Micronutrient Supply Research Articles

β-Carotene and other carotenoids in protection from sunlight

Protection against skin damage from sunlight by nutritional means has been examined. Likewise, there has been work on the topical application of phytochemicals to the skin. This review focuses on the nutritional aspect of phytochemicals in humans-ie, the provision of carotenoid micronutrients by dietary means to the skin and their role in protection. Human intervention studies have documented protective effects for β-carotene or for lycopene provided either by a carotenoid-rich diet or by supplementation. In exposed tissues, light induces primary and secondary photooxidative processes. Scavenging of reactive oxygen species is considered to be a mechanism of action underlying the protective activity of carotenoids. However, food comprises a complex mixture of numerous constituents, so that other components may also contribute to the observed activity. Molecules with suitable structures absorb UV light and prevent direct damage of cellular targets. Phytoene and phytofluene are precursor molecules of higher unsaturated carotenoids and occur in various fruit and vegetables. Their absorption spectra cover the UVB and UVA range, respectively, thus potentially contributing to photoprotective effects of carotenoid-rich food. Because of the physiologic turnover time of skin, several weeks are required for protective effects to appear. Photoprotection through individual dietary components such as β-carotene or lycopene in terms of sun protection factor is considerably lower than that achieved by using topical sunscreens. However, an optimal supply of antioxidant micronutrients in the skin increases basal dermal defense against UV irradiation, supports longer-term protection, and contributes to maintenance of skin health and appearance.

Influence of NPK fertilization enriched with S, Mg, and micronutrients contained in liquid fertilizer Insol 7 on potato tubers yield (Solanum tuberosum L.) and infestation of tubers with Streptomyces scabies and Rhizoctonia solani

Elemental sulphur and Kieserite fertilization have been demonstrated to improve potato tuber (Solanum tuberosum) yield quality and resistance against Streptomyces scabies; the bacterial effect was attributed to reduced soil pH. So far, no information has been available about the influence of S, Mg and supply of micronutrients on bacterial and fungal diseases of potato plants. Field trials performed in a split-plot design with varied fertilization treatments (NPK with/without S and Mg and microelements B, Zn, Mn, Cu fertilization) including three potato cultivars were conducted in the south eastern region (near Zamoœae) of Poland in 2004-2006. The application of S and Mg and micronutrients decreased the tuber infection rate and severity of Streptomyces scabies and Rhizoctonia solani, while increasing potato tuber yield. Generally, tuber yield and wholesomeness were mostly related to a genotype (cultivar), mineral fertilization treatments and their interaction with

Potencial de fertilizantes e corretivos no aporte de micronutrientes ao solo

Fertilizantes e corretivos, ao serem aplicados nos solos, fornecem micronutrientes como impurezas residuais da sua fabricação, os quais podem ser importantes fontes para as culturas. Em decorrência disso, o objetivo deste trabalho foi quantificar os teores dos micronutrientes Zn, Cu, Fe, Mn e Ni em fertilizantes e corretivos comercializados no Nordeste brasileiro, visando avaliar o potencial desses insumos no fornecimento indireto de micronutrientes às culturas agrícolas. Os insumos analisados neste estudo (24 amostras de fertilizantes e 26 de corretivos) foram coletados nos Estados da Bahia e Pernambuco pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA) e digeridos pelo método 3051A (USEPA, 1998). As determinações dos micronutrientes foram feitas por espectrofotometria de absorção atômica. Amostras de fertilizante SRM 695 (National Institute of Standards and Technology - NIST) e spikes foram adicionadas para controle de qualidade das análises. Os fertilizantes fosfatados, em geral, apresentaram maiores teores de micronutrientes do que os demais produtos testados. Os fertilizantes e corretivos avaliados representam uma fonte de micronutrientes ao solo que não pode ser desprezada. No entanto, a real disponibilidade desses elementos aportados ao solo necessita ser avaliada em estudos com plantas, pois fatores como solubilidade dos insumos, absorção pelas culturas, reações com o solo e perdas por precipitação e lixiviação devem ser considerados.

