Top PDF Distribution of intermediate water masses in the subtropical northeast Atlantic

Distribution of intermediate water masses in the subtropical northeast Atlantic

Distribution of intermediate water masses in the subtropical northeast Atlantic

various modes of the North Atlantic Central Water are formed. The subduction is the most efficient in winter, when the internal water structure is not sheltered by the sea- sonal thermocline. The deep convection is a results of the gravitational instability and is mostly active in weakly stratified polar waters in winter due to intensive heat loss and salinification in the course of ice formation (van Aken, 2000a).

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The Northeast Atlantic is running out of excess carbonate in the horizon of cold-water corals communities

The Northeast Atlantic is running out of excess carbonate in the horizon of cold-water corals communities

The uptake of anthropogenic carbon from the atmosphere is unequivocally decreasing the amount of carbon- ate available for marine calcifiers in the upper (NACW) and intermediate water masses (MW and LSW) of the Northeast Atlantic Ocean. The northward spreading of MW plays a key role in limiting the arrival of subpolar- origin waters with low excess of carbonate available. The chemical conditions that made the Northeast Atlantic a region favorable for CWC development in preindustrial time are changing fast due to ocean acidification. Currently, provided the water masses contribution remain the same, living CWC would inhabit undersaturated waters when the atmospheric CO 2 concentration reaches 702 ± 57 ppm. If greenhouse gas emissions maintain
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Braz. j. oceanogr.  vol.64 número3

Braz. j. oceanogr. vol.64 número3

The contour current that encloses the subtropical gyre of the South Atlantic on its western border is the BC. This current originates at 10 °S in a region where the southernmost branch of the South Equatorial Current (SEC) bifurcates to form the North Brazil Current (NBC) (Figure 8). The BC then lows south, skirting the South American continent as far as the region of the Subtropical Convergence (33-38 °S), where it lows together with the MC and diverges from the coast (STRAMMA; ENGLAND, 1999; SILVEIRA et al., 2000). L. faxoni was observed north of the region that contains the BC and BC front, indicating that this species may be transported by this current. XU (2010) states that L. typus is a eurythermal and stenohaline species that occurs in tropical oceans. Thus, this species is considered oceanic and occurs at depths greater than 200 m (BOWMAN; MCCAIN, 1967). In this study, L. typus exhibited greater distribution in the sample area than did L. faxoni. This inding supports the literature on the occurrence of this species in oceanic regions with low variations in salinity. In contrast, L. faxoni is described in the literature as a species with a preference for coastlines, although records indicate that it has been found in regions of greater depth (BOWMAN; MCCAIN, 1967; D’INCAO, 1997). The results of this study indicate that L. typus may be transported in the South Atlantic Subtropical Gyre by the BC and SAC. The results also indicate that L. faxoni, despite having a preference for the coast, is transported to oceanic regions by the BC, and both species are limited in distribution to the subtropical gyre of the South Atlantic. The occurrence of these species covers an area where the SACW is formed by the sinking of waters in the conluence zones of the BC and the MC. This water is then transported in the direction of Africa by the SAC (STRAMMA; ENGLAND, 1999). These currents can limit the dispersion of these species in the subtropical gyre of the South Atlantic.
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Phytoplankton growth and microzooplankton grazing in the subtropical Northeast Atlantic.

Phytoplankton growth and microzooplankton grazing in the subtropical Northeast Atlantic.

operations. Containers were kept in dark during the whole process until placed in on-deck incubators. Incubations started always 1.5 h after water collection and lasted approximately 21 h. Blue sheets of light filters were combined to simulate in-situ light intensity and spectra. When necessary, the combination of light filters was corrected after light measurements in the morning, thus correcting possible small shifts in the amount of irradiance reaching the different depths. Temperature was kept within 60.5 o C of in situ temperature by connecting a cooler and a heater to two thermostats. Water inside the incubator was homogenized Figure 2. Properties of the water column during dilution experiments. Vertical profiles of temperature (A, H), salinity (B, I), fluorescence (C, J), oxygen (D, K), O 2 saturation (E, L), nitrate plus nitrite (F, M) and phosphate (G, N) in the upper 200 m during dilution experiments in WL (top) and EL
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Carbonate system buffering in the water masses of the Southwest Atlantic sector of the Southern Ocean during February–March 2008

