Descoberto como peixes elétricos controlam o "choque"

Alguns peixes de água doce presentes na América do sul e central são capazes geram eletricidade. Os campos elétricos são utilizados por estes peixes para navegação, luta e para atrair parceiros. Entretanto, a geração de eletricidade por estes peixes pode atrair predadores, além de requer um alto investimento energético. Por isso estes peixes são capazes de controlar os sinais elétricos que emitem para cima ou para baixo de forma bastante rápida.

Uma recente publicação na PLoS Biology de 29 de setembro, pesquisadores americanos investigaram como peixes elétricos regulam seus campos elétricos. De acordo com o artigo, a alteração dos impulsos elétricos é feita na forma de canais de sódio em membranas das células especiais (chamadas electrócitos) dentro dos órgãos elétricos. Quando mais canais de sódio estão presentes na membrana celular, maior o impulso elétrico emitido. Os pesquisadores também observaram que o processo está sob controle endócrino, apresenta variações circadianas (dia-noite) e que os campos elétricos podem mudar rapidamente durante encontros sociais.

Leia o artigo completo AQUI.

MIGRATORY FISHES OF SOUTH AMERICA - Biology, Fisheries, and Conservation Status

Edited by Joachim Carolsfield, Brian Harvey, Carmen Ross, and Anton Baer

World Fisheries Trust/World Bank/IDRC 2004
ISBN 9-68395-821-2
e-ISBN 1-55250-114-0
380 pp

Download the book free HERE.

Fish species that migrate within the great rivers of South America support important local fisheries but are little known outside their native range. This book represents the first collection of the work of local scientific experts on these remarkable fish. The authors cover the Upper Paraná, Paraguay-Paraná, Uruguay and São Francisco basins in Brazil, as well as the Brazilian and Colombian Amazon. They discuss not only the principal migratory species and their fascinating relationship with the water cycle in the rivers and wetlands, but also the fisheries they support, and their often precarious conservation status.

Lasers do Espaço mostram a redução das camadas de gelo na Groelândia e Antártica

A imagem mais detalhada da redução rápida das geleiras ao longo do litoral da Antártida e Groenlândia foi criada usando lasers em satélites. Os resultados são um importante passo na busca de previsões mais precisas para futuro aumento do nível do mar.

Em reportagem publicada esta semana na revista Nature, pesquisadores do British Antarctic Survey e da Universidade de Bristol descrevem como a análise de milhões de medições das camadas de gelo na Antártida e Groenlândia através de um satélite da NASA mostraram que a maior perda de gelo é resultado da aceleração do fluxo das geleiras em direção ao mar.

Os autores concluem que essa "dinâmica de afinamento" das geleiras agora atinge todas as latitudes na Groenlândia, intensificou ao longo do litoral da Antártida, está penetrando no em direçào ao interior e está se espalhando nas plataformas de gelo.

Leia a notícia completa AQUI.

Climate in Peril - A popular guide to the latest IPCC reports

Climate in Peril: A Popular Guide to the Latest IPCC Reports presents the substance of the Climate Change 2007 Synthesis Report of the Intergovernmental Panel on Climate Change in simplified language and structure. The guide, intended for lay readers, is a joint publication of GRID-Arendal and SMI Books, with the generous support of the Norwegian Pollution Control Authority and the Swedish Environmental Protection Agency..

World's river deltas sinking due to human activity

Source: physorg.com
A new study led by the University of Colorado at Boulder indicates most of the world's low-lying river deltas are sinking from human activity, making them increasingly vulnerable to flooding from rivers and ocean storms and putting tens of millions of people at risk.

While the 2007 Intergovernmental Panel on Climate Change report concluded many river deltas are at risk from sea level rise, the new study indicates other human factors are causing deltas to sink significantly. The researchers concluded the sinking of deltas from Asia and India to the Americas is exacerbated by the upstream trapping of sediments by reservoirs and dams, man-made channels and levees that whisk sediment into the oceans beyond coastal floodplains, and the accelerated compacting of floodplain sediment caused by the extraction of groundwater and natural gas.

The study concluded that 24 out of the world's 33 major deltas are sinking and that 85 percent experienced severe flooding in recent years, resulting in the temporary submergence of roughly 100,000 square miles of land. About 500 million people in the world live on river deltas.