Zonal variability in primary production and nitrogen uptake rates in the southwestern Indian Ocean and the Southern Ocean

Hydrographic parameters along with the primary and new production measurements were carried out during the austral summer, 2009, in the southwestern Indian Ocean and Indian sector of the Southern Ocean (SO). The production varies from 185 to >900mgCm−2d−1 in different zones of SO. The zonal variations in production accompany variations in SST, salinity and nutrients. Further, the new production (0.3 to 4.1mmolNm−2d−1) covaries with the overall production, while the uptake of reduced forms of nitrogen (both NH4 and urea) show opposite trends. In the NO3 limiting environment (north of subtropical convergence), NH4 uptake dominates the total regenerated production, whereas, urea uptake dominates the regenerated production under Si, light and micronutrient (e.g., Fe) limiting conditions (found between the subtropical convergence and Antarctica). On the basis of the C and N uptake data, the studied region can be divided into five zones (from the south to the north) viz., located between (i) the Antarctic continent and the polar front (Antarctic zone; ANZ), (ii) the polar and subantarctic fronts (SAF) (Polar frontal zone; PFZ), (iii) SAF and Agulhas Retroflection fronts (ARF) (South Subtropical front; SSTF), (iv) subtropical frontal zone (STFZ), and (v) ARF and the north subtropical front (Subtropical zone; STZ). Except at SSTF, regenerated production dominates in all the zones. From the south to the north, this could be due to different reasons e.g., light, grazing by zooplankton, supply of key micronutrients (probably Fe), Si-limitation, or NO3-limitation. In the absence of such limitations, the maximum possible f-ratio in SO could be as high as 0.78±0.12 and under such conditions the region could export most of the total production to the deep. Supply of micronutrients through the Agulhas return current and from the Crozet Island supports the higher chl a, C uptake and new production at the 48°E transect relative to the 57.5°E transect. The C:N assimilation ratio is found to be 5.64, marginally lower than the canonical Redfield ratio. This slight difference is likely due to the variation in the composition of phytoplankton and NO3-limitation in some zones. A comparison with earlier results shows that seasonal and spatial variations in f-ratios in these zones are much higher than its inter-annual variability.

The Southern Kalahari: a potential new dust source in the Southern Hemisphere?

Most sources of atmospheric dust on Earth are located in the Northern Hemisphere. The lower dust emissions in the Southern Hemisphere in part limit the supply of micronutrients (primarily soluble iron) to the Southern Ocean, thereby constraining its productivity. Climate and land use change can alter the current distribution of dust source regions on Earth. Can new dust sources be activated in the Southern Hemisphere? Here we show that vegetation loss and dune remobilization in the Southern Kalahari can promote dust emissions comparable to those observed from major contemporary dust sources in the Southern African region. Dust generation experiments support the hypothesis that, in the Southern Kalahari, aeolian deposits that are currently mostly stabilized by savanna vegetation are capable of emitting substantial amounts of dust from interdune areas. We show that dust from these areas is relatively rich in soluble iron, an important micronutrient for ocean productivity. Trajectory analyses show that dust from the Kalahari commonly reaches the Southern Ocean and could therefore enhance its productivity.

An evaluation of macronutrient nutritional status of sugar beets in critical stages of growth in response to foliar application of multi-micronutrient fertilizers

The actual yields of sugar beets harvested by farmers in Poland are much below the yielding potential of currently cultivated varieties, even when grown on fertile soils. Deficiency of micronutrients can be considered as a factor which prohibits reaching a state of nutrient balance, especially in nitrogen, by a crop. The aim of the study was to assess the effect of foliar application of multi-microelement fertilizers on a sugar beet nutritional status in early stages of canopy growth and, in turn, on yields of taproots and recoverable sugar. For this purpose, in two growing seasons, 2005 and 2006, eight field trials were set up in the region of Wielkopolska on fertile soils originated from sandy loam. A simple experimental design comprised three treatments: (1) control (a plot fertilized only with NPK), and (2) multi-microelement fertilizer composed of cations (Mi), (3) cations plus boron (MiB). It has been found that the applied micronutrient fertilizers had a significant effect, irrespectively of the field location and seasonal yield variability, on the sugar beet nutritional status, especially in terms of nitrogen. Yields of taproots have increased by 31.6% and 22.1% for the NPK+Mi and NPK+MiB treatments, respectively. Almost the same degree of increase was noted for yields of recoverable sugar. The achieved nitrogen balance at the stage of harvestable part development, as measured at BBCH43, was probably the main reason for high positive response of sugar beet crop to external supply of micronutrients. All the analyzed standards of sugar beet nutritional status, DRIS indices, responded to the investigated experimental factor, i.e., foliar application of multi-microelement fertilizer, but only

