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The flow of water through food commodity trade has been rationalized in the virtual water concept. Estimates of future virtual water flows under climate, land use, and population changes could have instrumental value for policy and strategic trade decisions. This paper estimated the virtual water flows associated with feed barley and meat imports to the UK under projected climate, land use, and population changes from the 2030s to the 2050s. The results show that future virtual water inflows associated with barley imports to balance domestic deficits are larger than total volume of water used in domestic barley production in the UK. Mean virtual water associated with total UK barley production ranged from 206 to 350 million m3. This is much less than the mean total virtual water associated with barley imports (if total barley produced in the UK is used for feed), which ranged from 2.5 to 5.6 billion m3 in the 2030s to the 2050s for all land use and climate change scenarios. If domestic barley production is distributed to the different end uses, the total virtual water inflows associated with imports to balance domestic feed barley supply could be as high as 7.4 billion m3. Larger virtual water inflows (as high as 9.9 billion m3) were associated with feed barley equivalent meat imports. While the UK barley production would be entirely green, imports of either barley or meat would result in large blue water inflows to the UK. Virtual water inflows increased across the time slices for all emissions scenarios, indicating weak effectiveness of yield or productivity gains to moderate virtual water inflows. While increase in yield and land allocated to barley production should be adaptive targets, the UK needs to take policy and strategic actions to diversify trade partners and shift imports away from countries where blue water flows can exacerbate existing or potential water stresses.

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RESUMO O conceito de água virtual tem sido muito utilizado como importante indicador de consumo, sendo cada vez mais aceito na literatura, constituindo-se da água incorporada à produção de um bem ou serviço. Visando a estimar o volume de água virtual presente nos 25 principais produtos da pauta de exportação brasileira no período 2003-2014, utilizou-se o método de pesquisa exploratória a partir dos principais produtos que representavam aproximadamente 60% do montante arrecadado. Os resultados indicaram inflexão entre a relevância dos produtos manufaturados e dos produtos básicos (principalmente minério de ferro e soja) no período de 2009-2010, com apenas quatro produtos respondendo, em 2014, por 32% da receita auferida pelo País. Como consequência, a estimativa do dispêndio de água virtual realizada para os produtos avaliados indicou que o Brasil despendeu, em média, 191 Gm3.ano-1 (6.025 m3.s-1), com os produtos básicos respondendo por 95% desse volume. Considerando-se apenas 2014, essa vazão elevou-se para 7.836 m3.s-1, aproximadamente 14 vezes superior à demanda para abastecimento da população urbana brasileira.

ABSTRACT The Virtual Water concept has long been used as an important indicator of water consumption, increasingly being accepted in the literature, becoming the embedded water in the production of a good or service. In order to estimate the volume of virtual water present in the top 25 products of Brazilian exports in the period 2003-2014, we used the exploratory method from the main products that represented approximately 60% of the collected amount. Results indicated a shift between the relevance of manufactured products and commodities (mainly iron ore and soybeans) in the 2009-2010 period, with only four products accounting in 2014 for 32% of the revenue earned by the country. As a result, the estimated virtual water expenditure for the products evaluated indicated that Brazil spent, on average, 191 Gm3.year-1 (about 6,025 m3.s-1), with commodities accounting for 95% of this volume. Considering only 2014, this flow increased to about 7,836 m3.s-1, 14 times higher than the supply demand of the Brazilian urban population.

