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21.
Conformational changes in the structures of humic acids (HA) extracted from compost with varying degrees of maturity were monitored by high performance size exclusion chromatography (HPSEC). The molecular size distribution of HA was compared in solutions containing sodium or ammonium counterions at pH 7 and pH 4.5. These findings indicate that the humates' molecular size depended not only on the nature of the counterions but also on their concentration in the solution. The physicochemical nature of sodium counterions determined smaller molecular sizes than those of the more hydrated ammonium counterions, at low concentrations of humates. Conversely, at higher humate concentrations, the more compact conformation of sodium humates produced larger molecular sizes than those of ammonium humates due to the aggregation of more hydrophobic surfaces in the sodium humates. Composting led to the degradation of labile microbial components with accumulation of hydrophobic constituents. This caused self-association of hydrophobic compounds into humic superstructures of larger molecular size over composting time. At lower pH, changes in conformational stability by the addition of acetic acid to humate solutions were explained by the supramolecular model of humified organic matter. 相似文献
22.
Maria do Carmo R. Peralba Dirce Pozebon João H. Z. dos Santos Sandra M. Maia Tânia M. Pizzolato Giovani Cioccari Simone Barrionuevo 《Environmental monitoring and assessment》2010,167(1-4):33-47
The impact of drilling oil activities in the Brazilian Bonito Field/Campos Basin (Rio de Janeiro) shell drilling (300 m) using nonaqueous fluids (NAFs) was investigated with respect to Al, Fe, Mn, Ba, Co, Pb, Cu, As, Hg, Cr, Ni, Zn, Cd, V, and aliphatic and polynuclear aromatic hydrocarbons concentrations in the sediment. Sampling took place in three different times during approximately 33 months. For the metals Al, As, Co, Cr, Cu, Cd, Fe, Ni, Mn, V, and Zn, no significant variation was observed after drilling activities in most of the stations. However, an increase was found in Ba concentration—due to the drilling activity—without return to the levels found 22 months after drilling. High Ba contents was already detected prior to well drilling, probably due to drilling activities in other wells nearby. Hydrocarbon contents also suggest previous anthropogenic activities. Aliphatic hydrocarbon contents were in the range usually reported in other drilling sites. The same behavior was observed in the case of polyaromatic hydrocarbons. Nevertheless, the n-alkane concentration increased sharply after drilling, returning almost to predrilling levels 22 months after drilling activities. 相似文献
23.
Maia Lordkipanidze Hans Bressers Kris Lulofs 《Journal of Environmental Planning and Management》2019,62(4):647-670
This paper addresses the challenge of appropriate governance of complexity and diversity in the Dutch national park of Alde Feanen. The issue is how to enhance ecosystem resilience. Our focus relates to a navigable waterway within the park that affects the natural values of the area. The governance assessment tool is used to assess the governance context of the waterway and ecosystem resilience in the area. The study shows that a lack of a long-term integrated vision makes the governance context less supportive. Such a vision could maximize the focus on the resilience of the park's nature and motivate actors to work towards a common future for a concerned area. However, institutional complexity, combined with institutional inertia, is revealed as a hindrance to the quality of governance and shapes a weak ability to adapt the current situation to move towards resilience. 相似文献
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25.
Lacerda LD Molisani MM Sena D Maia LP 《Environmental monitoring and assessment》2008,141(1-3):149-164
The Northeastern semi-arid Brazilian region is experiencing rapid social and economic development based on improving water
management and even in areas of low human occupation, anthropogenic emissions of N and P surpass natural emissions in at least
one order of magnitude and these additional loads can alter the water quality of the receiving estuaries. This study estimates,
using an emission factor approach, the annual emissions of N and P from natural processes and anthropogenic sources for estuaries
along the Ceará State, NE Brazil. Emission factors from natural sources are one to two orders of magnitude lower than those
for anthropogenic sources. Among the anthropogenic activities, the aquaculture is responsible for most N emission (0.52 t
km−2 year−1) followed by waste water and husbandry. For P, the largest average emission factors are from husbandry (0.30 t km−2 year−1), waste water and agriculture. 相似文献
26.
Downs PW Singer MS Orr BK Diggory ZE Church TC Stella JC 《Environmental management》2011,48(4):847-864
The goal of restoring ecological integrity in rivers is frequently accompanied by an assumption that a comparative reference
reach can be identified to represent minimally impaired conditions. However, in many regulated rivers, no credible historical,
morphological or process-based reference reach exists. Resilient restoration designs should instead be framed around naturalization,
using multiple analytical references derived from empirically-calibrated field- and model-based techniques to develop an integrated
ecological reference condition. This requires baseline data which are rarely collected despite increasing evidence for systematic
deficiencies in restoration practice. We illustrate the utility of baseline data collection in restoration planning for the
highly fragmented and regulated lower Merced River, California, USA. The restoration design was developed using various baseline
data surveys, monitoring, and modeling within an adaptive management framework. Baseline data assisted in transforming conceptual
models of ecosystem function into specific restoration challenges, defining analytical references of the expected relationships
among ecological parameters required for restoration, and specifying performance criteria for post-project monitoring and
evaluation. In this way the study is an example of process-based morphological restoration designed to prompt recovery of
ecosystem processes and resilience. For the Merced River, we illustrate that project-specific baseline data collection is
a necessary precursor in developing performance-based restoration designs and addressing scale-related uncertainties, such
as whether periodic gravel augmentation will sustain bed recovery and whether piecemeal efforts will improve ecological integrity.
Given the numerous impediments to full, historical, restoration in many river systems, it seems apparent that projects of
naturalization are a critical step in reducing the deleterious impacts of fragmented rivers worldwide. 相似文献
27.
Eiró Luciana Guimarães Ferreira Maria Karolina Martins Frazão Déborah Ribeiro Aragão Walessa Alana Bragança Souza-Rodrigues Renata Duarte Fagundes Nathalia Carolina Fernandes Maia Lucianne Cople Lima Rafael Rodrigues 《Environmental science and pollution research international》2021,28(28):37001-37015
Environmental Science and Pollution Research - Lead (Pb) is one of the most toxic and abundant elements in the earth’s crust, which is pointed out that the intoxication caused by it... 相似文献
28.
Karki Neeta Parajulee Colombo Robert E. Gaines Karen F. Maia Anabela 《Environmental science and pollution research international》2021,28(6):6450-6458
Environmental Science and Pollution Research - Estrogenic compounds including 17β estradiol (or E2) are known to negatively affect the reproductive system of many animals, including fish,... 相似文献
29.
Silva Wesley Douglas Oliveira Morais Danielle Costa Urtiga Marcella Maia 《Environment, Development and Sustainability》2022,24(8):10443-10469
Environment, Development and Sustainability - An integrative negotiation model is proposed so that watershed committees (WSC) can deal better with conflicts over alternatives for protecting water... 相似文献
30.
Theerthagiri Jayaraman Park Juhyeon Das Himadri Tanaya Rahamathulla Nihila Cardoso Eduardo S. F. Murthy Arun Prasad Maia Gilberto Vo Dai‑Viet N. Choi Myong Yong 《Environmental Chemistry Letters》2022,20(5):2929-2949
Environmental Chemistry Letters - The electrocatalytic reduction of nitrate waste into ammonia allows both the removal of nitrate contaminants and an alternative production of ammonia compared to... 相似文献