Deficiency symptoms and uptake of micronutrients by castor bean grown in nutrient solution

Castor bean is a nutrient-demanding species, but there is still little information on its micronutrient requirements. The objectives of this study were to evaluate the effects of levels of B (2.5, 12.5 and 25.0 µmol L-1), Cu (0.05, 0.25 and 0.50 µmol L-1), Mn (0.2, 1.0 and 2.0 µmol L-1) and Zn (0.2, 1.0 and 2.0 µmol L-1) in a nutrient solution on plant B, Cu, Mn and Zn concentrations and uptake, vegetative growth and fruit yield of castor bean "Iris", grown in greenhouse. The experiment was arranged in a completely randomized block design with three replicates. The first deficiency symptoms were observed for B, followed by Zn, Cu and Mn. The main changes in the cell ultrastructure due to lack of B were thickening of the cell walls and middle lamellae, distorted chloroplasts and tightly stacked thylakoids, besides the absence of starch grains. The Mn, Zn and Cu deficiencies led to disruption of chloroplasts, disintegration of thylakoids and absence of amyloplasts. The concentration and uptake of B, Cu, Mn, and Zn in castor bean plants increased with micronutrient supply in the solution. Fruit yield was drastically reduced by B and Mn deficiencies. On the other hand, the dry matter yield of the shoot and root of castor bean plants was not. In the treatment with full nutrient solution, the leaves accumulated 56 and 48 % of the total B and Mn taken up by the plants, respectively, and the seeds and roots 85 and 61 % of the total Cu and Zn taken up, respectively. This shows the high demand of castor bean Iris for B and Mn for fruit yield.

Pemberian fortifikasi multi-mikronutrien berpengaruh terhadap pertumbuhan balita keluarga miskin

Background: Underfives from poor communities are susceptible group that will unlikely have suffcient nutrition (micronutrient) meanwhile this micronutrient is essential for growth. Some studies show the supplementation of micronutrient has good effects to child growth. Therefore it is necessary to study the supply of fortified multi-micronutrient and its effect to growth of underfives from poor communities.Objective: To identify the supply of fortifed multi micronutrient and its effect to growth of underfves of 6-59 months from poor communities.Method: The study was a pre-experiment that used a group pre test-post test design. Subject were underfives of 6-59 months from poor communities that got fortifed multi micronutrient. The intervention of fortifed multi micronutrient supply was given once a week (1 sachet/day) within 4 months. Data of family characteristics and identity of the subject were collected at the beginning of the study. Measurement of physical weight and height/length, consumption recall, collection of data on disease infection (acute respiratory tract and diarrhea) were carried out at the beginning and end of the study.Results: The result of statistics test showed there was signifcant increase (p<0.05) in weight, height/length and nutrition status (z-score) to index of weight for height/length, height for age, and that there was signifcant descent to acute respiratory tract infection and diarrhea of underfves of 6-59 months from poor communities after the supply of fortifed micronutrient containing vitamin A, B1, B2, B3, B6, B12, folate acid, vitamin C, D3, E, Fe and zink.Conclusion: The supply of fortifed multi micronutrient could increase weight, height/length and nutrition status (z-score), index of weight for height/length and index of weight for age and decreased of acute respiratory tract infection and diarrhea disease in underfives of 6-59 months from poor communities.

Nitrogen fertilization does not affect micronutrient uptake in grain maize (Zea mays L.)

Due to continuous single nitrogen fertilization, we hypothesized a built-up deficiency of micronutrients in crops that would limit plant growth and crop quality. In 2-year field experiments using urea-N fertilized grain maize (Zea mays L.), hybrid KWS 2376 at 0, 120 and 240 kg N ha−1 crop uptake of Zn, Mn, Cu and Fe was studied at DC 32, DC 61 and in the grain harvested. Micronutrient contents at DC 32 stage – 1st node (aboveground phytomass) and DC 61 – flowering (ear leaf) were all at levels indicative of adequate micronutrient supply to the crop. At both sampling occasions the Fe:Zn and Fe:Mn ratios were adequate implying that Fe did not inhibit the uptake of Zn and Mn. The application of nitrogen increased the Fe content at the 1st sampling in both years; in the second year the same was also the case for the Zn content. Nitrogen nutrition increased the contents of Mn and Fe at the 2nd sampling only in year 2; in the other treatments no changes were observed in the micronutrient contents. Micronutrient correlations in the grain were discovered between Zn and Mn contents and between Fe and Mn contents. In the second year the highest N-rate significantly increased the Fe and Zn content of the grain compared with the lower rates of nitrogen fertilization. Grain yields were not affected by the rate of nitrogen and ranged between 13.65 and 14.34 t ha−1 (1st year) and between 13.68 and 14.18 t ha−1 (2nd year). Nitrogen fertilization did not reduce the content of micronutrients in the plant or grain of maize. It is evident that the continuous single use of N fertilization so far has not resulted in a micronutrient deficiency of the plants limiting the nutrient density of the grain or reducing its quality.

