, but also by evaluations about their value as important members of the group. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Effects of organizational citizenship behaviors on selection decisions in employment interviews.

PubMed

Podsakoff, Nathan P; Whiting, Steven W; Podsakoff, Philip M; Mishra, Paresh

2011-03-01

This article reports on an experiment examining the effects of job candidates' propensity to exhibit organizational citizenship behaviors (OCBs) on selection decisions made in the context of a job interview. We developed videos that manipulated candidate responses to interview questions tapping task performance and citizenship behavior content in 2 administrative positions. Results obtained from 480 undergraduates provided support for our hypotheses that job candidates who exhibited higher levels of helping, voice, and loyalty behaviors were generally rated as more competent, received higher overall evaluations, and received higher salary recommendations than job candidates who exhibited lower levels of these behaviors. These effects held even after taking into account candidate responses regarding task performance. We also found that candidate responses to OCB-related questions tended to have a greater effect on selection decisions for the higher level position (supervisor of administrative personnel) than for the lower level one (administrative assistant). Finally, content analyses of open-ended responses indicated that participants' selection decisions were particularly sensitive to candidates who exhibited low levels of voice and helping behaviors. Implications and future research are discussed. PsycINFO Database Record (c) 2011 APA, all rights reserved.

Is Charismatic Leadership Effective When Workers Are Pressured To Be Good Citizens?

PubMed

Horn, Dewaynna; Mathis, Christopher J; Robinson, Sammie L; Randle, Natasha

2015-01-01

Prior research has explored how employees' perceptions of their leaders impact their work attitudes and behaviors. Studies have shown that charismatic leaders motivate individuals to be more engaged and to exhibit more organizational citizenship behaviors. This study considers how a moderator, citizenship pressure, affects how charismatic leaders might inspire their followers to go above and beyond and be more engaged in their work. Using a sample of 243 workers, this study's findings show that charismatic leadership has a stronger positive effect on job engagement when employees perceive less citizenship pressure. Citizenship pressure did not moderate the relationship between charismatic leadership and organizational citizenship behavior. Implications of this study include an examination of the moderating influence of citizenship pressure, a relatively new construct. Practically, the implications may shed some light on leadership factors that encourage increased effort from employees and greater employee engagement. More specifically, findings suggest that persons are motivated to exhibit more OCBs to meet high expectations of charismatic leaders. However, when seeking engagement, feeling pressure to perform these OCBs has a reverse effect as more job engagement results with less citizenship pressure. Future research suggestions and limitations are discussed.

Relationships between in-role performance and individual values, commitment, and organizational citizenship behavior among Israeli teachers.

PubMed

Cohen, Aaron; Liu, Ying

2011-08-01

This study examines the relationship between (1) individual values, (2) organizational and occupational commitment, and (3) organizational citizenship behavior (OCB) and in-role performance in a sample of 192 teachers employed in 10 secular Jewish schools (response rate of 64%). The results showed that individual values were related to all commitment forms examined here, but contrary to expectations, there was no clear distinction between values that represent conservation and self-transcendence and values that represent openness to change and self-enhancement in terms of their relationship either to commitment or to behavioral outcomes. Likewise, there was no clear distinction between the three dimensions of commitment (affective, continuance, and normative) or two commitment foci (organizational and occupational) in terms of their relationships to different values. Unsurprisingly, the findings showed a strong effect of commitment on OCB and in-role performance. The findings show that both individual values and commitment are concepts that can increase our understanding of employees' behavior in the workplace. We conclude by emphasizing the need for further research on the relationship between values, commitment, and performance and by suggesting some directions for such research.

Remote sensing of vegetation pattern and condition to monitor changes in Everglades biogeochemistry

USGS Publications Warehouse

Jones, John W.

2011-01-01

Ground-based studies of biogeochemistry and vegetation patterning yield process understanding, but the amount of information gained by ground-based studies can be greatly enhanced by efficient, synoptic, and temporally resolute monitoring afforded by remote sensing. The variety of presently available Everglades vegetation maps reflects both the wide range of application requirements and the need to balance cost and capability. More effort needs to be applied to documenting and understanding vegetation distribution and condition as indicators of biogeochemistry and contamination. Ground-based and remote sensing studies should be modified to maximize their synergy and utility for adaptive management.

Slow science: the value of long ocean biogeochemistry records

PubMed Central

Henson, Stephanie A.

2014-01-01

Sustained observations (SOs) have provided invaluable information on the ocean's biology and biogeochemistry for over 50 years. They continue to play a vital role in elucidating the functioning of the marine ecosystem, particularly in the light of ongoing climate change. Repeated, consistent observations have provided the opportunity to resolve temporal and/or spatial variability in ocean biogeochemistry, which has driven exploration of the factors controlling biological parameters and processes. Here, I highlight some of the key breakthroughs in biological oceanography that have been enabled by SOs, which include areas such as trophic dynamics, understanding variability, improved biogeochemical models and the role of ocean biology in the global carbon cycle. In the near future, SOs are poised to make progress on several fronts, including detecting climate change effects on ocean biogeochemistry, high-resolution observations of physical–biological interactions and greater observational capability in both the mesopelagic zone and harsh environments, such as the Arctic. We are now entering a new era for biological SOs, one in which our motivations have evolved from the need to acquire basic understanding of the ocean's state and variability, to a need to understand ocean biogeochemistry in the context of increasing pressure in the form of climate change, overfishing and eutrophication. PMID:25157192

Arctic-COLORS (Coastal Land Ocean Interactions in the Arctic) - a NASA field campaign scoping study to examine land-ocean interactions in the Arctic

NASA Astrophysics Data System (ADS)

Hernes, P.; Tzortziou, M.; Salisbury, J.; Mannino, A.; Matrai, P.; Friedrichs, M. A.; Del Castillo, C. E.

2014-12-01

The Arctic region is warming faster than anywhere else on the planet, triggering rapid social and economic changes and impacting both terrestrial and marine ecosystems. Yet our understanding of critical processes and interactions along the Arctic land-ocean interface is limited. Arctic-COLORS is a Field Campaign Scoping Study funded by NASA's Ocean Biology and Biogeochemistry Program that aims to improve understanding and prediction of land-ocean interactions in a rapidly changing Arctic coastal zone, and assess vulnerability, response, feedbacks and resilience of coastal ecosystems, communities and natural resources to current and future pressures. Specific science objectives include: - Quantify lateral fluxes to the arctic inner shelf from (i) rivers and (ii) the outer shelf/basin that affect biology, biodiversity, biogeochemistry (i.e. organic matter, nutrients, suspended sediment), and the processing rates of these constituents in coastal waters. - Evaluate the impact of the thawing of Arctic permafrost within the river basins on coastal biology, biodiversity and biogeochemistry, including various rates of community production and the role these may play in the health of regional economies. - Assess the impact of changing Arctic landfast ice and coastal sea ice dynamics. - Establish a baseline for comparison to future change, and use state-of-the-art models to assess impacts of environmental change on coastal biology, biodiversity and biogeochemistry. A key component of Arctic-COLORS will be the integration of satellite and field observations with coupled physical-biogeochemical models for predicting impacts of future pressures on Arctic, coastal ocean, biological processes and biogeochemical cycles. Through interagency and international collaborations, and through the organization of dedicated workshops, town hall meetings and presentations at international conferences, the scoping study engages the broader scientific community and invites participation of experts from a wide range of disciplines, to refine our science objectives and outline detailed research strategies needed to attain these objectives. The deliverable will be a comprehensive report to NASA outlining the major scientific questions, and developing the initial study design and implementation concept.

Biogeochemistry of hydrothermally and adjacent non-altered soils

USDA-ARS?s Scientific Manuscript database

As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized seven pedons, developed in hydrothermally and adjacent non-hydrothermally altered andesitic parent material near Reno, NV. Hydrothermally altered soils had considerably lo...

Hydrology and Hyporheic Nitrogen Biogeochemistry in a Geomorphically Degraded Urban Stream

EPA Science Inventory

Few studies have investigated the relationship between hydrology and nitrogen biogeochemistry in hyporheic zones of degraded urban streams despite significant national efforts to restore such streams in attempts to improve the nutrient uptake functions in these ecosystems. We ex...

Remote sensing of vegetation pattern and condition to monitor changes in everglades biogeochemistry

USGS Publications Warehouse

Jones, J.W.

2011-01-01

Ground-based studies of biogeochemistry and vegetation patterning yield process understanding, but the amount of information gained by ground-based studies can be greatly enhanced by efficient, synoptic, and temporally resolute monitoring afforded by remote sensing. The variety of presently available Everglades vegetation maps reflects both the wide range of application requirements and the need to balance cost and capability. More effort needs to be applied to documenting and understanding vegetation distribution and condition as indicators of biogeochemistry and contamination. Ground-based and remote sensing studies should be modified to maximize their synergy and utility for adaptive management. Copyright ?? 2011 Taylor & Francis Group, LLC.

Expanding the Boundaries of Behavioral Integrity in Organizations

DTIC Science & Technology

2010-07-01

2005), emotional exhaustion (Johnson & O’Leary-Kelly, 2003), burnout , job tension (James, 2005), and intentions to engage in OCBs (Andersson...related to stress- related outcomes (i.e., job tension and teacher burnout ), and showed significant relationships with some behavioral outcomes (i.e...on job burnout . Academy of Management Review, 18(4): 621-656. 214 Cording, M. & Simons, T. 2009. Merging under hypocrites: The performance

Organizational Citizenship Behavior at Catholic Institutions of Higher Education: Effects of Organizational Commitment, Interpersonal- and System-Level Trust

ERIC Educational Resources Information Center

Ball, Justin Ashby

2013-01-01

The purpose of this study was to conduct an exploratory investigation of OCB, trust, and commitment among faculty and staff within Catholic IHEs. Faculty and staff from two Catholic IHEs were the focus of the study. Twenty-five schools were randomly selected from the 50 largest Catholic IHEs by undergraduate enrollment, identified from the 2012…

An Analysis of Cesarean Section and Emergency Hernia Ratios as Markers of Surgical Capacity in Low-Income Countries Affected by Humanitarian Emergencies from 2008 - 2014 at Médecins sans Frontières Operations Centre Brussels Projects.

PubMed

Stewart, Barclay; Wong, Evan; Papillon-Smith, Jessica; Trelles Centurion, Miguel Antonio; Dominguez, Lynette; Ao, Supongmeren; Jean-Paul, Basimuoneye Kahutsi; Kamal, Mustafa; Helmand, Rahmatullah; Naseer, Aamer; Kushner, Adam L

2015-03-27

Surgical capacity assessments in low-income countries have demonstrated critical deficiencies. Though vital for planning capacity improvements, these assessments are resource intensive and impractical during the planning phase of a humanitarian crisis. This study aimed to determine cesarean sections to total operations performed (CSR) and emergency herniorrhaphies to all herniorrhaphies performed (EHR) ratios from Médecins Sans Frontières Operations Centre Brussels (MSF-OCB) projects and examine if these established metrics are useful proxies for surgical capacity in low-income countries affected by crisis. All procedures performed in MSF-OCB operating theatres from July 2008 through June 2014 were reviewed. Projects providing only specialty care, not fully operational or not offering elective surgeries were excluded. Annual CSRs and EHRs were calculated for each project. Their relationship was assessed with linear regression. After applying the exclusion criteria, there were 47,472 cases performed at 13 sites in 8 countries. There were 13,939 CS performed (29% of total cases). Of the 4,632 herniorrhaphies performed (10% of total cases), 30% were emergency procedures. CSRs ranged from 0.06 to 0.65 and EHRs ranged from 0.03 to 1.0. Linear regression of annual ratios at each project did not demonstrate statistical evidence for the CSR to predict EHR [F(2,30)=2.34, p=0.11, R2=0.11]. The regression equation was: EHR = 0.25 + 0.52(CSR) + 0.10(reason for MSF-OCB assistance). Surgical humanitarian assistance projects operate in areas with critical surgical capacity deficiencies that are further disrupted by crisis. Rapid, accurate assessments of surgical capacity are necessary to plan cost- and clinically-effective humanitarian responses to baseline and acute unmet surgical needs in LICs affected by crisis. Though CSR and EHR may meet these criteria in 'steady-state' healthcare systems, they may not be useful during humanitarian emergencies. Further study of the relationship between direct surgical capacity improvements and these ratios is necessary to document their role in humanitarian settings.

An Analysis of Cesarean Section and Emergency Hernia Ratios as Markers of Surgical Capacity in Low-Income Countries Affected by Humanitarian Emergencies from 2008 – 2014 at Médecins sans Frontières Operations Centre Brussels Projects

PubMed Central

Stewart, Barclay; Wong, Evan; Papillon-Smith, Jessica; Trelles Centurion, Miguel Antonio; Dominguez, Lynette; Ao, Supongmeren; Jean-Paul, Basimuoneye Kahutsi; Kamal, Mustafa; Helmand, Rahmatullah; Naseer, Aamer; Kushner, Adam L.

2015-01-01

Background: Surgical capacity assessments in low-income countries have demonstrated critical deficiencies. Though vital for planning capacity improvements, these assessments are resource intensive and impractical during the planning phase of a humanitarian crisis. This study aimed to determine cesarean sections to total operations performed (CSR) and emergency herniorrhaphies to all herniorrhaphies performed (EHR) ratios from Médecins Sans Frontières Operations Centre Brussels (MSF-OCB) projects and examine if these established metrics are useful proxies for surgical capacity in low-income countries affected by crisis. Methods: All procedures performed in MSF-OCB operating theatres from July 2008 through June 2014 were reviewed. Projects providing only specialty care, not fully operational or not offering elective surgeries were excluded. Annual CSRs and EHRs were calculated for each project. Their relationship was assessed with linear regression. Results: After applying the exclusion criteria, there were 47,472 cases performed at 13 sites in 8 countries. There were 13,939 CS performed (29% of total cases). Of the 4,632 herniorrhaphies performed (10% of total cases), 30% were emergency procedures. CSRs ranged from 0.06 to 0.65 and EHRs ranged from 0.03 to 1.0. Linear regression of annual ratios at each project did not demonstrate statistical evidence for the CSR to predict EHR [F(2,30)=2.34, p=0.11, R2=0.11]. The regression equation was: EHR = 0.25 + 0.52(CSR) + 0.10(reason for MSF-OCB assistance). Conclusion: Surgical humanitarian assistance projects operate in areas with critical surgical capacity deficiencies that are further disrupted by crisis. Rapid, accurate assessments of surgical capacity are necessary to plan cost- and clinically-effective humanitarian responses to baseline and acute unmet surgical needs in LICs affected by crisis. Though CSR and EHR may meet these criteria in ‘steady-state’ healthcare systems, they may not be useful during humanitarian emergencies. Further study of the relationship between direct surgical capacity improvements and these ratios is necessary to document their role in humanitarian settings. PMID:25905025

Solidification of a liquid crystal: Morphologies and transitions. Ph.D. thesis, Simon Fraser University (Canada)

NASA Astrophysics Data System (ADS)

Hutter, Jeffrey Lee

When a material freezes, the form it takes depends on the solidification conditions. For instance, as the undercooling is increased, one typically sees solidification into less-ordered forms. The resulting growth modes appear to be generic, with qualitative similarities between systems whose microscopic details are quite dissimilar. I have used both optical and atomic-force microscopy to study the transitions between different growth morphologies during the solidification of a particular liquid crystal, 10 OCB. We have observed six different solidification modes, each with a distinct micro and meso structure. The front-velocity-vs.-undercooling curve has a discontinuity in its slope and, in some cases, in the curve itself at mode transitions, suggesting that these transitions are analogous to phase transitions. Such transitions have been seen in other systems, but no general rule has been found that can predict which morphology will be selected. We show that, contrary to intuition and widespread speculation, the fastest-growing mode is not always the one selected. One of the growth modes exhibited by 10 OCB is known as banded spherulitic growth. Spherulites have been seen in a wide variety of materials including minerals, pure elements, polymers, biomolecules, and metal alloys. However, despite a century of study, there is no generally accepted theory of spherulitic growth. In particular, the cause of the concentric banding seen in many spherulites remains a mystery. Our studies of banded spherulites in 10 OCB using both optical and atomic-force microscopy show that the bands are associated with a density modulation and thus are not merely the result of a birefringent effect, as is commonly believed. As the atomic-force microscope (AFM) is a relatively new tool, some time was spent studying its capabilities. We found that because the AFM resolution is largely determined by attractive forces between the tip of the probe and the sample, resolution can be improved by imaging in a suitable liquid medium. We also developed a simple method for calibrating AFM cantilevers--a crucial step in using the AFM to obtain quantitative force data. This work is presented in an appendix.

Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US-CRCM

NASA Astrophysics Data System (ADS)

Buzulukova, Natalia; Goldstein, Jerry; Fok, Mei-Ching; Glocer, Alex; Valek, Phil; McComas, David; Korth, Haje; Anderson, Brian

2018-01-01

During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases (dropouts) in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere-ionosphere (M-I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US-CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensification of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open-closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M-I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global model results enable the reconstruction of a more complete system-level picture of the dropout events and provides insight into M-I coupling aspects that have not previously been investigated.

Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US–CRCM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buzulukova, Natalia; Goldstein, Jerry; Fok, Mei-Ching

During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases ("dropouts") in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere–ionosphere (M–I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US–CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensificationmore » of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open–closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M–I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global model results enable the reconstruction of a more complete system-level picture of the dropout events and provides insight into M–I coupling aspects that have not previously been investigated.« less

Magnetosphere Dynamics During the 14 November 2012 Storm Inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US-CRCM

NASA Technical Reports Server (NTRS)

Buzulukova, Natalia; Goldstein, Jerry; Fok, Mei-Ching; Glocer, Alex; Valek, Phil; McComas, David; Korth, Haje; Anderson, Brian

2018-01-01

During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases ('dropouts') in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere- ionosphere (M-I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US-CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensification of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open-closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M-I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global model results enable the reconstruction of a more complete system-level picture of the dropout events and provides insight into M-I coupling aspects that have not previously been investigated.

Going above and beyond for implementation: the development and validity testing of the Implementation Citizenship Behavior Scale (ICBS).

PubMed

Ehrhart, Mark G; Aarons, Gregory A; Farahnak, Lauren R

2015-05-07

In line with recent research on the role of the inner context of organizations in implementation effectiveness, this study extends research on organizational citizenship behavior (OCB) to the domain of evidence-based practice (EBP) implementation. OCB encompasses those behaviors that go beyond what is required for a given job that contribute to greater organizational effectiveness. The goal of this study was to develop and test a measure of implementation citizenship behavior (ICB) or those behaviors that employees perform that go above and beyond what is required in order to support EBP implementation. The primary participants were 68 supervisors from ten mental health agencies throughout California. Items measuring ICB were developed based on past research on OCB and in consultation with experts on EBP implementation in mental health settings. Supervisors rated 357 of their subordinates on ICB and implementation success. In addition, 292 of the subordinates provided data on self-rated performance, attitudes towards EBPs, work experience, and full-time status. The supervisor sample was randomly split, with half used for exploratory factor analyses and the other half for confirmatory factor analyses. The entire sample of supervisors and subordinates was utilized for analyses assessing the reliability and construct validity of the measure. Exploratory factor analyses supported the proposed two-factor structure of the Implementation Citizenship Behavior Scale (ICBS): (1) Helping Others and (2) Keeping Informed. Confirmatory factor analyses with the other half of the sample supported the factor structure. Additional analyses supported the reliability and construct validity for the ICBS. The ICBS is a pragmatic brief measure (six items) that captures critical behaviors employees perform to go above and beyond the call of duty to support EBP implementation, including helping their fellow employees on implementation-related activities and keeping informed about issues related to EBP and implementation efforts. The ICBS can be used by researchers to better understand the outcomes of improved organizational support for implementation (i.e., implementation climate) and the proximal predictors of implementation effectiveness. The ICBS can also provide insight for organizations, practitioners, and managers by focusing on key employee behaviors that should increase the probability of implementation success.

Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US–CRCM

DOE PAGES

Buzulukova, Natalia; Goldstein, Jerry; Fok, Mei-Ching; ...

2018-01-25

During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases ("dropouts") in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere–ionosphere (M–I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US–CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensificationmore » of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open–closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M–I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global model results enable the reconstruction of a more complete system-level picture of the dropout events and provides insight into M–I coupling aspects that have not previously been investigated.« less

FROM THE FOREST TO THE SEA AND BACK AGAIN: MARINE INPUTS AND TERRESTRIAL BIOGEOCHEMISTRY IN THE PACIFIC NORTHWEST

EPA Science Inventory

Most models of watershed biogeochemistry include the movement of materials from land to rivers and eventually the ocean. Few conceptual views, however, acknowledge the influence of materials derived from the ocean on terrestrial ecosystem processes. Based on spatial patterns of...

WATERSHED BIOGEOCHEMISTRY IN THE OREGON COAST RANGE: THE ROLE OF RED ALDER AND SALMON

EPA Science Inventory

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species influence is the role of N2-fixing red alder (Alnus rubra) in the biogeochemistry of Pacific Northwest forests. T...

From the forest to the sea and back again: Biogeochemistry in the Oregon Coast Range

EPA Science Inventory

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species influence is the role of N2-fixing red alder (Alnus rubra) in the biogeochemistry of Pacific Northwest forests. A...

Salt additions increase soil nitrate leaching: Implications for near-coastal watershed biogeochemistry

EPA Science Inventory

Deposition of sea salt aerosols is often elevated along the coast relative to inland areas, yet little is known about the effects of this deposition on terrestrial ecosystem biogeochemistry. Spatial patterns of stream chemistry in the Oregon Coast Range led us to hypothesize tha...

Chapter 2: Sampling strategies in forest hydrology and biogeochemistry

Treesearch

Roger C. Bales; Martha H. Conklin; Branko Kerkez; Steven Glaser; Jan W. Hopmans; Carolyn T. Hunsaker; Matt Meadows; Peter C. Hartsough

2011-01-01

Many aspects of forest hydrology have been based on accurate but not necessarily spatially representative measurements, reflecting the measurement capabilities that were traditionally available. Two developments are bringing about fundamental changes in sampling strategies in forest hydrology and biogeochemistry: (a) technical advances in measurement capability, as is...

Tourette's syndrome in a special education population: a pilot study involving a single school district.

PubMed

Kurlan, R; Whitmore, D; Irvine, C; McDermott, M P; Como, P G

1994-04-01

To determine whether children requiring special education represent a high-risk group for identifying Tourette's syndrome (TS), we performed direct examinations for the presence of tics in 35 special education and 35 regular classroom students from a single school district. Of the special education students, nine (26%) had definite or probable tics as compared with only two (6%) of the regular classroom students. About one-third of the students with tics currently meet diagnostic criteria for TS and probably more will do so in the future. About one-half of the subjects with tics have evidence of obsessive-compulsive behavior (OCB) or an attention-deficit hyperactivity disorder (ADHD). For three randomly selected students with definite tics, direct examinations of first-degree relatives revealed the presence of tics in all families. Subjects to the limitations of this pilot study, we conclude that TS and related tic disorders are commonly associated with the need for special education in this single school district. TS might also be an important contributor to school problems in the childhood population at large and may be a highly prevalent condition. In addition, we conclude that childhood tics are associated with OCB and ADHD, are genetically determined, and are part of the TS clinical spectrum.

Biogeochemistry of a soil catena in the eastern Sierra Nevada Range, NV

USDA-ARS?s Scientific Manuscript database

As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized five pedons at Little Valley, NV, at the eastern edge of the Sierra Nevada. Developed largely from granite, the catena encompassed five pedons, which from high to low elev...

Nitrogen Biogeochemistry in Urban Wetlands and Bioretention Systems: The Evolving Roles of Urban Stormwater Management Practices.

EPA Science Inventory

Description for AGU 2009 Fall Meeting, San Francisco, CA, December 14-18, 2009. I have been invited to speak in a session hosted by the Biogeosciences section of the American Geophysical Union. The session is titled “Biogeochemistry of Soil and Surface Water in Rural, Suburban ...

Linking LiDAR with streamwater biogeochemistry in coastal temperate rainforest watersheds

Treesearch

Jason B. Fellman; Brian Buma; Eran Hood; Richard T. Edwards; David V. D’Amore

2017-01-01

The goal of this study was to use watershed characteristics derived from light detection and ranging (LiDAR) data to predict stream biogeochemistry in Perhumid Coastal Temperate Rainforest (PCTR) watersheds. Over a 2-day period, we sampled 37 streams for concentrations of dissolved C, N, P, major cations, and measures of dissolved organic matter quality (specific...

Student Presentations of Case Studies to Illustrate Core Concepts in Soil Biogeochemistry

ERIC Educational Resources Information Center

Duckworth, Owen W.; Harrington, James M.

2012-01-01

Soil biogeochemistry, a discipline that explores the chemical speciation and transformations of elements in soils and the relationships between soils and global biogeochemical cycles, is becoming a popular course offering because it unites themes from a number of other courses. In this article, we present a set of case studies that have been used…

The ecology and biogeochemistry of stream biofilms.

PubMed

Battin, Tom J; Besemer, Katharina; Bengtsson, Mia M; Romani, Anna M; Packmann, Aaron I

2016-04-01

Streams and rivers form dense networks, shape the Earth's surface and, in their sediments, provide an immensely large surface area for microbial growth. Biofilms dominate microbial life in streams and rivers, drive crucial ecosystem processes and contribute substantially to global biogeochemical fluxes. In turn, water flow and related deliveries of nutrients and organic matter to biofilms constitute major constraints on microbial life. In this Review, we describe the ecology and biogeochemistry of stream biofilms and highlight the influence of physical and ecological processes on their structure and function. Recent advances in the study of biofilm ecology may pave the way towards a mechanistic understanding of the effects of climate and environmental change on stream biofilms and the biogeochemistry of stream ecosystems.

Development of BFMCOUPLER (v1.0), the coupling scheme that links the MITgcm and BFM models for ocean biogeochemistry simulations

NASA Astrophysics Data System (ADS)

Cossarini, Gianpiero; Querin, Stefano; Solidoro, Cosimo; Sannino, Gianmaria; Lazzari, Paolo; Di Biagio, Valeria; Bolzon, Giorgio

2017-04-01

In this paper, we present a coupling scheme between the Massachusetts Institute of Technology general circulation model (MITgcm) and the Biogeochemical Flux Model (BFM). The MITgcm and BFM are widely used models for geophysical fluid dynamics and for ocean biogeochemistry, respectively, and they benefit from the support of active developers and user communities. The MITgcm is a state-of-the-art general circulation model for simulating the ocean and the atmosphere. This model is fully 3-D (including the non-hydrostatic term of momentum equations) and is characterized by a finite-volume discretization and a number of additional features enabling simulations from global (O(107) m) to local scales (O(100) m). The BFM is a biogeochemical model based on plankton functional type formulations, and it simulates the cycling of a number of constituents and nutrients within marine ecosystems. The online coupling presented in this paper is based on an open-source code, and it is characterized by a modular structure. Modularity preserves the potentials of the two models, allowing for a sustainable programming effort to handle future evolutions in the two codes. We also tested specific model options and integration schemes to balance the numerical accuracy against the computational performance. The coupling scheme allows us to solve several processes that are not considered by each of the models alone, including light attenuation parameterizations along the water column, phytoplankton and detritus sinking, external inputs, and surface and bottom fluxes. Moreover, this new coupled hydrodynamic-biogeochemical model has been configured and tested against an idealized problem (a cyclonic gyre in a mid-latitude closed basin) and a realistic case study (central part of the Mediterranean Sea in 2006-2012). The numerical results consistently reproduce the interplay of hydrodynamics and biogeochemistry in both the idealized case and Mediterranean Sea experiments. The former reproduces correctly the alternation of surface bloom and deep chlorophyll maximum dynamics driven by the seasonal cycle of winter vertical mixing and summer stratification; the latter simulates the main basin-wide and mesoscale spatial features of the physical and biochemical variables in the Mediterranean, thus demonstrating the applicability of the new coupled model to a wide range of ocean biogeochemistry problems.

Influence of Organizational Culture on the Relationship Between Psychological Contracts and Organizational Citizenship Behavior

DTIC Science & Technology

2006-03-01

Vroom, VV. H. (1964). Work and motivation. New York, NY: Wiley. Yeung, A., Brockbank , J.W., & Ulrich , D.O. (1991). Organizational culture and human...Podsakoff, Ahearne, & MacKenzie, 1997 ) that OCB is a critical area that must be researched, since these contributions may be essential to the...Ahearne & MacKenzie, 1997 ) have also found 18 organizational citizenship behavior to be essential to effective functioning of an organization. For

The biogeochemistry of phosphorus across an alpine topographic/snow gradient

Treesearch

M. I. Litaor; T. R. Seastedt; M. D. Walker; M. Carbone; A. Townsend

2005-01-01

Phosphorus (P) availability has generally been assumed to be the limiting or co-limiting factor for plant growth in alpine environments. To test this assumption, the biogeochemistry of phosphorus (P) along an alpine topographic/snow gradient located on Niwot Ridge, Colorado Front Range was studied in the context of P limitation for plant growth. We measured the various...

Impact of Antarctic Polar Front Variability on Southern Ocean Biogeochemistry

NASA Astrophysics Data System (ADS)

Freeman, N. M.; Lovenduski, N. S.; Gent, P. R.

2016-12-01

The Antarctic Polar Front (PF) is an important biogeochemical divide in the Southern Ocean, often coinciding with sharp gradients in silicate and nitrate concentration at the surface. Variability in the PF has the potential to influence Southern Ocean biogeochemistry and biological productivity both locally and at the basin scale. Characterizing PF variability is important for contextualizing recent biogeochemical observations from ORCAS, SOCCOM, and the Drake Passage time-series, as well as for understanding how anthropogenic change is influencing Southern Ocean biogeochemistry. Here, we employ a suite of remote sensing observations and output from the Community Earth System Model (CESM) to better understand the relationship between the PF and local biogeochemistry in the Southern Ocean. Using microwave SST measurements spanning 2002-2014 that avoid cloud contamination, we show that the PF has shifted northward (southward) in the Pacific (Indian) sector and intensified at nearly all longitudes along its circumpolar path. We identify the PF in CESM at both coarse (1°x1°) and fine (0.1°x0.1°) horizontal resolutions using temperature and silicate gradient maxima, and quantify its spatial and temporal variability. We further investigate co-variance between the position and intensity of the PF and local phytoplankton community structure.

Phytozome Comparative Plant Genomics Portal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodstein, David; Batra, Sajeev; Carlson, Joseph

2014-09-09

The Dept. of Energy Joint Genome Institute is a genomics user facility supporting DOE mission science in the areas of Bioenergy, Carbon Cycling, and Biogeochemistry. The Plant Program at the JGI applies genomic, analytical, computational and informatics platforms and methods to: 1. Understand and accelerate the improvement (domestication) of bioenergy crops 2. Characterize and moderate plant response to climate change 3. Use comparative genomics to identify constrained elements and infer gene function 4. Build high quality genomic resource platforms of JGI Plant Flagship genomes for functional and experimental work 5. Expand functional genomic resources for Plant Flagship genomes

BOREAS TGB-5 CO2, CH4 and CO Chamber Flux Data Over the NSA

NASA Technical Reports Server (NTRS)

Burke, Roger; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Zepp, Richard

2000-01-01

The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-5) team collected a variety of trace gas concentration and flux measurements at several NSA sites. This data set contains carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) chamber flux measurements conducted in 1994 at upland forest sites that experienced stand-replacement fires. These measurements were acquired to understand the impact of fires on soil biogeochemistry and related changes in trace gas exchange in boreal forest soils. Relevant ancillary data, including data concerning the soil temperature, solar irradiance, and information from nearby un-burned control sites, are included to provide a basis for modeling the regional impacts of fire and climate changes on trace gas biogeochemistry. The data are provided in tabular ASCII files.

Annual and solar cycle dependencies of SuperDARN scatter occurrence and ionospheric convection measurements

NASA Astrophysics Data System (ADS)

Lester, M.; Imber, S. M.; Milan, S. E.

2012-12-01

The Super Dual Auroral Radar Network (SuperDARN) provides a long term data series which enables investigations of the coupled magnetosphere-ionosphere system. The network has been in existence essentially since 1995 when 6 radars were operational in the northern hemisphere and 4 in the southern hemisphere. We have been involved in an analysis of the data over the lifetime of the project and present results here from two key studies. In the first study we calculated the amount of ionospheric scatter which is observed by the radars and see clear annual and solar cycle variations in both hemispheres. The recent extended solar minimum also produces a significant effect in the scatter occurrence. In the second study, we have determined the latitude of the Heppner-Maynard Boundary (HMB) using the northern hemisphere SuperDARN radars. The HMB represents the equatorward extent of ionospheric convection for the interval 1996 - 2011. We find that the average latitude of the HMB at midnight is 61° magnetic latitude during solar the maximum of 2003, but it moves significantly poleward during solar minimum, averaging 64° latitude during 1996, and 68° during 2010. This poleward motion is observed despite the increasing number of low latitude radars built in recent years as part of the StormDARN network, and so is not an artefact of data coverage. We believe that the recent extreme solar minimum led to an average HMB location that was further poleward than the previous solar cycle. We have also calculated the Open-Closed field line Boundary (OCB) from auroral images during a subset of the interval (2000 - 2002) and find that on average the HMB is located equatorward of the OCB by ~7o. We suggest that the HMB may be a useful proxy for the OCB when global images are not available. The work presented in this paper has been undertaken as part of the European Cluster Assimilation Technology (ECLAT) project which is funded through the EU FP7 programme and involves groups at Leicester, Helsinki, Uppsala, FMI, Graz and St. Petersburg. The aim of the project is to provide additional data sets, primarily ground based data, to the Cluster Active Archive, and its successor the Cluster Final Archive, in order to enhance the scientific productivity of the archives.

Biogeochemistry Science and Education. Part One: Using Non-Traditional Stable Isotopes as Environmental Tracers. Part Two: Identifying and Measuring Undergraduate Misconceptions in Biogeochemistry

ERIC Educational Resources Information Center

Mead, Chris

2014-01-01

This dissertation is presented in two sections. First, I explore two methods of using stable isotope analysis to trace environmental and biogeochemical processes. Second, I present two related studies investigating student understanding of the biogeochemical concepts that underlie part one. Fe and Hg are each biogeochemically important elements in…

CSF profile in primary progressive multiple sclerosis: Re-exploring the basics.

PubMed

Abdelhak, Ahmed; Hottenrott, Tilman; Mayer, Christoph; Hintereder, Gudrun; Zettl, Uwe K; Stich, Oliver; Tumani, Hayrettin

2017-01-01

The aim of this study was to report the basic cerebrospinal fluid (CSF) profile in patients with primary progressive multiple sclerosis (PPMS). The results of CSF analysis from 254 patients with PPMS were collected at four university hospitals in Germany. Routine CSF parameters and different indices of intrathecal immunoglobulin synthesis were evaluated. We assessed possible correlations between the various CSF parameters and the expanded disability status scale (EDSS) both at the time of lumbar puncture and during the course of the disease. The median cell count and albumin concentration in the CSF did not deviate from normal values. The CSF-serum albumin-quotient (QALB) was elevated in 29.6% of the patients, while intrathecal immunoglobulin G (IgG) oligoclonal bands (OCBs) were detected in 91.1% of the patients. CSF-lactate levels as well as local IgM- and IgA-synthesis were correlated with the yearly disease progression rate, as assessed by EDSS. We present the results of the hitherto largest and most detailed CSF biomarker profile in a cohort of 254 patients with PPMS. As reported previously, OCBs are the most sensitive marker for intrathecal IgG synthesis. CSF-lactate concentrations are positively correlated with the progression rate, which might suggest that mitochondrial dysfunction plays a relevant role in PPMS. The negative correlation between intrathecally produced IgM and IgA and disease progression may indicate their hitherto unexplored protective role.

Contrasting impacts of light reduction on sediment biogeochemistry in deep- and shallow-water tropical seagrass assemblages (Green Island, Great Barrier Reef).

PubMed

Schrameyer, Verena; York, Paul H; Chartrand, Kathryn; Ralph, Peter J; Kühl, Michael; Brodersen, Kasper Elgetti; Rasheed, Michael A

2018-05-01

Seagrass meadows increasingly face reduced light availability as a consequence of coastal development, eutrophication, and climate-driven increases in rainfall leading to turbidity plumes. We examined the impact of reduced light on above-ground seagrass biomass and sediment biogeochemistry in tropical shallow- (∼2 m) and deep-water (∼17 m) seagrass meadows (Green Island, Australia). Artificial shading (transmitting ∼10-25% of incident solar irradiance) was applied to the shallow- and deep-water sites for up to two weeks. While above-ground biomass was unchanged, higher diffusive O 2 uptake (DOU) rates, lower O 2 penetration depths, and higher volume-specific O 2 consumption (R) rates were found in seagrass-vegetated sediments as compared to adjacent bare sand (control) areas at the shallow-water sites. In contrast, deep-water sediment characteristics did not differ between bare sand and vegetated sites. At the vegetated shallow-water site, shading resulted in significantly lower hydrogen sulphide (H 2 S) levels in the sediment. No shading effects were found on sediment biogeochemistry at the deep-water site. Overall, our results show that the sediment biogeochemistry of shallow-water (Halodule uninervis, Syringodium isoetifolium, Cymodocea rotundata and C. serrulata) and deep-water (Halophila decipiens) seagrass meadows with different species differ in response to reduced light. The light-driven dynamics of the sediment biogeochemistry at the shallow-water site could suggest the presence of a microbial consortium, which might be stimulated by photosynthetically produced exudates from the seagrass, which becomes limited due to lower seagrass photosynthesis under shaded conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biogeochemical Transformations in the History of the Ocean.

PubMed

Lenton, Timothy M; Daines, Stuart J

2017-01-03

The ocean has undergone several profound biogeochemical transformations in its 4-billion-year history, and these were an integral part of the coevolution of life and the planet. This review focuses on changes in ocean redox state as controlled by changes in biological activity, nutrient concentrations, and atmospheric O 2 . Motivated by disparate interpretations of available geochemical data, we aim to show how quantitative modeling-spanning microbial mats, shelf seas, and the open ocean-can help constrain past ocean biogeochemical redox states and show what caused transformations between them. We outline key controls on ocean redox structure and review pertinent proxies and their interpretation. We then apply this quantitative framework to three key questions: How did the origin of oxygenic photosynthesis transform ocean biogeochemistry? How did the Great Oxidation transform ocean biogeochemistry? And how was ocean biogeochemistry transformed in the Neoproterozoic-Paleozoic?

Preface - 'Biogeochemistry-ecosystem interaction on changing continental margins in the Anthropocene'

NASA Astrophysics Data System (ADS)

Liu, K.-K.; Emeis, Kay-Christian; Levin, Lisa A.; Naqvi, Wajih; Roman, Michael

2015-01-01

This special issue is a product of Workshop 1 of IMBIZO III held in Goa, India in January 2013 (Bundy et al., 2013). This IMBIZO (a Zulu word for gathering) has been organized by IMBER (Integrated Marine Biogeochemistry and Ecosystem Research) biannually since 2008. It employs a format of three concurrent but interacting workshops designed to synthesize information on topical research areas in marine science. Workshop 1 addressed the issue, "Biogeochemistry-ecosystem interaction in changing continental margins," which belongs to the purview of the Continental Margins Working Group (CMWG), co-sponsored by IMBER and LOICZ (Land-Ocean Interaction in the Coastal Zone). As a way to explore the emerging issues that concern the CMWG, the workshop had attracted 25 talks and 18 posters that explored the following topics: Human impacts on continental margins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hettiarachchi, Ganga M.; Donner, Erica; Doelsch, Emmanuel

To understand the biogeochemistry of nutrients and contaminants in environmental media, their speciation and behavior under different conditions and at multiple scales must be determined. Synchrotron radiation-based X-ray techniques allow scientists to elucidate the underlying mechanisms responsible for nutrient and contaminant mobility, bioavailability, and behavior. The continuous improvement of synchrotron light sources and X-ray beamlines around the world has led to a profound transformation in the field of environmental biogeochemistry and, subsequently, to significant scientific breakthroughs. Following this introductory paper, this special collection includes 10 papers that either present targeted reviews of recent advancements in spectroscopic methods that are applicablemore » to environmental biogeochemistry or describe original research studies conducted on complex environmental samples that have been significantly enhanced by incorporating synchrotron radiation-based X-ray technique(s). We believe that the current focus on improving the speciation of ultra-dilute elements in environmental media through the ongoing optimization of synchrotron technologies (e.g., brighter light sources, improved monochromators, more efficient detectors) will help to significantly push back the frontiers of environmental biogeochemistry research. As many of the relevant techniques produce extremely large datasets, we also identify ongoing improvements in data processing and analysis (e.g., software improvements and harmonization of analytical methods) as a significant requirement for environmental biogeochemists to maximize the information that can be gained using these powerful tools.« less

STS 41-G crew prepares to leave Operations and checkout bldg for launch

NASA Image and Video Library

1984-10-05

41G-90081 / S17-90081 (5 Oct 1984) --- The seven member crew leaves the Operations and Checkout Building (OCB) to take a van ride to the launch pad. Leading the way is Kathryn D. Sullivan followed in file by Robert L. Crippen, Paul D. Scully-Power and Jon A. McBride. On the right side are Sally K. Ride, David C. Leestma and Marc Garneau. Trailing the crew are George W. S. Abbey, Richard Nygren, Paul Bulver, and Paul J. Weitz.

International Workshop on Methane Hydrate Research and Development (4th) Held in Victoria, British Columbia, Canada on May 9-11, 2005

DTIC Science & Technology

2006-12-27

Research at the University of Victoria, Victoria, British Columbia, Canada; the Marine Biogeochemistry Section at the Naval Research Laboratory...was organized by the Centre for Earth and Ocean Research at the University of Victoria, Victoria, British Columbia, Canada; the Marine ...Richard Coffin, Marine Biogeochemistry Section, US Naval Research Laboratory, Washington DC, USA, rcoffin@ccs.nrl.navy.mil Dr. Bjørn Kvamme

Biogeochemistry and ecology of terrestrial ecosystems of Amazonia

NASA Astrophysics Data System (ADS)

Malhi, Yadvinder; Davidson, Eric A.

The last decade of research associated with the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) has led to substantial advances in our understanding of the biogeochemistry and ecology of Amazonian forests and savannas, in particular in relation to the carbon cycle of Amazonia. In this chapter, we present a synthesis of results and ideas that are presented in more detail in subsequent chapters, drawing together evidence from studies of forest ecology, ecophysiology, trace gas fluxes and atmospheric flux towers, large-scale rainfall manipulation experiments and soil surveys, satellite remote sensing, and quantification of carbon and nutrient stocks and flows. The studies have demonstrated the variability of the functioning and biogeochemistry of Amazonian forests at a range of spatial and temporal scales, and they provide clues as to how Amazonia will respond to ongoing direct pressure and global atmospheric change. We conclude by highlighting key questions for the next decade of research to address.