The authors predict that global delta flooding could increase by 50 percent under current projections of about 18 inches in sea level rise by the end of the century as forecast by the 2007 Intergovernmental Panel on Climate Change report. The flooding will increase even more if the capture of sediments upstream from deltas by reservoirs and other water diversion projects persists and prevents the growth and buffering of the deltas, according to the study.

The team used satellite data from NASA's Shuttle Radar Topography Mission, which carried a bevy of radar instruments that swept more than 80 percent of Earth's surface during a 12-day mission of the space shuttle Endeavour in 2000. The researchers compared the SRTM data with historical maps published between 1760 and 1922.

Read the compelte article HERE.

O impacto do mercado mundial de biocombustíveis na expansão da agricultura brasileira e suas consequências para as mudanças climáticas

Estudo mostra que é possível aumentar significativamente a área agrícola no país respeitando-se o Código Florestal e sem desmatar a Amazônia e o Cerrado desde que haja uma política efetiva de incentivo à conversão de pastagens degradadas em áreas agrícolas

Porém, se tudo continuar como hoje, deve haver desmatamento no Cerrado de aproximadamente 10 milhões de hectares nos próximos 10 anos para a produção de grãos e cana-de-açúcar.

O documento intitulado Impacto do mercado mundial de biocombustíveis na expansão da agricultura brasileira e suas consequências para as mudanças climáticas relaciona o crescimento de demanda por biocombustíveis com a expansão agrícola no Brasil, quantificando a área e apontando as regiões de expansão.

Toxic Waters

Read the articles of this series HERE.
These are very interesting articles showing the problem of water contamination in the United States.
Ryan Massey, 7, shows his caps. Dentists near Charleston, W.Va., say pollutants in drinking water have damaged residents’ teeth. Nationwide, polluters have violated the Clean Water Act more than 500,000 times.

Excerpt:

"The New York Times surveyed violations of the Clean Water Act in the USA. The survey found that in many states, more than 50 percent of regulated facilities violated the Clean Water Act, but enforcement actions against polluters were infrequent."

Comparative hydrology - An ecological approach to land and water resources

Comparative hydrology - An ecological approach to land and water resources

Edited by Malin Falkenmark and Tom Chapman

Publisher: Swedish Natural Science Research Council / UNESCO

Free textbook available at the SIWI website.

Description (from the book's preface):

Although the total amount of water on earth is generally assumed to have remained virtually constant, the rapid growth of population, together with the extension of irrigated agriculture and industrial development, are stressing the quantity and quality aspects of the natural system. Because of the increasing problems, man has begun to realize that he can no longer follow a “use and discard” philosophy - either with water resources or with any other natural resources. As a result, the need for a consistent policy of rational management of water resources has become evident.

Rational water management, however, should be founded upon a thorough understanding of water availability and movement. Thus, as a contribution to the solution of the world’s water problems, Unesco, in 1965, began the fi rst world-wide programme of studies of the hydrological cycle - the International Hydrological Decade (IHD).(...)

As part of Unesco’s contribution to the objectives of the International Hydrological Programme (IHP), two regular publication series are issued: “Studies and Reports in Hydrology” and “Technical Papers in Hydrology”. Occasionally, documents such as the present one are produced by special arrangements with IHP National Committees or other national entities associated with the production of the basic report and are made available for distribution from the IHP headquarters at Unesco, Paris.

This textbook Comparative Hydrology owes much to the enthusiasm, devotion and hard work of the two editors Malin Falkenmark and Tom Chapman, and their collaboration is acknowledged with gratitude. Special thanks go to Professor Chapman who devoted very many hours to development of the text and diagrams in computer-compatible form and to preparation of the book as camera-ready copy.

Solving the climate dilemma: The budget approach

Solving the climate dilemma: The budget approach

Publisher: WBGU, Berlin, 2009

Download a free copy of the book here.