Carbonate system buffering in the water masses of the Southwest Atlantic sector of the Southern Ocean during February–March 2008

the upwelling of carbonate depleted deep waters is the most dominant driver of winter- time carbon cycling, in comparison with the solubility or biological processes (McNeil et al., 2007). Physical processes such as deep water formation in the Weddell Sea, upwelling of deep water at the divergence zone and formation of intermediate water in the Antarctic Polar Zone (APZ) affect the carbon dioxide system parameters, which has

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Carbonate system in the water masses of the Southeast Atlantic sector of the Southern Ocean during February and March 2008

Carbonate system in the water masses of the Southeast Atlantic sector of the Southern Ocean during February and March 2008

The carbonate properties were presented as a function of the different water masses found in the region. In the sub- tropical zone, the distribution of all the properties was gov- erned by deep anticyclonic and cyclonic features generated by the Agulhas Current System. At the SAF, subduction of the South Atlantic variety of Antarctic Intermediate Wa- ter, the AAIW, was identified by the northward deepening of carbonate variables and elevated CFC concentrations. In the Cape Basin area, the Atlantic variety met the Indian AAIW injected with the Agulhas Rings, becoming saltier and warmer but also with a higher content of inorganic car- bon than that found at 45 ◦ S. At greater depths, two North Atlantic Deep Water branches were defined. The first one corresponds to the eastern NADW pathway, with low CFC- 12 concentration (<0.02 pmol kg −1 ). The second one, en- compassing the Antarctic Polar Zone, is associated with the NADW injected in the Antarctic Circumpolar Current in the south-western Argentine Basin with CFC-12 concentrations in the range of 0.08 to 0.1 pmol kg −1 .
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SUBDUCTION OF SOUTH ATLANTIC SUBTROPICAL MODE WATERS

SUBDUCTION OF SOUTH ATLANTIC SUBTROPICAL MODE WATERS

STMWs occur in all the oceans, and many studies have been developed in order to describe their spatial distribution and to understand the associated formation processes, especially in the northern hemisphere. For example, the 18 ◦ C water which is formed in the internal border of the Gulf Stream in a region of intense heat loss to the atmosphere and which covers a large ex- tension in the North Atlantic ocean, is probably the best described mode water in literature (e.g., Schroeder et al., 1959; Worthing- ton, 1959; Talley & Raymer, 1982; Jenkins, 1987; New et al., 1995; Klein & Hogg, 1996; Paiva & Chassignet, 2002; Peng et al., 2006). In spite of the relative stability of the main properties of this mode water, observational data indicate that interannual thickness and temperature anomalies can be intense, being asso- ciated to anomalous atmospheric forcing (Talley & Raymer, 1982; Talley, 1996; Hanawa & Talley, 2001; Paiva & Chassignet, 2002). On the other hand, in the North Pacific ocean, a colder mode wa- ter is formed in the Kuroshio extention, with temperature of 16 ◦ C and salinity of 34.8, which is called North Pacific Mode Water (Talley, 1988; Suga & Hanawa, 1995). Having a large zonal ex- tension, the Pacific ocean presents other two SMWs: the central subtropical mode water, with temperature varying from 9 to 12 ◦ C and the eastern subtropical mode water, with temperature varying from 12 to 22 ◦ C (Hanawa & Talley, 2001).
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Oxygen and hydrogen isotope signatures of Northeast Atlantic water masses