Planetary ecology; Proceedings of the Sixth International Symposium on Environmental Biogeochemistry, Santa Fe, NM, October 10-14, 1983

NASA Technical Reports Server (NTRS)

Caldwell, D. E. (Editor); Brierley, J. A. (Editor); Brierley, C. L. (Editor)

1985-01-01

Topics presented include biological evolution and planetary chemistry; C-1 compounds; transport, deposition, and weathering; sulfur transformations; ground water; transformation processes for nitrogen oxides; and soils. Papers are presented on immunological studies on the organic matrix of recent and fossil invertebrate shells; biogenic gases in sediments deposited since Miocene times on the Walvis Ridge, South Atlantic Ocean; aspects of the biogeochemistry of Big Soda Lake, NV; mesophilic manganese-oxidizing bacteria from hydrothermal discharge areas at 21 deg North on the East Pacific Rise; and autotrophic growth and iron oxidation and inhibition kinetics of Leptospirillum ferrooxidans. Consideration is also given to thermophilic archaebacteria occurring in submarine hydrothermal areas; fate of sulfate in a soft-water, acidic lake; geochemical conditions in the ground water environment; microbial transformations as sources and sinks for nitrogen oxides; and the biogeochemistry of soil phosphorus.

Climate and marine biogeochemistry during the Holocene from transient model simulations

NASA Astrophysics Data System (ADS)

Segschneider, Joachim; Schneider, Birgit; Khon, Vyacheslav

2018-06-01

Climate and marine biogeochemistry changes over the Holocene are investigated based on transient global climate and biogeochemistry model simulations over the last 9500 years. The simulations are forced by accelerated and non-accelerated orbital parameters, respectively, and atmospheric pCO2, CH4, and N2O. The analysis focusses on key climatic parameters of relevance to the marine biogeochemistry, and on the physical and biogeochemical processes that drive atmosphere-ocean carbon fluxes and changes in the oxygen minimum zones (OMZs). The simulated global mean ocean temperature is characterized by a mid-Holocene cooling and a late Holocene warming, a common feature among Holocene climate simulations which, however, contradicts a proxy-derived mid-Holocene climate optimum. As the most significant result, and only in the non-accelerated simulation, we find a substantial increase in volume of the OMZ in the eastern equatorial Pacific (EEP) continuing into the late Holocene. The concurrent increase in apparent oxygen utilization (AOU) and age of the water mass within the EEP OMZ can be attributed to a weakening of the deep northward inflow into the Pacific. This results in a large-scale mid-to-late Holocene increase in AOU in most of the Pacific and hence the source regions of the EEP OMZ waters. The simulated expansion of the EEP OMZ raises the question of whether the deoxygenation that has been observed over the last 5 decades could be a - perhaps accelerated - continuation of an orbitally driven decline in oxygen. Changes in global mean biological production and export of detritus remain of the order of 10 %, with generally lower values in the mid-Holocene. The simulated atmosphere-ocean CO2 flux would result in atmospheric pCO2 changes of similar magnitudes to those observed for the Holocene, but with different timing. More technically, as the increase in EEP OMZ volume can only be simulated with the non-accelerated model simulation, non-accelerated model simulations are required for an analysis of the marine biogeochemistry in the Holocene. Notably, the long control experiment also displays similar magnitude variability to the transient experiment for some parameters. This indicates that also long control runs are required when investigating Holocene climate and marine biogeochemistry, and that some of the Holocene variations could be attributed to internal variability of the atmosphere-ocean system.

Global Carbon Cycle Modeling in GISS ModelE2 GCM

NASA Astrophysics Data System (ADS)

Aleinov, I. D.; Kiang, N. Y.; Romanou, A.; Romanski, J.

2014-12-01

Consistent and accurate modeling of the Global Carbon Cycle remains one of the main challenges for the Earth System Models. NASA Goddard Institute for Space Studies (GISS) ModelE2 General Circulation Model (GCM) was recently equipped with a complete Global Carbon Cycle algorithm, consisting of three integrated components: Ent Terrestrial Biosphere Model (Ent TBM), Ocean Biogeochemistry Module and atmospheric CO2 tracer. Ent TBM provides CO2 fluxes from the land surface to the atmosphere. Its biophysics utilizes the well-known photosynthesis functions of Farqhuar, von Caemmerer, and Berry and Farqhuar and von Caemmerer, and stomatal conductance of Ball and Berry. Its phenology is based on temperature, drought, and radiation fluxes, and growth is controlled via allocation of carbon from labile carbohydrate reserve storage to different plant components. Soil biogeochemistry is based on the Carnegie-Ames-Stanford (CASA) model of Potter et al. Ocean biogeochemistry module (the NASA Ocean Biogeochemistry Model, NOBM), computes prognostic distributions for biotic and abiotic fields that influence the air-sea flux of CO2 and the deep ocean carbon transport and storage. Atmospheric CO2 is advected with a quadratic upstream algorithm implemented in atmospheric part of ModelE2. Here we present the results for pre-industrial equilibrium and modern transient simulations and provide comparison to available observations. We also discuss the process of validation and tuning of particular algorithms used in the model.

Pilot Study on Potential Impacts of Fisheries-Induced Changes in Zooplankton Mortality on Marine Biogeochemistry

NASA Astrophysics Data System (ADS)

Getzlaff, Julia; Oschlies, Andreas

2017-11-01

In this pilot study we link the yield of industrial fisheries to changes in the zooplankton mortality in an idealized way accounting for different target species (planktivorous fish—decreased zooplankton mortality; large predators—increased zooplankton mortality). This indirect approach is used in a global coupled biogeochemistry circulation model to estimate the range of the potential impact of industrial fisheries on marine biogeochemistry. The simulated globally integrated response on phytoplankton and primary production is in line with expectations—a high (low) zooplankton mortality results in a decrease (increase) of zooplankton and an increase (decrease) of phytoplankton. In contrast, the local response of zooplankton and phytoplankton depends on the region under consideration: In nutrient-limited regions, an increase (decrease) in zooplankton mortality leads to a decrease (increase) in both zooplankton and phytoplankton biomass. In contrast, in nutrient-replete regions, such as upwelling regions, we find an opposing response: an increase (decrease) of the zooplankton mortality leads to an increase (decrease) in both zooplankton and phytoplankton biomass. The results are further evaluated by relating the potential fisheries-induced changes in zooplankton mortality to those driven by CO2 emissions in a business-as-usual 21st century emission scenario. In our idealized case, the potential fisheries-induced impact can be of similar size as warming-induced changes in marine biogeochemistry.

Adoption of clinical decision support systems in a developing country: Antecedents and outcomes of physician's threat to perceived professional autonomy.

PubMed

Esmaeilzadeh, Pouyan; Sambasivan, Murali; Kumar, Naresh; Nezakati, Hossein

2015-08-01

The basic objective of this research is to study the antecedents and outcomes of professional autonomy which is a central construct that affects physicians' intention to adopt clinical decision support systems (CDSS). The antecedents are physicians' attitude toward knowledge sharing and interactivity perception (about CDSS) and the outcomes are performance expectancy and intention to adopt CDSS. Besides, we include (1) the antecedents of attitude toward knowledge sharing-subjective norms, social factors and OCB (helping behavior) and (2) roles of physicians' involvement in decision making, computer self-efficacy and effort expectancy in our framework. Data from a stratified sample of 335 Malaysian physicians working in 12 public and private hospitals in Malaysia were collected to test the hypotheses using Structural Equation Modeling (SEM). The important findings of our research are: (1) factors such as perceived threat to professional autonomy, performance expectancy, and physicians' involvement in making decision about CDSS have significant impact on physicians' intention to adopt CDSS; (2) physicians' attitude toward knowledge sharing, interactivity perception and computer self-efficacy of physicians play a crucial role in influencing their perceived threat to professional autonomy; and (3) social network, shared goals and OCB (helping behavior) impact physicians' attitude toward knowledge sharing. The findings provide a comprehensive understanding of the factors that influence physicians' intention to adopt CDSS in a developing country. The results can help hospital managers manage CDSS implementation in an effective manner. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

SOLAR MULTIPLE ERUPTIONS FROM A CONFINED MAGNETIC STRUCTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jeongwoo; Chae, Jongchul; Liu, Chang

2016-09-20

How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encirclingmore » the AR was present before the eruptions; (ii) expansion of the open–closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.« less

Examining the effects of turnover intentions on organizational citizenship behaviors and deviance behaviors: A psychological contract approach.

PubMed

Mai, Ke Michael; Ellis, Aleksander P J; Christian, Jessica Siegel; Porter, Christopher O L H

2016-08-01

Although turnover intentions are considered the most proximal antecedent of organizational exit, there is often temporal separation between thinking about leaving and actual exit. Using field data from 2 diverse samples of working adults, we explore a causal model of the effects of turnover intentions on employee behavior while they remain with the organization, focusing specifically on organizational citizenship behaviors (OCBs) and deviance behaviors (DBs). Utilizing expectancy theory as an explanatory framework, we argue that turnover intentions result in high levels of transactional contract orientation and low levels of relational contract orientation, which in turn lead to a decrease in the incidence of OCBs and an increase in the incidence of DBs. We first used a pilot study to investigate the direction of causality between turnover intentions and psychological contract orientations. Then, in Study 1, we tested our mediated model using a sample of employees from a large drug retailing chain. In Study 2, we expanded our model by arguing that the mediated effects are much stronger when the organization is deemed responsible for potential exit. We then tested our full model using a sample of employees from a large state-owned telecommunications corporation in China. Across both studies, results were generally consistent and supportive of our hypotheses. We discuss the implications of our findings for future theory, research, and practice regarding the management of both the turnover process and discretionary behaviors at work. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Microtopographic and depth controls on active layer chemistry in Arctic polygonal ground

DOE PAGES

Newman, Brent D.; Throckmorton, Heather M.; Graham, David E.; ...

2015-03-24

Polygonal ground is a signature characteristic of Arctic lowlands, and carbon release from permafrost thaw can alter feedbacks to Arctic ecosystems and climate. This study describes the first comprehensive spatial examination of active layer biogeochemistry that extends across high- and low-centered, ice wedge polygons, their features, and with depth. Water chemistry measurements of 54 analytes were made on surface and active layer pore waters collected near Barrow, Alaska, USA. Significant differences were observed between high- and low-centered polygons suggesting that polygon types may be useful for landscape-scale geochemical classification. However, differences were found for polygon features (centers and troughs) formore » analytes that were not significant for polygon type, suggesting that finer-scale features affect biogeochemistry differently from polygon types. Depth variations were also significant, demonstrating important multidimensional aspects of polygonal ground biogeochemistry. These results have major implications for understanding how polygonal ground ecosystems function, and how they may respond to future change.« less

Dynamic Biological Functioning Important for Simulating and Stabilizing Ocean Biogeochemistry

NASA Astrophysics Data System (ADS)

Buchanan, P. J.; Matear, R. J.; Chase, Z.; Phipps, S. J.; Bindoff, N. L.

2018-04-01

The biogeochemistry of the ocean exerts a strong influence on the climate by modulating atmospheric greenhouse gases. In turn, ocean biogeochemistry depends on numerous physical and biological processes that change over space and time. Accurately simulating these processes is fundamental for accurately simulating the ocean's role within the climate. However, our simulation of these processes is often simplistic, despite a growing understanding of underlying biological dynamics. Here we explore how new parameterizations of biological processes affect simulated biogeochemical properties in a global ocean model. We combine 6 different physical realizations with 6 different biogeochemical parameterizations (36 unique ocean states). The biogeochemical parameterizations, all previously published, aim to more accurately represent the response of ocean biology to changing physical conditions. We make three major findings. First, oxygen, carbon, alkalinity, and phosphate fields are more sensitive to changes in the ocean's physical state. Only nitrate is more sensitive to changes in biological processes, and we suggest that assessment protocols for ocean biogeochemical models formally include the marine nitrogen cycle to assess their performance. Second, we show that dynamic variations in the production, remineralization, and stoichiometry of organic matter in response to changing environmental conditions benefit the simulation of ocean biogeochemistry. Third, dynamic biological functioning reduces the sensitivity of biogeochemical properties to physical change. Carbon and nitrogen inventories were 50% and 20% less sensitive to physical changes, respectively, in simulations that incorporated dynamic biological functioning. These results highlight the importance of a dynamic biology for ocean properties and climate.

The Mojave Subsurface Bio-Geochemistry Explorer (MOSBE)

NASA Technical Reports Server (NTRS)

Guerrero, J.; Beegle, L.; Abbey, W.; Bhartia, R.; Kounaves, S.; Russell, M.; Towles, D.

2012-01-01

The MOSBE Team has developed a terrestrial field campaign to explore two subsurface biological habitats under the Mojave Desert. This field campaign will not only help us understand terrestrial desert biology, but also will develop methodologies and strategies for potential future Mars missions that would seek to explore the Martian subsurface. We have proposed to the ASTEP program to integrate a suite of field demonstrated instruments with a 20 m subsurface drill as a coherent unit, the Mojave Subsurface Bio-geochemistry Explorer. The ATK Space Modular Planetary Drill System (MPDS) requires no drilling fluid, which allows aseptic sampling, can penetrate lithic ground up to 20 meters of depth, and utilizes less than 100 Watts throughout the entire depth. The drill has been developed and demonstrated in field testing to a depth of 10 meters in Arizona, December 2002. In addition to caching a continuous core throughout the drilling depth, it also generates and caches cuttings and fines that are strata-graphically correlated with the core. As a core segment is brought to the surface, it will be analyzed for texture and structure by a color microscopic imager and for relevant chemistry and mineralogy with a UV fluorescence/Raman spectrometer. Organic and soluble ionic species will be identified through two instruments -- a microcapillary electrophoresis, and an ion trap mass spectrometer that have been developed under PIDDP, ASTID and MIDP funding.

Influence of nematic range on birefringence, heat capacity and elastic modulus near a nematic-smectic-A phase transition

NASA Astrophysics Data System (ADS)

Beaubois, F.; Claverie, T.; Marcerou, J. P.; Rouillon, J. C.; Nguyen, H. T.; Garland, C. W.; Haga, H.

1997-11-01

The birefringence Δn, the specific heat Cp, and the layer compressional elastic modulus B are reported for two liquid crystals near the nematic (N) to smectic-A (SmA) phase transition. As predicted long ago by MacMillan and de Gennes [P. G. de Gennes and J. Prost, The Physics of Liquid Crystals (Clarendon, Oxford, 1993)] the coupling of the nematic orientational order parameter to the smectic-A layering order parameter can substantially alter the critical behavior near the N-SmA transition if the nematic range is small and the nematic order parameter susceptibility is large. In this paper, we present a direct experimental comparison of two compounds: 4-octyloxy-4'-cyanobiphenyl (8OCB) with a short nematic range and 4-octyloxybenzoyloxy-4'-cyanotolane (C8tolane) with a very large N range. The temperature variations of the apparent birefringence Δn and the specific heat Cp across the N-SmA phase transition show the definite influence of the proximity of the isotropic phase in the case of 8OCB while the C8tolane behaves as expected for the three-dimensional XY universality class. The elastic modulus B in the SmA phase, measured at several wave vectors by the second-sound resonance technique, was studied with high resolution as a function of temperature on approaching Tc(N-SmA). These elastic data confirm the B leveling off in both cases with an apparent breakdown of hydrodynamics in the case of the C8tolane compound.

Barriers to and facilitators of the implementation of health promoting hospitals in Taiwan: a top-down movement in need of ground support.

PubMed

Lee, Chiachi Bonnie; Chen, Michael S; Wang, Ying Wei

2014-01-01

This study investigates barriers to and facilitators of health promoting hospitals (HPH) in Taiwan. The findings are based on a cross-sectional questionnaire survey involving 55 hospitals committed to health promotion (HP) as of the end of 2009, and 52 of them completed the questionnaire. The five most reported barriers are inadequate national health insurance coverage of HP, staff detachment, incoherence of government policies, weak inter-sectoral link and resistance to change. The five most reported facilitators are support from hospital superintendents, support from unit/department directors, HP-inclusive hospital development mission and goals, funding from the government, founding of HP-related committees, resources and healthy policies. The study also found that organizational capacity building (OCB) had a significantly negative association with the number of barriers and a positive association with the number of facilitators. Stepwise linear regressions further found that OCB in structure was a significant predictor of the fewer number of barriers and that in-staff participation was a significant predictor of the more perceived facilitators. It also confirmed the significant role of organizational capacity building and that of coordinators in the effective implementation of HPH. The transformational factors as well as transactional factors are very much at work as facilitators, but the transactional factors are trapped in a less-than-friendly environment. Comprehensive support from transformational factors as well as transactional factors is essential and further support for daily routine operations and staff participation are required to sustain the implementation of HPH in Taiwan. Copyright © 2012 John Wiley & Sons, Ltd.

Everglqades Mercury: Biogeochemistry, Modeling, and Possible Mitigation

NASA Astrophysics Data System (ADS)

Orem, W. H.

2015-12-01

In the 1980s high levels of methylmercury (MeHg) were found in fish and other biota in the Florida Everglades, prompting fish consumption advisories. As part of Everglades restoration efforts Federal and State Agencies initiated a research program to study the underlying causes of the MeHg contamination. As part of this multi-agency effort, the U.S. Geological Survey developed the ACME (Aquatic Cycling of Mercury in the Everglades) project to examine the underlying biogeochemical factors controlling MeHg production and bioaccumulation in the ecosystem. Field studies by ACME and others identified the many factors impacting MeHg production in the Everglades. Thes factors include: high mercury deposition, large wetland area with organic-rich anaerobic soil, high sulfate loading in surface runoff, circumneutral pH, and high dissolved organic matter (DOM) content. Florida Department of Environmental Protection efforts that reduced local mercury emissions by 90%, produced only a small reduction in mercury deposition on the Everglades, suggesting that most Hg deposited on the ecosystem originates from distant sources, and beyond the reach of regulators. ACME studies demonstrated that high sulfate loading to the Everglades comes from discharge of canal water originating in the Everglades Agricultural Area (EAA). The use of sulfur in agriculture and soil oxidation in the EAA have been shown to be the principal sources of the sulfate loading. Sulfate entering the ecosystem drives microbial sulfate reduction and MeHg production, but inhibition of MeHg production by sulfide (a byproduct of microbial sulfate reduction) makes the biogeochemistry complex. Laboratory microcosm and field mesocosm experiments by ACME helped define the complexity of the sulfur/MeHg biogeochemistry, and demonstrated the key role of dissolved organic matter in MeHg production. A conceptual model was developed that relates MeHg production to sulfate loading, DOM, and soil composition. This conceptual model was then used in the development of a mathematical model that relates how changes in sulfate loading affect MeHg production in the ecosystem. This model is currently being used to examine how limits on sulfate loading to the ecosystem could be used as a mitigation strategy to control MeHg production and levels of MeHg in Everglades biota.

Vegetation/Ecosystem Modeling and Analysis Project:Comparing biogeography and biogeochemistry models in a continental-scale study of terrestrial ecosystem responses to climate change and CO2 doubling

NASA Astrophysics Data System (ADS)

1995-12-01

We compare the simulations of three biogeography models (BIOME2, Dynamic Global Phytogeography Model (DOLY), and Mapped Atmosphere-Plant Soil System (MAPSS)) and three biogeochemistry models (BIOME-BGC (BioGeochemistry Cycles), CENTURY, and Terrestrial Ecosystem Model (TEM)) for the conterminous United States under contemporary conditions of atmospheric CO2 and climate. We also compare the simulations of these models under doubled CO2 and a range of climate scenarios. For contemporary conditions, the biogeography models successfully simulate the geographic distribution of major vegetation types and have similar estimates of area for forests (42 to 46% of the conterminous United States), grasslands (17 to 27%), savannas (15 to 25%), and shrublands (14 to 18%). The biogeochemistry models estimate similar continental-scale net primary production (NPP; 3125 to 3772 × 1012 gC yr-1) and total carbon storage (108 to 118 × 1015 gC) for contemporary conditions. Among the scenarios of doubled CO2 and associated equilibrium climates produced by the three general circulation models (Oregon State University (OSU), Geophysical Fluid Dynamics Laboratory (GFDL), and United Kingdom Meteorological Office (UKMO)), all three biogeography models show both gains and losses of total forest area depending on the scenario (between 38 and 53% of conterminous United States area). The only consistent gains in forest area with all three models (BIOME2, DOLY, and MAPSS) were under the GFDL scenario due to large increases in precipitation. MAPSS lost forest area under UKMO, DOLY under OSU, and BIOME2 under both UKMO and OSU. The variability in forest area estimates occurs because the hydrologic cycles of the biogeography models have different sensitivities to increases in temperature and CO2. However, in general, the biogeography models produced broadly similar results when incorporating both climate change and elevated CO2 concentrations. For these scenarios, the NPP estimated by the biogeochemistry models increases between 2% (BIOME-BGC with UKMO climate) and 35% (TEM with UKMO climate). Changes in total carbon storage range from losses of 33% (BIOME-BGC with UKMO climate) to gains of 16% (TEM with OSU climate). The CENTURY responses of NPP and carbon storage are positive and intermediate to the responses of BIOME-BGC and TEM. The variability in carbon cycle responses occurs because the hydrologic and nitrogen cycles of the biogeochemistry models have different sensitivities to increases in temperature and CO2. When the biogeochemistry models are run with the vegetation distributions of the biogeography models, NPP ranges from no response (BIOME-BGC with all three biogeography model vegetations for UKMO climate) to increases of 40% (TEM with MAPSS vegetation for OSU climate). The total carbon storage response ranges from a decrease of 39% (BIOME-BGC with MAPSS vegetation for UKMO climate) to an increase of 32% (TEM with MAPSS vegetation for OSU and GFDL climates). The UKMO responses of BIOME-BGC with MAPSS vegetation are primarily caused by decreases in forested area and temperature-induced water stress. The OSU and GFDL responses of TEM with MAPSS vegetations are primarily caused by forest expansion and temperature-enhanced nitrogen cycling.

Vegetation/ecosystem modeling and analysis project: Comparing biogeography and biogeochemistry models in a continental-scale study of terrestrial ecosystem responses to climate change and CO2 doubling

NASA Astrophysics Data System (ADS)

Melillo, J. M.; Borchers, J.; Chaney, J.; Fisher, H.; Fox, S.; Haxeltine, A.; Janetos, A.; Kicklighter, D. W.; Kittel, T. G. F.; McGuire, A. D.; McKeown, R.; Neilson, R.; Nemani, R.; Ojima, D. S.; Painter, T.

1995-12-01

We compare the simulations of three biogeography models (BIOME2, Dynamic Global Phytogeography Model (DOLY), and Mapped Atmosphere-Plant Soil System (MAPSS)) and three biogeochemistry models (BIOME-BGC (BioGeochemistry Cycles), CENTURY, and Terrestrial Ecosystem Model (TEM)) for the conterminous United States under contemporary conditions of atmospheric CO2 and climate. We also compare the simulations of these models under doubled CO2 and a range of climate scenarios. For contemporary conditions, the biogeography models successfully simulate the geographic distribution of major vegetation types and have similar estimates of area for forests (42 to 46% of the conterminous United States), grasslands (17 to 27%), savannas (15 to 25%), and shrublands (14 to 18%). The biogeochemistry models estimate similar continental-scale net primary production (NPP; 3125 to 3772×1012 gCyr-1) and total carbon storage (108 to 118×1015 gC) for contemporary conditions. Among the scenarios of doubled CO2 and associated equilibrium climates produced by the three general circulation models (Oregon State University (OSU), Geophysical Fluid Dynamics Laboratory (GFDL), and United Kingdom Meteorological Office (UKMO)), all three biogeography models show both gains and losses of total forest area depending on the scenario (between 38 and 53% of conterminous United States area). The only consistent gains in forest area with all three models (BIOME2, DOLY, and MAPSS) were under the GFDL scenario due to large increases in precipitation. MAPSS lost forest area under UKMO, DOLY under OSU, and BIOME2 under both UKMO and OSU. The variability in forest area estimates occurs because the hydrologic cycles of the biogeography models have different sensitivities to increases in temperature and CO2. However, in general, the biogeography models produced broadly similar results when incorporating both climate change and elevated CO2 concentrations. For these scenarios, the NPP estimated by the biogeochemistry models increases between 2% (BIOME-BGC with UKMO climate) and 35% (TEM with UKMO climate). Changes in total carbon storage range from losses of 33% (BIOME-BGC with UKMO climate) to gains of 16% (TEM with OSU climate). The CENTURY responses of NPP and carbon storage are positive and intermediate to the responses of BIOME-BGC and TEM. The variability in carbon cycle responses occurs because the hydrologic and nitrogen cycles of the biogeochemistry models have different sensitivities to increases in temperature and CO2. When the biogeochemistry models are run with the vegetation distributions of the biogeography models, NPP ranges from no response (BIOME-BGC with all three biogeography model vegetations for UKMO climate) to increases of 40% (TEM with MAPSS vegetation for OSU climate). The total carbon storage response ranges from a decrease of 39% (BIOME-BGC with MAPSS vegetation for UKMO climate) to an increase of 32% (TEM with MAPSS vegetation for OSU and GFDL climates). The UKMO responses of BIOME-BGC with MAPSS vegetation are primarily caused by decreases in forested area and temperature-induced water stress. The OSU and GFDL responses of TEM with MAPSS vegetations are primarily caused by forest expansion and temperature-enhanced nitrogen cycling.

Soil biogeochemistry in the age of big data

NASA Astrophysics Data System (ADS)

Cécillon, Lauric; Barré, Pierre; Coissac, Eric; Plante, Alain; Rasse, Daniel

2015-04-01

Data is becoming one of the key resource of the XXIst century. Soil biogeochemistry is not spared by this new movement. The conservation of soils and their services recently came into the political agenda. However, clear knowledge on the links between soil characteristics and the various processes ensuring the provision of soil services is rare at the molecular or the plot scale, and does not exist at the landscape scale. This split between society's expectations on its natural capital, and scientific knowledge on the most complex material on earth has lead to an increasing number of studies on soils, using an increasing number of techniques of increasing complexity, with an increasing spatial and temporal coverage. From data scarcity with a basic data management system, soil biogeochemistry is now facing a proliferation of data, with few quality controls from data collection to publication and few skills to deal with them. Based on this observation, here we (1) address how big data could help in making sense of all these soil biogeochemical data, (2) point out several shortcomings of big data that most biogeochemists will experience in their future career. Massive storage of data is now common and recent opportunities for cloud storage enables data sharing among researchers all over the world. The need for integrative and collaborative computational databases in soil biogeochemistry is emerging through pioneering initiatives in this direction (molTERdb; earthcube), following soil microbiologists (GenBank). We expect that a series of data storage and management systems will rapidly revolutionize the way of accessing raw biogeochemical data, published or not. Data mining techniques combined with cluster or cloud computing hold significant promises for facilitating the use of complex analytical methods, and for revealing new insights previously hidden in complex data on soil mineralogy, organic matter and biodiversity. Indeed, important scientific advances have already been made thanks to meta-analysis, chemometrics, machine-learning systems and bioinformatics. Some techniques like structural equation modeling eventually propose to explore causalities opening a way towards the mechanistic understanding of soil big data rather than simple correlations. We claim that data science should be fully integrated into soil biogeochemists basic education schemes. We expect the blooming of a new generation of soil biogeochemists highly skilled in manipulating big data. Will big data represent a net gain for soil biogeochemistry? Increasing the amount of data will increase associated biases that may further be exacerbated by the increasing distance between data manipulators, soil sampling and data acquisition. Integrating data science into soil biogeochemistry should thus not be done at the expenses of pedology and metrology. We further expect that the more data, the more spurious correlations will appear leading to possible misinterpretation of data. Finally, big data on soils characteristics and processes will always need to be confronted to biogeochemical theories and socio-economic knowledge to be useful. Big data could revolutionize soil biogeochemistry, fostering new scientific and business models around the conservation of the soil natural capital, but our community should go into this new era with clear-sightedness and discernment.

Biogeochemistry Science and Education Part One: Using Non-Traditional Stable Isotopes as Environmental Tracers Part Two: Identifying and Measuring Undergraduate Misconceptions in Biogeochemistry

NASA Astrophysics Data System (ADS)

Mead, Chris

This dissertation is presented in two sections. First, I explore two methods of using stable isotope analysis to trace environmental and biogeochemical processes. Second, I present two related studies investigating student understanding of the biogeochemical concepts that underlie part one. Fe and Hg are each biogeochemically important elements in their own way. Fe is a critical nutrient for phytoplankton, while Hg is detrimental to nearly all forms of life. Fe is often a limiting factor in marine phytoplankton growth. The largest source, by mass, of Fe to the open ocean is windblown mineral dust, but other more soluble sources are more bioavailable. To look for evidence of these non-soil dust sources of Fe to the open ocean, I measured the isotopic composition of aerosol samples collected on Bermuda. I found clear evidence in the fine size fraction of a non-soil dust Fe source, which I conclude is most likely from biomass burning. Widespread adoption of compact fluorescent lamps (CFL) has increased their importance as a source of environmental Hg. Isotope analysis would be a useful tool in quantifying this impact if the isotopic composition of Hg from CFL were known. My measurements show that CFL-Hg is isotopically fractionated, in a unique pattern, during normal operation. This fractionation is large and has a distinctive, mass-independent signature, such that CFL Hg can be uniquely identified from other sources. Misconceptions research in geology has been a very active area of research, but student thinking regarding the related field of biogeochemistry has not yet been studied in detail. From interviews with 40 undergraduates, I identified over 150 specific misconceptions. I also designed a multiple-choice survey (concept inventory) to measure understanding of these same biogeochemistry concepts. I present statistical evidence, based on the Rasch model, for the reliability and validity of this instrument. This instrument will allow teachers and researchers to easily quantify learning outcomes in biogeochemistry and will complement existing concept inventories in geology, chemistry, and biology.

Biogeochemistry of silica in Devils Lake: Implications for diatom preservation

USGS Publications Warehouse

Lent, R.M.; Lyons, B.

2001-01-01

Diatom-salinity records from sediment cores have been used to construct climate records of saline-lake basins. In many cases, this has been done without thorough understanding of the preservation potential of the diatoms in the sediments through time. The purpose of this study was to determine the biogeochemistry of silica in Devils Lake and evaluate the potential effects of silica cycling on diatom preservation. During the period of record, 1867-1999, lake levels have fluctuated from 427 m above sea level in 1940 to 441.1 m above sea level in 1999. The biogeochemistry of silica in Devils Lake is dominated by internal cycling. During the early 1990s when lake levels were relatively high, about 94% of the biogenic silica (BSi) produced in Devils Lake was recycled in the water column before burial. About 42% of the BSi that was incorporated in bottom sediments was dissolved and diffused back into the lake, and the remaining 58% was buried. Therefore, the BSi accumulation rate was about 3% of the BSi assimilation rate. Generally, the results obtained from this study are similar to those obtained from studies of the biogeochemistry of silica in large oligotrophic lakes and the open ocean where most of the BSi produced is recycled in surface water. During the mid 1960s when lake levels were relatively low, BSi assimilation and water-column dissolution rates were much higher than when lake levels were high. The BSi assimilation rate was as much as three times higher during low lake levels. Even with the much higher BSi assimilation rate, the BSi accumulation rate was about three times lower because the BSi water-column dissolution rate was more than 99% of the BSi assimilation rate compared to 94% during high lake levels. Variations in the biogeochemistry of silica with lake level have important implications for paleolimnologic studies. Increased BSi water-column dissolution during decreasing lake levels may alter the diatom-salinity record by selectively removing the less resistant diatoms. Also, BSi accumulation may be proportional to the amount of silica input from tributary sources. Therefore, BSi accumulation chronologies from sediment cores may be effective records of tributary inflow.

Sea Ice Biogeochemistry: A Guide for Modellers

PubMed Central

Tedesco, Letizia; Vichi, Marcello

2014-01-01

Sea ice is a fundamental component of the climate system and plays a key role in polar trophic food webs. Nonetheless sea ice biogeochemical dynamics at large temporal and spatial scales are still rarely described. Numerical models may potentially contribute integrating among sparse observations, but available models of sea ice biogeochemistry are still scarce, whether their relevance for properly describing the current and future state of the polar oceans has been recently addressed. A general methodology to develop a sea ice biogeochemical model is presented, deriving it from an existing validated model application by extension of generic pelagic biogeochemistry model parameterizations. The described methodology is flexible and considers different levels of ecosystem complexity and vertical representation, while adopting a strategy of coupling that ensures mass conservation. We show how to apply this methodology step by step by building an intermediate complexity model from a published realistic application and applying it to analyze theoretically a typical season of first-year sea ice in the Arctic, the one currently needing the most urgent understanding. The aim is to (1) introduce sea ice biogeochemistry and address its relevance to ocean modelers of polar regions, supporting them in adding a new sea ice component to their modelling framework for a more adequate representation of the sea ice-covered ocean ecosystem as a whole, and (2) extend our knowledge on the relevant controlling factors of sea ice algal production, showing that beyond the light and nutrient availability, the duration of the sea ice season may play a key-role shaping the algal production during the on going and upcoming projected changes. PMID:24586604

The Future of Marine Biogeochemistry, Ecosystems, and Societies

NASA Astrophysics Data System (ADS)

Bundy, Alida; Liu, Kon-Kee; Thomas, Helmuth

2013-05-01

The international project Integrated Marine Biogeochemistry and Ecosystem Research (IMBER) convenes an IMBIZO (a Zulu word meaning "a gathering") biennially, with a format of three concurrent, interacting workshops designed to synthesize information on topical research areas in marine science. IMBIZO III, held at the National Institute of Oceanography in Goa, India, focused on multidimensional approaches to challenges of global change in continental margins (CM), open ocean systems, and dependent human societies. More than 120 participants from 29 nations attended the meeting; the smaller workshop groups allowed in-depth discussions, and daily plenary sessions facilitated discussion among interdisciplinary experts.

Deep-sea piezosphere and piezophiles: geomicrobiology and biogeochemistry.

PubMed

Fang, Jiasong; Zhang, Li; Bazylinski, Dennis A

2010-09-01

The deep-sea piezosphere accounts for approximately 75% of the total ocean volume and hosts active and diverse biological communities. Evidence obtained thus far suggests that the microbial biomass present in the piezosphere is significant. Continued international interest in exploring the deep ocean provides impetus to increase our understanding of the deep-sea piezosphere and of the influence of piezophilic microbial communities on the global ocean environment and on biogeochemical cycling occurring in the deep sea. Here, we review the diversity, metabolic characteristics, geomicrobiology and biogeochemistry of the deep-sea piezophiles. Copyright 2010 Elsevier Ltd. All rights reserved.

Integrating Hydrology, Ecology, and Biogeochemistry in Stormwater Management: the Vermont Experience

NASA Astrophysics Data System (ADS)

Bowden, W. B.

2005-12-01

Although Vermont has had a stormwater management program since the 1970's, support for the program languished during a period intense suburban development in several counties in the state, most notably Chittenden County next to Lake Champlain. Beginning in 2000, the state renewed efforts to address concerns that stormwater runoff from suburban developments had significantly degraded streams in the area and threatened the health of the Lake. The state employs an extensive, EPA-approved biomonitoring program (based on macroinvertebrates and fish) to assess the health of streams. However, it is difficult to translate these data into targets for stormwater management or to predict how and especially when they will change as a result of future management practices. The challenge of managing stormwater in this area is further compounded by a complete lack of historical hydrologic monitoring data. Ultimately a stakeholder-driven process developed that has lead to an innovative partnership among state agencies, resource managers, NGO's, the US-EPA and scientists. Through this partnership a unique consensus evolved that management for hydrologic targets by themselves would address most of the stakeholders' concerns. The new regulations that are emerging are based on two components. The first component relies on flow-duration curves (FDC's) derived from a simple, widely-used stormwater model (P-8) for which adequate input data are available. The model was calibrated for streams in other areas for which long-term hydrologic data were available and then used to generate `synthetic' FDC's for the stormwater impaired and a suite of `attainment' (developing, but currently un-impaired) watersheds in Vermont. Statistical (cluster) analyses of synthetic FDC's provide watershed-wide targets for hydrologic reduction. Sub-watershed mapping linked to further multivariate analysis of the flow data identify specific locations to implement best management practices (BMP's) that will achieve these targets. This approach is firmly grounded in first principles of stormwater hydrology and recognition of the impacts of altered hydrology on stream ecology and biogeochemistry. Stakeholders have accepted the approach because it is objective, defensible, and subject to future, quantitative analysis and adjustment (adaptive management). This approach is not specific to Vermont and could be employed in any region.

A pilot Virtual Observatory (pVO) for integrated catchment science - Demonstration of national scale modelling of hydrology and biogeochemistry (Invited)

NASA Astrophysics Data System (ADS)

Freer, J. E.; Bloomfield, J. P.; Johnes, P. J.; MacLeod, C.; Reaney, S.

2010-12-01

There are many challenges in developing effective and integrated catchment management solutions for hydrology and water quality issues. Such solutions should ideally build on current scientific evidence to inform policy makers and regulators and additionally allow stakeholders to take ownership of local and/or national issues, in effect bringing together ‘communities of practice’. A strategy being piloted in the UK as the Pilot Virtual Observatory (pVO), funded by NERC, is to demonstrate the use of cyber-infrastructure and cloud computing resources to investigate better methods of linking data and models and to demonstrate scenario analysis for research, policy and operational needs. The research will provide new ways the scientific and stakeholder communities come together to exploit current environmental information, knowledge and experience in an open framework. This poster presents the project scope and methodologies for the pVO work dealing with national modelling of hydrology and macro-nutrient biogeochemistry. We evaluate the strategies needed to robustly benchmark our current predictive capability of these resources through ensemble modelling. We explore the use of catchment similarity concepts to understand if national monitoring programs can inform us about the behaviour of catchments. We discuss the challenges to applying these strategies in an open access and integrated framework and finally we consider the future for such virtual observatory platforms for improving the way we iteratively improve our understanding of catchment science.

Bacterial community characterization and biogeochemistry of sediments from a tropical upwelling system (Cabo Frio, Southeastern Brazil)

NASA Astrophysics Data System (ADS)

Castelo-Branco, R.; Barreiro, A.; Silva, F. S.; Carvalhal-Gomes, S. B. V.; Fontana, L. F.; Mendonça-Filho, J. G.; Vasconcelos, V.

2016-11-01

The Cabo Frio Upwelling System is one of the largest and most productive areas in southeastern Brazil. Although it is well-known that bacterial communities play a crucial role in the biogeochemical cycles and food chain of marine ecosystems, little is known regarding the microbial communities in the sediments of this upwelling region. In this research, we address the effect of different hydrological conditions on the biogeochemistry of sediments and the diversity of bacterial communities. Biogeochemistry profiles of sediments from four sampling stations along an inner-outer transect on the continental shelf were evaluated and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments was used to study the bacterial community composition in these sediments. Our sequencing analysis of excised bands identified Alpha- and Gammaproteobacteria, Bacteroidetes and bacteria belonging to the Firmicutes phyla as the phylogenetic groups, indicating the existence of great diversity in these marine sediments. In this multidisciplinary study, the use of multivariate analysis was crucial for understanding how biogeochemical profiles influence bacterial community distribution. A Principal Component Analysis (PCA) indicated that the biogeochemical variables exhibited a clear spatial pattern that is mainly related to hydrological conditions. A Correspondence Analysis (CA) revealed an important association between certain taxonomic groups and specific sampling locations. Canonical Correspondence Analysis (CCA) demonstrated that the biogeochemistry influences the structure of the bacterial community in sediments. Among the bacterial groups identified, the most taxonomically diverse classes (Alphaproteobacteria and Gammaproteobacteria) were found to be distributed regardless of any studied biogeochemical variables influences, whereas other groups responded to biogeochemical conditions which, in turn, were influenced by hydrological conditions. This finding was observed for members of the two classes in the Bacteroidetes phylum, which were associated with either proteins or carbohydrates.

Peatland Open-water Pool Biogeochemistry: The Influence of Hydrology and Vegetation

NASA Astrophysics Data System (ADS)

Arsenault, J.; Talbot, J.; Moore, T. R.

2017-12-01

Peatland open-water pools are net sources of carbon to the atmosphere. However, their interaction with the surrounding peat remains poorly known. In a previous study, we showed that shallow pools are richer in nutrients than deep pools. While depth was the main driver of biogeochemistry variations across time and space, analyses also showed that pool's adjacent vegetation may have an influence on water chemistry. Our goal is to understand the relationship between the biogeochemistry of open-water pools and their surroundings in a subboreal ombrotrophic peatland of southern Quebec (Canada). To assess the influence of vegetation on pool water chemistry, we compare two areas covered with different types of vegetation: a forested zone dominated by spruce trees and an open area mostly covered by Sphagnum spp. To evaluate the direction of water (in or out of the pools), we installed capacitance water level probes in transects linking pools in the two zones. Wells were also installed next to each probe to collect peat pore water samples. Samples were taken every month during summer 2017 and analyzed for dissolved organic carbon, nitrogen and phosphorus, pH and specific UV absorbance. Preliminary results show differences in peat water chemistry depending on the dominant vegetation. In both zones, water levels fluctuations are disconnected between peat and the pools, suggesting poor horizontal water movement. Pool water chemistry may be mostly influenced by the immediate surrounding vegetation than by the local vegetation pattern. Climate and land-use change may affect the vegetation structure of peatlands, thus affecting pool biogeochemistry. Considering the impact of pools on the overall peatland capacity to accumulate carbon, our results show that more focus must be placed on pools to better understand peatland stability over time.

Validation of the Oncentra Brachy Advanced Collapsed cone Engine for a commercial (192)Ir source using heterogeneous geometries.