Description:

At their meeting in the Italian city of L’Aquila in July 2009, the heads of state and government of the G8 countries and the Major Economies Forum on Energy and Climate (MEF), whose members include India, Brazil and China, acknowledged the importance that global warming must not exceed the 2°C guard rail if dangerous climate change is to be avoided. WBGU views this as an extremely important step towards the adoption of a binding international agreement which establishes a well-founded target for global climate protection. The task now is to build on this consensus and reach agreement, at Copenhagen, on a follow-up treaty to the Kyoto Protocol, which is due to expire in 2012. This new international agreement should translate the relevant scientific knowledge into a fair and practicable global strategy to combat global warming. So far, however, the lack of unanimity between the countries involved in the negotiating process has meant that there is no clear leitmotif pointing the way towards such an agreement.

This special report is licensed under a Creative Commons License.

Water - A Reflection Of Land Use Options For Counteracting Land And Water Mismanagement

Water A Reflection Of Land Use Options For Counteracting Land And Water Mismanagement
By M. Falkenmark, L. Andersson, R. Castensson, K. Sundblad

Publisher: Swedish Natural Science Research Council

Free textbook available at the SIWI website.

Description:
It is a fundamental principle that we are living at the mercy of the water cycle: it acts as the bloodstream of the biosphere. As human populations grow, their expectations grow as well. This translates into an increasing demand for livelihood opportunities and an increasing pollution of water resources. Thus, the need is urgent throughout the world for improved understanding of the ecohydrological linkages. This book has as its purpose to explain and demystify the water cycle, its integrity and key processes. It contributes towards understanding the complex issue of the interaction between humans and their environment which is the origin of the natural resources that support human society and prosperity. This understanding will enable better decision-making and more successful action to cope with the situation. The book will also give readers an opportunity to review and evaluate their own particular cases and to make informed decisions.

Blueprint for Clean Water

"U.S. Blueprint for Clean Water - Waterkeeper Alliance’s U.S. Blueprint for Clean Water offers remedies to past policy decisions and proposes a new way for the United States federal government to strengthen environmental protection in all areas relating to water."

It is a report focusing in the United States water problems, but many of these problems occur elsewhere in the planet. Download the full report HERE.

Blue Planet Run - The race to provide safe drinking water to the world

World Water Crisis: In the extraordinary new book Blue Planet Run, hundreds of photographers from all over the world track mankind's vital race to provide safe drinking water to the one billion people who lack it.

"Blue Planet Run provides readers with an extraordinary look at the water problems facing humanity and some of the hopeful solutions being pursued by large and small companies, by entrepreneurs and activists, and by nongovernmental organizations and foundations. By the end of the book, readers are left to form their own conclusions as to whether the human race is capable of taking the steps necessary to solve this global crisis before it’s too late."

If you like to see some more pictures from the book, check this photo gallery from Time Magazine. Here is an example:

Water, Earth's most precious resource, serves simultaneously as habitat, nourishment and cleanser. Brazil's Pantanal River, for example, is home to 3,500 species of plants, 400 kinds of fish, 650 bird species, 100 kinds of mammals and 80 types of reptiles. It is not only a vital waterway for man, but an essential filter for the impurities he leaves behind.

Is global warning reaching a point of no return?

Review recently published in Nature:
Early-warning signals for critical transitions. By Marten Scheffer, Jordi Bascompte, William A. Brock, Victor Brovkin, Stephen R. Carpenter, Vasilis Dakos, Hermann Held, Egbert H. van Nes, Max Rietkerk & George Sugihara

Editor's summary:

"Many complex systems, ranging from ecosystems to financial markets and the climate, can have critical thresholds or tipping points where a sudden shift from one stable state to a contrasting regime may occur. Predicting such critical points before they are reached is extremely difficult, but work in different fields of science is now suggesting the existence of generic early warning signals that may indicate for a wide class of systems if a critical threshold is approaching. Scheffer et al. conclude their review of this work optimistically: in situations where the existence of a critical transition is suspected, the generic character of the warning signs suggests that they may provide valuable information on whether the probability of a major event is increasing."

First paragraph:
"Complex dynamical systems, ranging from ecosystems to financial markets and the climate, can have tipping points at which a sudden shift to a contrasting dynamical regime may occur. Although predicting such critical points before they are reached is extremely difficult, work in different scientific fields is now suggesting the existence of generic early-warning signals that may indicate for a wide class of systems if a critical threshold is approaching."

THIRST - Why water is important

This is an educational presentation exploring humanity's water use and the emerging worldwide water shortage.

THIRST

View more presentations from Jeff Brenman.