Oxygen and hydrogen isotope signatures of Northeast Atlantic water masses

High precision stable isotope (δ 18 O, δD) analyses of fresh and ocean water were first discussed by Epstein and Mayeda (1953) and Friedman (1953). Craig and Gordon (1965) later showed that δ 18 O can be used as a water mass tracer and that the δ 18 O-salinity relationship follows a slope of 0.61 in the surface waters of the high-latitude North Atlantic and thus the North Atlantic Deep Water (NADW) but changes to a slope of 0.22 in the surface waters of the subtropical North Atlantic or even 0.11 in the Atlantic’s equatorial trough. Subsequent studies focused on specific regions (e.g., Fairbanks, 1982; Van Donk and Mathieu, 1969; Weiss et al., 1979) and a global study of seawater stable isotope transects and vertical profiles was made by the GEOSECS program (Östlund et al., 1987). Although the GEOSECS program provided the first global data set, the spatial coverage was limited. In the North Atlantic south of the Greenland-Iceland-Scotland ridge, six vertical stations covered the complete water column, but only Station 115 at 28°N and 26°W was located in the eastern basin. After the GEOSECS program a major gap followed in seawater stable isotope studies. In the last two decades, however, various studies provided new δ 18 O data that focused on high latitude regions and the influence of meltwater in the Atlantic sector (e.g., Azetsu-Scott and Tan, 1997; Bauch et al., 1995; Cox et al., 2010; Mackensen, 2001; Meredith et al., 1999a; Meredith et al., 1999b), the NW African upwelling region off Cape Blanc (Pierre et al., 1994: Fig. 1b) and the Mediterranean Sea (Pierre, 1999). Pierre et al. (1994) proposed a slope of 0.46 for the δ 18 O-salinity mixing line
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Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera

Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera

Several studies have been conducted regarding the sub- arctic Pacific, including the western North Pacific (Ahagon et al., 2003; Sagawa and Ikehara, 2008), the Okhotsk Sea (Ohkushi et al., 2003), and the Bering Sea (Horikawa et al., 2010; Rella et al., 2012). Together, this body of work has improved our understanding of intermediate and deep water formation and ocean circulation in the subarctic North Pa- cific since the Last Glacial Maximum (LGM). During the LGM, a centre of high-nutrient water, recognised by the lowest benthic carbon isotope values in direction of depth, existed at ∼ 3000 m water depth, which is ∼ 1000–1500 m deeper than the level of a similar layer today in the North Pacific, suggesting a more vertically compressed circulation than today (Keigwin, 1998; Matsumoto et al., 2002). During the last deglaciation, Pacific circulation seemed to shift from a glacial stratified mode to an interglacial upwelling mode during the transition between Heinrich event 1 (H1) and the Bølling–Allerød interval (B/A) (Okazaki et al., 2010, 2012). In particular, deep water formation during H1, which may have reached ∼ 2500 m water depth, was suggested by 14 C age differences between planktic and benthic foraminifers (Okazaki et al., 2010). Okazaki et al. (2010) argued that, dur- ing H1, a deep Pacific Meridional Overturning Circulation (PMOC) was established, driven by a collapse of the Atlantic Meridional Overturning Circulation (AMOC) that occurred after a large freshwater discharge into the high-latitude North Atlantic. However, recently, Jaccard and Galbraith (2013) ar- gued against such a deep water formation and claimed that waters deeper than ∼ 2400 m were poorly ventilated, while the upper portion of the North Pacific (i.e. above ∼ 1400 m depth) was well ventilated. Regardless of the conclusion of the debate regarding how deep the ventilated water reached during H1, the upper 1400 m of the water column appears
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Nitrous oxide in the North Atlantic Ocean

Nitrous oxide in the North Atlantic Ocean

The WOCE A2 transect (Gauss 384-1 cruise), is located at the boundary region between the subpolar gyre (Gor- don, 1986) and the subtropical gyre (Krauss, 1996). This region is highly variable, characterized by the exchange of upper-ocean water between the gyres mainly via the North Atlantic Current, and the Labrador Current. One of the most important water masses here is the Labrador Sea Wa- ter (LSW). These water masses provide the major part of the North Atlantic Intermediate Water in combination with the outflow of Mediterranean Sea Water (MW), which is de- tected in the eastern basin of the subtropical Atlantic Ocean near the Strait of Gibraltar (Richardson et al., 2000) and the Antarctic Intermediate Water (AAIW) from the south (Lorbacher, 2000). Additional water masses of the south- ern hemisphere that penetrate into the North Atlantic are the South Atlantic Central Water (SACW) and the Antarctic Bot- tom Water (AABW). SACW flows northwards, and mixes with the North Atlantic Central Water (NACW) at approxi- mately 15 ◦ N in the western and 20 ◦ N in the eastern basin (Poole and Tomczak, 1999; Aiken et al., 2000).
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CONTINUOUS CREATION IN THE PROBABILISTIC WORLD OF THE THEOLOGY OF CHANCE