PubMed

Ma, Yunzhi; Lacroix, Fréderic; Lavallée, Marie-Claude; Beaulieu, Luc

2015-01-01

To validate the Advanced Collapsed cone Engine (ACE) dose calculation engine of Oncentra Brachy (OcB) treatment planning system using an (192)Ir source. Two levels of validation were performed, conformant to the model-based dose calculation algorithm commissioning guidelines of American Association of Physicists in Medicine TG-186 report. Level 1 uses all-water phantoms, and the validation is against TG-43 methodology. Level 2 uses real-patient cases, and the validation is against Monte Carlo (MC) simulations. For each case, the ACE and TG-43 calculations were performed in the OcB treatment planning system. ALGEBRA MC system was used to perform MC simulations. In Level 1, the ray effect depends on both accuracy mode and the number of dwell positions. The volume fraction with dose error ≥2% quickly reduces from 23% (13%) for a single dwell to 3% (2%) for eight dwell positions in the standard (high) accuracy mode. In Level 2, the 10% and higher isodose lines were observed overlapping between ACE (both standard and high-resolution modes) and MC. Major clinical indices (V100, V150, V200, D90, D50, and D2cc) were investigated and validated by MC. For example, among the Level 2 cases, the maximum deviation in V100 of ACE from MC is 2.75% but up to ~10% for TG-43. Similarly, the maximum deviation in D90 is 0.14 Gy between ACE and MC but up to 0.24 Gy for TG-43. ACE demonstrated good agreement with MC in most clinically relevant regions in the cases tested. Departure from MC is significant for specific situations but limited to low-dose (<10% isodose) regions. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Poster - 07: Investigations of the Advanced Collapsed-cone Engine for HDR Brachytherapy Scalp Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cawston-Grant, Brie; Morrison, Hali; Sloboda, Ron

Purpose: To present an investigation of the Advanced Collapsed-cone Engine (ACE) in Oncentraê Brachy (OcB) v4.5 using a tissue equivalent phantom modeling scalp brachytherapy (BT) treatments. Methods: A slab phantom modeling the skin, skull, brain and mold was used. A dose of 400cGy was prescribed to just above the skull layer using TG-43 and was delivered using an HDR afterloader. Measurements were made using Gafchromic™ EBT3 film at four depths within the phantom. The TG-43 planned and film measured doses were compared to the standard (sACE) and high (hACE) accuracy ACE options in OcB between the surface and below themore » skull. Results: The average difference between the TG-43 calculated and film measured doses was −11.25±3.38% when there was no air gap between the mold and skin; sACE and hACE doses were on average lower than TG-43 calculated doses by 3.41±0.03% and 2.45±0.03%, respectively. With a 3mm air gap between the mold and skin, the difference between the TG-43 calculated and measured doses was −8.28±5.76%; sACE and hACE calculations yielded average doses 1.87±0.03% and 1.78±0.04% greater than TG-43, respectively. Conclusions: TG-43, sACE, and hACE were found to overestimate doses below the skull layer compared to film. With a 3mm air gap between the mold and skin, sACE and hACE more accurately predicted the film dose to the skin surface than TG-43. More clinical variations and their implications are currently being investigated.« less

Biogeochemistry of Framvaren, A permanently Anoxic Fjord

NASA Astrophysics Data System (ADS)

Millero, Frank J.

Recently (May 28-30, 1986), a workshop was held in Farsund, Norway, to discuss the biogeochemistry of an anoxic fjord called Framvaren. In the last 7 years a group of marine scientists from Norway, Sweden, Canada, and the United States has been studying this fjord. The workshop was held to discuss the recent findings of this international effort. A new expedition is planned in February 1987 (provided that the ice is thick enough) and in June 1988. Marine chemists, microbiologists, or geologists interested in participating in this study should contact Jens Skei (Norwegian Institute of Water Research, PB Box 333, Blindern, Oslo 3, Norway), who is coordinating the investigations.

Genes, isotopes, and ecosystem biogeochemistry. Dissecting methane flux at the leading edge of global change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saleska, Scott; Rich, Virginia; Tyson, Gene

This project integrates across three fields (microbiology, biogeochemistry, and modeling) to understand the mechanisms of methane cycling in thawing permafrost. We have made substantial progress in each area, and in cross-cutting interdisciplinary synthesis. Large releases of CH 4 from thawing permafrost to the atmosphere, a strong positive feedback to global warming, are plausible but little is known about the controls on such release. Our project (“IsoGenie”) addresses the key question: What is the interplay of microbial communities and soil organic matter composition in the decomposition of organic C to CH 4 across a permafrost thaw gradient?

Insights from Modeling the Integrated Climate, Biogeochemical Cycles, Human Activities and Their Interactions in the ACME Earth System Model

NASA Astrophysics Data System (ADS)

Leung, L. R.; Thornton, P. E.; Riley, W. J.; Calvin, K. V.

2017-12-01

Towards the goal of understanding the contributions from natural and managed systems to current and future greenhouse gas fluxes and carbon-climate and carbon-CO2 feedbacks, efforts have been underway to improve representations of the terrestrial, river, and human components of the ACME earth system model. Broadly, our efforts include implementation and comparison of approaches to represent the nutrient cycles and nutrient limitations on ecosystem production, extending the river transport model to represent sediment and riverine biogeochemistry, and coupling of human systems such as irrigation, reservoir operations, and energy and land use with the ACME land and river components. Numerical experiments have been designed to understand how terrestrial carbon, nitrogen, and phosphorus cycles regulate climate system feedbacks and the sensitivity of the feedbacks to different model treatments, examine key processes governing sediment and biogeochemistry in the rivers and their role in the carbon cycle, and exploring the impacts of human systems in perturbing the hydrological and carbon cycles and their interactions. This presentation will briefly introduce the ACME modeling approaches and discuss preliminary results and insights from numerical experiments that lay the foundation for improving understanding of the integrated climate-biogeochemistry-human system.

Potential effects of large-scale offshore tidal energy extraction in the Pentland Firth on North Sea biogeochemistry

NASA Astrophysics Data System (ADS)

van der Molen, Johan; Ruardij, Piet; Greenwood, Naomi

2016-04-01

Final results are presented of a model study to assess the potential wider area effects of large-scale tidal energy extraction in the Pentland Firth on the biogeochemistry. The coupled hydrodynamics-biogeochemistry model GETM-ERSEM-BFM was used in a shelf-wide application with a parameterisation of the effects of power extraction by tidal turbines on fluid momentum. Three secenario runs were carried out: a reference run without turbines, an 800 MW extraction run corresponding to current licenses, and an academic 8 GW extraction run. The changes simulated with the 800 MW extraction were negligible. The academic 8 GW extraction resulted in reductions in tidal elevations along the east coast of the UK that would be measurable (several cm.), and associated reductions in bed-shear stresses. These resulted in reductions in SPM concentrations, increased primary production, and increased biomass of zooplankton and benthic fauna. The effects were most pronounced in the shallow seas surrounding The Wash, with changes of up to 10%. These results indicate that, should tidal power generation substantially beyond the currently licensed amount be planned, either concentrated in one location or spread over multiple locations along the coast, further investigations are advisable.

Radioiodine Biogeochemistry and Prevalence in Groundwater

PubMed Central

Kaplan, D. I.; Denham, M. E.; Zhang, S.; Yeager, C.; Xu, C.; Schwehr, K. A.; Li, H. P.; Ho, Y. F.; Wellman, D.; Santschi, P. H.

2014-01-01

129I is commonly either the top or among the top risk drivers, along with 99Tc, at radiological waste disposal sites and contaminated groundwater sites where nuclear material fabrication or reprocessing has occurred. The risk stems largely from 129I having a high toxicity, a high bioaccumulation factor (90% of all the body's iodine concentrates in the thyroid), a high inventory at source terms (due to its high fission yield), an extremely long half-life (16M years), and rapid mobility in the subsurface environment. Another important reason that 129I is a key risk driver is that there is uncertainty regarding its biogeochemical fate and transport in the environment. We typically can define 129I mass balance and flux at sites, but cannot predict accurately its response to changes in the environment. As a consequence of some of these characteristics, 129I has a very low drinking water standard, which is set at 1 pCi/L, the lowest of all radionuclides in the Federal Register. Recently, significant advancements have been made in detecting iodine species at ambient groundwater concentrations, defining the nature of the organic matter and iodine bond, and quantifying the role of naturally occurring sediment microbes to promote iodine oxidation and reduction. These recent studies have led to a more mechanistic understanding of radioiodine biogeochemistry. The objective of this review is to describe these advances and to provide a state of the science of radioiodine biogeochemistry relevant to its fate and transport in the terrestrial environment and provide information useful for making decisions regarding the stewardship and remediation of 129I contaminated sites. As part of this review, knowledge gaps were identified that would significantly advance the goals of basic and applied research programs for accelerating 129I environmental remediation and reducing uncertainty associated with disposal of 129I waste. Together the information gained from addressing these knowledge gaps will not alter the observation that 129I is primarily mobile, but it will likely permit demonstration that the entire 129I pool in the source term is not moving at the same rate and some may be tightly bound to the sediment, thereby smearing the modeled 129I peak and reducing maximum calculated risk. PMID:25264421

Deterministic influences exceed dispersal effects on hydrologically-connected microbiomes.

PubMed

Graham, Emily B; Crump, Alex R; Resch, Charles T; Fansler, Sarah; Arntzen, Evan; Kennedy, David W; Fredrickson, Jim K; Stegen, James C

2017-04-01

Subsurface groundwater-surface water mixing zones (hyporheic zones) have enhanced biogeochemical activity, but assembly processes governing subsurface microbiomes remain a critical uncertainty in understanding hyporheic biogeochemistry. To address this obstacle, we investigated (a) biogeographical patterns in attached and waterborne microbiomes across three hydrologically-connected, physicochemically-distinct zones (inland hyporheic, nearshore hyporheic and river); (b) assembly processes that generated these patterns; (c) groups of organisms that corresponded to deterministic changes in the environment; and (d) correlations between these groups and hyporheic metabolism. All microbiomes remained dissimilar through time, but consistent presence of similar taxa suggested dispersal and/or common selective pressures among zones. Further, we demonstrated a pronounced impact of deterministic assembly in all microbiomes as well as seasonal shifts from heterotrophic to autotrophic microorganisms associated with increases in groundwater discharge. The abundance of one statistical cluster of organisms increased with active biomass and respiration, revealing organisms that may strongly influence hyporheic biogeochemistry. Based on our results, we propose a conceptualization of hyporheic zone metabolism in which increased organic carbon concentrations during surface water intrusion support heterotrophy, which succumbs to autotrophy under groundwater discharge. These results provide new opportunities to enhance microbially-explicit ecosystem models describing hyporheic zone biogeochemistry and its influence over riverine ecosystem function. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Limnology of the Green Lakes Valley: Phytoplankton ecology and dissolved organic matter biogeochemistry at a long-term ecological research site

USGS Publications Warehouse

Miller, Matthew P.; McKnight, Diane M.

2015-01-01

Background: Surface waters are the lowest points in the landscape, and therefore serve as excellent integrators and indicators of changes taking place in the surrounding terrestrial and atmospheric environment.Aims: Here we synthesise the findings of limnological studies conducted during the past 15 years in streams and lakes in the Green Lakes Valley, which is part of the Niwot Ridge Long-term Ecological Research (LTER) Site.Methods: The importance of these studies is discussed in the context of aquatic ecosystems as indicators, integrators, and regulators of environmental change. Specifically, investigations into climatic, hydrologic, and nutrient controls on present-day phytoplankton, and historical diatom, community composition in the alpine lake, Green Lake 4, are reviewed. In addition, studies of spatial and temporal patterns in dissolved organic matter (DOM) biogeochemistry and reactive transport modelling that have taken place in the Green Lakes Valley are highlighted.Results and conclusions: The findings of these studies identify specific shifts in algal community composition and DOM biogeochemistry that are indicative of changing environmental conditions and provide a framework for detecting future environmental change in the Green Lakes Valley and in other alpine watersheds. Moreover, the studies summarised here demonstrate the importance of long-term monitoring programmes such as the LTER programme.

iMarNet: an ocean biogeochemistry model inter-comparison project within a common physical ocean modelling framework

NASA Astrophysics Data System (ADS)

Kwiatkowski, L.; Yool, A.; Allen, J. I.; Anderson, T. R.; Barciela, R.; Buitenhuis, E. T.; Butenschön, M.; Enright, C.; Halloran, P. R.; Le Quéré, C.; de Mora, L.; Racault, M.-F.; Sinha, B.; Totterdell, I. J.; Cox, P. M.

2014-07-01

Ocean biogeochemistry (OBGC) models span a wide range of complexities from highly simplified, nutrient-restoring schemes, through nutrient-phytoplankton-zooplankton-detritus (NPZD) models that crudely represent the marine biota, through to models that represent a broader trophic structure by grouping organisms as plankton functional types (PFT) based on their biogeochemical role (Dynamic Green Ocean Models; DGOM) and ecosystem models which group organisms by ecological function and trait. OBGC models are now integral components of Earth System Models (ESMs), but they compete for computing resources with higher resolution dynamical setups and with other components such as atmospheric chemistry and terrestrial vegetation schemes. As such, the choice of OBGC in ESMs needs to balance model complexity and realism alongside relative computing cost. Here, we present an inter-comparison of six OBGC models that were candidates for implementation within the next UK Earth System Model (UKESM1). The models cover a large range of biological complexity (from 7 to 57 tracers) but all include representations of at least the nitrogen, carbon, alkalinity and oxygen cycles. Each OBGC model was coupled to the Nucleus for the European Modelling of the Ocean (NEMO) ocean general circulation model (GCM), and results from physically identical hindcast simulations were compared. Model skill was evaluated for biogeochemical metrics of global-scale bulk properties using conventional statistical techniques. The computing cost of each model was also measured in standardised tests run at two resource levels. No model is shown to consistently outperform or underperform all other models across all metrics. Nonetheless, the simpler models that are easier to tune are broadly closer to observations across a number of fields, and thus offer a high-efficiency option for ESMs that prioritise high resolution climate dynamics. However, simpler models provide limited insight into more complex marine biogeochemical processes and ecosystem pathways, and a parallel approach of low resolution climate dynamics and high complexity biogeochemistry is desirable in order to provide additional insights into biogeochemistry-climate interactions.

iMarNet: an ocean biogeochemistry model intercomparison project within a common physical ocean modelling framework

NASA Astrophysics Data System (ADS)

Kwiatkowski, L.; Yool, A.; Allen, J. I.; Anderson, T. R.; Barciela, R.; Buitenhuis, E. T.; Butenschön, M.; Enright, C.; Halloran, P. R.; Le Quéré, C.; de Mora, L.; Racault, M.-F.; Sinha, B.; Totterdell, I. J.; Cox, P. M.

2014-12-01

Ocean biogeochemistry (OBGC) models span a wide variety of complexities, including highly simplified nutrient-restoring schemes, nutrient-phytoplankton-zooplankton-detritus (NPZD) models that crudely represent the marine biota, models that represent a broader trophic structure by grouping organisms as plankton functional types (PFTs) based on their biogeochemical role (dynamic green ocean models) and ecosystem models that group organisms by ecological function and trait. OBGC models are now integral components of Earth system models (ESMs), but they compete for computing resources with higher resolution dynamical setups and with other components such as atmospheric chemistry and terrestrial vegetation schemes. As such, the choice of OBGC in ESMs needs to balance model complexity and realism alongside relative computing cost. Here we present an intercomparison of six OBGC models that were candidates for implementation within the next UK Earth system model (UKESM1). The models cover a large range of biological complexity (from 7 to 57 tracers) but all include representations of at least the nitrogen, carbon, alkalinity and oxygen cycles. Each OBGC model was coupled to the ocean general circulation model Nucleus for European Modelling of the Ocean (NEMO) and results from physically identical hindcast simulations were compared. Model skill was evaluated for biogeochemical metrics of global-scale bulk properties using conventional statistical techniques. The computing cost of each model was also measured in standardised tests run at two resource levels. No model is shown to consistently outperform all other models across all metrics. Nonetheless, the simpler models are broadly closer to observations across a number of fields and thus offer a high-efficiency option for ESMs that prioritise high-resolution climate dynamics. However, simpler models provide limited insight into more complex marine biogeochemical processes and ecosystem pathways, and a parallel approach of low-resolution climate dynamics and high-complexity biogeochemistry is desirable in order to provide additional insights into biogeochemistry-climate interactions.

Bridging Food Webs, Ecosystem Metabolism, and Biogeochemistry Using Ecological Stoichiometry Theory.

PubMed

Welti, Nina; Striebel, Maren; Ulseth, Amber J; Cross, Wyatt F; DeVilbiss, Stephen; Glibert, Patricia M; Guo, Laodong; Hirst, Andrew G; Hood, Jim; Kominoski, John S; MacNeill, Keeley L; Mehring, Andrew S; Welter, Jill R; Hillebrand, Helmut

2017-01-01

Although aquatic ecologists and biogeochemists are well aware of the crucial importance of ecosystem functions, i.e., how biota drive biogeochemical processes and vice-versa, linking these fields in conceptual models is still uncommon. Attempts to explain the variability in elemental cycling consequently miss an important biological component and thereby impede a comprehensive understanding of the underlying processes governing energy and matter flow and transformation. The fate of multiple chemical elements in ecosystems is strongly linked by biotic demand and uptake; thus, considering elemental stoichiometry is important for both biogeochemical and ecological research. Nonetheless, assessments of ecological stoichiometry (ES) often focus on the elemental content of biota rather than taking a more holistic view by examining both elemental pools and fluxes (e.g., organismal stoichiometry and ecosystem process rates). ES theory holds the promise to be a unifying concept to link across hierarchical scales of patterns and processes in ecology, but this has not been fully achieved. Therefore, we propose connecting the expertise of aquatic ecologists and biogeochemists with ES theory as a common currency to connect food webs, ecosystem metabolism, and biogeochemistry, as they are inherently concatenated by the transfer of carbon, nitrogen, and phosphorous through biotic and abiotic nutrient transformation and fluxes. Several new studies exist that demonstrate the connections between food web ecology, biogeochemistry, and ecosystem metabolism. In addition to a general introduction into the topic, this paper presents examples of how these fields can be combined with a focus on ES. In this review, a series of concepts have guided the discussion: (1) changing biogeochemistry affects trophic interactions and ecosystem processes by altering the elemental ratios of key species and assemblages; (2) changing trophic dynamics influences the transformation and fluxes of matter across environmental boundaries; (3) changing ecosystem metabolism will alter the chemical diversity of the non-living environment. Finally, we propose that using ES to link nutrient cycling, trophic dynamics, and ecosystem metabolism would allow for a more holistic understanding of ecosystem functions in a changing environment.

Agricultural Intensification Exacerbates Spillover Effects on Soil Biogeochemistry in Adjacent Forest Remnants

PubMed Central

Didham, Raphael K.; Barker, Gary M.; Bartlam, Scott; Deakin, Elizabeth L.; Denmead, Lisa H.; Fisk, Louise M.; Peters, Jennifer M. R.; Tylianakis, Jason M.; Wright, Hannah R.; Schipper, Louis A.

2015-01-01

Land-use intensification is a central element in proposed strategies to address global food security. One rationale for accepting the negative consequences of land-use intensification for farmland biodiversity is that it could ‘spare’ further expansion of agriculture into remaining natural habitats. However, in many regions of the world the only natural habitats that can be spared are fragments within landscapes dominated by agriculture. Therefore, land-sparing arguments hinge on land-use intensification having low spillover effects into adjacent protected areas, otherwise net conservation gains will diminish with increasing intensification. We test, for the first time, whether the degree of spillover from farmland into adjacent natural habitats scales in magnitude with increasing land-use intensity. We identified a continuous land-use intensity gradient across pastoral farming systems in New Zealand (based on 13 components of farmer input and soil biogeochemistry variables), and measured cumulative off-site spillover effects of fertilisers and livestock on soil biogeochemistry in 21 adjacent forest remnants. Ten of 11 measured soil properties differed significantly between remnants and intact-forest reference sites, for both fenced and unfenced remnants, at both edge and interior. For seven variables, the magnitude of effects scaled significantly with magnitude of surrounding land-use intensity, through complex interactions with fencing and edge effects. In particular, total C, total N, δ15N, total P and heavy-metal contaminants of phosphate fertilizers (Cd and U) increased significantly within remnants in response to increasing land-use intensity, and these effects were exacerbated in unfenced relative to fenced remnants. This suggests movement of livestock into surrounding natural habitats is a significant component of agricultural spillover, but pervasive changes in soil biogeochemistry still occur through nutrient spillover channels alone, even in fenced remnants set aside for conservation. These results have important implications for the viability of land-sparing as a strategy for balancing landscape-level conservation and production goals in agricultural landscapes. PMID:25575017

Ocean Monitoring Indicators for the Mediterranean Sea biogeochemistry derived from a high-resolution reanalysis

NASA Astrophysics Data System (ADS)

Solidoro, Cosimo; Cossarini, Gianpiero; Bolzon, Giorgio; Salon, Stefano; Teruzzi, Anna; Lazzari, Paolo; Crise, Alessandro

2017-04-01

In recent years the interest in multi-decadal reanalyses of the status of the Mediterranean marine ecosystem has been rising constantly, also in light of the need of information for a proper implementation of European directives (e.g. MSFD). State-of-art reanalyses of the Mediterranean Sea biogeochemistry - being an optimal integration of multi-platforms data and numerical models - constitute an extremely relevant source of information in evaluating the ecosystem status at basin and sub-basin scale. Furthermore, they provide highly valuable data to be used as boundary conditions for local studies. The objective of this work is to produce sensible environmental indicators useful to characterize the environmental status of the Mediterranean starting from an upgraded high-resolution reanalysis of Mediterranean Sea biogeochemistry delivered in the frame of the Copernicus Marine Environment Monitoring Services (CMEMS). The reanalysis was qualified by a comparison against several available data sets, in terms of the main surface and sub-surface biogeochemical essential climate variables (chlorophyll, carbon dioxide partial pressure, ocean acidity, nutrients, oxygen). The reanalysis outputs reproduced spatial patterns, seasonal cycle and inter-annual variability of the assessed variables, allowing for a proper description of recent trends and present status of the Mediterranean Sea biogeochemistry. Our results confirm the vision of the Mediterranean as a mainly oligotrophic ecosystem with the presence of significant biogeochemical gradients from the eastern to the western sub-basins (e.g. in chlorophyll, nutrients, primary production). Our reanalysis can be used to contribute estimating eutrophication MFSD descriptors, atmospheric carbon sequestration fluxes, first assessment of potential resources available for the higher trophic levels and more. Indeed, the reanalysis data set provides a suitable basis for the estimation of the so-called Ocean Monitoring Indicators (OMIs) and Essential Biogeochemical Variables (EBVs), developed within CMEMS for the Ocean State Report. Some of the OMIs that have been proposed so far for the Mediterranean biogeochemistry include indicators describing: the influence of physical forcing on ecosystem (e.g. mixed layer depth); the basic ecosystem status, functioning and changes (e.g. nutrient concentration, oxygen content, chlorophyll and their variability at monthly/seasonal/annual/decadal scale); the ecosystem health (e.g. anoxia indicators, N/P ratio); the relation of ocean ecosystem with fisheries (e.g. integrated primary production, phyto/zooplankton biomasses) and climate change (e.g. acidification, CO2 fluxes). Recent results in the Mediterranean Sea OMIs investigation will be widely discussed in our contribution.

Rice emissions during field flooding and air pollution feedbacks across South Korea

NASA Astrophysics Data System (ADS)

So, C.; Diskin, G. S.; DiGangi, J. P.; Choi, Y.; Rana, M.; Hughes, S.; Blake, D. R.; Nault, B.; Schroeder, J.; Campuzano Jost, P.; Jimenez, J. L.; Kim, M. J.; Teng, A.; Crounse, J. D.; Wenneberg, P.; Kaser, L.; Mikoviny, T.; Müller, M.; Wisthaler, A.; Pusede, S. E.

2017-12-01

Nitrous oxide (N2O) and methane (CH4) are important long-lived greenhouse gases. Known anthropogenic sources of these gases include rice cultivation, which represents anywhere between 5% and 20% of methane emissions globally. Other volatile molecules are also produced by soil biogeochemistry when rice fields are flooded, including small organic oxygenates. Here, we use recent aircraft measurements from the KORUS-AQ experiment to describe controls over rice emissions of N2O and CH4 at regional-scales across the South Korean Peninsula. We also investigate potential emissions of molecular hydrogen and volatile alcohols and organic acids and consider the effect of aerosol nitrate and sulfate deposition on rice soil biogeochemistry on paddies downwind of polluted urban areas.

A molecular dawn for biogeochemistry

USGS Publications Warehouse

Zak, D.R.; Blackwood, C.B.; Waldrop, M.P.

2006-01-01

Biogeochemistry is at the dawn of an era in which molecular advances enable the discovery of novel microorganisms having unforeseen metabolic capabilities, revealing new insight into the underlying processes regulating elemental cycles at local to global scales. Traditionally, biogeochemical inquiry began by studying a process of interest, and then focusing downward to uncover the microorganisms and metabolic pathways mediating that process. With the ability to sequence functional genes from the environment, molecular approaches now enable the flow of inquiry in the opposite direction. Here, we argue that a focus on functional genes, the microorganisms in which they reside, and the interaction of those organisms with the broader microbial community could transform our understanding of many globally important biogeochemical processes. ?? 2006 Elsevier Ltd. All rights reserved.

Has water limited our imagination for aridland biogeochemistry?

PubMed

Austin, Amy T

2011-05-01

The classic ecological paradigm for deserts, that all processes are controlled by water availability, has limited our imagination for exploring other controls on the cycling of carbon and nutrients in aridland ecosystems. This review of recent studies identifies alternative mechanisms that challenge the idea that all soil processes in aridlands are proximately water-limited, and highlights the significance of photodegradation of aboveground litter and the overriding importance of spatial heterogeneity as a modulator of biotic responses to water availability. Aridlands currently occupy >30% of the terrestrial land surface and are expanding. It is therefore critical to incorporate these previously unappreciated mechanisms in our understanding of aridland biogeochemistry to mitigate the effects of desertification and global change. Copyright © 2011 Elsevier Ltd. All rights reserved.

Southeastern U.S.A. Continental Shelf Respiratory Rates Revisited

NASA Technical Reports Server (NTRS)

Sheldon, Joan E.; Griffith, Peter C.; Peters Francesc; Sheldon, Wade M., Jr.; Blanton, Jackson O.; Amft, Julie; Pomeroy, Lawrence R.

2010-01-01

Respiratory rates on the U. S. southeastern continental shelf have been estimated several times by different investigators, most recently by Jiang et al. (Biogeochemistry 98:101-113, 2010) who report lower mean rates thanwere found in earlier work and attribute the differences to analytical error in all methods used in earlier studies. The differences are, instead, attributable to the differences in the geographical scope of the studies. The lower estimates of regional organic carbon flux of Jiang et al. (Biogeochemistry 98:101-113, 2010) are a consequence of their extrapolation of data from a small portion of the shelf to the entire South Atlantic Bight. This comment examines the methodologies used as well as the variability of respiratory rates in this region over space and time.

Bio-Optical Measurements in Upwelling Ecosystems in Support of SIMBIOS. Chapter 4

NASA Technical Reports Server (NTRS)

Chavez, Francisco P.; Strutton, Peter G.; Kuwahara, Victor S.; Mahoney, Kevin L.; Drake, Eric

2003-01-01

The upwelling region of the equatorial Pacific Ocean, which spans one quarter of the earth s circumference, strongly impacts global biogeochemistry. This upwelling system has significant implications for global CO2 fluxes (Tans et al., 1990; Takahashi et al., 1997; Feely et al., 1999), as well as primary and secondary production (Chavez and Barber, 1987; Chavez and Toggweiler, 1995; Chavez et al., 1996; Dugdale and Wilkerson, 1998; Chavez et al., 1999; Strutton and Chavez, 2000). In addition, the region represents a vast oceanic (case 1) region over which validation data for SeaWiFS are needed. This project consists of an optical mooring program and cruise-based measurements focused on measuring biological and chemical variability in the equatorial Pacific and obtaining validation data for SeaWiFS.

A microbial biogeochemistry network for soil carbon and nitrogen cycling and methane flux: model structure and application to Asia

NASA Astrophysics Data System (ADS)

Xu, X.; Song, C.; Wang, Y.; Ricciuto, D. M.; Lipson, D.; Shi, X.; Zona, D.; Song, X.; Yuan, F.; Oechel, W. C.; Thornton, P. E.

2017-12-01

A microbial model is introduced for simulating microbial mechanisms controlling soil carbon and nitrogen biogeochemical cycling and methane fluxes. The model is built within the CN (carbon-nitrogen) framework of Community Land Model 4.5, named as CLM-Microbe to emphasize its explicit representation of microbial mechanisms to biogeochemistry. Based on the CLM4.5, three new pools were added: bacteria, fungi, and dissolved organic matter. It has 11 pools and 34 transitional processes, compared with 8 pools and 9 transitional flow in the CLM4.5. The dissolve organic carbon was linked with a new microbial functional group based methane module to explicitly simulate methane production, oxidation, transport and their microbial controls. Comparing with CLM4.5-CN, the CLM-Microbe model has a number of new features, (1) microbial control on carbon and nitrogen flows between soil carbon/nitrogen pools; (2) an implicit representation of microbial community structure as bacteria and fungi; (3) a microbial functional-group based methane module. The model sensitivity analysis suggests the importance of microbial carbon allocation parameters on soil biogeochemistry and microbial controls on methane dynamics. Preliminary simulations validate the model's capability for simulating carbon and nitrogen dynamics and methane at a number of sites across the globe. The regional application to Asia has verified the model in simulating microbial mechanisms in controlling methane dynamics at multiple scales.

Modelling potential changes in marine biogeochemistry due to large-scale offshore tidal energy extraction

NASA Astrophysics Data System (ADS)

van der Molen, Johan

2015-04-01

Tidal power generation through submerged turbine-type devices is in an advanced stage of testing, and large-scale applications are being planned in areas with high tidal current speeds. The potential impact of such large-scale applications on the hydrography can be investigated using hydrodynamical models. In addition, aspects of the potential impact on the marine ecosystem can be studied using biogeochemical models. In this study, the coupled hydrodynamics-biogeochemistry model GETM-ERSEM is used in a shelf-wide application to investigate the potential impact of large-scale tidal power generation in the Pentland Firth. A scenario representing the currently licensed power extraction suggested i) an average reduction in M2 tidal current velocities of several cm/s within the Pentland Firth, ii) changes in the residual circulation of several mm/s in the vicinity of the Pentland Firth, iii) an increase in M2 tidal amplitude of up to 1 cm to the west of the Pentland Firth, and iv) a reduction of several mm in M2 tidal amplitude along the east coast of the UK. A second scenario representing 10 times the currently licensed power extraction resulted in changes that were approximately 10 times as large. Simulations including the biogeochemistry model for these scenarios are currently in preparation, and first results will be presented at the the conference, aiming at impacts on primary production and benthic production.

Ecological Functioning in Two Mid-Atlantic Bight Submarine Canyons: Macrofauna Community Trends and the Role of Canyon Specific Processes

NASA Astrophysics Data System (ADS)

Robertson, C.; Bourque, J. R.; Davies, A. J.; Duineveld, G.; Mienis, F.; Brooke, S.; Ross, S. W.; Demopoulos, A. W.

2016-02-01

Submarine canyons are complex systems, acting as major conduits of organic matter along continental shelves and promoting gradients in food resources, turbidity flows, habitat heterogeneity, and areas of sediment resuspension and deposition. In the western North Atlantic, a large multidisciplinary program was conducted in two major Mid-Atlantic Bight (MAB) canyons (Baltimore and Norfolk canyons). This Atlantic Deepwater Canyons project was funded by BOEM, NOAA, and USGS. Here we investigate the `canyon effect' on benthic ecosystem ecology and functioning of two canyon systems by defining canyon specific processes influencing MAB shelf benthic community trends. Sediment cores were collected in 2012 and 2013 with a NIOZ box corer along the main axes ( 180-1200m) of Baltimore and Norfolk Canyon and at comparable depths on the adjacent continental slope. Whole community macrofaunal (>300 μm) abundance and biomass data provided insight into community trends across depth and biogeochemical gradients by coupling diversity metrics and biological trait analyses with sediment biogeochemistry and hydrodynamic data. The canyons exhibited clear differences in sediment profiles, hydrodynamic regimes and enrichment depocenters as well as significantly distinct infauna communities. Interestingly, both canyons showed bimodal distributions in abundances and diversity of infauna and a shallowing of species maxima which was not present on adjacent slopes. We hypothesize that physical canyon processes are important regulators in the depth of observed species maxima and community functioning on the MAB shelf, on local and regional scales. Unique sediment dynamics, organic enrichment, and hydrographic conditions were significant factors in structuring benthic community differences in MAB canyons The study provides a complete benthic infaunal appraisal of two canyon systems in the western Atlantic, incorporating biogeochemistry and oceanography to increase our understanding of canyon ecosystem ecology and provide baseline information on canyon functioning.

Amanzi: An Open-Source Multi-process Simulator for Environmental Applications

NASA Astrophysics Data System (ADS)

Moulton, J. D.; Molins, S.; Johnson, J. N.; Coon, E.; Lipnikov, K.; Day, M.; Barker, E.

2014-12-01

The Advanced Simulation Capabililty for Environmental Management (ASCEM) program is developing an approach and open-source tool suite for standardized risk and performance assessments at legacy nuclear waste sites. These assessments begin with simplified models, and add geometric and geologic complexity as understanding is gained. The Platform toolsets (Akuna) generates these conceptual models and Amanzi provides the computational engine to perform the simulations, returning the results for analysis and visualization. In this presentation we highlight key elements of the design, algorithms and implementations used in Amanzi. In particular, the hierarchical and modular design is aligned with the coupled processes being sumulated, and naturally supports a wide range of model complexity. This design leverages a dynamic data manager and the synergy of two graphs (one from the high-level perspective of the models the other from the dependencies of the variables in the model) to enable this flexible model configuration at run time. Moreover, to model sites with complex hydrostratigraphy, as well as engineered systems, we are developing a dual unstructured/structured capability. Recently, these capabilities have been collected in a framework named Arcos, and efforts have begun to improve interoperability between the unstructured and structured AMR approaches in Amanzi. To leverage a range of biogeochemistry capability from the community (e.g., CrunchFlow, PFLOTRAN, etc.), a biogeochemistry interface library was developed called Alquimia. To ensure that Amanzi is truly an open-source community code we require a completely open-source tool chain for our development. We will comment on elements of this tool chain, including the testing and documentation development tools such as docutils, and Sphinx. Finally, we will show simulation results from our phased demonstrations, including the geochemically complex Savannah River F-Area seepage basins.

Total dissolved atmospheric nitrogen deposition in the anoxic Cariaco basin

NASA Astrophysics Data System (ADS)

Rasse, R.; Pérez, T.; Giuliante, A.; Donoso, L.

2018-04-01

Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August-September 2008) and dry (March-April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m-3 and 0.11-0.56 μg-N m-3 in total suspended particles samples and between 0.08 and 0.54 mg-N l-1 and 0.02-1.3 mg-N l-1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year-1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.

Wetland biogeochemistry and ecological risk assessment

NASA Astrophysics Data System (ADS)

Bai, Junhong; Huang, Laibin; Gao, Haifeng; Zhang, Guangliang

2017-02-01

Wetlands are an important ecotone between terrestrial and aquatic ecosystems and can provide great ecological service functions. Soils/sediments are one of the important components of wetland ecosystems, which support wetland plants and microorganisms and influence wetland productivity. Moreover, wetland soils/sediments serve as sources, sinks and transfers of carbon, nitrogen, phosphorus and chemical contaminants such as heavy metals. In natural wetland ecosystems, wetland soils/sediments play a great role in improving water quality as these chemical elements can be retained in wetland soils/sediments for a long time. Moreover, the biogeochemical processes of the abovementioned elements in wetland soils/sediments can drive wetland evolution and development, and their changes will considerably affect wetland ecosystem health. Therefore, a better understanding of wetland soil biogeochemistry will contribute to improving wetland ecological service functions.

Biogeochemistry: The soil carbon erosion paradox

NASA Astrophysics Data System (ADS)

Sanderman, Jonathan; Berhe, Asmeret Asefaw

2017-04-01

Erosion is typically thought to degrade soil resources. However, the redistribution of soil carbon across the landscape, caused by erosion, can actually lead to a substantial sink for atmospheric CO2.

Nutrient stoichiometry of temperate trees and effects on the coupled cycles of carbon, nitrogen, and cations in soil

NASA Astrophysics Data System (ADS)

Mueller, K. E.; Oleksyn, J.; Hobbie, S. E.; Reich, P.; Chorover, J. D.; Freeman, K. H.; Eissenstat, D.

2009-12-01

Nutrient stoichiometry of leaf litter (LL) is a potentially important driver of plant effects on soil biogeochemistry; it is also responsive to environmental perturbations and differs among plant functional groups that may have predictable responses to the environment. Thus variation in LL nutrient stoichiometry may provide a predictive framework for the influence of global change on soil. However, this approach depends on several key, but poorly tested assumptions, including: 1) other plant organs follow similar patterns and have similar effects on soil biogeochemistry, and 2) patterns in leaf traits, functional group dominance, and soil properties across large-spatial scales are predictive at smaller scales. To address these assumptions and test the utility of nutrient stoichiometry as a predictive framework for soil change, we synthesize data on tree stoichiometry and soil biogeochemistry from a long-term (> 30 yr) common garden experiment containing replicated, monoculture plots of 14 temperate tree species. LL nutrient stoichiometry alone is insufficient to explain differences in biogeochemical cycling among tree species, in part due to the dissimilarity of leaf and root traits within species. Notably, different elements and plant organs have independent impacts on soil biogeochemistry. LL nitrogen (N) concentration and lignin:N ratios have small or negligible effects on soil carbon (C), N, and cation cycling, while LL-calcium (Ca) drives differences in litter decomposition and soil pH among species in a manner consistent with nutrient requirements of anecic earthworms. However, LL-Ca effects on C and N cycles in soil appear minor compared to the influences of root N and, unexpectedly, green leaf N, which combine to drive differences in soil N dynamics via unique mechanisms consistent with nutrient requirements of soil microbes and the trees. In turn, soil N dynamics are strongly correlated with soil acidity and C stabilization. By taking into account the stoichiometry of each plant organ, of soil microbes and fauna, and the interactions among C, N, and cation cycles, the predictive capacity of tree nutrient stoichiometry for understanding soil change is apparent, albeit complex.

Disturbance-driven Changes in Soil Exoenzyme Activity and Biogeochemistry of Colorado Forests

NASA Astrophysics Data System (ADS)

Lybrand, R. A.; Gallery, R. E.; Trahan, N. A.; Dynes, E.; Moore, D. J.

2015-12-01

Forest disturbances alter rates of organic matter decomposition by microbes, which introduces uncertainty to the fate of soil carbon and aboveground carbon stocks. Quantifying soil microbial response to disturbance will reduce this uncertainty in dynamic, heterogeneous ecosystems. Here, we assessed how potential exoenzyme activities and biogeochemistry vary across Colorado landscapes disturbed by insect, fire, and flooding. We sampled 56 plots that spanned a burn severity gradient following the 2012 High Park Fire and a beetle kill chronosequence. Topsoil biogeochemistry, potential exoenzyme activity, and microbial biomass were quantified within each plot, and for a subset of 16 plots visited before and after a 2014 rainfall event. Terrain variables were generated from a LiDAR-derived DTM. Our results documented a shift in exoenzyme activity that corresponded to fire-driven changes in pH, which averaged 4.8 ± 0.2 in unburned plots to 6.3 ± 0.4 in severe burn plots. Stepwise multiple linear regressions were employed to predict exoenzyme activity using principal components derived from biogeochemical and terrain variables. The models explained up to 50% of the variance in exoenzyme activity, with the strongest relationships identified for phosphatase and the carbon degrading enzymes, β-Glucosidase and 4-MUB-β-D-cellobioside. The unexplained variance may result from the legacy of disturbance across sites. For example, burned and unburned plots presented contrasting geochemical responses to the 2014 rainfall event. Specifically, PO43- did not differ significantly between the burned and unburned plots in the pre-flood soils. Interestingly, PO43- was significantly different between the two groups in the post-flood soils due to a decrease in PO43- at the unburned plots and a slight increase at the burned plots. Similar trends were recognized for DIN and NH4+ in the burned and unburned sites yet the beetle kill plots exhibited little geochemical response pre- and post-flood. Our results demonstrate that exoenzyme activities are controlled, in part, by topography and disturbance-driven changes in biogeochemistry. Future work will examine how microclimate and disturbance history, such as undocumented flood events, contribute to soil ecological and geochemical variability across complex terrain.

A mechanistic soil biogeochemistry model with explicit representation of microbial and macrofaunal activities and nutrient cycles

NASA Astrophysics Data System (ADS)

Fatichi, Simone; Manzoni, Stefano; Or, Dani; Paschalis, Athanasios

2016-04-01

The potential of a given ecosystem to store and release carbon is inherently linked to soil biogeochemical processes. These processes are deeply connected to the water, energy, and vegetation dynamics above and belowground. Recently, it has been advocated that a mechanistic representation of soil biogeochemistry require: (i) partitioning of soil organic carbon (SOC) pools according to their functional role; (ii) an explicit representation of microbial dynamics; (iii) coupling of carbon and nutrient cycles. While some of these components have been introduced in specialized models, they have been rarely implemented in terrestrial biosphere models and tested in real cases. In this study, we combine a new soil biogeochemistry model with an existing model of land-surface hydrology and vegetation dynamics (T&C). Specifically the soil biogeochemistry component explicitly separates different litter pools and distinguishes SOC in particulate, dissolved and mineral associated fractions. Extracellular enzymes and microbial pools are explicitly represented differentiating the functional roles of bacteria, saprotrophic and mycorrhizal fungi. Microbial activity depends on temperature, soil moisture and litter or SOC stoichiometry. The activity of macrofauna is also modeled. Nutrient dynamics include the cycles of nitrogen, phosphorous and potassium. The model accounts for feedbacks between nutrient limitations and plant growth as well as for plant stoichiometric flexibility. In turn, litter input is a function of the simulated vegetation dynamics. Root exudation and export to mycorrhiza are computed based on a nutrient uptake cost function. The combined model is tested to reproduce respiration dynamics and nitrogen cycle in few sites where data were available to test plausibility of results across a range of different metrics. For instance in a Swiss grassland ecosystem, fine root, bacteria, fungal and macrofaunal respiration account for 40%, 23%, 33% and 4% of total belowground respiration, respectively. Root exudation and carbon export to mycorrhizal represent about 7% of plant Net Primary Production. The model allows exploring the temporal dynamics of respiration fluxes from the different ecosystem components and designing virtual experiments on the controls exerted by environmental variables and/or soil microbes and mycorrhizal associations on soil carbon storage, plant growth, and nutrient leaching.

Constraining terrestrial ecosystem CO2 fluxes by integrating models of biogeochemistry and atmospheric transport and data of surface carbon fluxes and atmospheric CO2 concentrations

NASA Astrophysics Data System (ADS)

Zhu, Q.; Zhuang, Q.; Henze, D.; Bowman, K.; Chen, M.; Liu, Y.; He, Y.; Matsueda, H.; Machida, T.; Sawa, Y.; Oechel, W.