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Increasing integration in global markets can foster economic growth, but also impacts the use of water resources for the production of traded goods. This is particularly critical for low-and middle-income countries where increasing agricultural exports, especially of high-value horticultural products such as fresh fruits and vegetables is promoted as a pro-poor development strategy. The aim of this paper is to quantify the contribution of agricultural trade to virtual water flows and economic gains. The focus is on Peru and trade flows since 1986, as this represents a case of rapidly increasing trade flows and a rapidly changing product composition of trade. We consider long-term trade trends and changes in the product composition of trade, using a product classification, and analyze the implications for trade revenues, VW flows, blue and green water use, and economic water use efficiency. We use an innovative decomposition analysis to disentangle the drivers behind increased virtual water exports. We find that despite sharp increase in agricultural exports Peru is a net importer of virtual water, which implies that participation in international trade has been conducive for both economic growth and saving water resources at national level. We find agricultural exports to have a high economic water efficiency but to increase water scarcity and the use of blue water in producing regions. Our results imply that a focus on high-value export sectors is a valid development strategy for low- and middle-income countries from both an economic and a water perspective but that the strategic location of export production with respect to the availability of water is important for policy-makers to consider. Our approach confirms the importance of considering long-term dynamics and regional differences in research on virtual water trade.

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The virtual water hypothesis offers the reasonable proposition that if water-abundant regions export water-intensive products to water-scarce regions, the latter could devote their scarce resources instead to uses yielding higher economic returns. Zhao et al. show that trade flows in China do not adhere to this hypothesis, use the economic theory of comparative advantage to explore why, and seek a solution where both the hypothesis and the theory are apparently satisfied. However, they have not fully utilized the power of the theory: this is made evident by the fact that their calculations quantify what they call "the comparative advantage of land, labor and water," as stated in the title of the article. This Comment describes the significance of comparative advantage for this inquiry and our comparable investigation for the regions of Mexico. It concludes with the case for a collaborative effort to situate such single-country studies in the context of a model of global comparative advantages.

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Abstract In this study we evaluated the long-term spatial memory in humans. A quasiexperimental design was used in which three groups of undergraduate students were trained in a virtual water maze to locate a hidden platform whose location was indicated by a set of cues. A pre-test without platform was performed prior to the training, and a post-test was conducted immediately after this (Group 0h), or after a retention interval of two (Group 48h) or seven days (Group 168h). For the pre-test, there was no evidence of preference for any area of the maze. Throughout the training trials, the time to find the goal decreased without differences between groups. During the post-test, all groups showed a preference for the reinforced quadrant, although the spent time, swimming distance, and accuracy of the search behavior in that area was equivalent between Group 0 h and Group 48 h, but higher than that shown by the Group 168 h. These data indicate changes in long-term spatial memory in humans, occurring after an interval of 48 h after its acquisition. The results are discussed on the basis of general memory processes and specific processes proposed by particular spatial memory theories. The clinical and comparative psychology implications are also addressed.

Resumo Neste estudo, avaliou-se a memória espacial de longo prazo em humanos. Para isso, empregou-se um desenho quase-experimental no qual se treinou três grupos de estudantes de graduação num labirinto virtual de água para localizar uma plataforma oculta cuja posição era sinalizada por um conjunto de chaves. Realizou-se um pré-teste sem plataforma antes do treinamento, e imediatamente depois se conduziu um pós-teste (Grupo 0 h), assim como depois de um intervalo de retenção de dois dias (Grupo 48 h) e de sete dias (Grupo 168 h). No pré-teste, não se encontrou evidência de preferência por alguma área do labirinto. Ao longo dos ensaios de treinamento, o tempo para encontrar a meta diminuiu sem diferenças entre grupos. Durante o pós-teste, todos os grupos mostraram uma preferência pelo quadrante reforçado, contudo o tempo de permanência, a distância de nado e a precisão do comportamento de busca nessa área foi equivalente entre o Grupo 0 h e o Grupo 48 h, embora maior à amostragem pelo Grupo 168 h. Esses dados indicam mudanças ocorridas 48 h depois da aquisição na memória espacial de longo prazo em humanos. Discutem-se os resultados a partir de processos gerais de memória e de processos específicos propostos por teorias particulares de memória espacial; ao final, abordam-se as implicações clínicas e pertinentes ao campo da psicologia comparada.