CONTINUOUS CREATION IN THE PROBABILISTIC WORLD OF THE THEOLOGY OF CHANCE

The metaphysicians of chance point to the probabilistic nature of scien- tiic laws. Such probabilistic laws assert some dependencies and enable us to predict (with a given probability) the future of aggregates or collectives, but not the future of their individual parts. We also meet this kind of unpre- dictability in the case of human behaviour, individual as well as social. All these data give us evidence that our universe has not been created according to a very detailed and precise plan encompassing all substances and all of their properties. Protons, electrons, and genes, but also species, kinds, and particular human beings, are not part of a divine plan and creative volition (Bartholomew 1984, p. 145). How could it be that God brings about the existence of beings which are purposeless, unpredictable and, as such, not determined by his creative volition? If our non-deterministic universe has a Creator, He does not control every substance and every property, de facto, he is not the Creator of all contingent entities in our world. Thus, divine action consists in the creation of the universe in its initial stage, and the world is such that God need neither act continuously upon that world nor intervene from time to time in order to achieve His aims. God created the world in such a way that His providence does not have to control absolutely every contingent substance at every moment of its existence in order to realize all that divine will wills to be realized.
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Ecologia de besouros micetócolos: novas perspectivas para biomas da América do Sul e África

Ecologia de besouros micetócolos: novas perspectivas para biomas da América do Sul e África

We accepted only the clusters with high Jackknife value. Dendrograms with scoring coefficients are shown in Figs 1 –4. Substantial similarities within each set of dendrograms defined a large-scale structure for each dataset. These structures are described by the coloured ciid clusters, of which there are three, six, five, and two in the SA, SFP, TAF and CER datasets, respectively (Figs. 1 –4). For each dataset, these clusters were composed by grouping ciids that use the same resource; and after that we joined the ciid species similar between datasets. There were few exceptions, as follows: (1) Cis sp.A-SA, Cis sp.B-SA, Cis sp.N-SA and Xylographus madagascariensis-SA, that belong to the Trametes group, was registered in Ganoderma fungus; (2) Xylographus sp.-SA found in Hymenochaete was kept in the Lenzites group; (3) Ceracis limai-SFP was kept in the Rigidoporus group, even though it was also found in Phellinus; (4) The Pycnoporus group and Trametes group were placed together in the final analysis due to the biological similarities of their species and phylogenetic proximity (Table 5).
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Freshening of the labrador sea as a trigger for little ice age development