2014-09-01

Regional net carbon fluxes of terrestrial ecosystems could be estimated with either biogeochemistry models by assimilating surface carbon flux measurements or atmospheric CO2 inversions by assimilating observations of atmospheric CO2 concentrations. Here we combine the ecosystem biogeochemistry modeling and atmospheric CO2 inverse modeling to investigate the magnitude and spatial distribution of the terrestrial ecosystem CO2 sources and sinks. First, we constrain a terrestrial ecosystem model (TEM) at site level by assimilating the observed net ecosystem production (NEP) for various plant functional types. We find that the uncertainties of model parameters are reduced up to 90% and model predictability is greatly improved for all the plant functional types (coefficients of determination are enhanced up to 0.73). We then extrapolate the model to a global scale at a 0.5° × 0.5° resolution to estimate the large-scale terrestrial ecosystem CO2 fluxes, which serve as prior for atmospheric CO2 inversion. Second, we constrain the large-scale terrestrial CO2 fluxes by assimilating the GLOBALVIEW-CO2 and mid-tropospheric CO2 retrievals from the Atmospheric Infrared Sounder (AIRS) into an atmospheric transport model (GEOS-Chem). The transport inversion estimates that: (1) the annual terrestrial ecosystem carbon sink in 2003 is -2.47 Pg C yr-1, which agrees reasonably well with the most recent inter-comparison studies of CO2 inversions (-2.82 Pg C yr-1); (2) North America temperate, Europe and Eurasia temperate regions act as major terrestrial carbon sinks; and (3) The posterior transport model is able to reasonably reproduce the atmospheric CO2 concentrations, which are validated against Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) CO2 concentration data. This study indicates that biogeochemistry modeling or atmospheric transport and inverse modeling alone might not be able to well quantify regional terrestrial carbon fluxes. However, combining the two modeling approaches and assimilating data of surface carbon flux as well as atmospheric CO2 mixing ratios might significantly improve the quantification of terrestrial carbon fluxes.

Observed 20th Century Desert Dust Variability: Impact on Climate and Biogeochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahowald, Natalie; Kloster, Silvia; Engelstaedter, S.

2010-01-01

Desert dust perturbs climate by directly and indirectly interacting with incoming solar and outgoing long wave radiation, thereby changing precipitation and temperature, in addition to modifying ocean and land biogeochemistry. While we know that desert dust is sensitive to perturbations in climate and human land use, previous studies have been unable to determine whether humans were increasing or decreasing desert dust in the global average. Here we present observational estimates of desert dust based on paleodata proxies showing a doubling of desert dust during the 20th century over much, but not all the globe. Large uncertainties remain in estimates ofmore » desert dust variability over 20th century due to limited data. Using these observational estimates of desert dust change in combination with ocean, atmosphere and land models, we calculate the net radiative effect of these observed changes (top of atmosphere) over the 20th century to be -0.14 {+-} 0.11 W/m{sup 2} (1990-1999 vs. 1905-1914). The estimated radiative change due to dust is especially strong between the heavily loaded 1980-1989 and the less heavily loaded 1955-1964 time periods (-0.57 {+-} 0.46 W/m{sup 2}), which model simulations suggest may have reduced the rate of temperature increase between these time periods by 0.11 C. Model simulations also indicate strong regional shifts in precipitation and temperature from desert dust changes, causing 6 ppm (12 PgC) reduction in model carbon uptake by the terrestrial biosphere over the 20th century. Desert dust carries iron, an important micronutrient for ocean biogeochemistry that can modulate ocean carbon storage; here we show that dust deposition trends increase ocean productivity by an estimated 6% over the 20th century, drawing down an additional 4 ppm (8 PgC) of carbon dioxide into the oceans. Thus, perturbations to desert dust over the 20th century inferred from observations are potentially important for climate and biogeochemistry, and our understanding of these changes and their impacts should continue to be refined.« less

Bridging Food Webs, Ecosystem Metabolism, and Biogeochemistry Using Ecological Stoichiometry Theory

PubMed Central

Welti, Nina; Striebel, Maren; Ulseth, Amber J.; Cross, Wyatt F.; DeVilbiss, Stephen; Glibert, Patricia M.; Guo, Laodong; Hirst, Andrew G.; Hood, Jim; Kominoski, John S.; MacNeill, Keeley L.; Mehring, Andrew S.; Welter, Jill R.; Hillebrand, Helmut

2017-01-01

Although aquatic ecologists and biogeochemists are well aware of the crucial importance of ecosystem functions, i.e., how biota drive biogeochemical processes and vice-versa, linking these fields in conceptual models is still uncommon. Attempts to explain the variability in elemental cycling consequently miss an important biological component and thereby impede a comprehensive understanding of the underlying processes governing energy and matter flow and transformation. The fate of multiple chemical elements in ecosystems is strongly linked by biotic demand and uptake; thus, considering elemental stoichiometry is important for both biogeochemical and ecological research. Nonetheless, assessments of ecological stoichiometry (ES) often focus on the elemental content of biota rather than taking a more holistic view by examining both elemental pools and fluxes (e.g., organismal stoichiometry and ecosystem process rates). ES theory holds the promise to be a unifying concept to link across hierarchical scales of patterns and processes in ecology, but this has not been fully achieved. Therefore, we propose connecting the expertise of aquatic ecologists and biogeochemists with ES theory as a common currency to connect food webs, ecosystem metabolism, and biogeochemistry, as they are inherently concatenated by the transfer of carbon, nitrogen, and phosphorous through biotic and abiotic nutrient transformation and fluxes. Several new studies exist that demonstrate the connections between food web ecology, biogeochemistry, and ecosystem metabolism. In addition to a general introduction into the topic, this paper presents examples of how these fields can be combined with a focus on ES. In this review, a series of concepts have guided the discussion: (1) changing biogeochemistry affects trophic interactions and ecosystem processes by altering the elemental ratios of key species and assemblages; (2) changing trophic dynamics influences the transformation and fluxes of matter across environmental boundaries; (3) changing ecosystem metabolism will alter the chemical diversity of the non-living environment. Finally, we propose that using ES to link nutrient cycling, trophic dynamics, and ecosystem metabolism would allow for a more holistic understanding of ecosystem functions in a changing environment. PMID:28747904

Lighting Study Security System Modifications

DTIC Science & Technology

1978-05-01

I7, 7 ,177 uo~ 6w4, 7~% 4 1 :, 0 b17 1 7AS, ti19 1537 " 1 7Ž7 1 4bd 7c6 sP113 -oC-b 4I4 14, ൙ j 0 I ? I I I 󈧏 1 ,io i .Ž - 3?b A 1 . 󈧕 1 I t...113 j7 171k ~ 1 e~ 3 1 171~ tD 40 4’j 1 1 -0’ r17 171t d~7 In. -’Ao ?I M .4 P1 ro 4 3e" 34*v t 1~ -1 73- 1 - Itfi 3CI7 4e (.,4~?~~. 3 1i jlý A4 3 e b

JPRS Report, Soviet Union, Military History Journal, No. 3, March 1988.

DTIC Science & Technology

1988-06-28

S ) After its combat baptism at Sokolovo the Czechoslovak military unit blazed a glorious combat trail together with the Soviet Army. Kiev, Belaya...1988 15 L2 _Q • >> §§■ ocB La < e . ■ .!= SQ P4 cl so leg E < c . SO > c . SO •1 öS Q CL, . ’ S . *7 co 5< « « u o-a-5...o< CO ZQ 10 s.fc > a . z.fc a OS bs *,» . la V. C o n^E ■Sfi .5! E Ic.E ’ S . ^ O fc ’O £ £ -C T> o£«e CJ c- ü< Ub 5 Q o (L, a

Citizenship and withdrawal in the workplace: relationship between organizational citizenship behavior, intention to leave current job and intention to leave the organization.

PubMed

Paillé, Pascal; Grima, François

2011-01-01

This study investigates the relationship between organizational citizenship behavior (OCB) and employee intention to leave the organization and current job using a sample of French employees. A survey was sent to 1,200 alumni of a business school in France. Participation in the study was voluntary. The participants were 355 working adults with French citizenship. This paper provides several interesting findings. While no relationship was found between altruism and intention to leave both the organization and the current job, sportsmanship, civic virtue and helping others emerged as the strongest predictors of intention to leave the organization and intention to leave the current job. Results are discussed.

Development of Gene Centric Modeling for Nutrient Cycling

EPA Pesticide Factsheets

opportunity to participate in the development of a gene-centric model to help predict potential changes in the biogeochemistry of aquatic ecosystems that may arise from anthropogenic stressors and management decisions

Ocean science: The rise of Rhizaria

NASA Astrophysics Data System (ADS)

Caron, David A.

2016-04-01

Large amoeba-like organisms known as Rhizaria have often been overlooked in studies of ocean biology and biogeochemistry. Underwater imaging and ecological network analyses are revealing their roles. See Article p.465 & Letter p.504

Biogeochemistry and Spatial Distribution of the Microbial-Mineral Interface Using I2LD-FTMS

NASA Astrophysics Data System (ADS)

Scott, J. R.; Kauffman, M. E.; Kauffman, M. E.; Tremblay, P. L.

2001-12-01

Previous studies indicate that biogeochemistry can vary within individual mineral specimens in contact with microorganisms. These same studies have shown that microcosms containing a mixture of minerals simulating a heterogeneous geologic matrix do not yield the same results as the naturally occurring rock. Therefore, it is of utmost importance to develop analytical tools that can provide spatially correlative biogeochemical data of the microbial-mineral interface within naturally occurring geologic matrices. Imaging internal laser desorption Fourier transform mass spectrometry (I2LD-FTMS) can provide elemental and molecular information of the microbial-mineral interface at a spatial resolution limited only by the optical diffraction limit of the final focusing lens (down to 2 μ m). Additionally, the I2LD-FTMS used in this study has exceptional reproducibility, which can provide successive mapping sequences for depth-profiling studies. Basalt core samples, taken from the Snake River Plain Aquifer in southeastern Idaho, were mapped prior to, and after, exposure to a bacterial culture. The bacteria-basalt interface spectra were collected using the I2LD-FTMS at the INEEL. Mass spectra were recorded over a mass-to-charge range of 30-2500 Da with an average peak resolution of 15,000 using 10 μ m spots. Two-dimensional maps were constructed depicting the spatial distribution of the minerals within the basalt as well as the spatial distribution of the bacteria on the basalt surface. This represents the first reported application of I2LD-FTMS in the field of biogeochemistry.

Benthic iron and phosphorus release from river dominated shelf sediments under varying bottom water O2 concentrations.

NASA Astrophysics Data System (ADS)

Ghaisas, N. A.; Maiti, K.; White, J. R.

2017-12-01

Phosphorus (P) cycling in coastal ocean is predominantly controlled by river discharge and biogeochemistry of the sediments. In coastal Louisiana, sediment biogeochemistry is strongly influenced by seasonally fluctuating bottom water O2, which, in turn transitions the shelf sediments from being a sink to source of P. Sediment P-fluxes were 9.73 ± 0.76 mg / m2 /d and 0.67±0.16 mg/m2/d under anaerobic and aerobic conditions respectively, indicating a 14 times higher P-efflux from oxygen deprived sediments. A high sedimentary oxygen consumption rate of 889 ± 33.6 mg/m2/d was due to organic matter re-mineralization and resulted in progressively decreasing the water column dissolved O2 , coincident with a P-flux of 7.2 ± 5.5 mg/m2/d from the sediment. Corresponding water column flux of Fe total was 19.7 ± 7.80 mg/m2/d and the sediment-TP decreased from 545 mg/Kg to 513 mg/Kg. A simultaneous increase in pore water Fe and P concentrations in tandem with a 34.6% loss in sedimentary Fe-bound P underscores the importance of O2 on coupled Fe- P biogeochemistry. This study suggests that from a 14,025 sq. km hypoxia area, Louisiana shelf sediments can supply 1.33x105 kg P/day into the water column compared to 0.094 x 105 kg P/day during the fully aerobic water column conditions.

Applications of time-resolved laser fluorescence spectroscopy to the environmental biogeochemistry of actinides.

PubMed

Collins, Richard N; Saito, Takumi; Aoyagi, Noboru; Payne, Timothy E; Kimura, Takaumi; Waite, T David

2011-01-01

Time-resolved laser fluorescence spectroscopy (TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS differentiates chemical species of a fluorescent metal ion through analysis of different excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fluorescence decay lifetimes on the order of microseconds, such as UO , Cm, and Eu, continuing development of ultra-fast and cryogenic TRLFS systems offers the possibility to obtain speciation information on metal ions having room-temperature fluorescence decay lifetimes on the order of nanoseconds to picoseconds. The main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of (i) metal speciation in aqueous and solid phases and (ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Significant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Zeli; Zhuang, Qianlai; Shurpali, Narasinha J.

Recent studies indicated that Arctic lakes play an important role in receiving, processing, and storing organic carbon exported from terrestrial ecosystems. To quantify the contribution of Arctic lakes to the global carbon cycle, we developed a one-dimensional process-based Arctic Lake Biogeochemistry Model (ALBM) that explicitly simulates the dynamics of organic and inorganic carbon in Arctic lakes. By realistically modeling water mixing, carbon biogeochemistry, and permafrost carbon loading, the model can reproduce the seasonal variability of CO 2 fluxes from the study Arctic lakes. The simulated area-weighted CO 2 fluxes from yedoma thermokarst lakes, nonyedoma thermokarst lakes, and glacial lakes aremore » 29.5, 13.0, and 21.4 g C m -2 yr -1, respectively, close to the observed values (31.2, 17.2, and 16.5 ± 7.7 g C m -2 yr -1, respectively). The simulations show that the high CO 2 fluxes from yedoma thermokarst lakes are stimulated by the biomineralization of mobilized labile organic carbon from thawing yedoma permafrost. The simulations also imply that the relative contribution of glacial lakes to the global carbon cycle could be the largest because of their much larger surface area and high biomineralization and carbon loading. According to the model, sunlight-induced organic carbon degradation is more important for shallow nonyedoma thermokarst lakes but its overall contribution to the global carbon cycle could be limited. Overall, the ALBM can simulate the whole-lake carbon balance of Arctic lakes, a difficult task for field and laboratory experiments and other biogeochemistry models.« less

Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific Oceans

NASA Astrophysics Data System (ADS)

Löscher, C. R.; Bange, H. W.; Schmitz, R. A.; Callbeck, C. M.; Engel, A.; Hauss, H.; Kanzow, T.; Kiko, R.; Lavik, G.; Loginova, A.; Melzner, F.; Neulinger, S. C.; Pahlow, M.; Riebesell, U.; Schunck, H.; Thomsen, S.; Wagner, H.

2015-03-01

Recent modeling results suggest that oceanic oxygen levels will decrease significantly over the next decades to centuries in response to climate change and altered ocean circulation. Hence the future ocean may experience major shifts in nutrient cycling triggered by the expansion and intensification of tropical oxygen minimum zones (OMZs). There are numerous feedbacks between oxygen concentrations, nutrient cycling and biological productivity; however, existing knowledge is insufficient to understand physical, chemical and biological interactions in order to adequately assess past and potential future changes. We investigated the pelagic biogeochemistry of OMZs in the eastern tropical North Atlantic and eastern tropical South Pacific during a series of cruise expeditions and mesocosm studies. The following summarizes the current state of research on the influence of low environmental oxygen conditions on marine biota, viruses, organic matter formation and remineralization with a particular focus on the nitrogen cycle in OMZ regions. The impact of sulfidic events on water column biogeochemistry, originating from a specific microbial community capable of highly efficient carbon fixation, nitrogen turnover and N2O production is further discussed. Based on our findings, an important role of sinking particulate organic matter in controlling the nutrient stochiometry of the water column is suggested. These particles can enhance degradation processes in OMZ waters by acting as microniches, with sharp gradients enabling different processes to happen in close vicinity, thus altering the interpretation of oxic and anoxic environments.

Biogeochemistry: Deep ocean iron balance

NASA Astrophysics Data System (ADS)

Homoky, William B.

2017-02-01

Dissolved iron is mysteriously pervasive in deep ocean hydrothermal plumes. An analysis of gas, metals and particles from a 4,000 km plume transect suggests that dissolved iron is maintained by rapid and reversible exchanges with sinking particles.

Death by Ulva

EPA Science Inventory

We report on a series of field and laboratory mesocosm experiments where we examined the effects of two levels of decomposing Ulva on Spartina alterniflora growth, soil biogeochemistry, and nitrogen dynamics. Monitoring of porewater revealed rapid mineralization to ammonium from...

Biogeochemistry: Food for early animal evolution

NASA Astrophysics Data System (ADS)

Knoll, Andrew H.

2017-08-01

A revised timeline for when algae became ecologically important among plankton in the ancient oceans reveals a link between chemical changes in those waters and the emergence of animals in marine ecosystems. See Letter p.578

Remote sensing tools to study ocean biogeochemistry: state of the art

NASA Technical Reports Server (NTRS)

Carr, M. E.

2001-01-01

Remote sensing of the world ocean presently provides measurements of sea-surface temperature, sea surface height, wind speed and direction, and ocean color, from which chlorophyll concentration and aerosol optical thickness are obtained.

STORMWATER TREATMENT: WET/DRY PONDS VS. CONSTRUCTED WETLANDS

EPA Science Inventory

The presence of aquatic macrophytes in structural stormwater BMPs complicates the mechanistic interaction between biogeochemistry and hydraulic efficiency that dictates the performance of these management strategies. This project relies on extant data and controlled experiments t...

Environmental Biogeochemistry

ERIC Educational Resources Information Center

Nriagu, Jerome O.

1975-01-01

Discusses a symposium which centered on the interfaces between the biosphere and the geosphere, and the effects of industry at those interfaces. Topics include the food crisis, the nitrogen cycle, atmospheric carbon dioxide levels, and the transformations of metals in ecosystems. (MLH)

Marine biogeochemistry: Methylmercury manufacture

NASA Astrophysics Data System (ADS)

Cossa, Daniel

2013-10-01

The neurotoxin methylmercury can accumulate in marine food webs, contaminating seafood. An analysis of the isotopic composition of fish in the North Pacific suggests that much of the mercury that enters the marine food web originates from low-oxygen subsurface waters.

The formation of the ocean’s anthropogenic carbon reservoir

PubMed Central

Iudicone, Daniele; Rodgers, Keith B.; Plancherel, Yves; Aumont, Olivier; Ito, Takamitsu; Key, Robert M.; Madec, Gurvan; Ishii, Masao

2016-01-01

The shallow overturning circulation of the oceans transports heat from the tropics to the mid-latitudes. This overturning also influences the uptake and storage of anthropogenic carbon (Cant). We demonstrate this by quantifying the relative importance of ocean thermodynamics, circulation and biogeochemistry in a global biochemistry and circulation model. Almost 2/3 of the Cant ocean uptake enters via gas exchange in waters that are lighter than the base of the ventilated thermocline. However, almost 2/3 of the excess Cant is stored below the thermocline. Our analysis shows that subtropical waters are a dominant component in the formation of subpolar waters and that these water masses essentially form a common Cant reservoir. This new method developed and presented here is intrinsically Lagrangian, as it by construction only considers the velocity or transport of waters across isopycnals. More generally, our approach provides an integral framework for linking ocean thermodynamics with biogeochemistry. PMID:27808101

Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover

PubMed Central

Stegen, James C.; Fredrickson, James K.; Wilkins, Michael J.; Konopka, Allan E.; Nelson, William C.; Arntzen, Evan V.; Chrisler, William B.; Chu, Rosalie K.; Danczak, Robert E.; Fansler, Sarah J.; Kennedy, David W.; Resch, Charles T.; Tfaily, Malak

2016-01-01

Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater–surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater–surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds. PMID:27052662

Groundwater-surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover.

PubMed

Stegen, James C; Fredrickson, James K; Wilkins, Michael J; Konopka, Allan E; Nelson, William C; Arntzen, Evan V; Chrisler, William B; Chu, Rosalie K; Danczak, Robert E; Fansler, Sarah J; Kennedy, David W; Resch, Charles T; Tfaily, Malak

2016-04-07

Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater-surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater-surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds.

Controls on O2 Production in Cyanobacterial Mats and Implications for Earth's Oxygenation

NASA Astrophysics Data System (ADS)

Dick, Gregory J.; Grim, Sharon L.; Klatt, Judith M.

2018-05-01

Cyanobacterial mats are widely assumed to have been globally significant hot spots of biogeochemistry and evolution during the Archean and Proterozoic, but little is known about their quantitative contributions to global primary productivity or Earth's oxygenation. Modern systems show that mat biogeochemistry is the outcome of concerted activities and intimate interactions between various microbial metabolisms. Emerging knowledge of the regulation of oxygenic and sulfide-driven anoxygenic photosynthesis by versatile cyanobacteria, and their interactions with sulfur-oxidizing bacteria and sulfate-reducing bacteria, highlights how ecological and geochemical processes can control O2 production in cyanobacterial mats in unexpected ways. This review explores such biological controls on O2 production. We argue that the intertwined effects of light availability, redox geochemistry, regulation and competition of microbial metabolisms, and biogeochemical feedbacks result in emergent properties of cyanobacterial mat communities that are all critical yet largely overlooked mechanisms to potentially explain the protracted nature of Earth's oxygenation.

The Ecology, Biogeochemistry, and Optical Properties of Coccolithophores

NASA Astrophysics Data System (ADS)

Balch, William M.

2018-01-01

Coccolithophores are major contributors to phytoplankton communities and ocean biogeochemistry and are strong modulators of the optical field in the sea. New discoveries are changing paradigms about these calcifiers. A new role for silicon in coccolithophore calcification is coupling carbonate and silicon cycles. Phosphorus and iron play key roles in regulating coccolithophore growth. Comparing molecular phylogenies with coccolith morphometrics is forcing the reconciliation of biological and geological observations. Mixotrophy may be a possible life strategy for deep-dwelling species, which has ramifications for biological pump and alkalinity pump paradigms. Climate, ocean temperatures, and pH appear to be affecting coccolithophores in unexpected ways. Global calcification is approximately 1-3% of primary productivity and affects CO2 budgets. New measurements of the backscattering cross section of coccolithophores have improved satellite-based algorithms and their application in case I and case II optical waters. Remote sensing has allowed the detection of basin-scale coccolithophore features in the Southern Ocean.

Microbial antimony biogeochemistry: Enzymes, regulation, and related metabolic pathways

USGS Publications Warehouse

Li, Jingxin; Qian Wang,; Oremland, Ronald S.; Kulp, Thomas R.; Rensing, Christopher; Wang, Gejiao

2016-01-01

Antimony (Sb) is a toxic metalloid that occurs widely at trace concentrations in soil, aquatic systems, and the atmosphere. Nowadays, with the development of its new industrial applications and the corresponding expansion of antimony mining activities, the phenomenon of antimony pollution has become an increasingly serious concern. In recent years, research interest in Sb has been growing and reflects a fundamental scientific concern regarding Sb in the environment. In this review, we summarize the recent research on bacterial antimony transformations, especially those regarding antimony uptake, efflux, antimonite oxidation, and antimonate reduction. We conclude that our current understanding of antimony biochemistry and biogeochemistry is roughly equivalent to where that of arsenic was some 20 years ago. This portends the possibility of future discoveries with regard to the ability of microorganisms to conserve energy for their growth from antimony redox reactions and the isolation of new species of “antimonotrophs.”

Optimizing available network resources to address questions in environmental biogeochemistry

USGS Publications Warehouse

Hinckley, Eve-Lyn; Suzanne Andersen,; Baron, Jill S.; Peter Blanken,; Gordon Bonan,; William Bowman,; Sarah Elmendorf,; Fierer, Noah; Andrew Fox,; Keli Goodman,; Katherine Jones,; Danica Lombardozzi,; Claire Lunch,; Jason Neff,; Michael SanClements,; Katherine Suding,; Will Wieder,

2016-01-01

An increasing number of network observatories have been established globally to collect long-term biogeochemical data at multiple spatial and temporal scales. Although many outstanding questions in biogeochemistry would benefit from network science, the ability of the earth- and environmental-sciences community to conduct synthesis studies within and across networks is limited and seldom done satisfactorily. We identify the ideal characteristics of networks, common problems with using data, and key improvements to strengthen intra- and internetwork compatibility. We suggest that targeted improvements to existing networks should include promoting standardization in data collection, developing incentives to promote rapid data release to the public, and increasing the ability of investigators to conduct their own studies across sites. Internetwork efforts should include identifying a standard measurement suite—we propose profiles of plant canopy and soil properties—and an online, searchable data portal that connects network, investigator-led, and citizen-science projects.

Geomicrobiological redox cycling of the transuranic element neptunium.

PubMed

Law, Gareth T W; Geissler, Andrea; Lloyd, Jonathan R; Livens, Francis R; Boothman, Christopher; Begg, James D C; Denecke, Melissa A; Rothe, Jörg; Dardenne, Kathy; Burke, Ian T; Charnock, John M; Morris, Katherine

2010-12-01

Microbial processes can affect the environmental behavior of redox sensitive radionuclides, and understanding these reactions is essential for the safe management of radioactive wastes. Neptunium, an alpha-emitting transuranic element, is of particular importance because of its long half-life, high radiotoxicity, and relatively high solubility as Np(V)O(2)(+) under oxic conditions. Here, we describe experiments to explore the biogeochemistry of Np where Np(V) was added to oxic sediment microcosms with indigenous microorganisms and anaerobically incubated. Enhanced Np removal to sediments occurred during microbially mediated metal reduction, and X-ray absorption spectroscopy showed this was due to reduction to poorly soluble Np(IV) on solids. In subsequent reoxidation experiments, sediment-associated Np(IV) was somewhat resistant to oxidative remobilization. These results demonstrate the influence of microbial processes on Np solubility and highlight the critical importance of radionuclide biogeochemistry in nuclear legacy management.

Thinking outside the channel: Modeling nitrogen cycling in networked river ecosystems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helton, Ashley; Poole, Geoffrey C.; Meyer, Judy

2011-01-01

Agricultural and urban development alters nitrogen and other biogeochemical cycles in rivers worldwide. Because such biogeochemical processes cannot be measured empirically across whole river networks, simulation models are critical tools for understanding river-network biogeochemistry. However, limitations inherent in current models restrict our ability to simulate biogeochemical dynamics among diverse river networks. We illustrate these limitations using a river-network model to scale up in situ measures of nitrogen cycling in eight catchments spanning various geophysical and land-use conditions. Our model results provide evidence that catchment characteristics typically excluded from models may control river-network biogeochemistry. Based on our findings, we identify importantmore » components of a revised strategy for simulating biogeochemical dynamics in river networks, including approaches to modeling terrestrial-aquatic linkages, hydrologic exchanges between the channel, floodplain/riparian complex, and subsurface waters, and interactions between coupled biogeochemical cycles.« less

Biogeochemistry from Gliders at the Hawaii Ocean Times-Series

NASA Astrophysics Data System (ADS)

Nicholson, D. P.; Barone, B.; Karl, D. M.

2016-02-01

At the Hawaii Ocean Time-series (HOT) autonomous, underwater gliders equipped with biogeochemical sensors observe the oceans for months at a time, sampling spatiotemporal scales missed by the ship-based programs. Over the last decade, glider data augmented by a foundation of time-series observations have shed light on biogeochemical dynamics occuring spatially at meso- and submesoscales and temporally on scales from diel to annual. We present insights gained from the synergy between glider observations, time-series measurements and remote sensing in the subtropical North Pacific. We focus on diel variability observed in dissolved oxygen and bio-optics and approaches to autonomously quantify net community production and gross primary production (GPP) as developed during the 2012 Hawaii Ocean Experiment - DYnamics of Light And Nutrients (HOE-DYLAN). Glider-based GPP measurements were extended to explore the relationship between GPP and mesoscale context over multiple years of Seaglider deployments.

Bacterial Diversity and Biogeochemistry of Two Marine Shallow-Water Hydrothermal Systems off Dominica (Lesser Antilles).

PubMed

Pop Ristova, Petra; Pichler, Thomas; Friedrich, Michael W; Bühring, Solveig I

2017-01-01

Shallow-water hydrothermal systems represent extreme environments with unique biogeochemistry and high biological productivity, at which autotrophic microorganisms use both light and chemical energy for the production of biomass. Microbial communities of these ecosystems are metabolically diverse and possess the capacity to transform a large range of chemical compounds. Yet, little is known about their diversity or factors shaping their structure or how they compare to coastal sediments not impacted by hydrothermalism. To this end, we have used automated ribosomal intergenic spacer analysis (ARISA) and high-throughput Illumina sequencing combined with porewater geochemical analysis to investigate microbial communities along geochemical gradients in two shallow-water hydrothermal systems off the island of Dominica (Lesser Antilles). At both sites, venting of hydrothermal fluids substantially altered the porewater geochemistry by enriching it with silica, iron and dissolved inorganic carbon, resulting in island-like habitats with distinct biogeochemistry. The magnitude of fluid flow and difference in sediment grain size, which impedes mixing of the fluids with seawater, were correlated with the observed differences in the porewater geochemistry between the two sites. Concomitantly, individual sites harbored microbial communities with a significantly different community structure. These differences could be statistically linked to variations in the porewater geochemistry and the hydrothermal fluids. The two shallow-water hydrothermal systems of Dominica harbored bacterial communities with high taxonomical and metabolic diversity, predominated by heterotrophic microorganisms associated with the Gammaproteobacterial genera Pseudomonas and Pseudoalteromonas , indicating the importance of heterotrophic processes. Overall, this study shows that shallow-water hydrothermal systems contribute substantially to the biogeochemical heterogeneity and bacterial diversity of coastal sediments.

Biogeochemistry of the Amazon River Basin: the role of aquatic ecosystems in the Amazon functioning

NASA Astrophysics Data System (ADS)

Victoria, R. L.; Ballester, V. R.; Krushe, A. V.; Richey, J. E.; Aufdenkampe, A. K.; Kavaguishi, N. L.; Gomes, B. M.; Victoria, D. D.; Montebello, A. A.; Niell, C.; Deegan, L.

2004-12-01

In this study we present the results of an integrated analysis of physical and anthropogenic controls of river biogeochemistry in Amazônia. At the meso-scale level, our results show that both soil properties and land use are the main drivers of river biogeochemistry and metabolism, with pasture cover and soil exchange cation capacity explaining 99% (p < 0.01) of the variability observed in surface water ions and nutrients concentrations. In small rivers, forest clearing can increase cations, P and C inputs. P and light are the main PPL limiting factors in forested streams, while in pasture streams N becomes limiting. P export to streams may increase or remain nearly undetectable after forest-to-pasture conversion, depending on soil type. Pasture streams on Oxisols have very low P export, while on Ultisols P export is increased. Conversions of forest to pasture leads to extensive growth of in channel Paspalum resulting in higher DOC concentrations and respiration rates. Pasture streams have higher DOC fluxes when compared to the forest ones. In pasture areas the soil are compacted, there is less infiltration and higher surface run off, leaching soil superficial layers and caring more DOC to the streams. In forest areas infiltration is deeper into the soils and canopy interaction is higher. Mineralogy and soil properties are key factors determining exports of nutrients to streams. Therefore, land use change effects on nutrient export from terrestrial to aquatic ecosystems and the atmosphere must be understood within the context of varying soil properties across the Amazon Basin.

Modeling CO 2 emissions from Arctic lakes: Model development and site-level study

DOE PAGES

Tan, Zeli; Zhuang, Qianlai; Shurpali, Narasinha J.; ...

2017-09-14

Recent studies indicated that Arctic lakes play an important role in receiving, processing, and storing organic carbon exported from terrestrial ecosystems. To quantify the contribution of Arctic lakes to the global carbon cycle, we developed a one-dimensional process-based Arctic Lake Biogeochemistry Model (ALBM) that explicitly simulates the dynamics of organic and inorganic carbon in Arctic lakes. By realistically modeling water mixing, carbon biogeochemistry, and permafrost carbon loading, the model can reproduce the seasonal variability of CO 2 fluxes from the study Arctic lakes. The simulated area-weighted CO 2 fluxes from yedoma thermokarst lakes, nonyedoma thermokarst lakes, and glacial lakes aremore » 29.5, 13.0, and 21.4 g C m -2 yr -1, respectively, close to the observed values (31.2, 17.2, and 16.5 ± 7.7 g C m -2 yr -1, respectively). The simulations show that the high CO 2 fluxes from yedoma thermokarst lakes are stimulated by the biomineralization of mobilized labile organic carbon from thawing yedoma permafrost. The simulations also imply that the relative contribution of glacial lakes to the global carbon cycle could be the largest because of their much larger surface area and high biomineralization and carbon loading. According to the model, sunlight-induced organic carbon degradation is more important for shallow nonyedoma thermokarst lakes but its overall contribution to the global carbon cycle could be limited. Overall, the ALBM can simulate the whole-lake carbon balance of Arctic lakes, a difficult task for field and laboratory experiments and other biogeochemistry models.« less

Absence of snow cover reduces understory plant cover and alters plant community composition in boreal forests.

PubMed

Kreyling, Juergen; Haei, Mahsa; Laudon, Hjalmar

2012-02-01

Snow regimes affect biogeochemistry of boreal ecosystems and are altered by climate change. The effects on plant communities, however, are largely unexplored despite their influence on relevant processes. Here, the impact of snow cover on understory community composition and below-ground production in a boreal Picea abies forest was investigated using a long-term (8-year) snow cover manipulation experiment consisting of the treatments: snow removal, increased insulation (styrofoam pellets), and control. The snow removal treatment caused longer (118 vs. 57 days) and deeper soil frost (mean minimum temperature -5.5 vs. -2.2°C) at 10 cm soil depth in comparison to control. Understory species composition was strongly altered by the snow cover manipulations; vegetation cover declined by more than 50% in the snow removal treatment. In particular, the dominant dwarf shrub Vaccinium myrtillus (-82%) and the most abundant mosses Pleurozium schreberi (-74%) and Dicranum scoparium (-60%) declined strongly. The C:N ratio in V. myrtillus leaves and plant available N in the soil indicated no altered nitrogen nutrition. Fine-root biomass in summer, however, was negatively affected by the reduced snow cover (-50%). Observed effects are attributed to direct frost damage of roots and/ or shoots. Besides the obvious relevance of winter processes on plant ecology and distribution, we propose that shifts in the vegetation caused by frost damage may be an important driver of the reported alterations in biogeochemistry in response to altered snow cover. Understory plant performance clearly needs to be considered in the biogeochemistry of boreal systems in the face of climate change.

Projecting changes in Everglades soil biogeochemistry for carbon and other key elements, to possible 2060 climate and hydrologic scenarios.

PubMed

Orem, William; Newman, Susan; Osborne, Todd Z; Reddy, K Ramesh

2015-04-01

Based on previously published studies of elemental cycling in Everglades soils, we projected how soil biogeochemistry, specifically carbon, nitrogen, phosphorus, sulfur, and mercury might respond to climate change scenarios projected for 2060 by the South Florida Water Management Model. Water budgets and stage hydrographs from this model with future scenarios of a 10% increased or decreased rainfall, a 1.5 °C rise in temperature and associated increase in evapotranspiration (ET) and a 0.5 m rise in sea level were used to predict resulting effects on soil biogeochemistry. Precipitation is a much stronger driver of soil biogeochemical processes than temperature, because of links among water cover, redox conditions, and organic carbon accumulation in soils. Under the 10% reduced rainfall scenario, large portions of the Everglades will experience dry down, organic soil oxidation, and shifts in soil redox that may dramatically alter biogeochemical processes. Lowering organic soil surface elevation may make portions of the Everglades more vulnerable to sea level rise. The 10% increased rainfall scenario, while potentially increasing phosphorus, sulfur, and mercury loading to the ecosystem, would maintain organic soil integrity and redox conditions conducive to normal wetland biogeochemical element cycling. Effects of increased ET will be similar to those of decreased precipitation. Temperature increases would have the effect of increasing microbial processes driving biogeochemical element cycling, but the effect would be much less than that of precipitation. The combined effects of decreased rainfall and increased ET suggest catastrophic losses in carbon- and organic-associated elements throughout the peat-based Everglades.

Impacts of global changes on the biogeochemistry and environmental effects of dissolved organic matter at the land-ocean interface: a review.

PubMed

Zhuang, Wan-E; Yang, Liyang

2018-02-01

Dissolved organic matter (DOM) is an important component in the biogeochemistry and ecosystem function of aquatic environments at the highly populated land-ocean interface. The mobilization and transformation of DOM at this critical interface are increasingly affected by a series of notable global changes such as the increasing storm events, intense human activities, and accelerating glacier loss. This review provides an overview of the changes in the quantity and quality of DOM under the influences of multiple global changes. The profound implications of changing DOM for aquatic ecosystem and human society are further discussed, and future research needs are suggested for filling current knowledge gaps. The fluvial export of DOM is strongly intensified during storm events, which is accompanied with notable changes in the chemical composition and reactivity of DOM. Land use not only changes the mobilization of natural DOM source pools within watersheds but also adds DOM of distinct chemical composition and reactivity from anthropogenic sources. Glacier loss brings highly biolabile DOM to downstream water bodies. The changing DOM leads to significant changes in heterotrophic activity, CO 2 out gassing, nutrient and pollutant biogeochemistry, and disinfection by-product formation. Further studies on the source, transformations, and downstream effects of storm DOM, temporal variations of DOM and its interactions with other pollutants in human-modified watersheds, photo-degradability of glacier DOM, and potential priming effects, are essential for better understanding the responses and feedbacks of DOM at the land-ocean interface under the impacts of global changes.

Using In-Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

NASA Astrophysics Data System (ADS)

Wymore, Adam S.; Potter, Jody; Rodríguez-Cardona, Bianca; McDowell, William H.

2018-04-01

The advent of high-frequency in situ optical sensors provides new opportunities to study the biogeochemistry of dissolved organic matter (DOM) in aquatic ecosystems. We used fDOM (fluorescent dissolved organic matter) to examine the spatial and temporal variability in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) across a heterogeneous stream network that varies in NO3- concentration. Across the ten study streams fDOM explained twice the variability in the concentration of DOC (r2 = 0.82) compared to DON (r2 = 0.39), which suggests that the N-rich fraction of DOM is either more variable in its sources or more bioreactive than the more stable C-rich fraction. Among sites, DON molar fluorescence was approximately 3x more variable than DOC molar fluorescence and was correlated with changes in inorganic N, indicating that DON is both more variable in composition as well as highly responsive to changes in inorganic N. Laboratory results also indicate that the fDOM sensors we used perform as well as the excitation-emission wavelength pair generally referred to as the "tryptophan-like" peak when measured under laboratory conditions. However, since neither the field sensor not the laboratory measurements explained a large percentage of variation in DON concentrations, challenges still remain for monitoring the ambient pool of dissolved organic nitrogen. Sensor networks provide new insights into the potential reactivity of DOM and the variability in DOC and DON biogeochemistry across sites. These insights are needed to build spatially explicit models describing organic matter dynamics and water quality.

Bacterial Diversity and Biogeochemistry of Two Marine Shallow-Water Hydrothermal Systems off Dominica (Lesser Antilles)

PubMed Central

Pop Ristova, Petra; Pichler, Thomas; Friedrich, Michael W.; Bühring, Solveig I.

2017-01-01

Shallow-water hydrothermal systems represent extreme environments with unique biogeochemistry and high biological productivity, at which autotrophic microorganisms use both light and chemical energy for the production of biomass. Microbial communities of these ecosystems are metabolically diverse and possess the capacity to transform a large range of chemical compounds. Yet, little is known about their diversity or factors shaping their structure or how they compare to coastal sediments not impacted by hydrothermalism. To this end, we have used automated ribosomal intergenic spacer analysis (ARISA) and high-throughput Illumina sequencing combined with porewater geochemical analysis to investigate microbial communities along geochemical gradients in two shallow-water hydrothermal systems off the island of Dominica (Lesser Antilles). At both sites, venting of hydrothermal fluids substantially altered the porewater geochemistry by enriching it with silica, iron and dissolved inorganic carbon, resulting in island-like habitats with distinct biogeochemistry. The magnitude of fluid flow and difference in sediment grain size, which impedes mixing of the fluids with seawater, were correlated with the observed differences in the porewater geochemistry between the two sites. Concomitantly, individual sites harbored microbial communities with a significantly different community structure. These differences could be statistically linked to variations in the porewater geochemistry and the hydrothermal fluids. The two shallow-water hydrothermal systems of Dominica harbored bacterial communities with high taxonomical and metabolic diversity, predominated by heterotrophic microorganisms associated with the Gammaproteobacterial genera Pseudomonas and Pseudoalteromonas, indicating the importance of heterotrophic processes. Overall, this study shows that shallow-water hydrothermal systems contribute substantially to the biogeochemical heterogeneity and bacterial diversity of coastal sediments. PMID:29255454

Microbial Community Structure and Arsenic Biogeochemistry in an Acid Vapor-Formed Spring in Tengchong Geothermal Area, China.

PubMed

Jiang, Zhou; Li, Ping; Jiang, Dawei; Dai, Xinyue; Zhang, Rui; Wang, Yanhong; Wang, Yanxin

2016-01-01

Arsenic biogeochemistry has been studied extensively in acid sulfate-chloride hot springs, but not in acid sulfate hot springs with low chloride. In this study, Zhenzhuquan in Tengchong geothermal area, a representative acid sulfate hot spring with low chloride, was chosen to study arsenic geochemistry and microbial community structure using Illumina MiSeq sequencing. Over 0.3 million 16S rRNA sequence reads were obtained from 6-paired parallel water and sediment samples along its outflow channel. Arsenic oxidation occurred in the Zhenxhuquan pool, with distinctly high ratios of arsenate to total dissolved arsenic (0.73-0.86). Coupled with iron and sulfur oxidation along the outflow channel, arsenic accumulated in downstream sediments with concentrations up to 16.44 g/kg and appeared to significantly constrain their microbial community diversity. These oxidations might be correlated with the appearance of some putative functional microbial populations, such as Aquificae and Pseudomonas (arsenic oxidation), Sulfolobus (sulfur and iron oxidation), Metallosphaera and Acidicaldus (iron oxidation). Temperature, total organic carbon and dissolved oxygen significantly shaped the microbial community structure of upstream and downstream samples. In the upstream outflow channel region, most microbial populations were microaerophilic/anaerobic thermophiles and hyperthermophiles, such as Sulfolobus, Nocardia, Fervidicoccus, Delftia, and Ralstonia. In the downstream region, aerobic heterotrophic mesophiles and thermophiles were identified, including Ktedonobacteria, Acidicaldus, Chthonomonas and Sphingobacteria. A total of 72.41-95.91% unassigned-genus sequences were derived from the downstream high arsenic sediments 16S rRNA clone libraries. This study could enable us to achieve an integrated understanding on arsenic biogeochemistry in acid hot springs.

