Origin of major ions in monthly rainfall events at the Bamenda Highlands, North West Cameroon

Rainwater characteristics can reveal emissions from various anthropogenic and natural sources into the atmosphere. The physico-chemical characteristics of 44 monthly rainfall events （collected between January and December 2012） from 4 weather stations （Bamenda, Ndop plain, Ndawara and Kumbo） in the Bamenda Highlands （BH） were investigated. The purpose was to determine the sources of chemical species, their seasonal inputs and suitability of the rainwater for drinking. The mean pH of 5 indicated the slightly acidic nature of the rainwater. Average total dissolved solids （TDS） were low （6.7 mg/L）, characteristic of unpolluted atmospheric moisture/air. Major ion concentrations （mg/L） were low and in the order K＋ 〉 Ca2＋ 〉 Mg2~ 〉 Na＋ for cations and NO3 〉〉 HCO3 〉 SO] 〉 CI- 〉 PO3- 〉 F- for anions. The average rainwater in the area was mixed Ca-Mg-SO4-CI water type. The CI-/Na＋ ratio （1.04） was comparable to that of seawater （1.16）, an indication that N a＋ and CI originated mainly from marine （Atlantic Ocean） aerosols. High enrichments of Ca2＋, Mg2＋ and SO2- to Na＋ ratios relative to seawater ratios （constituting 44% of the total ions） demonstrated their terrigenous origin, mainly from Saharan and Sahelian arid dusts. The K＋/Na＋ ratio （2.24）, which was similar to tropical vegetation ash （2.38）, and NO3 was essentially from biomass burning. Light （〈 100 mm） pre-monsoon and post-monsoon convective rains were enriched in major ions than the heavy （〉 100 mm） monsoon rains, indicating a high contribution of major ions during the low convective showers. Despite the acidic nature, the TDS and major ion concentrations classified the rainwater as potable based on the WHO guidelines.     

Studies with natural and anthropogenic iodine isotopes: iodine distribution and cycling in the global environment

Iodine is an important trace element in geological and biological processes. We summarize here recent results and new data of experiments and observations carried out to improve the understanding of concentration levels and behavior of natural and anthropogenic iodine nuclides in the global environment. The distribution of stable iodine in the Earth's crust was estimated using concentration data in a suite of representative samples and the influence of subduction on the marine iodine cycle was investigated using (129)I systematics on iodine-rich brines from Japan. The importance of microorganisms for the natural iodine cycle is shown in recent studies of iodine sorption on soil and of iodine volatilization from terrestrial and marine environments. Levels of anthropogenic (129)I were measured in samples collected around a spent fuel reprocessing plant in Japan.     

Degree-day accumulation controlling allopatric and sympatric variations in the sociality of sweat bees, <Emphasis Type="Italic">Lasioglossum</Emphasis> (<Emphasis Type="Italic">Evylaeus</Emphasis>) <Emphasis Type="Italic">baleicum</Emphasis> (Hymenoptera: Halictidae)

Halictine bees exhibit a wide range of social behaviour that varies both inter- and intraspecifically. Although previous studies suggested that the intraspecific variation might be attributed to temperature differences, there was no direct evidence to detect the relationships between temperature and socialities. Lasioglossum (Evylaeus) baleicum exhibited solitary behaviour in a cooler locality (Kawakita) because of the shorter breeding season; in a warmer locality (Nishioka Park), however, this bee species exhibited eusociality at sunny site and solitary behaviour at shady site, whereas a molecular phylogeny confirms that all of these colonies are evidently conspecific. Therefore, we examined the effect of degree-day accumulation on the sympatric social variation of L. baleicum by rearing the bees to calculate the threshold temperature. Whereas they showed high mortality, the threshold temperature was estimated to be 10.33°C and the expected degree-day accumulation was 340 degree days. When we use this value of a degree-day accumulation to estimate the expected eclosion date, the estimated dates were always consistent with observed eclosion dates. In any sites where the bees were solitary, the degree-day accumulation was not enough for the second eclosion by the end of the bee-active season. In Nishioka Park, sex ratio of the first brood was female biased, and daughters were smaller than mothers; in Kawakita, however, there was no sex bias, and daughters were as large as their mothers indicating that the foundresses seem to produce gyne-sized females in Kawakita but worker-sized females in Nishioka though these females do not become workers at shady site.     