Changes in micronutrient supply to the surface Southern Ocean (Atlantic sector) across the glacial termination

Major deepwater masses upwell and reach the surface in the Southern Ocean, forming an important conduit supplying nutrients and micronutrients to the surface and playing a key role in the regulation of global climate through ocean-atmosphere gas exchange. Here, we reconstruct changes in micronutrient distribution in this region in response to past changes in upwelling, oceanic mixing, and sea-ice seasonality. We present two downcore (Zn/Si)opal records from the Scotia Sea and Drake Passage region, which we interpret in the context of micronutrient distribution in the Atlantic sector of the Southern Ocean over the last glacial termination. Previous work shows that micronutrient availability in the surface waters in the South Atlantic appear to be controlled dominantly by upwelling and mixing of micronutrient rich deepwaters, which are additionally fuelled by the terrestrial sediment sources of the Scotia Arc and South Georgia. This is supported by our reconstructions, which show micronutrient availability to the west of the Scotia Arc and South Georgia are consistently lower than to the east over the last glacial termination due to downstream transport and mixing into surface waters of continentally derived material in the Antarctic Circumpolar Current. Micronutrient availability in this region was at a minimum from 20 to 25 ky BP, coinciding with maximum sea-ice coverage, and increased due to an expansion of the seasonal sea-ice zone and increased mixing of subsurface waters. Our findings are consistent with largely diminished upwelling of micronutrients during the maximum glacial extent, and reduced mixing due to the presence of persistent sea-ice. During the deglacial there was an increase in micronutrient availability, as well as other nutrients and inorganic carbon, within the Antarctic Circumpolar Current as a result of an increase in deep oceanic upwelling, mixing and strengthened zonal transport.

Escória de siderurgia e seus efeitos nos teores de nutrientes e metais pesados em cana-de-açúcar

Tipos de escórias se acumulam nos pátios das indústrias, tornando-se um problema ambiental, cuja disposição final em campos agrícolas é uma prática que pode minimizar a acumulação desses resíduos e, ao mesmo tempo, fornecer nutrientes às plantas e corrigir a acidez dos solos; apesar disto, há necessidade de se avaliar que riscos esses resíduos podem gerar ao ambiente. Objetivou-se, com este trabalho, avaliar a disposição final da escória de aciaria de forno elétrico e o fornecimento de silício, macronutrientes (Ca, Mg e P), micronutrientes (Fe, Mn, Zn, Cu, Ni) e elementos tóxicos (Cd e Pb) para a cana-de-açúcar. O experimento foi realizado em solo classificado como Argissolo Vermelho-Amarelo. Doses de escória de 0; 0,5; 1,0; 2,0 e 4,0 t ha-1 foram aplicadas no sulco de plantio no qual foi semeada; posteriormente, a cana-de-açúcar (var. RB92579). A escória de aciaria aumentou significativamente os teores de Ca, Mg, P, Si, Fe, Mn e Zn no solo e reduziu a acidez potencial. Houve aumento na área foliar e na altura dos colmos, tanto quanto no teor de Zn nas folhas. Não foi detectada a presença de Ni, Cd e Pb no solo nem na planta, indicando que a utilização de escória de aciaria não causou contaminação com esses elementos.