CHANGING CLIMATE AND PHOTOBIOGEOCHEMICAL CYCLES IN AQUATIC ENVIRONMENTS

EPA Science Inventory

Global biogeochemistry plays a critical role in controlling life processes, climate and their interactions, including effects on atmospheric greenhouse gas concentrations. Recent evidence indicates that the light-driven part of aquatic biogeochemical cycles is being altered by in...

Effects of hypoxia on archaeal communities in Gulf of Mexico sediments

EPA Science Inventory

Sediments may contribute significantly to Louisiana continental shelf “dead zone” hypoxia but limited information hinders understanding how sediment biogeochemistry differs between normoxic and hypoxic seasons. Archaea of the family Thaumarchaeota are largely responsible for nit...

BAE Systems Radiation Hardened SpaceWire ASIC and Roadmap

NASA Technical Reports Server (NTRS)

Berger, Richard; Milliser, Myrna; Kapcio, Paul; Stanley, Dan; Moser, David; Koehler, Jennifer; Rakow, Glenn; Schnurr, Richard

2006-01-01

An Application Specific Integrated Circuit (ASIC) that implements the SpaceWire protocol has been developed in a radiation hardened 0.25 micron CMOS, technology. This effort began in March 2003 as a joint development between the NASA Goddard Space Flight Center (GSFC) and BAE Systems. The BAE Systems SpaceWire ASlC is comprised entirely of reusable core elements, many of which are already flight-proven. It incorporates a 4-port SpaceWire router with two local ports, dual PC1 bus interfaces, a microcontroller, 32KB of internal memory, -and a memory controller for additional external memory use. The SpaceWire ASlC is planned for use on both the Geostationary Operational Environmental Satellites (GOES)-R and the Lunar Reconnaissance Orbiter (LRO). Engineering parts have already been delivered to both programs. This paper discusses the SpaceWire protocol and those elements of it that have been built into the current SpaceWire reusable core. There are features within the core that go beyond the current standard that can be enabled or disabled by the user and these will be described. The adaptation of SpaceWire to BAE Systems' On Chip Bus (OCB) for compatibility with the other reusable cores will be discussed. Optional configurations within user systems will be shown. The physical imp!ementation of the design will be described and test results from the hardware will be discussed. Finally, the BAE Systems roadmap for SpaceWire developments will be discussed, including some products already in design as well as longer term plans.

Assessing the impact of caring for a child with Dravet syndrome: Results of a caregiver survey.

PubMed

Campbell, Jonathan D; Whittington, Melanie D; Kim, Chong H; VanderVeen, Gina R; Knupp, Kelly G; Gammaitoni, Arnold

2018-03-01

The objective of this study was to describe and quantify the impact of caring for a child with Dravet syndrome (DS) on caregivers. We surveyed DS caregivers at a single institution with a large population of patient with DS. Survey domains included time spent/difficulty performing caregiving tasks (Oberst Caregiving Burden Scale, OCBS); caregiver health-related quality of life (EuroQoL 5D-5L, EQ-5D); and work/activity impairment (Work Productivity and Activity Impairment questionnaire, WPAI). Modified National Health Interview Survey (NHIS) questions were included to assess logistical challenges associated with coordinating medical care. Thirty-four primary caregivers responded, and 30/34 respondents completed the survey. From OCBS, providing transportation, personal care, and additional household tasks required the greatest caregiver time commitment; arranging for child care, communication, and managing behavioral problems presented the greatest difficulty. EuroQoL 5D-5L domains with the greatest impact on caregivers (0=none, 5=unable/extreme) were anxiety/depression (70% of respondents≥slight problems, 34%≥moderate) and discomfort/pain (57% of respondents≥slight problems, 23%≥moderate). The mean EQ-5D general health visual analogue scale (VAS) score (0=death; 100=perfect health) was 67 (range, 11-94). Respondents who scored <65 were two- to fourfold more likely to report ≥moderate time spent and difficulty managing child behavior problems and assisting with walking, suggesting that children with DS with high degrees of motor or neurodevelopmental problems have an especially high impact on caregiver health. On the WPAI, 26% of caregivers missed >1day of work in the previous week, with 43% reporting substantial impact (≥6, scale=1-10) on work productivity; 65% reported switching jobs, quitting jobs, or losing a job due to caregiving responsibilities. National Health Interview Survey responses indicated logistical burdens beyond the home; 50% of caregivers made ≥10 outpatient visits in the past year with their child with DS. Caring for patients with DS exerts physical, emotional, and time burdens on caregivers. Supportive services for DS families are identified to highlight an unmet need for DS treatments. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

New Insights into Clinical Characteristics of Gilles de la Tourette Syndrome: Findings in 1032 Patients from a Single German Center.

PubMed

Sambrani, Tanvi; Jakubovski, Ewgeni; Müller-Vahl, Kirsten R

2016-01-01

Gilles de la Tourette syndrome (TS) is a complex neuropsychiatric disorder defined by the presence of motor and phonic tics, but often associated with psychiatric comorbidities. The main objective of this study was to explore the clinical presentation and comorbidities of TS. We analyzed clinical data obtained from a large sample (n = 1032; 529 children and 503 adults) of patients with tic disorders from one single German TS center assessed by one investigator. Data was collected with the help of an expert-reviewed semi-structured interview, designed to assess tic severity and certain comorbidities. Group comparisons were carried out via independent sample t-tests and chi-square tests. The main findings of the study are: (1) tic severity is associated with the presence of premonitory urges (PU), copro-, echo-, and paliphenomena and the number of comorbidities, but not age at tic onset; it is higher in patients with comorbid obsessive-compulsive disorder (OCD) than in patients with comorbid attention deficit/hyperactivity disorder (ADHD). (2) PU were found to be highly associated with "not just right experiences" and to emerge much earlier than previously thought alongside with the ability to suppress tics (PU in >60% and suppressibility in >75% at age 8-10 years). (3) Self-injurious behavior (SIB) is highly associated with complex motor tics and coprophenomena, but not with OCD/obsessive-compulsive behavior (OCB). While comorbid ADHD is associated with a lower ability to suppress tics, comorbid depression is associated with sleeping problems. Our results demonstrate that tic severity is not influenced by age at onset. From our data, it is suggested that PU represent a specific type of "not just right experience" that is not a prerequisite for tic suppression. Comorbid ADHD reduces patients' ability of successful tic suppression. Our data suggest that SIB belongs to the coprophenomena spectrum and hence should be conceptualized as a complex tic rather than a compulsion. Finally, this study strongly supports the hypothesis that TS+OCD is a more severe form of TS and that comorbid OCD/OCB, depression, and anxiety belong to the TS spectrum, while ADHD should be better conceptualized as a separate problem.

Demographic and clinical profile of Multiple Sclerosis in Kashmir: A short report.

PubMed

Zahoor, Insha; Asimi, Ravouf; Haq, Ehtishamul; Yousuf Wani, Irfan

2017-04-01

Multiple sclerosis (MS) is a chronic autoimmune and inflammatory disease of the central nervous system (CNS). There have been only few population/hospital based studies on MS in India, and at the same time there is no data on its profile in Kashmir. A total of 41 MS patients diagnosed on the basis of 2010 Revised Mc Donald criteria were enrolled in this study from Kashmir region of India. Clinical, demographic, radiological and biochemical parameters were analyzed for most of the patients. Male to female ratio was found to be 1:3.1 with mean age at the time of analysis 32.26±7.54 (range 18-48) years. The mean disease duration was found to be 3.2±3.6 years. The most common course was relapsing-remitting (RR) present in 87.80% of cases followed by secondary progressive (SP) in 9.76% and primary progressive (PP) in 2.44%. Numbness, weakness of limbs, prickling and tingling sensations, muscle stiffness, and visual disturbances were most common manifestations. Condition of bilateral internuclear ophthalmoplegia (INO) and vertigo was rarely observed. Oligoclonal bands (OCB) were present in cerebrospinal fluid (CSF) of majority of the patients. Symptomatic and steroidal treatment mode was given to majority of the patients (92.68%) and only 7.32% patients were given disease modifying drug. This is the first preliminary report on MS profile in Kashmir. The high prevalence of female patients and RR course of MS, low prevalence of progressive cases, predominance of OCB positive cases, insignificant family history in all cases, predominance of cases with low socio-economic status, and high rate of less educated and unemployed cases are the most important findings. By and large MS pattern in Kashmir was found to be relatively similar to West and rest of the Asia. Larger comprehensive studies are mandatory to completely understand MS pattern in Kashmir. There is utmost requirement to maintain a local MS registry in Kashmir so as to get an idea about the actual number of persons suffering from the disease and compare the data with other regions of India. Copyright © 2017 Elsevier B.V. All rights reserved.

MARINE AEROSOLS ALTER SOIL PROCESSES IN COASTAL FORESTS

EPA Science Inventory

Most models of watershed biogeochemistry include the movement of materials from land to rivers and eventually the ocean. Few conceptual views, however, acknowledge the influence of materials derived from the ocean on terrestrial ecosystems processes. Based on spatial patterns o...

Analysis of archaeal communities in Gulf of Mexico dead zone sediments.

EPA Science Inventory

Sediments may contribute significantly to Louisiana continental shelf “dead zone” hypoxia but limited information hinders comparison of sediment biogeochemistry between norm-oxic and hypoxic seasons. Dead zone sediment cores collected during hypoxia (September 2006) had higher l...

Dissolved low-molecular weight thiol concentrations from the U.S. GEOTRACES North Atlantic Ocean zonal transect

NASA Astrophysics Data System (ADS)

Swarr, Gretchen J.; Kading, Tristan; Lamborg, Carl H.; Hammerschmidt, Chad R.; Bowman, Katlin L.

2016-10-01

Low-molecular weight thiols, including cysteine and glutathione, are biomolecules involved in a variety of metabolic pathways and act as important antioxidant and metal buffering agents. In this last capacity, they represent a potential mechanism for modulating the bioavailability and biogeochemistry of many trace elements in the ocean, particularly for chalcophilic elements (e.g., Cu, Zn, Cd, Ag and Hg). For this reason, and in the context of the international GEOTRACES program that seeks to understand the biogeochemistry of trace elements in the ocean, we measured the concentration of individual dissolved low-molecular weight thiols during the U.S. GEOTRACES North Atlantic Zonal Transect (USGNAZT). Only two thiols were identified, cysteine and glutathione, in contrast to results from the northeast subarctic Pacific Ocean, where the dipeptides glycine-cysteine and arginine-cysteine were also present and γ-glutamylcysteine was dominant. Concentrations of cysteine and glutathione in the North Atlantic Ocean were lower than in the Pacific and ranged from below detection ( 0.01 nM) to 0.61 nM of cysteine and up to 1.0 nM of glutathione, with cysteine generally more abundant than glutathione. Vertical profiles of cysteine and glutathione were broadly consistent with their biological production, being more abundant in surface water and usually below detection at depths greater than about 200 m. Subsurface concentration maxima, often co-incident with the deep chlorophyll maximum, were frequently observed but not universal. We conclude that cysteine and glutathione do not make up significant portions of complexation capacity for Cu and Zn in the upper open ocean but could be important for Cd, Hg, and potentially other chalcophiles. Extremely low concentrations of cysteine and glutathione in deep water suggest that higher molecular-weight thiols are a more important ligand class for chalcophiles in that portion of the ocean.

SOLAR UV RADIATION AND AQUATIC BIOGEOCHEMISTRY

EPA Science Inventory

During the past decade significant interest has developed in the influence of solar UV radiation on biogeochemical cycles in surface waters of lakes and the sea. A major portion of this research has focused on photoreactions of the colored component of dissolved organic matter, ...

The Biogeochemistry of Bioenergy Landscapes: Carbon, Nitrogen, and Water Considerations

USDA-ARS?s Scientific Manuscript database

The biogeochemical liabilities of grain-based crop production for bioenergy are no different from those of grain-based food production: excessive nitrate leakage, soil carbon and phosphorus loss, nitrous oxide production, and attenuated methane uptake. Contingent problems are well-known, increasingl...

BIOGEOCHEMISTRY OF CHLORINATED ORGANIC CONTAMINANTS IN AQUATIC ECOSYSTEMS

EPA Science Inventory

Over the last several years we have conducted both laboratory and field studies to develop a better understanding of the movement of chlorinated organic compounds through aquatic ecosystems, with special emphasis on the differential movement of these compounds due to physical/che...

Biogeochemistry of vertebrate decomposition in a forest ecosystem

USDA-ARS?s Scientific Manuscript database

Decomposing plants and animals provide critical nutrients for ecosystems, including forests. During vertebrate decay, the rapid release of limiting nutrients, including N, P, C, and S fundamentally transforms the soil environment by stimulating endogenous organisms. The goal of this study was t...

Soil biogeochemistry, plant physiology and phytoremediation of cadmium contaminated soils

USDA-ARS?s Scientific Manuscript database

Cadmium (Cd) loading in soil and the environment has been accelerated worldwide due to enhanced industrialization and intensified agricultural production, particularly in the developing countries. Soil Cd pollution, resulting from both anthropogenic and geogenic sources, has posed an increasing chal...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Zeli; Zhuang, Qianlai; Shurpali, Narasinha J.

Recent studies indicated that Arctic lakes play an important role in receiving, processing, and storing organic carbon exported from terrestrial ecosystems. To quantify the contribution of Arctic lakes to the global carbon cycle, we developed a one-dimensional process-based Arctic Lake Biogeochemistry Model (ALBM) that explicitly simulates the dynamics of organic and inorganic carbon in Arctic lakes. By realistically modeling water mixing, carbon biogeochemistry, and permafrost carbon loading, the model can reproduce the seasonal variability of CO2 fluxes from the study Arctic lakes. The simulated area-weighted CO2 fluxes from yedoma thermokarst lakes, non-yedoma thermokarst lakes and glacial lakes are 29.5 gmore » C m-2 yr-1, 13.0 g C m-2 yr-1 and 21.4 g C m-2 yr-1, respectively, close to the observed values (31.2 g C m-2 yr-1, 17.2 g C m-2 yr-1 and 16.5±7.7 g C m-2 yr-1, respectively). The simulations show that the high CO2 fluxes from yedoma thermokarst lakes are stimulated by the biomineralization of mobilized labile organic carbon from thawing yedoma permafrost. The simulations also imply that the relative contribution of glacial lakes to the global carbon cycle could be the largest because of their much larger surface area and high biomineralization and carbon loading. According to the model, sunlight-induced organic carbon degradation is more important for shallow non-yedoma thermokarst lakes but its overall contribution to the global carbon cycle could be limited. Overall, the ALBM model can simulate the whole-lake carbon balance of Arctic lakes, a difficult task for field and laboratory experiments and other biogeochemistry models.« less

Microbial Community Structure and Arsenic Biogeochemistry in an Acid Vapor-Formed Spring in Tengchong Geothermal Area, China

PubMed Central

Jiang, Zhou; Li, Ping; Jiang, Dawei; Dai, Xinyue; Zhang, Rui; Wang, Yanhong; Wang, Yanxin

2016-01-01

Arsenic biogeochemistry has been studied extensively in acid sulfate-chloride hot springs, but not in acid sulfate hot springs with low chloride. In this study, Zhenzhuquan in Tengchong geothermal area, a representative acid sulfate hot spring with low chloride, was chosen to study arsenic geochemistry and microbial community structure using Illumina MiSeq sequencing. Over 0.3 million 16S rRNA sequence reads were obtained from 6-paired parallel water and sediment samples along its outflow channel. Arsenic oxidation occurred in the Zhenxhuquan pool, with distinctly high ratios of arsenate to total dissolved arsenic (0.73–0.86). Coupled with iron and sulfur oxidation along the outflow channel, arsenic accumulated in downstream sediments with concentrations up to 16.44 g/kg and appeared to significantly constrain their microbial community diversity. These oxidations might be correlated with the appearance of some putative functional microbial populations, such as Aquificae and Pseudomonas (arsenic oxidation), Sulfolobus (sulfur and iron oxidation), Metallosphaera and Acidicaldus (iron oxidation). Temperature, total organic carbon and dissolved oxygen significantly shaped the microbial community structure of upstream and downstream samples. In the upstream outflow channel region, most microbial populations were microaerophilic/anaerobic thermophiles and hyperthermophiles, such as Sulfolobus, Nocardia, Fervidicoccus, Delftia, and Ralstonia. In the downstream region, aerobic heterotrophic mesophiles and thermophiles were identified, including Ktedonobacteria, Acidicaldus, Chthonomonas and Sphingobacteria. A total of 72.41–95.91% unassigned-genus sequences were derived from the downstream high arsenic sediments 16S rRNA clone libraries. This study could enable us to achieve an integrated understanding on arsenic biogeochemistry in acid hot springs. PMID:26761709

Trace element biogeochemistry in the soil-water-plant system of a temperate agricultural soil amended with different biochars.

PubMed

Kloss, Stefanie; Zehetner, Franz; Buecker, Jannis; Oburger, Eva; Wenzel, Walter W; Enders, Akio; Lehmann, Johannes; Soja, Gerhard

2015-03-01

Various biochar (BC) types have been investigated as soil amendment; however, information on their effects on trace element (TE) biogeochemistry in the soil-water-plant system is still scarce. In the present study, we determined aqua-regia (AR) and water-extractable TEs of four BC types (woodchips (WC), wheat straw (WS), vineyard pruning (VP), pyrolyzed at 525 °C, of which VP was also pyrolyzed at 400 °C) and studied their effects on TE concentrations in leachates and mustard (Sinapis alba L.) tissue in a greenhouse pot experiment. We used an acidic, sandy agricultural soil and a BC application rate of 3% (w/w). Our results show that contents and extractability of TEs in the BCs and effectuated changes of TE biogeochemistry in the soil-water-plant system strongly varied among the different BC types. High AR-digestable Cu was found in VP and high B contents in WC. WS had the highest impact on TEs in leachates showing increased concentrations of As, Cd, Mo, and Se, whereas WC application resulted in enhanced leaching of B. All BC types increased Mo and decreased Cu concentrations in the plant tissue; however, they showed diverging effects on Cu in the leachates with decreased concentrations for WC and WS, but increased concentrations for both VPs. Our results demonstrate that BCs may release TEs into the soil-water-plant system. A BC-induced liming effect in acidic soils may lead to decreased plant uptake of cationic TEs, including Pb and Cd, but may enhance the mobility of anionic TEs like Mo and As. We also found that BCs with high salt contents (e.g., straw-based BCs) may lead to increased mobility of both anionic and cationic TEs in the short term.

Comparative Cryptogam Ecology: A Review of Bryophyte and Lichen Traits that Drive Biogeochemistry

PubMed Central

Cornelissen, Johannes H. C.; Lang, Simone I.; Soudzilovskaia, Nadejda A.; During, Heinjo J.

2007-01-01

Background Recent decades have seen a major surge in the study of interspecific variation in functional traits in comparative plant ecology, as a tool to understanding and predicting ecosystem functions and their responses to environmental change. However, this research has been biased almost exclusively towards vascular plants. Very little is known about the role and applicability of functional traits of non-vascular cryptogams, particularly bryophytes and lichens, with respect to biogeochemical cycling. Yet these organisms are paramount determinants of biogeochemistry in several biomes, particularly cold biomes and tropical rainforests, where they: (1) contribute substantially to above-ground biomass (lichens, bryophytes); (2) host nitrogen-fixing bacteria, providing major soil N input (lichens, bryophytes); (3) control soil chemistry and nutrition through the accumulation of recalcitrant polyphenols (bryophytes) and through their control over soil and vegetation hydrology and temperatures; (4) both promote erosion (rock weathering by lichens) and prevent it (biological crusts in deserts); (5) provide a staple food to mammals such as reindeer (lichens) and arthropodes, with important feedbacks to soils and biota; and (6) both facilitate and compete with vascular plants. Approach Here we review current knowledge about interspecific variation in cryptogam traits with respect to biogeochemical cycling and discuss to what extent traits and measuring protocols needed for bryophytes and lichens correspond with those applied to vascular plants. We also propose and discuss several new or recently introduced traits that may help us understand and predict the control of cryptogams over several aspects of the biogeochemistry of ecosystems. Conclusions Whilst many methodological challenges lie ahead, comparative cryptogam ecology has the potential to meet some of the important challenges of understanding and predicting the biogeochemical and climate consequences of large-scale environmental changes driving shifts in the cryptogam components of vegetation composition. PMID:17353205

Psychological mechanism linking abusive supervision and compulsory citizenship behavior: a moderated mediation study.

PubMed

Zhao, Hongdan; Peng, Zhenglong; Han, Yong; Sheard, Geoff; Hudson, Alan

2013-01-01

This study seeks to examine the effect of abusive supervision on the "dark side" of organizational citizenship behavior (OCB) and, specifically, compulsory citizenship behavior (CCB). The study focuses on the mediating role of psychological safety underpinning the relationship between abusive supervision and CCB, and the moderating role of Chinese traditionality in influencing the mediation. The authors tested the model with data of 434 dyads (employee-coworker pairs) in a large Chinese service company. Results indicated that psychological safety fully mediated the relationship between abusive supervision and CCB. The authors also found that Chinese traditionality moderated the strength of the mediated relationship between abusive supervision and CCB via psychological safety, such that the mediated relationship is weaker under high Chinese traditionality than under low Chinese traditionality. The article also discusses the implications, limitations, and future research directions.

Energy Underground.

ERIC Educational Resources Information Center

Wiley, Catherina L.

2003-01-01

Describes a unit to study the cycling of matter and energy through speleology using cooperative learning groups. Integrates the topic with zoology, biogeochemistry, paleontology, and meteorology. Includes a sample rubric for a salt block cave presentation, unit outline, and processes for studying matter and energy processes in caves. (Author/KHR)

Nitrogen dynamics at the ground water-surface water interface of a degraded urban stream

EPA Science Inventory

Urbanization degrades stream ecosystems by altering hydrology and nutrient dynamics. We investigated temporal and spatial patterns in biogeochemistry and hydrology in and near the stream channel of a geomorphically degraded urban stream of Baltimore County, Maryland, USA. Our o...

Nitrogen Dynamics in a Degraded Urban Stream: Can the Patient be Revived? (Balitmore, MD)

EPA Science Inventory

Urbanization degrades stream ecosystems by altering hydrology and nutrient dynamics. We investigated temporal and spatial patterns in biogeochemistry and hydrology in and near the stream channel of a geomorphically degraded urban stream of Baltimore County, Maryland, USA. Our o...

CONTROLS ON NUTRIENT LOSSES FROM A FORESTED BASIN IN THE OREGON COAST RANGE

EPA Science Inventory

Although conceptual models of watershed biogeochemistry emphasize the movement of materials from the land to the sea, important transfers occur in the reverse direction in coastal watersheds through salt spray deposition and returning anadromous fish. To understand the connectio...

Biogeochemistry and Hydrology in Streams Impacted by Legacy Sediments and Urbanization: Implications for Stream Restoration

EPA Science Inventory

The groundwater–surface water interface, consisting of shallow groundwater adjacent to stream channels, is a hot spot for nitrogen removal processes, a storage zone for other solutes, and a target for restoration activities. Characterizing groundwater-surface water interac...

NITROGEN BIOGEOCHEMISTRY IN THE OLIGOHALINE ZONE OF A NEW ENGLAND ESTUARY. (R824767)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Nitrogen dynamics at the groundwater-surface water interface of a degraded urban stream (journal)

EPA Science Inventory

Urbanization degrades stream ecosystems by altering hydrology and nutrient dynamics, yet relatively little effort has been devoted to understanding biogeochemistry of urban streams at the ground water-surface water interface. This zone may be especially important for nitrogen re...

Microbial Community Structure and Biogeochemistry of Three Small Eutrophic Lakes

EPA Science Inventory

Background: The three Jackson Lakes within the Bayou Chico Watershed in NW FL, USA were formed at different times from abandoned sand pits. The lakes experienced inundation with marine water during Hurricane Ivan 2004 and, despite their proximity and similar physical structures, ...

Parameterization of biogeochemical sediment-water fluxes using in-situ measurements and a steady-state diagenetic model

EPA Science Inventory

Diagenetic processes are important drivers of water column biogeochemistry in coastal areas. For example, sediment oxygen consumption can be a significant contributor to oxygen depletion in hypoxic systems, and sediment–water nutrient fluxes support primary productivity in ...

Mississippi and Atchafalaya River Influence on Sediment Porewater Chemistry

EPA Science Inventory

The Louisiana continental shelf (LCS) receives 380 km3 of freshwater per year from the Mississippi and Atchafalaya Rivers. Sources and transport of nutrients and organic matter (OM) delivered to the LCS may result in spatial variation in sediment biogeochemistry important for un...

Stochastic Convection Parameterizations

NASA Technical Reports Server (NTRS)

Teixeira, Joao; Reynolds, Carolyn; Suselj, Kay; Matheou, Georgios

2012-01-01

computational fluid dynamics, radiation, clouds, turbulence, convection, gravity waves, surface interaction, radiation interaction, cloud and aerosol microphysics, complexity (vegetation, biogeochemistry, radiation versus turbulence/convection stochastic approach, non-linearities, Monte Carlo, high resolutions, large-Eddy Simulations, cloud structure, plumes, saturation in tropics, forecasting, parameterizations, stochastic, radiation-clod interaction, hurricane forecasts

In-Situ Lake Bio-Geochemistry Using Laser Raman Spectroscopy and Optrode Sensing

NASA Astrophysics Data System (ADS)

Sobron, P.; Sanz, A.; Thompson, C.; Cabrol, N.; Planetary Lake Lander Project Team

2014-06-01

We have used LRS for characterizing the organic content of a lake through real-time, in-situ analyses and through lab analyses of returned samples. β-carotene and fatty acids (triglycerides) were identified as major components of the organic samples.

The legacy of land-use is revealed in the biogeochemistry of urban streams

EPA Science Inventory

Urban streams are among the most profoundly impacted aquatic ecosystems, characterized by altered hydrology or burial, increased sediment input, and myriad pollutants. We present results from a series of urban stream studies that revealed unique geochemical and biochemical patte...

Isotopic Biogeochemistry

NASA Technical Reports Server (NTRS)

Hayes, J. M.

1985-01-01

An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

The role of trans-disciplinary skills in environmental education and science

EPA Science Inventory

In the past three decades there have been tremendous changes in how environmental scientists address issues relating to societal needs. In the early 1980s interdisciplinary work may have involved one or two related disciplines such as limnology, statistics and biogeochemistry in...

Global terrestrial biogeochemistry: Perturbations, interactions, and time scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braswell, B.H. Jr.

1996-12-01

Global biogeochemical processes are being perturbed by human activity, principally that which is associated with industrial activity and expansion of urban and agricultural complexes. Perturbations have manifested themselves at least since the beginning of the 19th Century, and include emissions of CO{sub 2} and other pollutants from fossil fuel combustion, agricultural emissions of reactive nitrogen, and direct disruption of ecosystem function through land conversion. These perturbations yield local impacts, but there are also global consequences that are the sum of local-scale influences. Several approaches to understanding the global-scale implications of chemical perturbations to the Earth system are discussed. The lifetimemore » of anthropogenic CO{sub 2} in the atmosphere is an important concept for understanding the current and future commitment to an altered atmospheric heat budget. The importance of the terrestrial biogeochemistry relative to the lifetime of excess CO{sub 2} is demonstrated using dynamic, aggregated models of the global carbon cycle.« less

Paleodust variability since the Last Glacial Maximum and implications for iron inputs to the ocean

NASA Astrophysics Data System (ADS)

Albani, S.; Mahowald, N. M.; Murphy, L. N.; Raiswell, R.; Moore, J. K.; Anderson, R. F.; McGee, D.; Bradtmiller, L. I.; Delmonte, B.; Hesse, P. P.; Mayewski, P. A.

2016-04-01

Changing climate conditions affect dust emissions and the global dust cycle, which in turn affects climate and biogeochemistry. In this study we use observationally constrained model reconstructions of the global dust cycle since the Last Glacial Maximum, combined with different simplified assumptions of atmospheric and sea ice processing of dust-borne iron, to provide estimates of soluble iron deposition to the oceans. For different climate conditions, we discuss uncertainties in model-based estimates of atmospheric processing and dust deposition to key oceanic regions, highlighting the large degree of uncertainty of this important variable for ocean biogeochemistry and the global carbon cycle. We also show the role of sea ice acting as a time buffer and processing agent, which results in a delayed and pulse-like soluble iron release into the ocean during the melting season, with monthly peaks up to ~17 Gg/month released into the Southern Oceans during the Last Glacial Maximum (LGM).

Biogeochemistry and community ecology in a spring-fed urban river following a major earthquake.

PubMed

Wells, Naomi S; Clough, Tim J; Condron, Leo M; Baisden, W Troy; Harding, Jon S; Dong, Y; Lewis, G D; Lear, Gavin

2013-11-01

In February 2011 a MW 6.3 earthquake in Christchurch, New Zealand inundated urban waterways with sediment from liquefaction and triggered sewage spills. The impacts of, and recovery from, this natural disaster on the stream biogeochemistry and biology were assessed over six months along a longitudinal impact gradient in an urban river. The impact of liquefaction was masked by earthquake triggered sewage spills (~20,000 m(3) day(-1) entering the river for one month). Within 10 days of the earthquake dissolved oxygen in the lowest reaches was <1 mg l(-1), in-stream denitrification accelerated (attenuating 40-80% of sewage nitrogen), microbial biofilm communities changed, and several benthic invertebrate taxa disappeared. Following sewage system repairs, the river recovered in a reverse cascade, and within six months there were no differences in water chemistry, nutrient cycling, or benthic communities between severely and minimally impacted reaches. This study highlights the importance of assessing environmental impact following urban natural disasters. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microbial Transformation of Iodine: From Radioisotopes to Iodine Deficiency.

PubMed

Yeager, Chris M; Amachi, Seigo; Grandbois, Russell; Kaplan, Daniel I; Xu, Chen; Schwehr, Kathy A; Santschi, Peter H

2017-01-01

Iodine is a biophilic element that is important for human health, both as an essential component of several thyroid hormones and, on the other hand, as a potential carcinogen in the form of radioiodine generated by anthropogenic nuclear activity. Iodine exists in multiple oxidation states (-1, 0, +1, +3, +5, and +7), primarily as molecular iodine (I 2 ), iodide (I - ), iodate [Formula: see text] , or organic iodine (org-I). The mobility of iodine in the environment is dependent on its speciation and a series of redox, complexation, sorption, precipitation, and microbial reactions. Over the last 15years, there have been significant advances in iodine biogeochemistry, largely spurred by renewed interest in the fate of radioiodine in the environment. We review the biogeochemistry of iodine, with particular emphasis on the microbial processes responsible for volatilization, accumulation, oxidation, and reduction of iodine, as well as the exciting technological potential of these fascinating microorganisms and enzymes. Copyright © 2017 Elsevier Inc. All rights reserved.

Biogeochemistry of manganese in ferruginous Lake Matano, Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, C.; Crowe, S.A.; Sturm, A.

2012-12-13

This study explores Mn biogeochemistry in a stratified, ferruginous lake, a modern analogue to ferruginous oceans. Intense Mn cycling occurs in the chemocline where Mn is recycled at least 15 times before sedimentation. The product of biologically catalyzed Mn oxidation in Lake Matano is birnessite. Although there is evidence for abiotic Mn reduction with Fe(II), Mn reduction likely occurs through a variety of pathways. The flux of Fe(II) is insufficient to balance the reduction of Mn at 125m depth in the water column, and Mn reduction could be a significant contributor to CH{sub 4} oxidation. By combining results from synchrotron-basedmore » X-ray fluorescence and X-ray spectroscopy, extractions of sinking particles, and reaction transport modeling, we find the kinetics of Mn reduction in the lake's reducing waters are sufficiently rapid to preclude the deposition of Mn oxides from the water column to the sediments underlying ferruginous water. This has strong implications for the interpretation of the sedimentary Mn record.« less

Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover

DOE PAGES

Stegen, James C.; Fredrickson, James K.; Wilkins, Michael J.; ...

2016-04-07

Environmental transition zones are associated with geochemical gradients that overcome energy limitations to microbial metabolism, resulting in biogeochemical hot spots and moments. Riverine systems where groundwater mixes with surface water (the hyporheic zone) are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. To investigate the coupling among groundwater-surface water mixing, microbial communities, and biogeochemistry we applied ecological theory, aqueous biogeochemistry, DNA sequencing, and ultra-high resolution organic carbon profiling to field samples collected across times and locations representing amore » broad range of mixing conditions. Mixing of groundwater and surface water resulted in a shift from transport-driven stochastic dynamics to a deterministic microbial structure associated with elevated biogeochemical rates. While the dynamics of the hyporheic make predictive modeling a challenge, we provide new knowledge that can improve the tractability of such models.« less

HYDROLOGY-BIOGEOCHEMISTRY MODEL FOR INVESTIGATING IMPACTS OF CLIMATE CHANGE AND TIMBER HARVEST ON WATERSHEDS. (R824803)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Approaches to characterizing biogeochemistry effects of groundwater and surface water interaction at the riparian interface

EPA Science Inventory

Groundwater-surface water interaction (GSI) in riparian ecosystems strongly influences biological activity that controls nutrient flux and processes. Shallow groundwater in riparian zones is a hot spot for nitrogen removal processes, a storage zone for solutes, and a target for ...

MOLECULAR PHYLOGENETIC AND BIOGEOCHEMICAL STUDIES OF SULFATE-REDUCING BACTERIA IN THE RHIZOSPHERE OF SPARTINA ALTERNIFLORA

EPA Science Inventory

The population composition and biogeochemistry of sulfate-reducing bacteria (SRB) in the rhizosphere of the marsh grass Spartina alterniflora was investigated over two growing seasons using molecular probing, enumerations of culturable SRB, and measurements of SO42- reduction rat...

BIOGEOCHEMISTRY OF RA-226 IN CONTAMINATED BOTTOM SEDIMENTS AND OILFIELD WASTE PITS. (R825513C005)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Acetylene Fermentation: Relevance to Primordial Biogeochemistry and the Search for Life in the Outer Solar System

NASA Astrophysics Data System (ADS)

Oremland, R. S.; Baesman, S. M.; Miller, L. G.

2014-02-01

Acetylene supports the growth of some terrestrial anaerobes. The reaction is highly exothermic. The abundance of acetylene in the methane-rich planet(oid)s of the outer solar system could represent a means of nourishment for resident alien microbes.

Mud, Macrofauna and Microbes: An ode to benthic organism-abiotic interactions at varying scales

EPA Science Inventory

Benthic environments are dynamic habitats, subject to variable sources and rates of sediment delivery, reworking from the abiotic and biotic processes, and complex biogeochemistry. These activities do not occur in a vacuum, and interact synergistically to influence food webs, bi...

The legacy of land-use is revealed in the biogeochemistry of urban streams - 3-4-2014

EPA Science Inventory

Urban streams are among the most profoundly impacted aquatic ecosystems, characterized by altered hydrology or burial, increased sediment input, and myriad pollutants. We present results from a series of urban stream studies that revealed unique geochemical and biochemical patte...

Advanced in situ Spectroscopic Techniques And Their Applications In Environmental Biogeochemistry: Introduction To The Special Section

EPA Science Inventory

Understanding the molecular-scale complexities and interplay of chemical and biological processes of contaminants at solid, liquid, and gas interfaces is a fundamental and crucial element to enhance our understanding of anthropogenic environmental impacts. The ability to describ...

Improved simulation of river water and groundwater exchange in an alluvial plain using the SWAT model

USDA-ARS?s Scientific Manuscript database

Hydrological interaction between surface and subsurface water systems has a significant impact on water quality, ecosystems and biogeochemistry cycling of both systems. Distributed models have been developed to simulate this function, but they require detailed spatial inputs and extensive computati...

Ulva additions alter soil biogeochemistry and negatively impact Spartina alterniflora growth

EPA Science Inventory

Decaying mats of Ulva can be washed into salt marshes by the tides as large wrack deposits, especially in eutrophic estuaries, where they can negatively impact marsh vegetation. We report on a series of field and laboratory mesocosm experiments where we examined the effects of d...

THE AGWA – KINEROS2 SUITE OF MODELING TOOLS

USDA-ARS?s Scientific Manuscript database

A suite of modeling tools ranging from the event-based KINEROS2 flash-flood forecasting tool to the continuous (K2-O2) KINEROS-OPUS biogeochemistry tool. The KINEROS2 flash flood forecasting tool is being tested with the National Weather Service (NEW) is described. Tne NWS version assimilates Dig...

ROLE OF RED ALDER IN NITROGEN LOSSES FROM FORESTED WATERSHEDS IN THE OREGON COAST RANGE

EPA Science Inventory

Variations in plant community composition across the landscape may have strong impacts on nutrient losses from small forested watersheds. One extreme example of this impact is the role of the nitrogen-fixing tree, red alder, in the biogeochemistry of forested watersheds in the P...

Interannual Variation in Stable Carbon and Nitrogen Isotope Biogeochemistry of the Mattaponi River, Virginia

EPA Science Inventory

This manuscript addresses the difficult issue of identifying the origin of particulate organic matter (POM) in estuaries . . . The objectives of this study were to quantify spatial and temporal variability of the C and N stable isotope composition of suspended POM, and to identif...

An integrated spectroscopic and wet chemical approach to investigate grass litter decomposition chemistry

USDA-ARS?s Scientific Manuscript database

Litter decomposition is a key process for soil organic matter formation and terrestrial biogeochemistry. Yet we still lack complete understanding of the chemical transformations which occur in the litter residue as it decomposes. A number of methods such as bulk nutrient concentrations, chemical fra...

Spectroscopic Evidence of Uranium Immobilization in Acidic Wetlands by Natural Organic Matter and Plant Roots

EPA Science Inventory

Biogeochemistry of uranium in wetlands plays important roles in U immobilization in storage ponds of U mining and processing facilities but has not been well understood. The objective of this work was to study molecular mechanisms responsible for high U retention by Savannah Ri...

Burial affects the biogeochemistry of headwater streams in a midwestern US metropolitan area

EPA Science Inventory

Nitrogen (N) retention in stream networks is an important ecosystem service that may be affected by the widespread burial of headwater streams in urban basins. Urban stream burial has only recently been recognized by ecologists and little research has addressed the extent to whi...

Burial affects the biogeochemistry of headwater streams in a midwestern US metropolitan area - slides

EPA Science Inventory

Nitrogen (N) retention in stream networks is an important ecosystem service that may be affected by the widespread burial of headwater streams in urban basins. Urban stream burial has only recently been recognized by ecologists as a regional environmental impact and little resea...

Thinking outside the channel: modeling nitrogen cycling in networked river ecosystems

Treesearch

Ashley M. Helton; Geoffrey C. Poole; Judy L. Meyer; Wilfred M. Wollheim; Bruce J. Peterson; Patrick J. Mulholland; Emily S. Bernhardt; Jack A. Stanford; Clay Arango; Linda R. Ashkenas; Lee W. Cooper; Walter K. Dodds; Stanley V. Gregory; Robert O. Hall; Stephen K. Hamilton; Sherri L. Johnson; William H. McDowell; Jody D. Potter; Jennifer L. Tank; Suzanne M. Thomas; H. Maurice Valett; Jackson R. Webster; Lydia Zeglin

2011-01-01

Agricultural and urban development alters nitrogen and other biogeochemical cycles in rivers worldwide. Because such biogeochemical processes cannot be measured empirically across whole river networks, simulation models are critical tools for understanding river-network biogeochemistry. However, limitations inherent in current models restrict our ability to simulate...

Biogeochemistry of three small Eutrophic Lakes Differentially Influenced by Marine Waters from Bayou Chico Bay, Pensacola, Florida

EPA Science Inventory

Biogeochemical models predict microbial mediated pathways but generally do not account for microorganisms. This study was undertaken to better understand relationships among microbial communities and N, S, Fe and C cycling in three lakes. Jackson Lakes formed from abandoned sand...

Sara Fairchild | NREL

Science.gov Websites

Sara.Fairchild@nrel.gov | 303-384-7114 Sara brings strong data management and editing skills to NREL, gained through her work at the Institute of Alpine and Arctic Research. She specialized in biogeochemistry with an emphasis on soil science and had the opportunity to study soils throughout Northern California in

ARSENIC BIOAVAILABILITY ASSOCIATED WITH THE PRESENCE OF CCA-TREATED WOOD PRODUCTS

EPA Science Inventory

This is an invited paper/slide presentation to be presented by Dr. Karen Bradham at the 8th International Conference on the Biogeochemistry of Trace Elements, Adelaide, Australia, April 3 - 7, 2005. The PowerPoint slides describe the study design of projects currently being perf...

METHODS TO EVALUATE ARSENIC BIOAVAILABILITY ASSOCIATED WITH THE PRESENCE OF CCA-TREATED WOOD PRODUCTS

EPA Science Inventory

This is an invited paper to be presented by Dr. Karen Bradham at the 8th International Conference on the Biogeochemistry of Trace Elements, Adelaide, Australia, April 3 - 7, 2005. The abstract describes methods to evaluate arsenic bioavailability associated with the presence of ...

"Advances in Coupled Air Quality, Farm Management and Biogeochemistry to address bidirectional ammonia flux"

EPA Science Inventory

A cropland farm management modeling system for regional air quality and field-scale applications of bi-directional ammonia exchange was presented at ITM XXI. The goal of this research is to improve estimates of nitrogen deposition to terrestrial and aquatic ecosystems and ambien...

EXPERIMENTAL ACIDIFICATION CAUSES SOIL BASE-CATION DEPLETION AT THE BEAR BROOK WATERSHED IN MAINE

EPA Science Inventory

There is concern that changes in atmospheric deposition, climate, or land use have altered the biogeochemistry of forests causing soil base-cation depletion, particularly Ca. The Bear Brook Watershed in Maine (BBWM) is a paired watershed experiment with one watershed subjected to...

ISOTOPIC BIOGEOCHEMISTRY OF DISSOLVED ORGANIC NITROGEN: A NEW TECHNIQUE AND APPLICATION. (R825151)

EPA Science Inventory

We present a new technique for isolating and isotopically characterizing dissolved organic nitrogen (DON) for non-marine waters, ¹⁵N values for DON from lacustrine samples and data suggesting that this technique will be a...

Giving advice on cost effective measures for a cleaner Baltic Sea: a challenge for science.

PubMed

Wulff, F; Bonsdorff, E; Gren, I M; Johansson, S; Stigebrandt, A

2001-08-01

The Baltic Sea is one of the world's seas that is most severely affected by human activities. Although there is an international agreement that nutrient input to the Baltic should be reduced, the measures taken so far have not resulted in major reductions in nutrient inputs nor in environmental improvements. The reasons for this are partly due to lack of knowledge on large-scale relationships and couplings between physics, biogeochemistry and ecological properties. But there is also a lack of overall drainage basin-wide analyses on cost-effective measures. There is a danger in making the wrong decisions, e.g. implement reduction schemes that are at worst ineffective or at best, far from cost effective. Researchers from many disciplines are faced with a common challenge: To develop a decision-support system, which can be used as the scientific base for cost-effective measures for the entire Baltic Sea. Such an effort is now being made within the research program MARE (http://www.mare.su.se).