Resumen En este estudio se evaluó la memoria espacial a largo plazo en humanos. Para ello, se empleó un diseño cuasiexperimental en el que se entrenó a tres grupos de estudiantes de pregrado en un laberinto virtual de agua para localizar una plataforma oculta cuya ubicación era señalada por un conjunto de claves. Se realizó un pretest sin plataforma antes del entrenamiento, e inmediatamente después se condujo un postest (Grupo 0 h), así como después de un intervalo de retención de dos días (Grupo 48 h) y siete días (Grupo 168 h). En el pretest no se encontró evidencia de preferencia por alguna zona del laberinto. A lo largo de los ensayos de entrenamiento, el tiempo para encontrar la meta disminuyó sin diferencias entre grupos. Durante el postest, todos los grupos mostraron una preferencia por el cuadrante reforzado, sin embargo, el tiempo de permanencia, la distancia de nado y la precisión de la conducta de búsqueda en dicha zona fue equivalente entre el Grupo 0 h y el Grupo 48 h, aunque mayor a la mostrada por el Grupo 168 h. Estos datos indican cambios ocurridos 48 h después de la adquisición en la memoria espacial a largo plazo en humanos. Se discuten los resultados a partir de procesos generales de memoria y procesos específicos propuestos por teorías particulares de memoria espacial; y al final se abordan las implicaciones clínicas y pertinentes al campo de la psicología comparada.

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Participantes humanos fueron entrenados en un laberinto virtual de agua para localizar en dos fases sucesivas una plataforma cuya ubicación fue específica a la fase vigente. Posteriormente realizaron una prueba sin plataforma. El Grupo ABA realizó la primera fase y la prueba en un contexto A, y la segunda fase en un contexto B. El Grupo ABB realizó la primera fase en el contexto A, y la segunda fase y la prueba en el contexto B. Ambos grupos localizaron la plataforma en cada fase. Durante la prueba, la última ubicación de la plataforma fue preferida por el Grupo ABB, mientras que la primera ubicación fue preferida por el Grupo ABA. Estos resultados indican renovación de la memoria espacial en humanos.

Human participants were trained in a virtual water maze throughout two immediate phases, in order to locate a platform which particular location was specific to each phase. Afterwards, a trial without the platform was conducted.The ABA group experienced phase 1 and the test trial in Context A, while the second phase occurred in Context B. The ABB group received the first phase in Context A and the phase 2 and test trial training in Context B. Both groups had to locate the platform in each phase. During the test trial, the last platform location was preferred by the ABB group but the first platform location was preferred by the group ABA. These results suggest renewal of spatial memory in humans.

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Virtual water trade is often considered a solution for restricted water availability in many regions of the world. Brazil is the world leader in the production and export of various agricultural and livestock products. The country is either a strong net importer or a strong net exporter of these products. The objective of this study is to determine the volume of virtual water contained in agricultural and livestock products imported/exported by Brazil from 1997 to 2012, and to define the water self-sufficiency index of agricultural and livestock products in Brazil. The indexes of water scarcity (WSI), water dependency (WDI) and water self-sufficiency (WSSI) were calculated for each Brazilian state. These indexes and the virtual water balance were calculated following the methodology developed by Chapagain and Hoekstra (2008) and Hoekstra and Hung (2005). The total water exports and imports embedded in agricultural and livestock products were 5.28 × 1010 and 1.22 × 1010 Gm3 yr-1, respectively, which results in positive virtual water balance of 4.05 × 1010 Gm3 yr-1. Brazil is either a strong net importer or a strong net exporter of agricultural and livestock products among the Mercosur countries. Brazil has a positive virtual water balance of 1.85 × 1010 Gm3 yr-1. The indexes used in this study reveal that Brazil is self-sufficient in food production, except for a few products such as wheat and rice. Horticultural products (tomato, onion, potato, cassava and garlic) make up a unique product group with negative virtual water balance in Brazil.

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