Freshening of the labrador sea as a trigger for little ice age development

Regardless of the mineralogy of the grains, it is worth not- ing the high number of lithics per gram of sediment recorded in several samples during the MCA (Fig. 2). A recent com- prehensive study of the last 2 millennia (PAGES 2k Con- sortium, 2013) shows this interval presented sustained warm temperatures from AD 830 to 1100 in the Northern Hemi- sphere, including the Arctic region. The high occurrence of IRD from AD 1000 to 1250 suggests that during the MCA either a substantial amount of icebergs drifted to the study area or the drifting icebergs contained considerable amounts of IRD, or a combination of both explanations. Several stud- ies on East Greenland glaciers and fjords point to the con- sistent relationship between calving rate acceleration and the presence of warm Atlantic water in East Greenland fjords, brought by the Irminger Current (Andresen et al., 2012; Jen- nings and Weiner, 1996). Warm atmospheric temperatures as well as the presence of Atlantic water prevent the formation of sea ice in the fjords and in front of the glacier, thus in- creasing the calving rate by destabilizing the glacier tongue (Andresen et al., 2012; Murray et al., 2010). When tidewater glaciers are released from the sea ice, their speed increases due to the decreased flow resistance and increased along- flow stresses during the retreat of the ice front, and rapid changes may be observed in calving rates in response to dis- equilibrium at the front (Joughin et al., 2008). At present, Kangerdlugssuaq and Helheim glaciers, located in the cen- tral East Greenland coast, represent the 35 % of East Green- land’s total discharge (Rignot and Kanagaratnam, 2006). If conditions during the MCA were similar to or warmer than present, the calving rates of these glaciers may have been even higher than at present, delivering vast numbers of ice- bergs to the EGC, where they would release IRD as they melted. Moreover, during the MCA it is likely that other fjords, such us Nansen and Scoresby Sund, were also ice free during the summer, allowing them to contribute consid- erable numbers of icebergs to the EGC. The massive diamic- ton found in Nansen fjord sediments between AD 730 and 1100 demonstrates that there was continuous iceberg rafting due to warmer conditions (Jennings and Weiner, 1996). In this context, we postulate that warm temperatures were the driver of the increased iceberg calving at Greenland fjords and the high accumulation of IRD at Eirik Drift during late MCA.
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Assessment Of Some Acceleration Schemes In The Solution Of Systems Of Linear Equations.

Assessment Of Some Acceleration Schemes In The Solution Of Systems Of Linear Equations.

Chebyshev acceleration method [10] has been one of the favorite Krylov space methods for solving large sparse linear systems of equations in a parallel environment, since, unlike methods based on orthogonalization (such as Conjugate Gradient) it does not require computing computation-intensive inner products for the determination of the recurrence coefficients. The Chebyshev method, which in earlier literature has often been referred to as Chebyshev semi-iterative method, requires some preliminary knowledge about the spectrum of the coefficient matrix A, The concept of spectral radius allows us to make a complete description of eigenvalues of a matrix and is independent of any particular matrix norm [12]. Chebyshev acceleration method can be applied to any stationary iterative method provided it is symmetrizable. It requires the iteration matrix to have real spectrum. Given a nonsingular matrix Q, we define a basic
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SOCIAL ECONOMY – A FORM OF INCLUSION AND OF ''REACTIVATING'' OF LABOR IN THE CONTEXT OF THE CURRENT CRISIS

SOCIAL ECONOMY – A FORM OF INCLUSION AND OF ''REACTIVATING'' OF LABOR IN THE CONTEXT OF THE CURRENT CRISIS

The essence of social economy is the inclusive function of the labor market through which the different forms of social economy that exist in the member states can play a role in the overcoming the crisis, especially in the creating of jobs, including in social services field Opinion of the European Economic and Social Committee on the post‐ 2010 Lisbon Strategy 9, p. .

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Investigating The Use Of Mobile Computing In Zimbabwe Polytechnics Case Of A Polytechnic In Zimbabwe

Investigating The Use Of Mobile Computing In Zimbabwe Polytechnics Case Of A Polytechnic In Zimbabwe

Zimmerman (1999) in his article titled ―Mobile Computing: Characteristics, Benefits, and the Mobile fra mework‖ defined mobile computing as ―the use of computing devices, which usually interact in some way with a centralised information system while away from the normal fixed workplace‖. He went on to say that, Mobile computing technology enables the mobile person to create, access, process, store and communicate information without being constrained to a single location. It is on the above basis that this researcher views mobile computing as embracing a host of portable technologies the can access internet using wireless fidelity (WIFI). These range from notebook computers to tablets, to smartphones and e-book readers. Such devices have brought about Mobile learning (m-Learning) in Zimbabwe Polytechnics, enabling staff and students to share academic resources, be able to research and develop applications from wherever they are. Zimmerman (1999) went on to identify mobile computing hardware, software and communications in use then. He identified hardware as palmtops, clamshells, handheld Pen Keys, pen slates, and laptops. The characteristics of such devices in terms of screen size was small, processing capability was limited and supported a few mobile applications. Over the years mobile devices have improved in such characteristics to make mobile computing easy, fast and user friendly. Great improvements also came with the associated systems software, with the modern devices now running on Android, Symbian and windows 8 mobile, as compared to then when MS DOS, Windows 3.1, Pen DOS were used. In communications Zimmerman talked of internet speeds in kilobytes per second (Kbps), while today’s communications devices have speeds of gigabytes per second (Gbps
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WATSON ARANTES GAMA JUNIOR 2,5 , MARIA TERESA DE PAIVA AZEVEDO2, JAROSLAVA KOMÁRKOVÁ-LEGNEROVÁ 3,4 and CÉLIA LEITE SANT’ANNA2