SEQUESTERING AGENTS FOR METAL IMMOBILIZATION APPLICATION TO THE DEVELOPMENT OF ACTIVE CAPS IN FRESH AND SALT WATER SEDIMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knox, A; Michael Paller, M

2006-11-17

This research evaluated the removal of inorganic contaminants by a variety of amendments and mixtures of amendments in fresh and salt water. A series of removal and retention batch experiments was conducted to identify the best treatment for metal removal. Metal removal by the amendments was evaluated by calculating the partition coefficient and percent removal. Retention of metals by the amendments was evaluated in retention (desorption) studies in which residue from the removal studies was extracted with 1 M MgCl{sub 2} solution. The results indicated that phosphate amendments, some organoclays (e.g., OCB-750), and the biopolymer, chitosan, are very effective inmore » removal and retention of metals in both fresh and salt water. These amendments are being evaluated further as components in the development of active caps for sediment remediation.« less

Imaging Systems Provide Maps for U.S. Soldiers

NASA Technical Reports Server (NTRS)

2012-01-01

Spanning nearly four decades, the remarkable Landsat program has continuously provided data about the Earth s surface, including detailed maps of vegetation, land use, forest extent and health, surface water, population distribution, as well as how these features have changed over time. Managed by NASA and the U.S. Geological Survey, Landsat s series of satellites obtain data through passive remote sensing, or the use of sensors to read the energy reflected or emitted from the Earth s surface. After the data from the sensors is processed and analyzed, it can be applied to create information-rich images of the planet. While the Landsat program has launched seven satellites since 1972, only Landsat 5 and 7 are currently operating. The next spacecraft in line to ensure continuity of data for years to come is the Landsat Data Continuity Mission (LDCM). Planned for launch in 2012, LDCM will take measurements of the Earth in visible, nearinfrared, shortwave infrared, and thermal infrared bands. In addition to widespread use for land use planning and monitoring on local to regional scales, support for disaster response and evaluations, as well as water use monitoring, LDCM measurements will directly serve NASA s research in the areas of climate, the carbon cycle, ecosystems, the water cycle, biogeochemistry, and Earth s surface and interior.

The Molecular Ecophysiology of Programmed Cell Death in Marine Phytoplankton

NASA Astrophysics Data System (ADS)

Bidle, Kay D.

2015-01-01

Planktonic, prokaryotic, and eukaryotic photoautotrophs (phytoplankton) share a diverse and ancient evolutionary history, during which time they have played key roles in regulating marine food webs, biogeochemical cycles, and Earth's climate. Because phytoplankton represent the basis of marine ecosystems, the manner in which they die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining upper-ocean biogeochemistry. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of nutrient stressors and are employed by parasitic viruses, play an integral role in determining the cell fate of diverse photoautotrophs in the modern ocean. Indeed, these multifaceted death pathways continue to shape the success and evolutionary trajectory of diverse phytoplankton lineages at sea. Research over the past two decades has employed physiological, biochemical, and genetic techniques to provide a novel, comprehensive, mechanistic understanding of the factors controlling this key process. Here, I discuss the current understanding of the genetics, activation, and regulation of PCD pathways in marine model systems; how PCD evolved in unicellular photoautotrophs; how it mechanistically interfaces with viral infection pathways; how stress signals are sensed and transduced into cellular responses; and how novel molecular and biochemical tools are revealing the impact of PCD genes on the fate of natural phytoplankton assemblages.

Land-use and hydroperiod affect kettle hole sediment carbon and nitrogen biogeochemistry

Treesearch

Kai Nils Nitzsche; Thomas Kalettka; Katrin Premke; Gunnar Lischeid; Arthur Gessler; Zachary Eric Kayler

2017-01-01

Kettle holes are glaciofluvially created depressional wetlands that collect organic matter (OM) and nutrients from their surrounding catchment. Kettle holes mostly undergo pronounced wet-dry cycles. Fluctuations in water table, land-use, andmanagement can affect sediment biogeochemical transformations and perhaps threaten the carbon stocks of these unique ecosystems....

DIRECT MERCURY ANALYSIS IN ENVIRONMENTAL SOLIDS BY ICPMS WITH ON-LINE SAMPLE ASHING AND MERCURY PRECONCENTRATION USING A DIRECT MERCURY ANALYZER

EPA Science Inventory

Mercury is a persistent, mobile, and highly toxic pollutant. It's biogeochemistry is probably the most complex of any metal. For these reasons, the U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), has developed a comprehensive res...

Differences in net primary production and biogeochemistry between contrasting floodplain forests

Treesearch

Erik B. Schilling; B. Graeme Lockaby

2000-01-01

A firm understanding of the driving forces controlling variation among wetland forests continues to elude scientists and land managers—specifically the biogeochemical processes controlling vegetation production. Within contrasting wetland forests, insight into the biogeochemical processes driving productivity levels may befound by examining the degree to which nitrogen...

Reservoir N2O data

EPA Pesticide Factsheets

Dissolved oxygen, dissolved nitrous oxide, and water temperature in reservoirs.This dataset is associated with the following publication:Beaulieu , J., C. Nietch , and J. Young. Source or sink: Insight on controls of nitrous oxide biogeochemistry from a 20 reservoir survey. Journal of Geophysical Research - Biogeosciences. American Geophysical Union, Washington, DC, USA, 120(10): 1995-2010, (2015).

A NON-STEADY-STATE DIAGENETIC MODEL FOR CHANGES IN SEDIMENT BIOGEOCHEMISTRY IN RESPONSE TO SEASONALLY HYPOXIC/ANOXIC CONDITIONS BENEATH THE MISSISSIPPI RIVER PLUME

EPA Science Inventory

Although the bottom waters of many freshwater and marine environments are either permanently oxic or anoxic, there is a growing appreciation that in many bodies of water near-bottom conditions seasonally oscillate between these extreme. Although observational databases for these ...

Modeling carbon and nitrogen biogeochemistry in forest ecosystems

Treesearch

Changsheng Li; Carl Trettin; Ge Sun; Steve McNulty; Klaus Butterbach-Bahl

2005-01-01

A forest biogeochemical model, Forest-DNDC, was developed to quantify carbon sequestration in and trace gas emissions from forest ecosystems. Forest-DNDC was constructed by integrating two existing moels, PnET and DNDC, with several new features including nitrification, forest litter layer, soil freezing and thawing etc, PnET is a forest physiological model predicting...

Marshes on the Move: Testing effects of seawater intrusion on vegetation communities of the salt marsh-upland ecotone

EPA Science Inventory

The Northeastern United States is a hotspot for sea level rise (SLR), subjecting coastal salt marshes to erosive loss, shifts in vegetation communities, and altered biogeochemistry due to seawater intrusion. Salt marsh plant community zonation is driven by tradeoffs in stress to...

Biogeochemistry of aragonite mud and oolites.

NASA Technical Reports Server (NTRS)

Mitterer, R. M.

1972-01-01

Amino acids were determined on an analyzer similar to that described by Hare (1969) in carbonate mud samples from locations in the Bahamas, Bermuda, Persian Gulf, and Florida Bay, and in oolites from the Gulf of Suez, the Abu Dhabi coast, the Bahamas, and Baffin Bay, Texas. A histogram, tables, and chromatograms of the results are given.

Forest ecosystem changes from annual methane source to sink depending on late summer water balance

Treesearch

Julie K. Shoemaker; Trevor F. Keenan; David Y. Hollinger; Andrew D. Richardson

2014-01-01

Forests dominate the global carbon cycle, but their role in methane (CH4) biogeochemistry remains uncertain. We analyzed whole-ecosystem CH4 fluxes from 2 years, obtained over a lowland evergreen forest in Maine, USA. Gross primary productivity provided the strongest correlation with the CH4 flux in...

NITROGEN EXPORT FROM FORESTED WATERSHEDS IN THE OREGON COAST RANGE: THE ROLE OF N2-FIXING RED ALDER

EPA Science Inventory

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species influence is the role of N2-fixing red alder (Alnus rubra) in the biogeochemistry of Pacific Northwest forests. T...

Elevated CO2 induces substantial and persistent declines in forage quality irrespective of warming in mixed grass prairie

USDA-ARS?s Scientific Manuscript database

Increasing atmospheric [CO2] and temperature are expected to affect the productivity, species composition, biogeochemistry, and therefore the quantity and quality of forage available to herbivores in rangeland ecosystems. Both elevated CO2 (eCO2) and warming affect plant tissue chemistry through mul...

Developing a model for the mercury cycle in the Marano-Grado Lagoon (Italy)

EPA Science Inventory

The Marano-Grado Lagoon is a wetland system of about 160 km2 located in the Northern Adriatic Sea (Italy) between the Tagliamento and the Isonzo River mouths. The lagoon morphology and biogeochemistry are primarily controlled by the exchange with the Adriatic Sea and, to a lesser...

Capturing Spatial Variability of Biogeochemical Mass Exchanges and Reaction Rates in Wetland Water and Soil through Model Compartmentalization

EPA Science Inventory

A common phenomenon observed in natural and constructed wetlands is short-circuiting of flow and formation of stagnant zones that are only indirectly connected with the incoming water. Biogeochemistry of passive areas is potentially much different than that of active zones. In ...

STABLE CARBON ISOTOPE BIOGEOCHEMISTRY OF A SHALLOW SAND AQUIFER CONTAMINATED WITH FUEL HYDROCARBONS

EPA Science Inventory

Ground-water chemistry and the stable C isotope composition ( 13CDIC) of dissolved C (DIC) were measured in a sand aquifer contaminated with JP-4 fuel hydrocarbons. Results show that ground water in the upgradient zone was characterized by DIC content of 14-20 mg C/L and 13CDIC...

Bound Flavin-Cytochrome Model of Extracellular Electron Transfer in Shewanella oneidensis: Analysis by Free Energy Molecular (Postprint)

DTIC Science & Technology

2016-06-06

toxic chemicals,4 protection of steel from corrosion,5 or in bioremediation .6 Of special interest is the potential use of the exoelectrogens in... Bioremediation of Uranium-Contaminated Groundwater: A Systems Approach to Subsurface Biogeochemistry. Curr. Opin. Biotechnol. 2013, 24, 489−497. (7

Microbial Biogeochemistry of Seafloor Fluid Flow on Earth and Implications for Biological Potential on Enceladus

NASA Astrophysics Data System (ADS)

Huber, J. A.

2017-12-01

The interaction between liquid water and the rocky seafloor provides high potential for release of chemical energy, thus seafloor fluid flow is viewed an essential driver of subseafloor microbial life in Earth's oceans. Given predictions that Enceladus hosts a global-scale ocean underlain by a rocky seafloor, and new data suggesting on-going hydrothermal activity on Enceladus based on detection of hydrogen by Cassini, it is timely to investigate those subseafloor Earth analogs that may be informative when developing future missions to and interpreting mission data from Enceladus. Over the last 35 years, the breadth of seafloor fluid flow regimes that have been discovered and studied on Earth has expanded to include a wide spectrum of geological settings, geochemical characteristics, and microorganisms, including environments that were not previously known to exist, e.g. hydrogen-rich mafic systems, ridge-flank oxic systems, etc. This presentation will provide an overview of the latest and most exciting findings on the microbial biogeochemistry of seafloor fluid flow in Earth's oceans and place these findings in the context of biological potential for Enceladus.

Desert dust and anthropogenic aerosol interactions in the Community Climate System Model coupled-carbon-climate model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahowald, Natalie; Rothenberg, D.; Lindsay, Keith

2011-02-01

Coupled-carbon-climate simulations are an essential tool for predicting the impact of human activity onto the climate and biogeochemistry. Here we incorporate prognostic desert dust and anthropogenic aerosols into the CCSM3.1 coupled carbon-climate model and explore the resulting interactions with climate and biogeochemical dynamics through a series of transient anthropogenic simulations (20th and 21st centuries) and sensitivity studies. The inclusion of prognostic aerosols into this model has a small net global cooling effect on climate but does not significantly impact the globally averaged carbon cycle; we argue that this is likely to be because the CCSM3.1 model has a small climatemore » feedback onto the carbon cycle. We propose a mechanism for including desert dust and anthropogenic aerosols into a simple carbon-climate feedback analysis to explain the results of our and previous studies. Inclusion of aerosols has statistically significant impacts on regional climate and biogeochemistry, in particular through the effects on the ocean nitrogen cycle and primary productivity of altered iron inputs from desert dust deposition.« less

Watershed responses to Amazon soya bean cropland expansion and intensification.

PubMed

Neill, Christopher; Coe, Michael T; Riskin, Shelby H; Krusche, Alex V; Elsenbeer, Helmut; Macedo, Marcia N; McHorney, Richard; Lefebvre, Paul; Davidson, Eric A; Scheffler, Raphael; Figueira, Adelaine Michela e Silva; Porder, Stephen; Deegan, Linda A

2013-06-05

The expansion and intensification of soya bean agriculture in southeastern Amazonia can alter watershed hydrology and biogeochemistry by changing the land cover, water balance and nutrient inputs. Several new insights on the responses of watershed hydrology and biogeochemistry to deforestation in Mato Grosso have emerged from recent intensive field campaigns in this region. Because of reduced evapotranspiration, total water export increases threefold to fourfold in soya bean watersheds compared with forest. However, the deep and highly permeable soils on the broad plateaus on which much of the soya bean cultivation has expanded buffer small soya bean watersheds against increased stormflows. Concentrations of nitrate and phosphate do not differ between forest or soya bean watersheds because fixation of phosphorus fertilizer by iron and aluminium oxides and anion exchange of nitrate in deep soils restrict nutrient movement. Despite resistance to biogeochemical change, streams in soya bean watersheds have higher temperatures caused by impoundments and reduction of bordering riparian forest. In larger rivers, increased water flow, current velocities and sediment flux following deforestation can reshape stream morphology, suggesting that cumulative impacts of deforestation in small watersheds will occur at larger scales.

Microbial communities acclimate to recurring changes in soil redox potential status

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeAngelis, Kristen M.; Silver, Whendee; Thompson, Andrew

Rapidly fluctuating environmental conditions can significantly stress organisms, particularly when fluctuations cross thresholds of normal physiological tolerance. Redox potential fluctuations are common in humid tropical soils, and microbial community acclimation or avoidance strategies for survival will in turn shape microbial community diversity and biogeochemistry. To assess the extent to which indigenous bacterial and archaeal communities are adapted to changing in redox potential, soils were incubated under static anoxic, static oxic or fluctuating redox potential conditions, and the standing (DNA-based) and active (RNA-based) communities and biogeochemistry were determined. Fluctuating redox potential conditions permitted simultaneous CO{sub 2} respiration, methanogenesis, N{sub 2}O productionmore » and iron reduction. Exposure to static anaerobic conditions significantly changed community composition, while 4-day redox potential fluctuations did not. Using RNA: DNA ratios as a measure of activity, 285 taxa were more active under fluctuating than static conditions, compared with three taxa that were more active under static compared with fluctuating conditions. These data suggest an indigenous microbialcommunity adapted to fluctuating redox potential.« less

New Insights into Clinical Characteristics of Gilles de la Tourette Syndrome: Findings in 1032 Patients from a Single German Center

PubMed Central

Sambrani, Tanvi; Jakubovski, Ewgeni; Müller-Vahl, Kirsten R.

2016-01-01

Background: Gilles de la Tourette syndrome (TS) is a complex neuropsychiatric disorder defined by the presence of motor and phonic tics, but often associated with psychiatric comorbidities. The main objective of this study was to explore the clinical presentation and comorbidities of TS. Method: We analyzed clinical data obtained from a large sample (n = 1032; 529 children and 503 adults) of patients with tic disorders from one single German TS center assessed by one investigator. Data was collected with the help of an expert-reviewed semi-structured interview, designed to assess tic severity and certain comorbidities. Group comparisons were carried out via independent sample t-tests and chi-square tests. Results: The main findings of the study are: (1) tic severity is associated with the presence of premonitory urges (PU), copro-, echo-, and paliphenomena and the number of comorbidities, but not age at tic onset; it is higher in patients with comorbid obsessive-compulsive disorder (OCD) than in patients with comorbid attention deficit/hyperactivity disorder (ADHD). (2) PU were found to be highly associated with “not just right experiences” and to emerge much earlier than previously thought alongside with the ability to suppress tics (PU in >60% and suppressibility in >75% at age 8–10 years). (3) Self-injurious behavior (SIB) is highly associated with complex motor tics and coprophenomena, but not with OCD/obsessive-compulsive behavior (OCB). While comorbid ADHD is associated with a lower ability to suppress tics, comorbid depression is associated with sleeping problems. Discussion: Our results demonstrate that tic severity is not influenced by age at onset. From our data, it is suggested that PU represent a specific type of “not just right experience” that is not a prerequisite for tic suppression. Comorbid ADHD reduces patients' ability of successful tic suppression. Our data suggest that SIB belongs to the coprophenomena spectrum and hence should be conceptualized as a complex tic rather than a compulsion. Finally, this study strongly supports the hypothesis that TS+OCD is a more severe form of TS and that comorbid OCD/OCB, depression, and anxiety belong to the TS spectrum, while ADHD should be better conceptualized as a separate problem. PMID:27672357

Sublgacial Antarctic Lake Environments (SALE)

NASA Astrophysics Data System (ADS)

Kennicutt, M. C.; Bell, R. E.; Priscu, J. C.

2004-12-01

Subglacial Antarctic lake environments are emerging as one of the new frontiers targeted for exploration during the IPY 2007-2009. Several campaigns by various nations are in the early stages of planning and implementation with timelines that will coincide with the IPY. The ambitious interdisciplinary objectives will best be realized by multiple exploration programs investigating diverse subglacial environments continent-wide over the next decade or more. A concerted, multi-target approach wil be taken to advance our understanding of the range of possible lake evolutionary histories; the character of the physical, chemical, and biological niches; the interconnectivity of subglacial lake environments; the coupling of the ice sheet, climate and the evolution of life under the ice; the tectonic settings; and the interplay of biogeochemical cycles. Research and exploration programs spanning the continent will investigate subglacial lake environments of differing ages, evolutionary histories, and biogeochemical settings. The combined efforts will provide a holistic view of these environments over millions of years and under changing climatic conditions. The IPY will provide an opportunity for an intense period of initial exploration that will advance scientific discoveries in glaciology, biogeochemistry, paleoclimate, biology, geology and tectonics, and ecology. While early discoveries and exciting findings are expected during the IPY 2007-2009, a long term sustained program of research and exploration will continue far beyond the IPY. Within the five year period that spans the IPY, specific accomplishments will be targeted, accelerating the research agenda and setting a framework for follow-on studies. Four phases of exploration and discovery are envisioned.

Biogeochemistry of the coupled manganese-iron-sulfur cycles of intertidal surface sediments

NASA Astrophysics Data System (ADS)

Bosselmann, K.; Boettcher, M. E.; Billerbeck, M.; Walpersdorf, E.; Debeer, D.; Brumsack, H.-J.; Huettel, M.; Joergensen, B. B.

2003-04-01

The biogeochemistry of the coupled iron-manganese-sulfur-carbon cycles was studied in temperate intertidal surface sediments of the German Wadden Sea (North Sea). Coastal sampling sites include sand, mixed and mud flats with different organic matter and metal contents and permeability reflecting different hydrodynamic regimes. The field study focusses on the influence of temperature, organic matter load, and sediment types on the dynamics of biogeochemical reactions on different time scales (season, day-night, tidal cycles). One of the main interests was related to the cycling of metals (Mn, Fe) in relation to the activity of sulfate-reducing bacteria. Pore water profiles were investigated by sediment sectioning and high resolution gel sampling techniques. Microbial sulfate reduction rates were measured using radiolabeled sulfate with the whole core incubation technique and the spatial distribution of bacterial activity was visualised by using "2D-photoemulsion-monitoring technique". The biogeochemical sulfur cycle was additionally characterised by the stable isotope ratios (S,O) of different sulfur species (e.g., SO_4, AVS, pyrite). Element transfers (metals, nutrients) across the sediment-water interface were additionally quantified by the application of benthic flux chambers. Microbial sulfate reduction was generally highest in the suboxic zone of the surface sediments indicating its potential importance for the mobilization of iron and manganese. In organic matter poor permeable sediments tidal effects additionally influence the spatial and temporal distribution of dissolved redox-sensitive metals. In organic matter-rich silty and muddy sediments, temperature controlled the microbial sulfate reduction rates. Depth-integrated sulfate reduction rates in sandy sediments were much lower and controlled by both temperature and organic matter. Formation of anoxic sediment surfaces due to local enhanced organic matter load (so-called "black spots") may create windows of an increase flux of metals, nutrients and hydrogen sulfide. Acknowledgements: The study was supported by German Science Foundation within the DFG-research group "BioGeoChemistry of the Waddensea" and Max Planck Society.

Using a spatially-distributed hydrologic biogeochemistry model with a nitrogen transport module to study the spatial variation of carbon processes in a Critical Zone Observatory

DOE PAGES

Shi, Yuning; Eissenstat, David M.; He, Yuting; ...

2018-05-12

Terrestrial carbon processes are affected by soil moisture, soil temperature, nitrogen availability and solar radiation, among other factors. Most of the current ecosystem biogeochemistry models represent one point in space, and have limited characterization of hydrologic processes. Therefore these models can neither resolve the topographically driven spatial variability of water, energy, and nutrient, nor their effects on carbon processes. A spatially-distributed land surface hydrologic biogeochemistry model, Flux-PIHM-BGC, is developed by coupling the Biome-BGC model with a physically-based land surface hydrologic model, Flux-PIHM. In the coupled system, each Flux-PIHM model grid couples a 1-D Biome-BGC model. In addition, a topographic solarmore » radiation module and an advection-driven nitrogen transport module are added to represent the impact of topography on nutrient transport and solar energy distribution. Because Flux-PIHM is able to simulate lateral groundwater flow and represent the land surface heterogeneities caused by topography, Flux-PIHM-BGC is capable of simulating the complex interaction among water, energy, nutrient, and carbon in time and space. The Flux-PIHM-BGC model is tested at the Susquehanna/Shale Hills Critical Zone Observatory. Model results show that distributions of carbon and nitrogen stocks and fluxes are strongly affected by topography and landscape position, and tree growth is nitrogen limited. The predicted aboveground and soil carbon distributions generally agree with the macro patterns observed. Although the model underestimates the spatial variation, the predicted watershed average values are close to the observations. Lastly, the coupled Flux-PIHM-BGC model provides an important tool to study spatial variations in terrestrial carbon and nitrogen processes and their interactions with environmental factors, and to predict the spatial structure of the responses of ecosystems to climate change.« less

Modelling Biogeochemistry Across Domains with The Modular System for Shelves and Coasts (MOSSCO)

NASA Astrophysics Data System (ADS)

Burchard, H.; Lemmen, C.; Hofmeister, R.; Knut, K.; Nasermoaddeli, M. H.; Kerimoglu, O.; Koesters, F.; Wirtz, K.

2016-02-01

Coastal biogeochemical processes extend from the atmosphere through the water column and the epibenthos into the ocean floor, laterally they are determined by freshwater inflows and open water exchange, and in situ they are mediated by physical, chemical and biological interactions. We use the new Modular System for Shelves and Coasts (MOSSCO, http://www.mossco.de) to obtain an integrated view of coastal biogeochemistry. MOSSCO is a coupling framework that builds on existing coupling technologies like the Earth System Modeling Framework (ESMF, for domain-coupling) and the Framework for Aquatic Biogeochemistry (FABM, for process coupling). MOSSCO facilitates the communication about and the integration of existing and of new process models into a threedimensional regional coastal modelling context. In the MOSSCO concept, the integrating framework imposes very few restrictions on contributed data or models; in fact, there is no distinction made between data and models. The few requirements are: (1) principle coupleability, i.e. access to I/O and timing information in submodels, which has recently been referred to as the Basic Model Interface (BMI) (2) open source/open data access and licencing and (3) communication of metadata, such as spatiotemporal information, naming conventions, and physical units. These requirements suffice to integrate different models and data sets into the MOSSCO infrastructure and subsequently built a modular integrated modeling tool that can span a diversity of processes and domains. Here, we demonstrate a MOSSCO application for the southern North Sea, where atmospheric deposition, biochemical processing in the water column and the ocean floor, lateral nutrient replenishment, and wave- and current-dependent remobilization from sediments are accounted for by modular components. A multi-annual simulation yields realistic succession of the spatial gradients of dissolved nutrients, of chlorophyll variability and gross primary production rates and of benthic denitrification rates for this intriguing coastal system.

The effect of anthropogenic emissions corrections on the seasonal cycle of atmospheric CO2

NASA Astrophysics Data System (ADS)

Brooks, B. J.; Hoffman, F. M.; Mills, R. T.; Erickson, D. J.; Blasing, T. J.

2009-12-01

A previous study (Erickson et al. 2008) approximated the monthly global emission estimates of anthropogenic CO2 by applying a 2-harmonic Fourier expansion with coefficients as a function of latitude to annual CO2 flux estimates derived from United States data (Blasing et al. 2005) that were extrapolated globally. These monthly anthropogenic CO2 flux estimates were used to model atmospheric concentrations using the NASA GEOS-4 data assimilation system. Local variability in the amplitude of the simulated CO2 seasonal cycle were found to be on the order of 2-6 ppmv. Here we used the same Fourier expansion to seasonally adjust the global annual fossil fuel CO2 emissions from the SRES A2 scenario. For a total of four simulations, both the annual and seasonalized fluxes were advected in two configurations of the NCAR Community Atmosphere Model (CAM) used in the Carbon-Land Model Intercomparison Project (C-LAMP). One configuration used the NCAR Community Land Model (CLM) coupled with the CASA‧ (carbon only) biogeochemistry model and the other used CLM coupled with the CN (coupled carbon and nitrogen cycles) biogeochemistry model. All four simulations were forced with observed sea surface temperatures and sea ice concentrations from the Hadley Centre and a prescribed transient atmospheric CO2 concentration for the radiation and land forcing over the 20th century. The model results exhibit differences in the seasonal cycle of CO2 between the seasonally corrected and uncorrected simulations. Moreover, because of differing energy and water feedbacks between the atmosphere model and the two land biogeochemistry models, features of the CO2 seasonal cycle were different between these two model configurations. This study reinforces previous findings that suggest that regional near-surface atmospheric CO2 concentrations depend strongly on the natural sources and sinks of CO2, but also on the strength of local anthropogenic CO2 emissions and geographic position. This work further attests to the need for remotely sensed CO2 observations from space.

Climate engineering and the ocean: effects on biogeochemistry and primary production

NASA Astrophysics Data System (ADS)

Lauvset, Siv K.; Tjiputra, Jerry; Muri, Helene

2017-12-01

Here we use an Earth system model with interactive biogeochemistry to project future ocean biogeochemistry impacts from the large-scale deployment of three different radiation management (RM) climate engineering (also known as geoengineering) methods: stratospheric aerosol injection (SAI), marine sky brightening (MSB), and cirrus cloud thinning (CCT). We apply RM such that the change in radiative forcing in the RCP8.5 emission scenario is reduced to the change in radiative forcing in the RCP4.5 scenario. The resulting global mean sea surface temperatures in the RM experiments are comparable to those in RCP4.5, but there are regional differences. The forcing from MSB, for example, is applied over the oceans, so the cooling of the ocean is in some regions stronger for this method of RM than for the others. Changes in ocean net primary production (NPP) are much more variable, but SAI and MSB give a global decrease comparable to RCP4.5 (˜ 6 % in 2100 relative to 1971-2000), while CCT gives a much smaller global decrease of ˜ 3 %. Depending on the RM methods, the spatially inhomogeneous changes in ocean NPP are related to the simulated spatial change in the NPP drivers (incoming radiation, temperature, availability of nutrients, and phytoplankton biomass) but mostly dominated by the circulation changes. In general, the SAI- and MSB-induced changes are largest in the low latitudes, while the CCT-induced changes tend to be the weakest of the three. The results of this work underscore the complexity of climate impacts on NPP and highlight the fact that changes are driven by an integrated effect of multiple environmental drivers, which all change in different ways. These results stress the uncertain changes to ocean productivity in the future and advocate caution at any deliberate attempt at large-scale perturbation of the Earth system.

The ecological module of BOATS-1.0: a bioenergetically-constrained model of marine upper trophic levels suitable for studies of fisheries and ocean biogeochemistry

NASA Astrophysics Data System (ADS)

Carozza, D. A.; Bianchi, D.; Galbraith, E. D.

2015-12-01

Environmental change and the exploitation of marine resources have had profound impacts on marine communities, with potential implications for ocean biogeochemistry and food security. In order to study such global-scale problems, it is helpful to have computationally efficient numerical models that predict the first-order features of fish biomass production as a function of the environment, based on empirical and mechanistic understandings of marine ecosystems. Here we describe the ecological module of the BiOeconomic mArine Trophic Size-spectrum (BOATS) model, which takes an Earth-system approach to modeling fish biomass at the global scale. The ecological model is designed to be used on an Earth System model grid, and determines size spectra of fish biomass by explicitly resolving life history as a function of local temperature and net primary production. Biomass production is limited by the availability of photosynthetic energy to upper trophic levels, following empirical trophic efficiency scalings, and by well-established empirical temperature-dependent growth rates. Natural mortality is calculated using an empirical size-based relationship, while reproduction and recruitment depend on both the food availability to larvae from net primary production and the production of eggs by mature adult fish. We describe predicted biomass spectra and compare them to observations, and conduct a sensitivity study to determine how the change as a function of net primary production and temperature. The model relies on a limited number of parameters compared to similar modeling efforts, while retaining realistic representations of biological and ecological processes, and is computationally efficient, allowing extensive parameter-space analyses even when implemented globally. As such, it enables the exploration of the linkages between ocean biogeochemistry, climate, and upper trophic levels at the global scale, as well as a representation of fish biomass for idealized studies of fisheries.

The GRASP project - a multidisciplinary study of hydrology and biogeochemistry in a periglacial catchment area

NASA Astrophysics Data System (ADS)

Johansson, Emma; Lindborg, Tobias

2017-04-01

The Arctic region is sensitive to global warming, and permafrost thaw and release of old carbon are examples of processes that may have a positive feedback effect to the global climate system. Quantification and assumptions on future change are often based on model predictions. Such models require cross-disciplinary data of high quality that often is lacking. Biogeochemical processes in the landscape are highly influenced by the hydrology, which in turn is intimately related to permafrost processes. Thus, a multidisciplinary approach is needed when collecting data and setting up field experiments aiming at increase the understanding of these processes. Here we summarize and present data collected in the GRASP, Greenland Analogue Surface Project. GRASP is a catchment-scale field study of the periglacial area in the Kangerlussuaq region, West Greenland, focusing on hydrological and biogeochemical processes in the landscape. The site investigations were initiated in 2010 and have since then resulted in three separate data sets published in ESSD (Earth system and Science Data) each one focusing on i) meteorological data and hydrology, ii) biogeochemistry and iii) geometries of sediments and the active layer. The three data-sets, which are freely available via the PANGAEA data base, enable conceptual and coupled numerical modeling of hydrological and biogeochemical processes. An important strength with the GRASP data is that all data is collected within the same, relatively small, catchment area. This implies that measurements are more easily linked to the right source area or process. Despite the small catchment area it includes the major units of the periglacial hydrological system; a lake, a talik, a supra- and subpermafrost aquifer and, consequently, biogeochemical processes in each of these units may be studied. The new data from GRASP is both used with the aim to increase the knowledge of present day periglacial hydrology and biogeochemistry but also in order to predict consequences within these subjects of future climate change.

Evaluating the effect of oceanic striations on biogeochemistry in the eastern South Pacific

NASA Astrophysics Data System (ADS)

Auger, P. A.; Belmadani, A.; Donoso, D.; Hormazabal, S.

2017-12-01

In recent years, quasi-zonal mesoscale jet-like features or striations have been ubiquitously detected in the time-mean circulation of the world ocean using satellite altimetry and in situ data. Most likely the result of some organization of the mesoscale eddy field such as preferred eddy tracks, these striations may be able to advect and mix physical properties. Yet, their impact on biogeochemistry has not been assessed yet. Off central Chile, the interaction between striations and sharp background gradients of biogeochemical properties may spatially structure biogeochemistry, with potential implications for marine ecosystems. For instance, striations may affect the mean horizontal distribution of surface phytoplankton biomass in the coastal transition zone (CTZ), or the structure and variability of the oxygen-minimum zone (OMZ). Here, we evaluate the expression of striations in satellite records of ocean color and in a set of numerically simulated biogeochemical tracers off central Chile (chlorophyll, carbon, primary production, oxygen, nutrients), averaged over the surface productive layer, the OMZ at intermediate depths or the water column. A multi-decadal hindcast simulation of the physical-biogeochemical dynamics was run over the period 1984-2013 using the ROMS-PISCES (for Regional Oceanic Modeling System - Pelagic Interactions Scheme for Carbon and Ecosystem Studies) platform at an eddy-resolving resolution. Satellite data and model outputs are spatially high-pass filtered to remove the large-scale signal and evaluate the match between striations and biogeochemical tracer anomalies in the model and observations. The effect of striations on the mean shape of the zonal gradient of phytoplankton biomass in the CTZ between eutrophic coastal waters and oligotrophic offshore waters is then deduced. The fraction of tracer anomalies due to striations is quantified, and the structuring roles of stationary and transient striations are respectively explored by matching striations and biogeochemical tracers on moving frames of variable widths from 6 months to several years.

The ecological module of BOATS-1.0: a bioenergetically constrained model of marine upper trophic levels suitable for studies of fisheries and ocean biogeochemistry

NASA Astrophysics Data System (ADS)

Carozza, David Anthony; Bianchi, Daniele; Galbraith, Eric Douglas

2016-04-01

Environmental change and the exploitation of marine resources have had profound impacts on marine communities, with potential implications for ocean biogeochemistry and food security. In order to study such global-scale problems, it is helpful to have computationally efficient numerical models that predict the first-order features of fish biomass production as a function of the environment, based on empirical and mechanistic understandings of marine ecosystems. Here we describe the ecological module of the BiOeconomic mArine Trophic Size-spectrum (BOATS) model, which takes an Earth-system approach to modelling fish biomass at the global scale. The ecological model is designed to be used on an Earth-system model grid, and determines size spectra of fish biomass by explicitly resolving life history as a function of local temperature and net primary production. Biomass production is limited by the availability of photosynthetic energy to upper trophic levels, following empirical trophic efficiency scalings, and by well-established empirical temperature-dependent growth rates. Natural mortality is calculated using an empirical size-based relationship, while reproduction and recruitment depend on both the food availability to larvae from net primary production and the production of eggs by mature adult fish. We describe predicted biomass spectra and compare them to observations, and conduct a sensitivity study to determine how they change as a function of net primary production and temperature. The model relies on a limited number of parameters compared to similar modelling efforts, while retaining reasonably realistic representations of biological and ecological processes, and is computationally efficient, allowing extensive parameter-space analyses even when implemented globally. As such, it enables the exploration of the linkages between ocean biogeochemistry, climate, and upper trophic levels at the global scale, as well as a representation of fish biomass for idealized studies of fisheries.

Toward a multivariate reanalysis of the North Atlantic ocean biogeochemistry during 1998-2006 based on the assimilation of SeaWiFS chlorophyll data

NASA Astrophysics Data System (ADS)

Fontana, C.; Brasseur, P.; Brankart, J.-M.

2012-04-01

Today, the routine assimilation of satellite data into operational models of the ocean circulation is mature enough to enable the production of global reanalyses describing the ocean circulation variability during the past decades. The expansion of the "reanalysis" concept from ocean physics to biogeochemistry is a timely challenge that motivates the present study. The objective of this paper is to investigate the potential benefits of assimilating satellite-estimated chlorophyll data into a basin-scale three-dimensional coupled physical-biogeochemical model of the North-Atlantic. The aim is on one hand to improve forecasts of ocean biogeochemical properties and on the other hand to define a methodology for producing data-driven climatologies based on coupled physical-biogeochemical modelling. A simplified variant of the Kalman filter is used to assimilate ocean color data during a 9 year-long period. In this frame, two experiences are carried out, with and without anamorphic transformations of the state vector variables. Data assimilation efficiency is assessed with respect to the assimilated data set, the nitrate World Ocean Atlas database and a derived climatology. Along the simulation period, the non-linear assimilation scheme clearly improves the surface chlorophyll concentrations analysis and forecast, especially in the North Atlantic bloom region. Nitrate concentration forecasts are also improved thanks to the assimilation of ocean color data while this improvement is limited to the upper layer of the water column, in agreement with recent related litterature. This feature is explained by the weak correlation taken into account by the assimilation between surface phytoplankton and nitrate concentration deeper than 50 m. The assessement of the non-linear assimilation experiments indicates that the proposed methodology provides the skeleton of an assimilative system suitable for reanalysing the ocean biogeochemistry based on ocean color data.

Toward a multivariate reanalysis of the North Atlantic Ocean biogeochemistry during 1998-2006 based on the assimilation of SeaWiFS chlorophyll data

NASA Astrophysics Data System (ADS)

Fontana, C.; Brasseur, P.; Brankart, J.-M.

2013-01-01

Today, the routine assimilation of satellite data into operational models of ocean circulation is mature enough to enable the production of global reanalyses describing the ocean circulation variability during the past decades. The expansion of the "reanalysis" concept from ocean physics to biogeochemistry is a timely challenge that motivates the present study. The objective of this paper is to investigate the potential benefits of assimilating satellite-estimated chlorophyll data into a basin-scale three-dimensional coupled physical-biogeochemical model of the North Atlantic. The aim is on the one hand to improve forecasts of ocean biogeochemical properties and on the other hand to define a methodology for producing data-driven climatologies based on coupled physical-biogeochemical modeling. A simplified variant of the Kalman filter is used to assimilate ocean color data during a 9-year period. In this frame, two experiments are carried out, with and without anamorphic transformations of the state vector variables. Data assimilation efficiency is assessed with respect to the assimilated data set, nitrate of the World Ocean Atlas database and a derived climatology. Along the simulation period, the non-linear assimilation scheme clearly improves the surface analysis and forecast chlorophyll concentrations, especially in the North Atlantic bloom region. Nitrate concentration forecasts are also improved thanks to the assimilation of ocean color data while this improvement is limited to the upper layer of the water column, in agreement with recent related literature. This feature is explained by the weak correlation taken into account by the assimilation between surface phytoplankton and nitrate concentrations deeper than 50 meters. The assessment of the non-linear assimilation experiments indicates that the proposed methodology provides the skeleton of an assimilative system suitable for reanalyzing the ocean biogeochemistry based on ocean color data.

Using a spatially-distributed hydrologic biogeochemistry model with a nitrogen transport module to study the spatial variation of carbon processes in a Critical Zone Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Yuning; Eissenstat, David M.; He, Yuting

Terrestrial carbon processes are affected by soil moisture, soil temperature, nitrogen availability and solar radiation, among other factors. Most of the current ecosystem biogeochemistry models represent one point in space, and have limited characterization of hydrologic processes. Therefore these models can neither resolve the topographically driven spatial variability of water, energy, and nutrient, nor their effects on carbon processes. A spatially-distributed land surface hydrologic biogeochemistry model, Flux-PIHM-BGC, is developed by coupling the Biome-BGC model with a physically-based land surface hydrologic model, Flux-PIHM. In the coupled system, each Flux-PIHM model grid couples a 1-D Biome-BGC model. In addition, a topographic solarmore » radiation module and an advection-driven nitrogen transport module are added to represent the impact of topography on nutrient transport and solar energy distribution. Because Flux-PIHM is able to simulate lateral groundwater flow and represent the land surface heterogeneities caused by topography, Flux-PIHM-BGC is capable of simulating the complex interaction among water, energy, nutrient, and carbon in time and space. The Flux-PIHM-BGC model is tested at the Susquehanna/Shale Hills Critical Zone Observatory. Model results show that distributions of carbon and nitrogen stocks and fluxes are strongly affected by topography and landscape position, and tree growth is nitrogen limited. The predicted aboveground and soil carbon distributions generally agree with the macro patterns observed. Although the model underestimates the spatial variation, the predicted watershed average values are close to the observations. Lastly, the coupled Flux-PIHM-BGC model provides an important tool to study spatial variations in terrestrial carbon and nitrogen processes and their interactions with environmental factors, and to predict the spatial structure of the responses of ecosystems to climate change.« less

Small-scale variability in peatland pore-water biogeochemistry, Hudson Bay Lowland, Canada.

PubMed

Ulanowski, T A; Branfireun, B A

2013-06-01

The Hudson Bay Lowland (HBL) of northern Ontario, Manitoba and Quebec, Canada is the second largest contiguous peatland complex in the world, currently containing more than half of Canada's soil carbon. Recent concerns about the ecohydrological impacts to these large northern peatlands resulting from climate change and resource extraction have catalyzed a resurgence in scientific research into this ecologically important region. However, the sheer size, heterogeneity and elaborate landscape arrangements of this ecosystem raise important questions concerning representative sampling of environmental media for chemical or physical characterization. To begin to quantify such variability, this study assessed the small-scale spatial (1m) and short temporal (21 day) variability of surface pore-water biogeochemistry (pH, dissolved organic carbon, and major ions) in a Sphagnum spp.-dominated, ombrotrophic raised bog, and a Carex spp.-dominated intermediate fen in the HBL. In general, pore-water pH and concentrations of dissolved solutes were similar to previously reported literature values from this region. However, systematic sampling revealed consistent statistically significant differences in pore-water chemistries between the bog and fen peatland types, and large within-site spatiotemporal variability. We found that microtopography in the bog was associated with consistent differences in most biogeochemical variables. Temporal changes in dissolved solute chemistry, particularly base cations (Na(+), Ca(2+) and Mg(2+)), were statistically significant in the intermediate fen, likely a result of a dynamic connection between surficial waters and mineral-rich deep groundwater. In both the bog and fen, concentrations of SO4(2-) showed considerable spatial variability, and a significant decrease in concentrations over the study period. The observed variability in peatland pore-water biogeochemistry over such small spatial and temporal scales suggests that under-sampling in northern peatland environments could lead to erroneous conclusions concerning the abundance and distribution of natural elements and pollutants alike. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparing the influence of wildfire and prescribed burns on watershed nitrogen biogeochemistry using 15N natural abundance in terrestrial and aquatic ecosystem components.