Dietary Antioxidants: Immunity and Host Defense

Natural antioxidants may be defined as molecules that prevent cell damage against free radicals and are critical for maintaining optimum health in both animals and humans. In all living systems, cells require adequate levels of antioxidant defenses in order to avoid the harmful effect of an excessive production of reactive oxygen species (ROS) and to prevent damage to the immune cells. During the inflammatory processes, the activation of phagocytes and/or the action of bacterial products with specific receptors are capable of promoting the assembly of the multicomponent flavoprotein NADPH oxidase, which catalyzes the production of high amounts of the superoxide anion radical (O(2)(-)). Under these particular circumstances, neutrophils and macrophages are recognized to produce superoxide free radicals and H(2)O(2), which are essential for defence against phagocytized or invading microbes. In this state, antioxidants are absolutely necessary to regulate the reactions that release free radicals. Antioxidant nutrients commonly included in the diet such as vitamin E, vitamin C, β-carotene, selenium, copper, iron and zinc improve different immune function exhibiting an important protective role in infections caused by bacteria, viruses or parasites. As a result, dietary antioxidants have been related to modulate the host susceptibility or resistance to infectious pathogens. Overall, numerous studies have suggested that the development of tolerance, and control of inflammation are strongly correlated with specific immune mechanisms that may be altered by an inadequate supply of either macronutrients or micronutrients. Therefore, the present paper will review the effects of dietary antioxidants on immune cell function and the impact on protection against infectious microorganisms.

Oceanography of the subantarctic and Polar Frontal Zones south of Australia during summer: Setting for the SAZ-Sense study

This paper provides a description of the physical and chemical properties (temperature, salinity, macro-nutrient, and oxygen concentrations) and bulk biomass indicators (chlorophyll and beam attenuation) prevailing in the subantarctic zone and polar front zones south of Tasmania (Australia) during the ‘Sensitivity of the subantarctic zone to environmental change’ (SAZ-Sense) expedition carried out in the austral summer of 2007. Phytoplankton biomass showed a characteristic north–south gradient of decreasing chlorophyll from the subantarctic zone to Polar Frontal Zone, as well as a zonal gradient in the northern subantarctic zone, with an increase in chlorophyll from southwest to southeast of Tasmania. The representativeness of the observations was assessed by comparison to previous studies including satellite observation of chlorophyll biomass over a 10-year period. We consider the possible role of spatial differences in: (i) ocean water masses and frontal systems, (ii) upper mixed layer stratification at three process stations, and (iii) nutrient availability, in controlling the observed variations in phytoplankton biomass in the region. Zonal gradients of the basic oceanographic physical and chemical conditions in the subantarctic zone were relatively small and therefore unlikely to control the three-fold west-to-east differences observed in the accumulation of phytoplankton biomass. The zonal variation in subantarctic zone chlorophyll biomass appears to be driven at least partly by greater micro-nutrient (iron) supply to the waters east of Tasmania, as reported also by others ( Bowie et al., 2009; Mongin et al., 2011a). Despite this condition, the region of higher phytoplankton biomass to the southeast of Tasmania was only marginally more productive than the region of lower biomass west of Tasmania and south of the polar front, and exported less particulate carbon than the lower biomass waters ( Jacquet et al., 2011).

Farming for balanced nutrition: an agricultural approach to addressing micronutrient deficiency among the vulnerable poor in Africa

Concepts on malnutrition have evolved from an emphasis on protein deficiency through energy deficit, to the realization that food quality in general and an adequate supply of micronutrients in particular, is often more of a problem than food quantity. Throughout the developing world, micronutrient deficiency is one of the most important factors influencing human health, being directly responsible for conditions such as xeropthalmia, associated with vitamin A deficiency and anaemia, due to iron deficiency. In addition, micronutrient deficiency predisposes children to infection and retards recovery from common infections such as malaria, measles and diarrhoea. The groups most at risk from micronutrient deficiency are usually children and those for whom labour for food production is limited by ill health (HIV sufferers), advancedage or intense social commitments (single mothers, for example). There have been numerous health projects in sub-Saharan Africa and elsewhere in the developing world, to address micronutrient deficiency through the distribution of vitamin and mineral supplements, which usually have to be imported. An alternative (or complementary) approach is to promote the inclusion of high quality food crops in the farming system to enrich the diet with essential vitamins and minerals. This agricultural approach to the problem of micronutrient deficiency can provide sustainable solutions, which improve diet quality. An increase in the cultivation ofhigh quality foods such as legumes, fruits and green vegetables, may be able to deliver a balanced diet to households, without necessarily requiring additional land and labour. Agricultural approaches to enhance dietary intake of vitamins and minerals have the additional advantage that they foster community self-reliance, they are sustainable in the absence of external funding, and, offer the opportunity for enhanced income by marketing surplus production. Diet diversification through betteruse of existing biodiversity offers an immediate means to address poor diet quality and can also include the use of presently available nutritionally enhanced crops, such as orange-fleshed sweet potato.