WATSON ARANTES GAMA JUNIOR 2,5 , MARIA TERESA DE PAIVA AZEVEDO2, JAROSLAVA KOMÁRKOVÁ-LEGNEROVÁ 3,4 and CÉLIA LEITE SANT’ANNA2

ABSTRACT – (A new species of Lemmermanniella (Cyanobacteria) from the Atlantic Rainforest, Brazil). The Brazilian Atlantic Rainforest is a highly heterogeneous ecosystem comprising large numbers of tropical and subtropical habitats favorable to the development of cyanobacteria. Studies on cyanobacteria in this ecosystem are still rare, however, especially those involving unicellular and colonial types. The high biodiversity and endemism of this biome has been extremely impacted and fragmented, and less than 10% of its original vegetation cover remains today. We describe here a new species of a colonial cyanobacteria, Lemmermanniella terrestris, found on dry soils in a subtropical region of the Atlantic Rainforest in the municipality of Cananéia in southern São Paulo State, Brazil. This new taxon demonstrated all of the diacritical features of the genus Lemmermanniella but, unlike the other species of the genus, it was growing on the soil surface and not in an aquatic environment. A set of morphological features, including colonies composed of subcolonies, and cell dimensions, shapes and contents distinguish it from other species of the genus. Considering that species of Lemmermanniella are found in very distinct habitats (such as thermal and brackish waters) and that they maintain the same life cycle described for the genus in all of those environments, the morphological structures of the colonies can be used as reliable markers for identifying the genus, and its species differ primarily in relation to the habitats they occupy.
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The hydromedusae and water masses of the Indlan Ocean

The hydromedusae and water masses of the Indlan Ocean

Otherwise, this species was always taken at the boundary layer between surfaceand subsurface layers in the Bay of Bengal and in the Arabian Sea; all specimens come from salin[r]

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Increasing and decreasing trends of the atmospheric deposition   of organochlorine compounds in European remote areas during the last   decade

Increasing and decreasing trends of the atmospheric deposition of organochlorine compounds in European remote areas during the last decade

ited a different spatial pattern with similar fluxes in Lochnagar, Redòn and Gossenkölle- see, and one order of magnitude higher in Skalnaté. The high volatility and atmospheric mobility of this compound has resulted in rather uniform air concentrations in remote areas (Jaward et al., 2004). In contrast, the spatial pattern observed in the present study suggests that there are emission sources of this pollutant near the Tatra Mts,

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An Analysis Of The Difference In Gender Level Of Cassava Production And Access To Land In Abia State Nigeria

An Analysis Of The Difference In Gender Level Of Cassava Production And Access To Land In Abia State Nigeria

technique was employed in sample selection. In the first stage, the three agricultural zones in the state were purposively selected. Aba, Umuahia and Ohafia. In the second stage three local governments actively involved in agricultural production was purposively selected from each of the agricultural zone making it a total of nine blocks. While In the third stage two communities was randomly selected from each of the local government. Twelve respondents was randomly selected from two sampling group. six each for male and female giving twelve respondents from each cell. A total of 218 respondents was selected for the study. The research instrument used for this study was structured questionnaire and scheduled interview. The result of the objective of the study was analyzed using descriptive statistics such as frequency, percentage, and mean inferential which involves the use of Z-test analysis. The formula used to compute the mean used in this study is specified below. The mean was computed by multiplying the frequency (f) of the responses under each response category by assigned value and dividing the (∑) of the product by the (N) no of respondents to the particular indicator as shown:
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