PubMed

Stephan, Kirsten; Kavanagh, Kathleen L; Koyama, Akihiro

2015-01-01

We evaluated differences in the effects of three low-severity spring prescribed burns and four wildfires on nitrogen (N) biogeochemistry in Rocky Mountain headwater watersheds. We compared paired (burned/unburned) watersheds of four wildfires and three spring prescribed burns for three growing seasons post-fire. To better understand fire effects on the entire watershed ecosystem, we measured N concentrations and δ15N in both the terrestrial and aquatic ecosystems components, i.e., soil, understory plants in upland and riparian areas, streamwater, and in-stream moss. In addition, we measured nitrate reductase activity in foliage of Spiraea betulifolia, a dominant understory species. We found increases of δ15N and N concentrations in both terrestrial and aquatic ecosystem N pools after wildfire, but responses were limited to terrestrial N pools after prescribed burns indicating that N transfer from terrestrial to aquatic ecosystem components did not occur in low-severity prescribed burns. Foliar δ15N differed between wildfire and prescribed burn sites; the δ15N of foliage of upland plants was enriched by 2.9 ‰ (difference between burned and unburned watersheds) in the first two years after wildfire, but only 1.3 ‰ after prescribed burns. In-stream moss δ15N in wildfire-burned watersheds was enriched by 1.3 ‰, but there was no response by moss in prescription-burned watersheds, mirroring patterns of streamwater nitrate concentrations. S. betulifolia showed significantly higher nitrate reductase activity two years after wildfires relative to corresponding unburned watersheds, but no such difference was found after prescribed burns. These responses are consistent with less altered N biogeochemistry after prescribed burns relative to wildfire. We concluded that δ15N values in terrestrial and aquatic plants and streamwater nitrate concentrations after fire can be useful indicators of the magnitude and duration of fire effects and the fate of post-fire available N.

Comparing the Influence of Wildfire and Prescribed Burns on Watershed Nitrogen Biogeochemistry Using 15N Natural Abundance in Terrestrial and Aquatic Ecosystem Components

PubMed Central

Stephan, Kirsten; Kavanagh, Kathleen L.; Koyama, Akihiro

2015-01-01

We evaluated differences in the effects of three low-severity spring prescribed burns and four wildfires on nitrogen (N) biogeochemistry in Rocky Mountain headwater watersheds. We compared paired (burned/unburned) watersheds of four wildfires and three spring prescribed burns for three growing seasons post-fire. To better understand fire effects on the entire watershed ecosystem, we measured N concentrations and δ15N in both the terrestrial and aquatic ecosystems components, i.e., soil, understory plants in upland and riparian areas, streamwater, and in-stream moss. In addition, we measured nitrate reductase activity in foliage of Spiraea betulifolia, a dominant understory species. We found increases of δ15N and N concentrations in both terrestrial and aquatic ecosystem N pools after wildfire, but responses were limited to terrestrial N pools after prescribed burns indicating that N transfer from terrestrial to aquatic ecosystem components did not occur in low-severity prescribed burns. Foliar δ15N differed between wildfire and prescribed burn sites; the δ15N of foliage of upland plants was enriched by 2.9 ‰ (difference between burned and unburned watersheds) in the first two years after wildfire, but only 1.3 ‰ after prescribed burns. In-stream moss δ15N in wildfire-burned watersheds was enriched by 1.3 ‰, but there was no response by moss in prescription-burned watersheds, mirroring patterns of streamwater nitrate concentrations. S. betulifolia showed significantly higher nitrate reductase activity two years after wildfires relative to corresponding unburned watersheds, but no such difference was found after prescribed burns. These responses are consistent with less altered N biogeochemistry after prescribed burns relative to wildfire. We concluded that δ15N values in terrestrial and aquatic plants and streamwater nitrate concentrations after fire can be useful indicators of the magnitude and duration of fire effects and the fate of post-fire available N. PMID:25885257

The Shenandoah Watershed Study: 20 years of Catchment Hydrogeochemistry

NASA Astrophysics Data System (ADS)

Galloway, J.

2002-05-01

The Shenandoah Watershed Study (SWAS) is a cooperative program between the Department of Environmental Sciences at the University of Virginia and the National Park Service. The scientific objective of the SWAS program is to improve understanding of processes and factors that govern hydrobiogeochemical conditions in forested watersheds of the Shenandoah National Park (SNP), VA, and the central Appalachian Mountain region. The SWAS program was initiated in 1979, with the establishment of water quality monitoring on two streams. The current SWAS network involves 14 primary study watersheds, in which a combination of discharge gauging, quarterly and weekly water quality sampling, and episodic storm-flow sampling take place. In addition, a number of extensive water quality surveys, fish population surveys, soil surveys, vegetation surveys, and plot-scale manipulations have been conducted in the SWAS watersheds in support of basic research in watershed science. The SWAS program is presently coordinated with the Virginia Trout Stream Sensitivity Study (VTSSS), which extends the watershed-based research to an additional 51 native brook trout streams located on public lands throughout western Virginia. During the past two decades the SWAS program has developed a uniquely comprehensive watershed database for SNP resource managers, while making major contributions to scientific understanding of surface water acidification and the biogeochemistry of forested mountain watersheds. The SWAS program is characterized by long-term continuity of sampling, a wide range of temporal resolution, and the availability of data from multiple watersheds within the landscape. These attributes enable both detection of long-term trends in response to chronic anthropogenic influences (e.g., acidic deposition) and interpretation of transient natural disturbances (e.g., pest outbreaks, fire, etc.). The spatial redundancy of the network provides insight into the regional homogeneity of observed changes and understanding of landscape controls (especially geologic setting) on watershed processes. This poster will present an overview of the critical findings of this 20-year research program.

Modeling the biogeochemical impact of atmospheric phosphate deposition from desert dust and combustion sources to the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Richon, Camille; Dutay, Jean-Claude; Dulac, François; Wang, Rong; Balkanski, Yves

2018-04-01

Daily modeled fields of phosphate deposition to the Mediterranean from natural dust, anthropogenic combustion and wildfires were used to assess the effect of this external nutrient on marine biogeochemistry. The ocean model used is a high-resolution (1/12°) regional coupled dynamical-biogeochemical model of the Mediterranean Sea (NEMO-MED12/PISCES). The input fields of phosphorus are for 2005, which are the only available daily resolved deposition fields from the global atmospheric chemical transport model LMDz-INCA. Traditionally, dust has been suggested to be the main atmospheric source of phosphorus, but the LMDz-INCA model suggests that combustion is dominant over natural dust as an atmospheric source of phosphate (PO4, the bioavailable form of phosphorus in seawater) for the Mediterranean Sea. According to the atmospheric transport model, phosphate deposition from combustion (Pcomb) brings on average 40.5×10-6 mol PO4 m-2 yr-1 over the entire Mediterranean Sea for the year 2005 and is the primary source over the northern part (e.g., 101×10-6 mol PO4 m-2 yr-1 from combustion deposited in 2005 over the north Adriatic against 12.4×10-6 from dust). Lithogenic dust brings 17.2×10-6 mol PO4 m-2 yr-1 on average over the Mediterranean Sea in 2005 and is the primary source of atmospheric phosphate to the southern Mediterranean Basin in our simulations (e.g., 31.8×10-6 mol PO4 m-2 yr-1 from dust deposited in 2005 on average over the south Ionian basin against 12.4×10-6 from combustion). The evaluation of monthly averaged deposition flux variability of Pdust and Pcomb for the 1997-2012 period indicates that these conclusions may hold true for different years. We examine separately the two atmospheric phosphate sources and their respective flux variability and evaluate their impacts on marine surface biogeochemistry (phosphate concentration, chlorophyll a, primary production). The impacts of the different phosphate deposition sources on the biogeochemistry of the Mediterranean are found localized, seasonally varying and small, but yet statistically significant. Differences in the geographical deposition patterns between phosphate from dust and from combustion will cause contrasted and significant changes in the biogeochemistry of the basin. We contrast the effects of combustion in the northern basin (Pcomb deposition effects are found to be 10 times more important in the northern Adriatic, close to the main source region) to the effects of dust in the southern basin. These different phosphorus sources should therefore be accounted for in modeling studies.

Impacts of Deepwater Horizon Oil on Marsh Sediment Biogeochemistry in Barataria Bay, LA, USA

NASA Astrophysics Data System (ADS)

Mills, C. T.; Windham-Myers, L.; Waldrop, M. P.; Krabbenhoft, D. P.; Marvin-DiPasquale, M. C.; Orem, W. H.; Piazza, S.; Haw, M.; McFarland, J.; Varonka, M. S.

2012-12-01

Oil from the Deepwater Horizon spill came ashore on many salt marsh islands in Barataria Bay, LA in summer 2010, coating plants and settling on the sediment surface. In coordination with a plant community study of affected marshes, we investigated impacts of oiling on marsh sediment microbial biogeochemistry. Sediment samples (upmost 2 cm) were collected along transects perpendicular and parallel to the shore at three oiled and three non-oiled sites in both July and Oct. 2011. Samples from both collections were analyzed for sediment characteristics, total and methylmercury, and microbial membrane phospholipid fatty acids (PLFAs) which are a proxy for viable microbial cell numbers. Sediment DNA collected in Oct. 2011 was analyzed for bacterial, fungal, and archaeal community composition and abundance as well as various enzyme activities. Select Oct. 2011 samples were assayed to determine the rates of terminal electron accepting processes (oxygen demand, denitrification, iron reduction, sulfate reduction, methanogenesis). All sites had similar sediment characteristics. Impacts on sediment biogeochemistry were greatest at marsh edges, and reduced microbial abundance appeared to be more important than changes in microbial community structure. In July 2011, the mean PLFA concentration in oiled marsh edge sediments (0.15±0.03 μmol g-1; 95% CI; n=9) was substantially lower than for non-oiled sites (0.33±0.08 μmol g-1; n=9). Mean PLFA concentrations for interior marsh samples were more similar for oiled (0.30±0.08 μmol g-1; n=8) and non-oiled (0.37±0.04 μmol g-1; n=9) sites. This PLFA pattern was also observed in Oct. 2011 samples, and other measures of microbial abundance and activity showed similar trends. Cellulase, phosphatase, and chitinase mean activities were nearly twice as great in non-oiled versus oiled edge sites. Lower microbial activity in oiled sites was also inferred by somewhat lower denitrification and sulfate reduction potentials. Conversely, both methanogenesis rates and concentrations of methanogen DNA were somewhat greater in oiled edge samples, suggesting an effect of oiling on terminal electron accepting processes. The mean methylmercury concentration was lower in oiled versus non-oiled edge sites, likely as a result of decreased sulfate-reducer activity. The reduced microbial activity in near-edge sediments of the oiled marsh is likely an indirect effect of reduced plant productivity which supports rhizosphere communities. Both mean above- and below-ground live biomass at oiled edge sites were less than half that at non-oiled edge sites. Some marsh edge samples from the oiled site contained relatively large amounts of oil and we are currently quantifying oil-derived hydrocarbons to understand impacts of the oil itself on sediment biogeochemistry.

Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model.

PubMed

Gebauer, S; Grenfell, J L; Stock, J W; Lehmann, R; Godolt, M; von Paris, P; Rauer, H

2017-01-01

Understanding the evolution of Earth and potentially habitable Earth-like worlds is essential to fathom our origin in the Universe. The search for Earth-like planets in the habitable zone and investigation of their atmospheres with climate and photochemical models is a central focus in exoplanetary science. Taking the evolution of Earth as a reference for Earth-like planets, a central scientific goal is to understand what the interactions were between atmosphere, geology, and biology on early Earth. The Great Oxidation Event in Earth's history was certainly caused by their interplay, but the origin and controlling processes of this occurrence are not well understood, the study of which will require interdisciplinary, coupled models. In this work, we present results from our newly developed Coupled Atmosphere Biogeochemistry model in which atmospheric O 2 concentrations are fixed to values inferred by geological evidence. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles that governed O 2 in early Earth's atmosphere near the Great Oxidation Event. Complicated oxidation pathways play a key role in destroying O 2 , whereas in the upper atmosphere, most O 2 is formed abiotically via CO 2 photolysis. The O 2 bistability found by Goldblatt et al. ( 2006 ) is not observed in our calculations likely due to our detailed CH 4 oxidation scheme. We calculate increased CH 4 with increasing O 2 during the Great Oxidation Event. For a given atmospheric surface flux, different atmospheric states are possible; however, the net primary productivity of the biosphere that produces O 2 is unique. Mixing, CH 4 fluxes, ocean solubility, and mantle/crust properties strongly affect net primary productivity and surface O 2 fluxes. Regarding exoplanets, different "states" of O 2 could exist for similar biomass output. Strong geological activity could lead to false negatives for life (since our analysis suggests that reducing gases remove O 2 that masks its biosphere over a wide range of conditions). Key Words: Early Earth-Proterozoic-Archean-Oxygen-Atmosphere-Biogeochemistry-Photochemistry-Biosignatures-Earth-like planets. Astrobiology 16, 27-54.

Influences of community composition on biogeochemistry of loblolly pine (Pinus taeda) systems

Treesearch

B.G. Lockaby; J.H. Miller; R.G. Clawson

1995-01-01

Litterfall and decomposition processes were compared among four forest plantations that were dominated by loblolly pine (Pinus taeda L) but that differed.in terms of presence or absence of deciduous and herbaceous components. Based on aboveground litterfall, the pine-only community was the most productive but had the slowest turnover of organic...

"Advances in Linked Air Quality, Farm Management and Biogeochemistry Models to Address Bidrectional Ammonia Flux in CMAQ"

EPA Science Inventory

Recent increases in anthropogenic inputs of nitrogen to air, land and water media pose a growing threat to human health and ecosystems. Modeling of air-surface N flux is one area in need of improvement. Implementation of a linked air quality and cropland management system is de...

Ectomycorrhizal mats alter forest soil biogeochemistry

Treesearch

Laurel A. Kluber; Kathryn M. Tinnesand; Bruce A. Caldwell; Susie M. Dunham; Rockie R. Yarwood; Peter J. Bottomley; David D. Myrold

2010-01-01

Dense hyphal mats formed by ectomycorrhizal (EcM) fungi are prominent features in Douglas-fir forest ecosystems, and have been estimated to cover up to 40% of the soil surface in some forest stands. Two morphotypes of EcM mats have been previously described: rhizomorphic mats, which have thick hyphal rhizomorphs and are found primarily in the organic horizon, and...

Elevated CO2 induces substantial and persistent declines in forage digestibility and protein content irrespective of warming in mixed-grass prairie

USDA-ARS?s Scientific Manuscript database

Increasing atmospheric [CO2] and temperature are expected to affect the productivity, species composition, biogeochemistry, and therefore the quantity and quality of forage available to herbivores in rangeland ecosystems. Both elevated CO2 (eCO2) and warming affect plant tissue chemistry through mul...

Spatial patterns in oxygen and redox sensitive biogeochemistry in tropical forest soils

Treesearch

Daniel Liptzin; Whendee L. Silver

2015-01-01

Humid tropical forest soils are characterized by warm temperatures, abundant rainfall, and high rates of biological activity that vary considerably in both space and time. These conditions, together with finely textured soils typical of humid tropical forests lead to periodic low redox conditions, even in well-drained upland environments. The relationship between redox...

Atmosphere, ocean, and land: Critical gaps in Earth system models

NASA Technical Reports Server (NTRS)

Prinn, Ronald G.; Hartley, Dana

1992-01-01

We briefly review current knowledge and pinpoint some of the major areas of uncertainty for the following fundamental processes: (1) convection, condensation nuclei, and cloud formation; (2) oceanic circulation and its coupling to the atmosphere and cryosphere; (3) land surface hydrology and hydrology-vegetation coupling; (4) biogeochemistry of greenhouse gases; and (5) upper atmospheric chemistry and circulation.

Variation in chemistry of stream water and bulk deposition across the Hubbard Brook Valley, New Hampshire, USA

Treesearch

Gene E. Likens; Donald C. Buso; James W. Hornbeck

2002-01-01

Chemistry and volume of precipitation and stream water have been measured in south-facing watersheds of the Hubbard Brook Experimental Forest (HBEF), continuously for 37 years. These long-term data have provided important insights into the bio-geochemistry of these watershed ecosystems and the region (e.g. LIKENS & BORMANN 1995).

Geographic, environmental and biotic sources of variation in the nutrient relations of tropical montane forests

Treesearch

James W. Dalling; Katherine Heineman; Grizelle Gonzalez; Rebecca Ostertag

2016-01-01

Tropicalmontane forests (TMF) are associated with a widely observed suite of characteristics encompassing forest structure, plant traits and biogeochemistry.With respect to nutrient relations, montane forests are characterized by slow decomposition of organic matter, high investment in below-ground biomass and poor litter quality, relative to tropical lowland forests....

Merging perspectives in the catchment sciences: the US-Japan Joint Seminar on catchment hydrology and forest biogeochemistry

Treesearch

Kevin J. McGuire; Stephen D. Sebestyen; Nobuhito Ohte; Emily M. Elliott; Takashi Gomi; Mark B. Green; Brian L. McGlynn; Naoko Tokuchi

2014-01-01

Japan has strong research programmes in the catchment sciences that overlap with interests in the US catchment science community, particularly in experimental and field-based research. Historically, however, there has been limited interaction between these two hydrologic science communities because of differences in language, culture, and research approaches. These...

Advances in Linked Air Quality, Farm Management and Biogeochemistry Models to Address Bidirectional Ammonia Flux in CMAQ

EPA Science Inventory

Recent increases in anthropogenic inputs of nitrogen to air, land and water media pose a growing threat to human health and ecosystems. Modeling of air-surface N flux is one area in need of improvement. Implementation of a linked air quality and cropland management system is de...

A One Chip Hardened Solution for High Speed SpaceWire System Implementations. Session: Components

NASA Technical Reports Server (NTRS)

Marshall, Joseph R.; Berger, Richard W.; Rakow, Glenn P.

2007-01-01

An Application Specific Integrated Circuit (ASIC) that implements the SpaceWire protocol has been developed in a radiation hardened 0.25 micron CMOS technology. This effort began in March 2003 as a joint development between the NASA Goddard Space Flight Center (GSFC) and BAE Systems. The BAE Systems SpaceWire ASIC is comprised entirely of reusable core elements, many of which are already flight-proven. It incorporates a router with 4 SpaceWire ports and two local ports, dual PC1 bus interfaces, a microcontroller, 32KB of internal memory, and a memory controller for additional external memory use. The SpaceWire cores are also reused in other ASICs under development. The SpaceWire ASIC is planned for use on the Geostationary Operational Environmental Satellites (GOES)-R, the Lunar Reconnaissance Orbiter (LRO) and other missions. Engineering and flight parts have been delivered to programs and users. This paper reviews the SpaceWire protocol and those elements of it that have been built into the current and next SpaceWire reusable cores and features within the core that go beyond the current standard and can be enabled or disabled by the user. The adaptation of SpaceWire to BAE Systems' On Chip Bus (OCB) for compatibility with the other reusable cores will be reviewed and highlighted. Optional configurations within user systems and test boards will be shown. The physical implementation of the design will be described and test results from the hardware will be discussed. Application of this ASIC and other ASICs containing the SpaceWire cores and embedded microcontroller to Plug and Play and reconfigurable implementations will be described. Finally, the BAE Systems roadmap for SpaceWire developments will be updated, including some products already in design as well as longer term plans.

Tropical forest soil microbial communities couple iron and carbon biogeochemistry

Treesearch

Eric A. Dubinsky; Whendee L. Silver; Mary K. Firestone

2010-01-01

We report that iron-reducing bacteria are primary mediators of anaerobic carbon oxidation in upland tropical soils spanning a rainfall gradient (3500–5000 mm/yr) in northeast Puerto Rico. The abundant rainfall and high net primary productivity of these tropical forests provide optimal soil habitat for iron-reducing and iron-oxidizing bacteria. Spatially and temporally...

Linkage of mike she to wetland-dndc for carbon budgeting and anaerobic biogeochemistry simulation

Treesearch

Jianbo Cui; Changsheng Li; Ge Sun; Carl Trettin

2005-01-01

This study reports the linkage between MIKE SHE and Wetland-DNDC for carbon dynamics and greenhouse gases (GHGs) emissions simulation in forested wetland.Wet1and-DNDC was modified by parameterizing management measures, refining anaerobic biogeochemical processes, and was linked to the hydrological model - MIKE SHE. As a preliminary application, we simulated the effect...

Forest biogeochemistry in response to drought

Treesearch

William H. Schlesinger; Michael C. Dietze; Robert B. Jackson; Richard P. Phillips; Charles C. Rhoades; Lindsey E. Rustad; James M. Vose

2015-01-01

Trees alter their use and allocation of nutrients in response to drought, and changes in soil nutrient cycling and trace gas flux (N2O and CH4) are observed when experimental drought is imposed on forests. In extreme droughts, trees are increasingly susceptible to attack by pests and pathogens, which can lead to major changes in nutrient flux to the soil....

BIOGEOCHEMISTRY OF MERCURY IN VERMONT AND NEW HAMPSHIRE LAKES: AN ASSESSMENT OF MERCURY IN WATER, SEDIMENT, AND BIOTA OF VERMONT AND NEW HAMPSHIRE LAKES - COMPREHENSIVE FINAL PROJECT REPORT

EPA Science Inventory

This report summarizes findings of a three-year field study of mercury in freshwater lakes of Vermont and New Hampshire. The study was undertaken jointly by the Vermont Department of Environmental Conservation, New Hampshire Department of Environmental Services, and Syracuse Univ...

Experimental evidence of two mechanisms coupling leaf-level C assimilation to rhizosphere CO2 release

Treesearch

Zachary Kayler; Claudia Keitel; Kirstin Jansen; Arthur Gessler

2017-01-01

The time span needed for carbon fixed by plants to induce belowground responses of root and rhizosphere microbial metabolic processing is of high importance for quantifying the coupling between plant canopy physiology and soil biogeochemistry, but recent observations of a rapid link cannot be explained by new assimilate transport by phloem mass flow alone. We performed...

Isotopic evidence for determining the sources of dissolved organic sulfur in a forested catchment

Treesearch

Phil-Goo Kang; Myron J. Mitchell; Bernhard Mayer; John L. Campbell

2014-01-01

Understanding sulfur (S) biogeochemistry, especially in those watersheds subject to elevated levels of atmospheric S inputs, is needed for determining the factors that contribute to acidification, nutrient losses and the mobilization of toxic solutes (e.g., monomeric aluminum and methylmercury). S is found in a variety of both organic and inorganic forms undergoing a...

Biogeochemical Considerations Related To The Remediation Of I-129 Plumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaplan, D. I.; Yeager, C.; Denham, M. E.

2012-09-24

The objectives of this report were to: provide a current state of the science of radioiodine biogeochemistry relevant to its fate and transport at the Hanford Site; conduct a review of Hanford Site data dealing with groundwater {sup 129}I; and identify critical knowledge gaps necessary for successful selection, implementation, and technical defensibility in support of remediation decisions.

Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins

USGS Publications Warehouse

Levin, Lisa A.; Liu, Kon-Kee; Emeis, Kay-Christian; Breitburg, Denise L.; Cloern, James; Deutsch, Curtis; Giani, Michele; Goffart, Anne; Hofmann, Eileen E.; Lachkar, Zouhair; Limburg, Karin; Liu, Su-Mei; Montes, Enrique; Naqvi, Wajih; Ragueneau, Olivier; Rabouille, Christophe; Sarkar, Santosh Kumar; Swaney, Dennis P.; Wassman, Paul; Wishner, Karen F.

2014-01-01

The ocean’s continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO2-induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO2-induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services including primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins.

Seasonal Hydrologic Controls on Uranium and Iron Biogeochemistry in a Riparian Aquifer

NASA Astrophysics Data System (ADS)

Wilkins, M.; Williams, K. H.; Danczak, R. E.; Yabusaki, S.; Fang, Y.; Hobson, C.

2015-12-01

The maintenance of geochemically reducing conditions is generally optimal for the formation and preservation of reduced metals and mineral phases that can limit contaminant fate and transport. At a riparian aquifer near Rifle, CO, we tracked over six months the biogeochemical response within the aquifer to an annual pulse of dissolved oxygen (DO) that results from snowmelt-driven changes in Colorado River stage. In reduced portions of the aquifer (naturally reduced zones; NRZs) the re-oxidation of abundant iron sulfide minerals was the dominant oxygen-consuming process, and resulted in little DO intrusion into the deeper aquifer. In less reduced areas, DO intruded through the entire vertical profile of the aquifer. Across both regions, these perturbations resulted in changes to the microbial community structure, and aqueous metal pools. Two potentially different mechanisms of uranium mobilization were observed; (1) re-oxidation of reduced U(IV) phases in response to DO intrusion, and (2) mobilization of U(VI) from the vadose zone during water table rise. This high-resolution, long-term monitoring of aquifer biogeochemistry at the Rifle site has revealed dynamic microbial and geochemical responses to predictable, annual hydrologic perturbations, and offers an opportunity to further refine modeling approaches for such regions.

The biogeochemistry and occurrence of unusual plant species inhabiting acidic, metal-rich water, Red Mountain, Bonnifield district, Alaska Range: Chapter J in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

USGS Publications Warehouse

Gough, Larry P.; Eppinger, Robert G.; Briggs, Paul H.

2007-01-01

This report presents results on the occurrence and biogeochemistry of unusual plant species, and of their supporting sediment, in an undisturbed volcanogenic massive sulfide deposit in the Tintina Gold Province (see fig. 1 of Editors’ Preface and Overview). The extraordinary plant assemblage found growing in the acidic metal-rich waters that drain the area is composed predominantly of bryophytes (liverworts and mosses). Ferricrete-cemented silty alluvial sediments within seeps and streams are covered with the liverwort Gymnocolea inflata, whereas the mosses Polytrichum commune and P. juniperinum inhabit the area adjacent to the water and within the splash zone. Both the liverwort-encrusted sediment and Polytrichum thalli have high concentrations of major- and trace-metal cations (for example, Al, As, Cu, Fe, Hg, La, Mn, Pb, and Zn). Soils in the area do not reflect the geochemical signature of the mineral deposit, and we suspect that they are most influenced by the chemistry of airborne dust (aeolian material) derived from outside the area.

Watershed responses to Amazon soya bean cropland expansion and intensification

PubMed Central

Neill, Christopher; Coe, Michael T.; Riskin, Shelby H.; Krusche, Alex V.; Elsenbeer, Helmut; Macedo, Marcia N.; McHorney, Richard; Lefebvre, Paul; Davidson, Eric A.; Scheffler, Raphael; Figueira, Adelaine Michela e Silva; Porder, Stephen; Deegan, Linda A.

2013-01-01

The expansion and intensification of soya bean agriculture in southeastern Amazonia can alter watershed hydrology and biogeochemistry by changing the land cover, water balance and nutrient inputs. Several new insights on the responses of watershed hydrology and biogeochemistry to deforestation in Mato Grosso have emerged from recent intensive field campaigns in this region. Because of reduced evapotranspiration, total water export increases threefold to fourfold in soya bean watersheds compared with forest. However, the deep and highly permeable soils on the broad plateaus on which much of the soya bean cultivation has expanded buffer small soya bean watersheds against increased stormflows. Concentrations of nitrate and phosphate do not differ between forest or soya bean watersheds because fixation of phosphorus fertilizer by iron and aluminium oxides and anion exchange of nitrate in deep soils restrict nutrient movement. Despite resistance to biogeochemical change, streams in soya bean watersheds have higher temperatures caused by impoundments and reduction of bordering riparian forest. In larger rivers, increased water flow, current velocities and sediment flux following deforestation can reshape stream morphology, suggesting that cumulative impacts of deforestation in small watersheds will occur at larger scales. PMID:23610178

Potential environmental impact of tidal energy extraction in the Pentland Firth at large spatial scales: results of a biogeochemical model

NASA Astrophysics Data System (ADS)

van der Molen, J.; Ruardij, P.; Greenwood, N.

2015-12-01

A model study was carried out of the potential large-scale (> 100 km) effects of marine renewable tidal energy generation in the Pentland Firth, using the 3-D hydrodynamics-biogeochemistry model GETM-ERSEM-BFM. A realistic 800 MW scenario and an exaggerated academic 8 GW scenario were considered. The realistic 800 MW scenario suggested minor effects on the tides, and undetectable effects on the biogeochemistry. The academic 8 GW scenario suggested effects would be observed over hundreds of kilometres away with changes of up to 10 % in tidal and ecosystem variables, in particular in a broad area in the vicinity of The Wash. There, waters became less turbid, and primary production increased with associated increases in faunal ecosystem variables. Moreover, a one-off increase in carbon storage in the sea bed was detected. Although these first results suggest positive environmental effects, further investigation is recommended of: (i) the residual circulation in the vicinity of the Pentland Firth and effects on larval dispersal using a higher resolution model, (ii) ecosystem effects with (future) state-of-the-art models if energy extraction substantially beyond 1 GW is planned.

Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins

NASA Astrophysics Data System (ADS)

Levin, Lisa A.; Liu, Kon-Kee; Emeis, Kay-Christian; Breitburg, Denise L.; Cloern, James; Deutsch, Curtis; Giani, Michele; Goffart, Anne; Hofmann, Eileen E.; Lachkar, Zouhair; Limburg, Karin; Liu, Su-Mei; Montes, Enrique; Naqvi, Wajih; Ragueneau, Olivier; Rabouille, Christophe; Sarkar, Santosh Kumar; Swaney, Dennis P.; Wassman, Paul; Wishner, Karen F.

2015-01-01

The oceans' continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO2-induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins, (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO2-induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services. These include primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins.

Millions of Boreal Shield Lakes can be used to Probe Archaean Ocean Biogeochemistry

NASA Astrophysics Data System (ADS)

Schiff, S. L.; Tsuji, J. M.; Wu, L.; Venkiteswaran, J. J.; Molot, L. A.; Elgood, R. J.; Paterson, M. J.; Neufeld, J. D.

2017-04-01

Life originated in Archaean oceans, almost 4 billion years ago, in the absence of oxygen and the presence of high dissolved iron concentrations. Early Earth oxidation is marked globally by extensive banded iron formations but the contributing processes and timing remain controversial. Very few aquatic habitats have been discovered that match key physico-chemical parameters of the early Archaean Ocean. All previous whole ecosystem Archaean analogue studies have been confined to rare, low sulfur, and permanently stratified lakes. Here we provide first evidence that millions of Boreal Shield lakes with natural anoxia offer the opportunity to constrain biogeochemical and microbiological aspects of early Archaean life. Specifically, we combined novel isotopic signatures and nucleic acid sequence data to examine processes in the anoxic zone of stratified boreal lakes that are naturally low in sulfur and rich in ferrous iron, hallmark characteristics predicted for the Archaean Ocean. Anoxygenic photosynthesis was prominent in total water column biogeochemistry, marked by distinctive patterns in natural abundance isotopes of carbon, nitrogen, and iron. These processes are robust, returning reproducibly after water column re-oxygenation following lake turnover. Evidence of coupled iron oxidation, iron reduction, and methane oxidation affect current paradigms of both early Earth and modern aquatic ecosystems.

Relationship between peatland hydrology and biogeochemistry

NASA Astrophysics Data System (ADS)

Roulet, N. T.

2012-04-01

The 'boreal forest' landscape is composed of upland forests, peatlands, some of which are treed, lakes, streams, and in North America, beaver ponds. Each of these landscapes present quite different biogeochemical environments due to differences in both abiotic and biotic processes and conditions. A significant amount of the carbon (C) in the boreal landscape is stored in peatlands, in part, due to the effect of the water storage on C cycling. The near saturated conditions affect the plants that can grow in peatlands and over the shorter term moisture variability controls the rate of C input to the peat. In the peat water limits the supply of electron donors and this has a profound effect on the C biogeochemistry. Near peat surface the moisture storage can be quite dynamic and mostly oxic conditions prevail, but redox conditions change significantly within a few tenth of a meter below the surface where water residence times increase orders of magnitude. This limits the supply of electron donors and other substrates that control the rate of C mineralization. Understanding the links among the moisture dynamics, the chemical thermodynamics of temporally variable saturated environments, and the quality of C is critical to determining the sensitivity of the C stored in peatlands to environmental change.

Nitrogen Cycling and Bacterial Diversity in Hot and Cold Desert Stream Margins

NASA Astrophysics Data System (ADS)

Zeglin, L. H.; Vesbach, C. D.; Dahm, C. N.; Barrett, J. E.; Gooseff, M. N.

2006-12-01

Desert environments offer harsh conditions for life. By definition, water is an extremely limiting resource in any desert. Also, the range of temperatures with which desert life must cope is extreme. Finally, essential nutrients like nitrogen (N) are available in very low amounts relative to temperate environments. Thus, desert organisms are subject to severe stresses like desiccation, temperature stress and starvation. Here, we review the N biogeochemistry of two desert stream systems: the Onyx River, Wright Valley, Victoria Land, Antarctica and the Rio Salado, Sevilleta National Wildlife Refuge, New Mexico, USA. Annually, the Antarctic system receives <100 mm precipitation and is subject to mean temperature ranges of -30 to -15 C. The Rio Salado, in the northern Chihuahuan desert, receives an average of 250 mm precipitation per year and experiences average temperatures from 1.5 to 25 C. The most important sources and sinks of the major forms of N at these sites are contrasted and biogeochemical processes controlling these pools discussed. Nutrient gradients and bacterial diversity patterns in the parafluvial zone of these streams are used to illustrate relationships between biological diversity, environmental stress and N biogeochemistry in the hot and cold desert systems.

The Modulation of Biological Production by Oceanic Mesoscale Turbulence

NASA Astrophysics Data System (ADS)

Lévy, Marina

This chapter reviews the current state of knowledge on bio-physical interactions at mesoscale and at sub-mesoscale. It is focused on the mid-latitudes open ocean. From examples taken from my own studies or selected in the literature, I show how high-resolution process-oriented model studies have helped to improve our understanding. I follow a process oriented approach; I first discuss the role of mesoscale eddies in moderating the nutrient flux into the well-lit euphotic zone. Then I address the impact on biogeochemistry of transport occurring on a horizontal scale smaller than the scale of an eddy. I show that submesoscale processes modulate biogeochemical budgets in a number of ways, through intense upwelling of nutrients, subduction of phytoplankton, and horizontal stirring. Finally, I emphasize that mesoscale and submesoscale dynamics have a strong impact on productivity through their influence on the stratification of the surface of the ocean. These processes have in common that they concern the short-term, local effect of oceanic turbulence on biogeochemistry. Efforts are still needed before we can get a complete picture, which would also include the far-field long-term effect of the eddies.

Predictability and Quantification of Complex Groundwater Table Dynamics Driven by Irregular Surface Water Fluctuations

NASA Astrophysics Data System (ADS)

Xin, Pei; Wang, Shen S. J.; Shen, Chengji; Zhang, Zeyu; Lu, Chunhui; Li, Ling

2018-03-01

Shallow groundwater interacts strongly with surface water across a quarter of global land area, affecting significantly the terrestrial eco-hydrology and biogeochemistry. We examined groundwater behavior subjected to unimodal impulse and irregular surface water fluctuations, combining physical experiments, numerical simulations, and functional data analysis. Both the experiments and numerical simulations demonstrated a damped and delayed response of groundwater table to surface water fluctuations. To quantify this hysteretic shallow groundwater behavior, we developed a regression model with the Gamma distribution functions adopted to account for the dependence of groundwater behavior on antecedent surface water conditions. The regression model fits and predicts well the groundwater table oscillations resulting from propagation of irregular surface water fluctuations in both laboratory and large-scale aquifers. The coefficients of the Gamma distribution function vary spatially, reflecting the hysteresis effect associated with increased amplitude damping and delay as the fluctuation propagates. The regression model, in a relatively simple functional form, has demonstrated its capacity of reproducing high-order nonlinear effects that underpin the surface water and groundwater interactions. The finding has important implications for understanding and predicting shallow groundwater behavior and associated biogeochemical processes, and will contribute broadly to studies of groundwater-dependent ecology and biogeochemistry.

The influence of precipitation, vegetation and soil properties on the ecohydrology of sagebrush steppe rangelands on the INL site

USGS Publications Warehouse

Germino, Matthew J.

2013-01-01

The INL Site and other landscapes having sagebrush steppe vegetation are experiencing a simultaneous change in climate and floristics that result from increases in exotic species. Determining the separate and combined/interactive effects of climate and vegetation change is important for assessing future changes on the landscape and for hydrologic processes. This research uses the 72 experimental plots established and initially maintained for many years as the “Protective Cap Biobarrier Experiment” by Dr. Jay Anderson and the Stoller ESER program, and the experiment is also now referred to as the “INL Site Ecohydrology Study.” We are evaluating long-term impacts of different plant communities commonly found throughout Idaho subject to different precipitation regimes and to different soil depths. Treatments of amount and timing of precipitation (irrigation), soil depth, and either native/perennial or exotic grass vegetation allow researchers to investigate how vegetation, precipitation and soil interact to influence soil hydrology and ecosystem biogeochemistry. This information will be used to improve a variety of models, as well as provide data for these models.

Variation of organic matter quantity and quality in streams at Critical Zone Observatory watersheds

USGS Publications Warehouse

Miller, Matthew P.; Boyer, Elizabeth W.; McKnight, Diane M.; Brown, Michael G.; Gabor, Rachel S.; Hunsaker, Carolyn T.; Iavorivska , Lidiia; Inamdar, Shreeram; Kaplan, Louis A.; Johnson, Dale W.; Lin, Henry; McDowell, William H.; Perdrial, Julia N.

2016-01-01

The quantity and chemical composition of dissolved organic matter (DOM) in surface waters influence ecosystem processes and anthropogenic use of freshwater. However, despite the importance of understanding spatial and temporal patterns in DOM, measures of DOM quality are not routinely included as part of large-scale ecosystem monitoring programs and variations in analytical procedures can introduce artifacts. In this study, we used consistent sampling and analytical methods to meet the objective of defining variability in DOM quantity and quality and other measures of water quality in streamflow issuing from small forested watersheds located within five Critical Zone Observatory sites representing contrasting environmental conditions. Results show distinct separations among sites as a function of water quality constituents. Relationships among rates of atmospheric deposition, water quality conditions, and stream DOM quantity and quality are consistent with the notion that areas with relatively high rates of atmospheric nitrogen and sulfur deposition and high concentrations of divalent cations result in selective transport of DOM derived from microbial sources, including in-stream microbial phototrophs. We suggest that the critical zone as a whole strongly influences the origin, composition, and fate of DOM in streams. This study highlights the value of consistent DOM characterization methods included as part of long-term monitoring programs for improving our understanding of interactions among ecosystem processes as controls on DOM biogeochemistry.

When do business units benefit more from collective citizenship behavior of management teams? An upper echelons perspective.

PubMed

Liu, Wu; Gong, Yaping; Liu, Jun

2014-05-01

Drawing upon the notion of managerial discretion from upper echelons theory, we theorize which external contingencies moderate the relationship between collective organizational citizenship behavior (COCB) and unit performance. Focusing on business unit (BU) management teams, we hypothesize that COCB of BU management teams enhances BU performance and that this impact depends on environmental uncertainty and BU management-team decision latitude, 2 determinants of managerial discretion. In particular, the positive effect of COCB is stronger when environmental uncertainty or the BU management-team decision latitude is greater. Time-lagged data from 109 BUs of a telecommunications company support the hypotheses. Additional exploratory analysis shows that the positive moderating effect of environmental uncertainty is further amplified at higher levels of BU management-team decision latitude. Overall, this study extends the internally focused view in the micro OCB literature by introducing external contingencies for the COCB-unit-performance relationship. (c) 2014 APA, all rights reserved.

Bound magnetic polaron in a semimagnetic double quantum well

NASA Astrophysics Data System (ADS)

Kalpana, P.; Jayakumar, K.

2017-09-01

The effect of different combinations of the concentration of Mn2+ ion in the Quantum well Cd1-xinMnxin Te and the barrier Cd1-xoutMnxout Te on the Bound Magnetic Polaron (BMP) in a Diluted Magnetic Semiconductors (DMS) Double Quantum Well (DQW) has been investigated. The Schrodinger equation is solved variationally in the effective mass approximation through which the Spin Polaronic Shift (SPS) due to the formation of BMP has been estimated for various locations of the donor impurity in the DQW. The results show that the effect of the increase of Mn2+ ion composition with different combinations on SPS is predominant for On Centre Well (OCW) impurity when compared to all other impurity locations when there is no application of magnetic field (γ = 0), γ being a dimensionless parameter for the magnetic field, and the same is predominant for On Centre Barrier (OCB) impurity with the application of external magnetic field (γ = 0.15).

Mediterranean monitoring and forecasting operational system for Copernicus Marine Service

NASA Astrophysics Data System (ADS)

Coppini, Giovanni; Drudi, Massimiliano; Korres, Gerasimos; Fratianni, Claudia; Salon, Stefano; Cossarini, Gianpiero; Clementi, Emanuela; Zacharioudaki, Anna; Grandi, Alessandro; Delrosso, Damiano; Pistoia, Jenny; Solidoro, Cosimo; Pinardi, Nadia; Lecci, Rita; Agostini, Paola; Cretì, Sergio; Turrisi, Giuseppe; Palermo, Francesco; Konstantinidou, Anna; Storto, Andrea; Simoncelli, Simona; Di Pietro, Pier Luigi; Masina, Simona; Ciliberti, Stefania Angela; Ravdas, Michalis; Mancini, Marco; Aloisio, Giovanni; Fiore, Sandro; Buonocore, Mauro

2016-04-01

The MEDiterranean Monitoring and Forecasting Center (Med-MFC) is part of the Copernicus Marine Environment Monitoring Service (CMEMS, http://marine.copernicus.eu/), provided on an operational mode by Mercator Ocean in agreement with the European Commission. Specifically, Med MFC system provides regular and systematic information about the physical state of the ocean and marine ecosystems for the Mediterranean Sea. The Med-MFC service started in May 2015 from the pre-operational system developed during the MyOcean projects, consolidating the understanding of regional Mediterranean Sea dynamics, from currents to biogeochemistry to waves, interfacing with local data collection networks and guaranteeing an efficient link with other Centers in Copernicus network. The Med-MFC products include analyses, 10 days forecasts and reanalysis, describing currents, temperature, salinity, sea level and pelagic biogeochemistry. Waves products will be available in MED-MFC version in 2017. The consortium, composed of INGV (Italy), HCMR (Greece) and OGS (Italy) and coordinated by the Euro-Mediterranean Centre on Climate Change (CMCC, Italy), performs advanced R&D activities and manages the service delivery. The Med-MFC infrastructure consists of 3 Production Units (PU), for Physics, Biogechemistry and Waves, a unique Dissemination Unit (DU) and Archiving Unit (AU) and Backup Units (BU) for all principal components, guaranteeing a resilient configuration of the service and providing and efficient and robust solution for the maintenance of the service and delivery. The Med-MFC includes also an evolution plan, both in terms of research and operational activities, oriented to increase the spatial resolution of products, to start wave products dissemination, to increase temporal extent of the reanalysis products and improving ocean physical modeling for delivering new products. The scientific activities carried out in 2015 concerned some improvements in the physical, biogeochemical and wave components of the system. Regarding the currents, new grid-point EOFs have been implemented in the Med-MFC assimilation system; the climatological CMAP precipitation was replaced by the ECMWF daily precipitation; reanalysis time-series have been increased by one year. Regarding the biogeochemistry, the main scientific achievement is related to the implementation of the carbon system in the Med-MFC biogeochemistry model system already available. The new model is able to reproduce the principal spatial patterns of the carbonate system variables in the Mediterranean Sea. Further, a key result consists of the calibration of the new variables (DIC and alkalinity), which serves to the estimation of the accuracy of the new products to be released in the next version of the system (i.e. pH and pCO2 at surface). Regarding the waves, the system has been validated against in-situ and satellite observations. For example, a very good agreement between model output and in-situ observations has been obtained at offshore and/or well-exposed wave buoys in the Mediterranean Sea.