Hybrid input-output analysis to evaluate economic impacts of biomass energy

ABSTRACT

The introduction of the new biomass industry exerts influences that change the interactions among economic sectors by drawing the resources for generating electricity, pricing alterations from the existing market and competitively selling electricity to the power grid. These influences should be described and identified to ensure the benefits to the local economy. In this article, we deem to test the potential of hybrid I-O analysis to analyze the economic impacts and address the change in characteristics of the economic impacts of the biomass power plant. The resource utilization data from the existing biomass power plant located in Kochi Prefecture (Japan) is collected and then analyzed by a hybrid input-output (I-O) analysis. We found that (1) the use of cutoff function could determine the new economy’s structure included the biomass power plant where the allocation of resource in the economy is changed according to the consumption and production of the biomass power plant, (2) The power plant increases the total production of Kochi prefecture’s economy, and this benefit overthrows the negative effect of the loss of resource demand of the existing economic sectors. The use of the hybrid I-O to forecast the economic impacts on the local economy could enhance the decision made by the policymaker.     

Mating frequency, colony size, polyethism and sex ratio in fungus-growing ants (Attini)

The mating frequency of queens was estimated for eight attine ant species, Myrmicocrypta ednaella, Apterostigma mayri, Cyphomyrmex costatus, C. rimosus (four lower attines), Trachymyrmex isthmicus, Serico-myrmex amabalis, Acromyrmex octospinosus and Atta colombica (four higher attines), and correlated to colony size, worker polyethism, and sex ratio. Mating frequency was calculated from within-colony relatedness estimated by CAP-PCR DNA fingerprinting. Most queens of lower attines and T. isthmicus mated with only one male, while those of the three higher attines mated with multiple males. Mating frequency was positively correlated with colony size. Polyethism among workers was dependent on worker age in lower attines but on body size in higher attines, suggesting some correlation between mating frequency (i.e., within-colony gene diversity) and caste complexity. The sex ratio was biased toward females in species where the mating frequency equaled one, but toward males in species where the mating frequency was greater than two. Changing in nest site from ground surface to deep underground may have facilitated the evolution of large colony size in Attini, and this may have resulted in the evolution of polyandry (a queen mates with multiple males). With the evolution of polyandry in higher attines, Atta and Acromyrmex in particular have generated high genetic diversity within their colonies and complex social structures. Received: 26 October 1999 / Revised: 25 May 2000 / Accepted: 24 June 2000     

Rate of iodine volatilization and accumulation by filamentous fungi through laboratory cultures

Five strains of basidiomycetes (Lentinula edodes, Coprinus phlyctidosporus, Hebeloma vinosophyllum, Pleurotus ostreatus and Agaricus bisporus), one strain of ascomycete (Hormoconis resinae) and six strains of imperfect fungi (Penicillium chrysogenum, Penicillium roquefortii, Cladosporium cladosporioides, Alternaria alternata, Aspergillus niger and Aspergillus oryzae) were cultured in a liquid medium containing a radioactive iodine tracer (¹²⁵I), and were tested for their abilities to volatilize or accumulate iodine. Of the fungal strains tested, 11 strains volatilized a considerable amount of iodine, with L. edodes showing the highest volatilization rate of 3.4%. The volatile organic iodine species emitted from imperfect fungi cultures was identified as methyl iodide (CH₃I). In contrast, six fungal strains in 12 strains accumulated a considerable amount of iodine from the medium with concentration factors of more than 1.0. Among these, Alt. alternata and Cl. cladosporioides accumulated more than 40% of the iodine in their hyphae, and showed high concentration factors of 22 and 18, respectively. These results suggest that filamentous fungi have a potential to influence the mobility and speciation of iodine by volatilization and accumulation. Considering their great biomass in soils, filamentous fungi may contribute to the global circulation of stable iodine and also the long-lived radioiodine, ¹²⁹I (half-life: 1.6 × 10⁷ years), released from nuclear facilities into the environment.