Micronutrients at the Interface Between Inflammation and Infection Ascorbic Acid and Calciferol. Part 2: Calciferol and the Significance of Nutrient Supplements

As explained in the first part of the article, vitamins and trace elements influence various metabolic functions that are directly related to immune function. In this context, secosteroid vitamin D has met with growing interest. The discussion has focused on whether and, if so, to what extent, vitamin D might contribute to the prevention and possibly the treatment of infections and autoimmune diseases. We know, for instance, that immune cells are capable of synthesizing calcitriol from its precursor calcidiol, whereby the former enhances the synthesis of antibacterial peptides by macrophages while simultaneously inhibiting the (auto)immune response mediated by T helper cells (Th1). Numerous observational studies support the hypothesis that a vitamin D deficit increases the risk of autoimmune diseases such as type 1 diabetes mellitus, multiple sclerosis, psoriasis and rheumatoid arthritis; however, there are few reliable interventional studies to date. In general, immune status represents a sensitive indicator of micronutrient supply. Conversely, the activity of the immune system has an effect on the status of and requirements for nutrients.

The importance of antioxidant micronutrients in pregnancy.

Pregnancy places increased demands on the mother to provide adequate nutrition to the growing conceptus. A number of micronutrients function as essential cofactors for or themselves acting as antioxidants. Oxidative stress is generated during normal placental development; however, when supply of antioxidant micronutrients is limited, exaggerated oxidative stress within both the placenta and maternal circulation occurs, resulting in adverse pregnancy outcomes. The present paper summarises the current understanding of selected micronutrient antioxidants selenium, copper, zinc, manganese, and vitamins C and E in pregnancy. To summarise antioxidant activity of selenium is via its incorporation into the glutathione peroxidase enzymes, levels of which have been shown to be reduced in miscarriage and preeclampsia. Copper, zinc, and manganese are all essential cofactors for superoxide dismutases, which has reduced activity in pathological pregnancy. Larger intervention trials are required to reinforce or refute a beneficial role of micronutrient supplementation in disorders of pregnancies.

The Micronutrient Genomics Project: a community-driven knowledge base for micronutrient research

Micronutrients influence multiple metabolic pathways including oxidative and inflammatory processes. Optimum micronutrient supply is important for the maintenance of homeostasis in metabolism and, ultimately, for maintaining good health. With advances in systems biology and genomics technologies, it is becoming feasible to assess the activity of single and multiple micronutrients in their complete biological context. Existing research collects fragments of information, which are not stored systematically and are thus not optimally disseminated. The Micronutrient Genomics Project (MGP) was established as a community-driven project to facilitate the development of systematic capture, storage, management, analyses, and dissemination of data and knowledge generated by biological studies focused on micronutrient–genome interactions. Specifically, the MGP creates a public portal and open-source bioinformatics toolbox for all “omics” information and evaluation of micronutrient and health studies. The core of the project focuses on access to, and visualization of, genetic/genomic, transcriptomic, proteomic and metabolomic information related to micronutrients. For each micronutrient, an expert group is or will be established combining the various relevant areas (including genetics, nutrition, biochemistry, and epidemiology). Each expert group will (1) collect all available knowledge, (2) collaborate with bioinformatics teams towards constructing the pathways and biological networks, and (3) publish their findings on a regular basis. The project is coordinated in a transparent manner, regular meetings are organized and dissemination is arranged through tools, a toolbox web portal, a communications website and dedicated publications.