Comment on “Dissolved organic sulfur in the ocean: Biogeochemistry of a petagram inventory”

NASA Astrophysics Data System (ADS)

Dittmar, Thorsten; Stubbins, Aron; Ito, Takamitsu; Jones, Daniel C.

2017-05-01

Ksionzek et al. (Reports, 28 October 2016, p. 456) provide important data describing the distribution of dissolved organic sulfur (DOS) in the Atlantic Ocean. Here, we show that mixing between water masses is sufficient to explain the observed distribution of DOS, concluding that the turnover time of refractory DOS that Ksionzek et al. present cannot be deduced from their data.

Separate effects of flooding and anaerobiosis on soil greenhouse gas emissions and redox sensitive biogeochemistry

Treesearch

Gavin McNicol; Whendee L. Silver

2014-01-01

Soils are large sources of atmospheric greenhouse gases, and both the magnitude and composition of soil gas emissions are strongly controlled by redox conditions. Though the effect of redox dynamics on greenhouse gas emissions has been well studied in flooded soils, less research has focused on redox dynamics without total soil inundation. For the latter, all that is...

Evaluating sulfur dynamics during storm events for three watersheds in the northeastern USA: a combined hydrological, chemical and isotopic approach

Treesearch

Myron J. Mitchell; Scott W. Bailey; James B. Shanley; Bernhard. Mayer

2008-01-01

Concerns related to climate change have resulted in an increasing interest in the importance of hydrological events such as droughts in affecting biogeochemical responses of watersheds. The effects of an unusually dry summer in 2002 had a marked impact on the biogeochemistry of three watersheds in the north-eastern USA. Chemical, isotopic and hydrological responses...

New Bedford, Some Aspects of the Biogeochemistry of Polychlorinated Biphenyls in the Acushnet River Estuary, Massachusetts, U.S.A.

EPA Pesticide Factsheets

2012-04-22

... 1 nil! ywi I :! c ,FI <: 1. 1 i r 1. 1. yon: tr, 1 11 in I a i 1 in ci: oi , «, in !'n- ... he in , II, V , „ I in 'a , I' 1 ,D , I! 1, , lisli- , ; /inmlanl.!' ITI'SHI \\ i. I , ,il , [• |:i , :i •• Hiii.l, ...

BOREAS TGB-4 NSA-BVP Tower Flux and Meteorological Data

NASA Technical Reports Server (NTRS)

Roulet, Nigel T.; Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-4) team measured the exchange of heat, water, and CO2 between a boreal forest beaver pond and the atmosphere in the Northern Study Area (NSA) for the ice-free period of BOREAS. The data cover the period of 28-May to 18-Sep-1994. The data are available in tabular ASCII files.

Coupled hydrological and biogeochemical processes controlling variability of nitrogen species in streamflow during autumn in an upland forest

Treesearch

Stephen D. Sebestyen; James B. Shanley; Elizabeth W. Boyer; Carol Kendall; Daniel H. Doctor

2014-01-01

Autumn is a season of dynamic change in forest streams of the northeastern United States due to effects of leaf fall on both hydrology and biogeochemistry. Few studies have explored how interactions of biogeochemical transformations, various nitrogen sources, and catchment flow paths affect stream nitrogen variation during autumn. To provide more information on this...

Biogeochemistry of beetle-killed forests: Explaining a weak nitrate response

Treesearch

Charles C. Rhoades; James H. McCutchan; Leigh A. Cooper; David Clow; Thomas M. Detmer; Jennifer S. Briggs; John D. Stednick; Thomas T. Veblen; Rachel M. Ertz; Gene E. Likens; William M. Lewis

2013-01-01

A current pine beetle infestation has caused extensive mortality of lodgepole pine (Pinus contorta) in forests of Colorado and Wyoming; it is part of an unprecedented multispecies beetle outbreak extending from Mexico to Canada. In United States and European watersheds, where atmospheric deposition of inorganic N is moderate to low (<10 kg�ha�y), disturbance of...

Experimental Acidification Causes Soil Base-Cation Depletion at the Bear Brook Watershed in Maine

Treesearch

Ivan J. Fernandez; Lindsey E. Rustad; Stephen A. Norton; Jeffrey S. Kahl; Bernard J. Cosby

2003-01-01

There is concern that changes in atmospheric deposition, climate, or land use have altered the biogeochemistry of forests causing soil base-cation depletion, particularly Ca. The Bear Brook Watershed in Maine (BBWM) is a paired watershed experiment with one watershed subjected to elevated N and S deposition through bimonthly additions of (NH4)2SO4. Quantitative soil...

The Marine Biogeochemistry of Zinc Isotopes

DTIC Science & Technology

2007-06-01

hydrothermal fluids and minerals, cultured marine phytoplankton, natural plankton, and seawater. By measuring Zn isotopes in a diverse array of...variations were discovered in hydrothermal fluids and minerals, with hydrothermal fluids ranging in 6 66Zn from 0.02 %o to +0.93 %o, and chimney minerals...drives much of the Zn isotope fractionation in hydrothermal systems. In cultured diatoms, a relationship was discovered between Zn transport by

Effect of long term organic amendments and vegetation of vineyard soils on the microscale distribution and biogeochemistry of copper.

PubMed

Navel, Aline; Martins, Jean M F

2014-01-01

In this study we evaluated the effect of the long term organic management of a vineyard-soil on the biogeochemistry of copper at the micro-aggregate scale. The model vineyard-soil (Mâcon-France) experienced a long-term field-experiment that consisted in amendments and vegetations with various materials and plants. We studied specifically the effect of Straw (S) and Conifer Compost (CC) organic amendments and Clover (Cl) and Fescue (F) vegetation on the fate of copper (fungicide) in the surface layer of this loamy soil, through a comparison with the Non Amended soil (NA). After collection the five soils were immediately physically fractionated in order to obtain 5 granulometric size-fractions. All soils and size-fractions were quantitatively characterized in terms of granulometry, chemical content and copper distribution, speciation and bioavailability to bacteria and plants. The results showed strong increases of soil-constituents aggregation for all treatments (Cl>CC>S>F>NA), in relation with the increased cementation of soil-constituents by organic matter (OM). The distribution patterns of all major elements and organic carbon were found highly variable within the soil sub-fractions and also between the 5 treatments. Due to their specific inorganic and organic composition, soil sub-fractions can thus be considered as a specific microbial habitat. Added OM accumulated preferentially in the 20-2 μm and in the >250 μm of the 5 soils. The distribution patterns of copper as well as its speciation and bioavailability to bacteria in the soil sub-fractions were shown to be strongly different among the five soils, in relation with OM distribution. Our results also suggest that Cu-bioavailability to plants is controlled by soil-rhizosphere structure. Altogether our results permitted to show that long-term organic management of a vineyard soil induced stable modifications of soil physical and chemical properties at both macro and micro-scales. These modifications affected in turn the micro-scale biogeochemistry of copper, and especially its bioavailability to bacteria and plants. © 2013.

Two-way Coupling of a Process-Based Crop Growth Model (BioCro) and a Biogeochemistry Model (DayCent) and its Application to an Energy Crop Site in the mid-west USA

NASA Astrophysics Data System (ADS)

Jaiswal, D.; Long, S.; Parton, W. J.; Hartman, M.

2012-12-01

A coupled modeling system of crop growth model (BioCro) and biogeochemical model (DayCent) has been developed to assess the two-way interactions between plant growth and biogeochemistry. Crop growth in BioCro is simulated using a detailed mechanistic biochemical and biophysical multi-layer canopy model and partitioning of dry biomass into different plant organs according to phenological stages. Using hourly weather records, the model partitions light between dynamically changing sunlit and shaded portions of the canopy and computes carbon and water exchange with the atmosphere and through the canopy for each hour of the day, each day of the year. The model has been parameterized for the bioenergy crops sugarcane, Miscanthus and switchgrass, and validation has shown it to predict growth cycles and partitioning of biomass to a high degree of accuracy. As such it provides an ideal input for a soil biogeochemical model. DayCent is an established model for predicting long-term changes in soil C & N and soil-atmosphere exchanges of greenhouse gases. At present, DayCent uses a relatively simple productivity model. In this project BioCro has replaced this simple model to provide DayCent with a productivity and growth model equal in detail to its biogeochemistry. Dynamic coupling of these two models to produce CroCent allows for differential C: N ratios of litter fall (based on rates of senescence of different plant organs) and calibration of the model for realistic plant productivity in a mechanistic way. A process-based approach to modeling plant growth is needed for bioenergy crops because research on these crops (especially second generation feedstocks) has started only recently, and detailed agronomic information for growth, yield and management is too limited for effective empirical models. The coupled model provides means to test and improve the model against high resolution data, such as that obtained by eddy covariance and explore yield implications of different crop and soil management.

Uncertainty in Earth System Models: Benchmarks for Ocean Model Performance and Validation

NASA Astrophysics Data System (ADS)

Ogunro, O. O.; Elliott, S.; Collier, N.; Wingenter, O. W.; Deal, C.; Fu, W.; Hoffman, F. M.

2017-12-01

The mean ocean CO2 sink is a major component of the global carbon budget, with marine reservoirs holding about fifty times more carbon than the atmosphere. Phytoplankton play a significant role in the net carbon sink through photosynthesis and drawdown, such that about a quarter of anthropogenic CO2 emissions end up in the ocean. Biology greatly increases the efficiency of marine environments in CO2 uptake and ultimately reduces the impact of the persistent rise in atmospheric concentrations. However, a number of challenges remain in appropriate representation of marine biogeochemical processes in Earth System Models (ESM). These threaten to undermine the community effort to quantify seasonal to multidecadal variability in ocean uptake of atmospheric CO2. In a bid to improve analyses of marine contributions to climate-carbon cycle feedbacks, we have developed new analysis methods and biogeochemistry metrics as part of the International Ocean Model Benchmarking (IOMB) effort. Our intent is to meet the growing diagnostic and benchmarking needs of ocean biogeochemistry models. The resulting software package has been employed to validate DOE ocean biogeochemistry results by comparison with observational datasets. Several other international ocean models contributing results to the fifth phase of the Coupled Model Intercomparison Project (CMIP5) were analyzed simultaneously. Our comparisons suggest that the biogeochemical processes determining CO2 entry into the global ocean are not well represented in most ESMs. Polar regions continue to show notable biases in many critical biogeochemical and physical oceanographic variables. Some of these disparities could have first order impacts on the conversion of atmospheric CO2 to organic carbon. In addition, single forcing simulations show that the current ocean state can be partly explained by the uptake of anthropogenic emissions. Combined effects of two or more of these forcings on ocean biogeochemical cycles and ecosystems are challenging to predict since additive or antagonistic effects may occur. A benchmarking tool for accurate assessment and validation of marine biogeochemical outputs will be indispensable as the model community continues to improve ESM developments. It will provide a first order tool in understanding climate-carbon cycle feedbacks.

The effect of anthropogenic emissions corrections on the seasonal cycle of atmospheric CO2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, Forrest M; Erickson III, David J; Blasing, T J

A previous study (Erickson et al. 2008) approximated the monthly global emission estimates of anthropogenic CO{sub 2} by applying a 2-harmonic Fourier expansion with coefficients as a function of latitude to annual CO{sub 2} flux estimates derived from United States data (Blasing et al. 2005) that were extrapolated globally. These monthly anthropogenic CO{sub 2} flux estimates were used to model atmospheric concentrations using the NASA GEOS-4 data assimilation system. Local variability in the amplitude of the simulated CO{sub 2} seasonal cycle were found to be on the order of 2-6 ppmv. Here we used the same Fourier expansion to seasonallymore » adjust the global annual fossil fuel CO{sub 2} emissions from the SRES A2 scenario. For a total of four simulations, both the annual and seasonalized fluxes were advected in two configurations of the NCAR Community Atmosphere Model (CAM) used in the Carbon-Land Model Intercomparison Project (C-LAMP). One configuration used the NCAR Community Land Model (CLM) coupled with the CASA (carbon only) biogeochemistry model and the other used CLM coupled with the CN (coupled carbon and nitrogen cycles) biogeochemistry model. All four simulations were forced with observed sea surface temperatures and sea ice concentrations from the Hadley Centre and a prescribed transient atmospheric CO{sub 2} concentration for the radiation and land forcing over the 20th century. The model results exhibit differences in the seasonal cycle of CO{sub 2} between the seasonally corrected and uncorrected simulations. Moreover, because of differing energy and water feedbacks between the atmosphere model and the two land biogeochemistry models, features of the CO{sub 2} seasonal cycle were different between these two model configurations. This study reinforces previous findings that suggest that regional near-surface atmospheric CO{sub 2} concentrations depend strongly on the natural sources and sinks of CO{sub 2}, but also on the strength of local anthropogenic CO{sub 2} emissions and geographic position. This work further attests to the need for remotely sensed CO{sub 2} observations from space.« less

The Science of Middle Nature (Invited)

NASA Astrophysics Data System (ADS)

Pataki, D. E.; Pincetl, S.; Hinners, S.

2013-12-01

In the field of biogeochemistry, urbanization is often considered as an 'alteration' or 'disturbance' to the earth's surface and its natural processes. This view is an outcome of the view of nature inherent in earth system science and ecology, in which nature is defined as separate from humans and society. However, other disciplines are based in alternative views of nature in which humans are more integral components of the landscape. Urban planning, landscape architecture, agriculture, and horticulture, for example, more fully integrate the role of landscape design and management in the functioning of human-dominated ecosystems. We suggest that the field of urban biogeochemistry has been somewhat limited by the predominant, disturbance-based view of the role of nature in cities, and that more deeply evaluating and broadening the concept of nature inherent in studies of urban processes can enhance our understanding of the role of urbanization in the earth system. A particularly useful concept is the 'middle nature' proposed by Cosgrove (1993), which serves a purpose of 'actively transforming nature into culture.' It is this view of urban landscapes as middle nature, or transformation of urban space into human-dominated nature with a purpose, that is lacking from the current scientific discourse about the role of biogeochemistry in urban ecosystem services. A scientific evaluation of middle nature implies studying the performance of urban designs to meet intended cultural and environmental goals, including beauty, social equity, governance, and social capital as well as environmental quality. We describe our work in evaluating the transformed urban landscapes of Los Angeles and Salt Lake City from multiple perspectives that focus on urban livability, equity, and beauty as well as the physical impacts of plants and soils on the environment. The outcomes of this process do not necessary meet the traditional demands of biophysical ecology such as utilizing native species, maximizing carbon sequestration, or minimizing human disturbance. Rather, in our project the discourse is shifting away from the ecosystem services framework, and towards a shared vision for middle nature as the intersection between nature as we have traditionally valued it outside of the city, and its integral role in urban culture, design, function, and quality of life.

The Science of Middle Nature

NASA Astrophysics Data System (ADS)

Pataki, D. E.; Pincetl, S.

2012-12-01

In the field of biogeochemistry, urbanization is often considered as an "alteration" or "disturbance" to the earth's surface and its natural processes. This view is an outcome of the view of nature inherent in earth system science and ecology, in which nature is defined as separate from humans and society. However, other disciplines are based in alternative views of nature in which humans are more integral components of the landscape. Urban planning, landscape architecture, agriculture, and horticulture, for example, more fully integrate the role of landscape design and management in the functioning of human-dominated ecosystems. We suggest that the field of urban biogeochemistry has been somewhat limited by the predominant, disturbance-based view of the role of nature in cities, and that more deeply evaluating and broadening the concept of nature inherent in studies of urban processes can enhance our understanding of the role of urbanization in the earth system. A particularly useful concept is the "middle nature" proposed by Cosgrove (1993), which serves a purpose of "actively transforming nature into culture." It is this view of urban landscapes as middle nature, or transformation of urban space into human-dominated nature with a purpose, that is lacking from the current scientific discourse about the role of biogeochemistry in urban ecosystem services. A scientific evaluation of middle nature implies studying the performance of urban designs to meet intended cultural and environmental goals, including beauty, social equity, governance, and social capital as well as environmental quality. We describe our work in evaluating the transformed urban landscapes of Los Angeles from multiple perspectives that focus on urban livability, equity, and beauty as well as the physical impacts of plants and soils on the environment. The outcomes of this process do not necessary meet the traditional demands of biophysical ecology such as utilizing native species, maximizing carbon sequestration, or minimizing human disturbance. Rather, in our project the discourse is shifting away from the ecosystem services framework, and towards a shared vision for middle nature as the intersection between nature as we have traditionally valued it outside of the city, and its integral role in urban culture, design, function, and quality of life.

Regional impacts of iron-light colimitation in a global biogeochemical model

NASA Astrophysics Data System (ADS)

Galbraith, E. D.; Gnanadesikan, A.; Dunne, J. P.; Hiscock, M. R.

2010-03-01

Laboratory and field studies have revealed that iron has multiple roles in phytoplankton physiology, with particular importance for light-harvesting cellular machinery. However, although iron-limitation is explicitly included in numerous biogeochemical/ecosystem models, its implementation varies, and its effect on the efficiency of light harvesting is often ignored. Given the complexity of the ocean environment, it is difficult to predict the consequences of applying different iron limitation schemes. Here we explore the interaction of iron and nutrient cycles in an ocean general circulation model using a new, streamlined model of ocean biogeochemistry. Building on previously published parameterizations of photoadaptation and export production, the Biogeochemistry with Light Iron Nutrients and Gasses (BLING) model is constructed with only four explicit tracers but including macronutrient and micronutrient limitation, light limitation, and an implicit treatment of community structure. The structural simplicity of this computationally-inexpensive model allows us to clearly isolate the global effect that iron availability has on maximum light-saturated photosynthesis rates vs. the effect iron has on photosynthetic efficiency. We find that the effect on light-saturated photosynthesis rates is dominant, negating the importance of photosynthetic efficiency in most regions, especially the cold waters of the Southern Ocean. The primary exceptions to this occur in iron-rich regions of the Northern Hemisphere, where high light-saturated photosynthesis rates allow photosynthetic efficiency to play a more important role. In other words, the ability to efficiently harvest photons has little effect in regions where light-saturated growth rates are low. Additionally, we speculate that the phytoplankton cells dominating iron-limited regions tend to have relatively high photosynthetic efficiency, due to reduced packaging effects. If this speculation is correct, it would imply that natural communities of iron-stressed phytoplankton may tend to harvest photons more efficiently than would be inferred from iron-limitation experiments with other phytoplankton. We suggest that iron limitation of photosynthetic efficiency has a relatively small impact on global biogeochemistry, though it is expected to impact the seasonal cycle of plankton as well as the vertical structure of primary production.

Mercury cycling in agricultural and managed wetlands of California: experimental evidence of vegetation-driven changes in sediment biogeochemistry and methylmercury production

USGS Publications Warehouse

Windham-Myers, Lisamarie; Marvin-DiPasquale, Mark; Stricker, Craig A.; Agee, Jennifer L.; Kieu, Le H.; Kakouros, Evangelos

2014-01-01

The role of live vegetation in sediment methylmercury (MeHg) production and associated biogeochemistry was examined in three types of agricultural wetlands (domesticated or white rice, wild rice, and fallow fields) and adjacent managed natural wetlands (cattail- and bulrush or tule-dominated) in the Yolo Bypass region of California's Central Valley, USA. During the active growing season for each wetland, a vegetated:de-vegetated paired plot experiment demonstrated that the presence of live plants enhanced microbial rates of mercury methylation by 20 to 669% (median = 280%) compared to de-vegetated plots. Labile carbon exudation by roots appeared to be the primary mechanism by which microbial methylation was enhanced in the presence of vegetation. Pore-water acetate (pw[Ac]) decreased significantly with de-vegetation (63 to 99%) among all wetland types, and within cropped fields, pw[Ac] was correlated with both root density (r = 0.92) and microbial Hg(II) methylation (kmeth. r = 0.65). Sediment biogeochemical responses to de-vegetation were inconsistent between treatments for “reactive Hg” (Hg(II)R), as were reduced sulfur and sulfate reduction rates. Sediment MeHg concentrations in vegetated plots were double those of de-vegetated plots (median = 205%), due in part to enhanced microbial MeHg production in the rhizosphere, and in part to rhizoconcentration via transpiration-driven pore-water transport. Pore-water concentrations of chloride, a conservative tracer, were elevated (median = 22%) in vegetated plots, suggesting that the higher concentrations of other constituents around roots may also be a function of rhizoconcentration rather than microbial activity alone. Elevated pools of amorphous iron (Fe) in vegetated plots indicate that downward redistribution of oxic surface waters through transpiration acts as a stimulant to Fe(III)-reduction through oxidation of Fe(II)pools. These data suggest that vegetation significantly affected rhizosphere biogeochemistry through organic exudation and transpiration-driven concentration of pore-water constituents and oxidation of reduced compounds. While the relative role of vegetation varied among wetland types, macrophyte activity enhanced MeHg production.

The Black Sea Monitoring and Forecasting Center (BS-MFC) in the framework of the Copernicus Marine Service

NASA Astrophysics Data System (ADS)

Palazov, Atanas; Coppini, Giovanni; Ciliberti, Stefania Angela; Gregoire, Marilaure; Staneva, Joanna; Peneva, Elisaveta; Özsoy, Emin; Vandenbulcke, Luc; Storto, Andrea; Lemieux-Dudon, Benedicte; Lovato, Tomas; Masina, Simona; Pinardi, Nadia; Palermo, Francesco; Creti, Sergio; Macchia, Francesca; Lecci, Rita; Behrens, Arno; Marinova, Veselka; Slabakova, Violeta

2017-04-01

The BS-MFC entered the Copernicus Marine Environment Monitoring Service (CMEMS, http://marine.copernicus.eu/) in October 2016, providing regular and systematic information about the ocean state in the Black Sea in operational mode. An expert team constitutes the BS-MFC Consortium: the Institute of Oceanology, Bulgarian Academy of Sciences (IO-BAS, Bulgaria) coordinates the service and the management in collaboration with Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici (CMCC, Italy), Helmholtz-Zentrum Geesthacht - Institute of Coastal Research (HZG, Germany), the University of Liege (ULG, Belgium), the Sofia University "St. Kliment Ohridski (USOF, Bulgaria) and the Eurasia Earth Sciences Institute - Istanbul Technical University (ITU, Turkey). The system provides a complete data catalogue for the Black Sea ocean variables such as temperature, salinity, sea level, currents, biogeochemistry and waves through a technologically advanced and resilient service, which is fully interconnected with the other Centers in the Copernicus network. The high level BS-MFC architecture is based on 3 Production Units, for Physics, Biogeochemistry and Waves products respectively, a Dissemination/Archiving Unit for the delivery of the products and their archiving/accessibility, a Local Service Desk connected to the CMEMS Service Desk devoted to support all the operational activities, and backup units for all the main service components. Products consist of analysis/hindcast, 10-days forecast and reanalysis, describing the physical (currents, temperature, salinity, sea level, mixed layer depth and bottom temperature), the biogeochemical state and waves. To implement and improve the service, the BS-MFC has detailed an evolution plan, actually under implementation, devoted to establish, assess and improve the systems and their operational functionalities, providing some improvements from the scientific point of view concerning the modeling components (e.g., the fully aligned Physics, Biogeochemistry and Waves systems, the open boundary conditions at the Bosporus, the state-of-the-art core models and increased spatial resolution among the major actions) and high quality products, towards an optimal interface between the Mediterranean and the Black Seas. The contribution will present the main operational and research & development activities at the basis of the systems, given an overview on the future plans for improving the service for the delivery of new products.

Complexity of Tropical Pacific Ecosystem and Biogeochemistry: Diurnal to Decadal, Plankters to Penguins

NASA Astrophysics Data System (ADS)

Murtugudde, R. G.; Wang, X.; Valsala, V.; Karnauskas, K. B.

2016-12-01

Tropical Pacific spans nearly 50% of the global tropics allowing to have its own mind in terms of climate variability and physical-biogeochemical interactions. While the El Niño-Southern Oscillation (ENSO) and its flavors get much attention, it is fairly clear by now that any further improvements in ENSO prediction skills and reliability of global warming projections must begin to observe and represent bio-physical interactions in the climate and Earth System models. Coupled climate variability over the tropical Pacific has a global reach with its diurnal to decadal timescales being manifest in ecosystem and biogechemistry. Zonal and meridional contrasts in biogeochemistry across the tropical Pacific is closely related to seasonal variability, ENSO diversity and the PDO. Apparent dominance of ocean dynamic controls on biogeochemistry belies the potential biogeochemical feedbacks on ocean dynamics which may well explain some of the chronic biases in the state-of-the-art climate models. The east Pacific cold-tongue is the most productive open ocean region in the world and home to a unique physical-biogeochmical laboratory, viz., the Galapagos. The Galapagos islands not only control the coupled climate variability via their ability to terminate the equatorial undercurrent but also offer a clear example of a biological loophole in terms of their impact on local upwelling and an expanding penguin habitat in the face of global warming. The complex bio-physical interactions in the cold-tongue and their influence on climate predictions and projections require a holisti thinking on future observing systems. Tropical Pacific offers a natural laboratory for designing a robust and sustained physical-biogeochemical observation system that can effectively bridge climate predictions and projections into a unified framework for subseasonal to multidecadal timescales. Such a system will be a foundation for establishing similar systems over the rest of the World ocean to seemlessly merge climate predictions and projections with the need to constantly monitor climate impacts on marine resources. This talk will focus on the zonal contrasts of the ocean dynamics and biogechemistry across the tropical Pacific to make a case for integrated physical-biogeochemical observations for climate predictions and projections.

Revisiting Seafloor-Spreading in the Red Sea: Basement Nature, Transforms and Ocean-Continent Boundary

NASA Astrophysics Data System (ADS)

Tapponnier, P.; Dyment, J.; Zinger, M. A.; Franken, D.; Afifi, A. M.; Wyllie, A.; Ali, H. G.; Hanbal, I.

2013-12-01

A new marine geophysical survey on the Saudi Arabian side of the Red Sea confirms early inferences that ~ 2/3 of the eastern Red Sea is floored by oceanic crust. Most seismic profiles south of 24°N show a strongly reflective, landward-deepening volcanic basement up to ~ 100 km east of the axial ridge, beneath thick evaporitic deposits. This position of the Ocean-Continent Boundary (OCB) is consistent with gravity measurements. The low amplitudes and long wavelengths of magnetic anomalies older than Chrons 1-3 can be accounted for by low-pass filtering due to thick sediments. Seafloor-spreading throughout the Red Sea started around 15 Ma, as in the western Gulf of Aden. Its onset was coeval with the activation of the Aqaba/Levant transform and short-cutting of the Gulf of Suez. The main difference between the southern and northern Red Sea lies not in the nature of the crust but in the direction and modulus of the plate motion rate. The ~ 30° counterclockwise strike change and halving of the spreading rate (~ 16 to ~ 8 mm/yr) between the Hermil (17°N) and Suez triple junctions results in a shift from slow (≈ North Atlantic) to highly oblique, ultra-slow (≈ Southwest Indian) ridge type. The obliquity of spreading in the central and northern basins is taken up by transform discontinuities that stop ~ 40 km short of the coastline, at the OCB. Three large transform fault systems (Jeddah, Zabargad, El Akhawein) nucleated as continental transfer faults reactivating NNE-trending Proterozoic shear zones. The former two systems divide the Red Sea into three main basins. Between ~15 and ~5 Ma, for about 10 million years, thick evaporites were deposited directly on top of oceanic crust in deep water, as the depositional environment, modulated by climate, became restricted by the Suez and Afar/Bab-el-Mandeb volcano-tectonic 'flood-gates.' The presence of these thick deposits (up to ~ 8 km) suffices to account for the difference between the Red Sea and the Gulf of Aden. Widespread salt tectonics was triggered by the flow of large evaporite sheets and salt glaciers toward the ridge axis. Such flow was more pervasive in the north, where slower spreading resulted in a deeper trough, and was guided by the rugged topography of the oceanic seafloor. The Red Sea may represent the best model for comparably deep evaporitic basins along the Earth's passive margins, particularly in the South Atlantic.

Impact of postfire logging on soil bacterial and fungal communities and soil biogeochemistry in a mixed-conifer forest in central Oregon

Treesearch

Tara N. Jennings; Jane E. Smith; Kermit Cromack; Elizabeth W. Sulzman; Donaraye McKay; Bruce A. Caldwell; Sarah I. Beldin

2012-01-01

Postfire logging recoups the economic value of timber killed by wildfire, but whether such forest management activity supports or impedes forest recovery in stands differing in structure from historic conditions remains unclear. The aim of this study was to determine the impact of mechanical logging after wildfire on soil bacterial and fungal communities and other...

Response to Comment on “Dissolved organic sulfur in the ocean: Biogeochemistry of a petagram inventory”

NASA Astrophysics Data System (ADS)

Koch, Boris P.; Ksionzek, Kerstin B.; Lechtenfeld, Oliver J.; McCallister, S. Leigh; Schmitt-Kopplin, Philippe; Geuer, Jana K.; Geibert, Walter

2017-05-01

Dittmar et al. proposed that mixing alone can explain our observed decrease in marine dissolved organic sulfur with age. However, their simple model lacks an explanation for the origin of sulfur-depleted organic matter in the deep ocean and cannot adequately reproduce our observed stoichiometric changes. Using radiocarbon age also implicitly models the preferential cycling of sulfur that they are disputing.

Molecular Biogeochemistry of Modern and Ancient Marine Microbes

DTIC Science & Technology

2010-02-01

number distributions in the late Archean bitumens fall within the range of compositions of Phanerozoic petroleum ( gray line in Fig. 7), suggesting that...bitumen extracts. The gray line indicates the range of compositions observed in Phanerozoic petroleum systems, from the GeoMark Reservoir Fluid Database...than that of mRNA are attributable to noisy, non-cycling protein timecourses ( gray points above 1:1 line). For clarity, only genes whose protein

Biogeochemical cycling of carbon, nitrogen, and sulfur at the Howland Integrated Forest Study site, Howland, Maine

Treesearch

James W. McLaughlin; Ivan J. Fernandez; Stewart M. Goltz; Lindsey E. Rustad; Larry Zibilske

1996-01-01

The biogeochemistry of C, N, and S was studied for six years at the Howland Integrated Forest Study (HIFS) site by measuring those constituents in major above- and below-ground pools and fluxes. Leaching losses of C from the solum were much less than CO2 efflux, with a mean annual leaching rate of 31.2 kg ha-1 yr

Potential environmental impact of tidal energy extraction in the Pentland Firth at large spatial scales: results of a biogeochemical model

NASA Astrophysics Data System (ADS)

van der Molen, Johan; Ruardij, Piet; Greenwood, Naomi

2016-05-01

A model study was carried out of the potential large-scale (> 100 km) effects of marine renewable tidal energy generation in the Pentland Firth, using the 3-D hydrodynamics-biogeochemistry model GETM-ERSEM-BFM. A realistic 800 MW scenario and a high-impact scenario with massive expansion of tidal energy extraction to 8 GW scenario were considered. The realistic 800 MW scenario suggested minor effects on the tides, and undetectable effects on the biogeochemistry. The massive-expansion 8 GW scenario suggested effects would be observed over hundreds of kilometres away with changes of up to 10 % in tidal and ecosystem variables, in particular in a broad area in the vicinity of the Wash. There, waters became less turbid, and primary production increased with associated increases in faunal ecosystem variables. Moreover, a one-off increase in carbon storage in the sea bed was detected. Although these first results suggest positive environmental effects, further investigation is recommended of (i) the residual circulation in the vicinity of the Pentland Firth and effects on larval dispersal using a higher-resolution model and (ii) ecosystem effects with (future) state-of-the-art models if energy extraction substantially beyond 1 GW is planned.

NEON Data Products: Supporting the Validation of GCOS Essential Climate Variables

NASA Astrophysics Data System (ADS)

Petroy, S. B.; Fox, A. M.; Metzger, S.; Thorpe, A.; Meier, C. L.

2014-12-01

The National Ecological Observatory Network (NEON) is a continental-scale ecological observation platform designed to collect and disseminate data that contributes to understanding and forecasting the impacts of climate change, land use change, and invasive species on ecology. NEON will collect in-situ and airborne data over 60 sites across the US, including Alaska, Hawaii, and Puerto Rico. The NEON Biomass, Productivity, and Biogeochemistry protocols currently direct the collection of samples from distributed, gradient, and tower plots at each site, with sampling occurring either multiple times during the growing season, annually, or on three- or five-year centers (e.g. for coarse woody debris). These data are processed into a series of field-derived data products (e.g. Biogeochemistry, LAI, above ground Biomass, etc.), and when combined with the NEON airborne hyperspectral and LiDAR imagery, are used support validation efforts of algorithms for deriving vegetation characteristics from the airborne data. Sites are further characterized using airborne data combined with in-situ tower measurements, to create additional data products of interest to the GCOS community, such as Albedo and fPAR. Presented here are a summary of tower/field/airborne sampling and observation protocols and examples of provisional datasets collected at NEON sites that may be used to support the ongoing validation of GCOS Essential Climate Variables.

Millions of Boreal Shield Lakes can be used to Probe Archaean Ocean Biogeochemistry

PubMed Central

Schiff, S. L.; Tsuji, J. M.; Wu, L.; Venkiteswaran, J. J.; Molot, L. A.; Elgood, R. J.; Paterson, M. J.; Neufeld, J. D.

2017-01-01

Life originated in Archaean oceans, almost 4 billion years ago, in the absence of oxygen and the presence of high dissolved iron concentrations. Early Earth oxidation is marked globally by extensive banded iron formations but the contributing processes and timing remain controversial. Very few aquatic habitats have been discovered that match key physico-chemical parameters of the early Archaean Ocean. All previous whole ecosystem Archaean analogue studies have been confined to rare, low sulfur, and permanently stratified lakes. Here we provide first evidence that millions of Boreal Shield lakes with natural anoxia offer the opportunity to constrain biogeochemical and microbiological aspects of early Archaean life. Specifically, we combined novel isotopic signatures and nucleic acid sequence data to examine processes in the anoxic zone of stratified boreal lakes that are naturally low in sulfur and rich in ferrous iron, hallmark characteristics predicted for the Archaean Ocean. Anoxygenic photosynthesis was prominent in total water column biogeochemistry, marked by distinctive patterns in natural abundance isotopes of carbon, nitrogen, and iron. These processes are robust, returning reproducibly after water column re-oxygenation following lake turnover. Evidence of coupled iron oxidation, iron reduction, and methane oxidation affect current paradigms of both early Earth and modern aquatic ecosystems. PMID:28447615

An Integrated Biogeochemical and Biophysical Analysis of Bioenergy Crops

NASA Astrophysics Data System (ADS)

Liang, M.; Song, Y.; Barman, R.; Jain, A. K.

2010-12-01

Bioenergy crops are becoming increasingly important with growing concerns about the energy demand and climate change and the need to replace fossil fuels with carbon-neutral renewable sources of energy. The transition to a biofuel-based energy supply raises many questions such as: how and where to grow energy crops, what will be the impacts of growing large scale biofuel crops on climate system, the hydrological cycle and soil biogeochemistry. We are developing and applying an integrated system modeling framework to investigate the biophysical, physiological, and biogeochemical systems governing important processes that regulate crop growth such as water, energy and nutrient cycles. The framework has a two-big-leaf canopy scheme for photosynthesis, stomatal conductance, leaf temperature and energy fluxes. The soil/snow hydrology consists of 10 layers for soil and up to 5 layers for snow. The biogeochemistry component explicitly accounts for coupled carbon and nitrogen dynamics. The feedstocks currently considered include corn stover, Miscanthus and switchgrass. The parameters used for simulation of each crop have been calibrated using field experimental data from the US. The use of this modeling capability will be demonstrated through its applications to study the environmental effects (through changes in albedo and evapotranspiration) of biofuel production as well as the effective management practice in the United States.

Characterization and Phenanthrene Sorption of Natural and Pyrogenic Organic Matter Fractions.

PubMed

Jin, Jie; Sun, Ke; Wang, Ziying; Yang, Yan; Han, Lanfang; Xing, Baoshan

2017-03-07

Pyrogenic humic acid (HA) is released into the environment during the large-scale application of biochar. However, the biogeochemistry of pyrogenic organic matter (PyOM) fractions and their sorption of hydrophobic organic compounds (HOCs) are poorly understood in comparison with natural organic matter (NOM) fractions. HA and humin (HM) fractions isolated from soils and the oxidized biochars were characterized. Sorption of phenanthrene (PHE) by these fractions was also examined. The characterization results demonstrate that pyrogenic HAs are different from natural HAs, with the former having lower atomic H/C ratios, more abundant aromatic C, and higher concentrations of surface carboxylic groups. Compared with the fresh biochars, the K oc of PHE on their oxidized biochars, pyrogenic HA, and HM fractions were undiminished, which is encouraging for the use of biochar in soil remediation. The PyOM fractions exhibited stronger nonlinear sorption than the NOM fractions. In addition, the PyOM fractions had higher sorption capacity than the NOM fractions due to their low polar C content and high aryl C content. The results obtained from this work will shed new light on the impact of the addition of biochar on the biogeochemistry of soil organic matter and on the fate of HOCs in biochar-amended soil.

Experiments with Seasonal Forecasts of ocean conditions for the Northern region of the California Current upwelling system

PubMed Central

Siedlecki, Samantha A.; Kaplan, Isaac C.; Hermann, Albert J.; Nguyen, Thanh Tam; Bond, Nicholas A.; Newton, Jan A.; Williams, Gregory D.; Peterson, William T.; Alin, Simone R.; Feely, Richard A.

2016-01-01

Resource managers at the state, federal, and tribal levels make decisions on a weekly to quarterly basis, and fishers operate on a similar timeframe. To determine the potential of a support tool for these efforts, a seasonal forecast system is experimented with here. JISAO’s Seasonal Coastal Ocean Prediction of the Ecosystem (J-SCOPE) features dynamical downscaling of regional ocean conditions in Washington and Oregon waters using a combination of a high-resolution regional model with biogeochemistry and forecasts from NOAA’s Climate Forecast System (CFS). Model performance and predictability were examined for sea surface temperature (SST), bottom temperature, bottom oxygen, pH, and aragonite saturation state through model hindcasts, reforecast, and forecast comparisons with observations. Results indicate J-SCOPE forecasts have measurable skill on seasonal timescales. Experiments suggest that seasonal forecasting of ocean conditions important for fisheries is possible with the right combination of components. Those components include regional predictability on seasonal timescales of the physical environment from a large-scale model, a high-resolution regional model with biogeochemistry that simulates seasonal conditions in hindcasts, a relationship with local stakeholders, and a real-time observational network. Multiple efforts and approaches in different regions would advance knowledge to provide additional tools to fishers and other stakeholders. PMID:27273473

Experiments with Seasonal Forecasts of ocean conditions for the Northern region of the California Current upwelling system

NASA Astrophysics Data System (ADS)

Siedlecki, Samantha A.; Kaplan, Isaac C.; Hermann, Albert J.; Nguyen, Thanh Tam; Bond, Nicholas A.; Newton, Jan A.; Williams, Gregory D.; Peterson, William T.; Alin, Simone R.; Feely, Richard A.

2016-06-01

Resource managers at the state, federal, and tribal levels make decisions on a weekly to quarterly basis, and fishers operate on a similar timeframe. To determine the potential of a support tool for these efforts, a seasonal forecast system is experimented with here. JISAO’s Seasonal Coastal Ocean Prediction of the Ecosystem (J-SCOPE) features dynamical downscaling of regional ocean conditions in Washington and Oregon waters using a combination of a high-resolution regional model with biogeochemistry and forecasts from NOAA’s Climate Forecast System (CFS). Model performance and predictability were examined for sea surface temperature (SST), bottom temperature, bottom oxygen, pH, and aragonite saturation state through model hindcasts, reforecast, and forecast comparisons with observations. Results indicate J-SCOPE forecasts have measurable skill on seasonal timescales. Experiments suggest that seasonal forecasting of ocean conditions important for fisheries is possible with the right combination of components. Those components include regional predictability on seasonal timescales of the physical environment from a large-scale model, a high-resolution regional model with biogeochemistry that simulates seasonal conditions in hindcasts, a relationship with local stakeholders, and a real-time observational network. Multiple efforts and approaches in different regions would advance knowledge to provide additional tools to fishers and other stakeholders.

Coupled Biogeochemical and Hydrodynamic Measurements over a Palauan Seagrass Bed: Can Seagrasses Mitigate Local Acidification Stress?

NASA Astrophysics Data System (ADS)

Hirsh, H.; Torres, W.; Shea, M.

2016-02-01

Interest in seagrass beds as a tool to locally mitigate ocean acidification is growing rapidly. Much of the interest in seagrasses is motivated by their root structure, which is able to sequester carbon over interannual and longer timescales. Far less is known about their biogeochemistry on shorter diel timescales, yet we know that diel cycle variation in CO2 chemistry on coral reefs can be quite substantial. Understanding short-term seagrass biogeochemistry is critical to evaluating if, and how, seagrasses may eventually be utilized to mitigate OA on coral reefs. We present the results of a high-resolution, 24-hour control volume experiment conducted in the Republic of Palau covering a 50m x 100m seagrass bed. Our dataset includes diel cycles of hydrodynamic (current profiles and turbulence), biogeochemical (pH, pCO2, TA, DIC, and O2), and environmental (temperature and salinity) parameters. We use these coupled hydrodynamic-biogeochemical measurements to estimate ecosystem metabolism and better quantify the capacity of seagrass to mitigate local acidification through the photosynthetic uptake of CO2. Combining our field observations with box model predictions allows us to gain better insight into the mechanisms that control seagrass metabolism and their ability to buffer CO2 for downstream corals.