Changes in the freshwater composition of the upper ocean west of the Antarctic Peninsula during the first decade of the 21st century

In recent decades, the west Antarctic Peninsula (WAP) has warmed more rapidly than anywhere else in the Southern Hemisphere. Associated with this, there has been a marked shortening of the sea ice season, a retreat of the majority of glaciers, and an increase in precipitation. Each of these changes in the freshwater system has the potential to exert significant influence on the ecosystem, via processes such as stabilisation of the upper water column, and supply of micronutrients to the mixed layer. Here we use a time series of hydrographic and stable oxygen isotope ( δ 18O) measurements collected at a near-coastal site in Marguerite Bay to quantify the prevalence of meteoric freshwater (glacial melt plus precipitation) separately from sea ice melt. During 2002–2009, meteoric water dominated, with summer water column inventories of order 4–6 m. Summer sea ice melt inventories were lower, ranging from −1 to 0.5 m (where a negative value indicates net sea ice formation from this water). In the near-surface layers, we find highest meteoric water prevalence in February 2006 (∼6%) and lowest in October 2007 (∼1%), whilst sea ice melt is highest in February 2005 (2%) and lowest in July 2002 (−2%). The ranges in both meteoric water and sea ice melt are significantly larger than derived previously using a subset of the data, reflecting the strong interannual variability present. The largest single determinant of the near-surface freshwater percentages is found to be changes in mixed layer depth. Notably deep layers occurred in the winters of 2003, 2007 and 2008, due to northerly winds associated with El Niño/Southern Oscillation and the Southern Annular Mode. These led to greatly reduced sea ice cover in northern Marguerite Bay, and allowed persistent air-sea heat fluxes and stronger rates of sea ice production, which is a key factor in controlling mixed layer depth. We also discuss the possible role of interannual changes in wind-induced mixing in this context. As climate change at the WAP continues, we expect further changes in each of the components of the freshwater budget, and also changes in the vertical redistribution of this freshwater by oceanographic processes. Our ongoing δ 18O monitoring will help track these changes, and elucidate their consequences for the operation of the marine ecosystem.

The continental shelf benthic iron flux and its isotope composition

Benthic iron fluxes from sites along the Oregon–California continental shelf determined using in situ benthic chambers, range from less than 10 μmol m −2 d −1 to values in excess of ∼300 μmol m −2 d −1. These fluxes are generally greater than previously published iron fluxes for continental shelves contiguous with the open ocean (as opposed to marginal seas, bays, or estuaries) with the highest fluxes measured in the regions around the high-sediment discharge Eel River and the Umpqua River. These benthic iron fluxes do not covary with organic carbon oxidation rates in any systematic fashion, but rather seem to respond to variations in bottom water oxygen and benthic oxygen demand. We hypothesize that the highest rates of benthic iron efflux are driven, in part, by the greater availability of reactive iron deposited along these river systems as compared to other more typical continental margin settings. Bioirrigation likely plays an important role in the benthic Fe flux in these systems as well. However, the influence of bottom water oxygen concentrations on the iron flux is significant, and there appears to be a threshold in dissolved oxygen (∼60–80 μM), below which sediment–ocean iron exchange is enhanced. The isotope composition of this shelf-derived benthic iron is enriched in the lighter isotopes, and appears to change by ∼3‰ (δ 56Fe) during the course of a benthic chamber experiment with a mean isotope composition of −2.7 ± 1.1‰ (2 SD, n = 9) by the end of the experiment. This average value is slightly heavier than those from two high benthic Fe flux restricted basins from the California Borderland region where δ 56Fe is −3.4 ± 0.4‰ (2 SD, n = 3). These light iron isotope compositions support previous ideas, based on sediment porewater analyses, suggesting that sedimentary iron reduction fractionates iron isotopes and produces an isotopically light iron pool that is transferred to the ocean water column. In sum, our data suggest that continental shelves may export a higher efflux of iron than previously hypothesized, with the likelihood that along river-dominated margins, the benthic iron flux could well be orders of magnitude larger than non-river dominated shelves. The close proximity of the continental shelf benthos to the productive surface ocean means that this flux is likely to be essential for maintaining ecosystem micronutrient supply.

Impact of off-farm income on food security and nutrition in Nigeria

While the poverty implications of off-farm income have been analyzed in different developing countries, much less is known about the impact of off-farm income on household food security and nutrition. Here, this research gap is addressed by using farm survey data from Nigeria. Econometric analyses are employed to examine the mechanisms through which off-farm income affects household calorie and micronutrient supply, dietary quality, and child anthropometry. We find that off-farm income has a positive net effect on food security and nutrition. The prevalence of child stunting, underweight, and wasting is lower in households with off-farm income than in households without. Using a structural model, we also show that off-farm income contributes to higher food production and farm income by easing capital constraints, thus improving household welfare in multiple ways.