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The Nigerian government is committed to sustaining rice production to meet national demand. Nevertheless, political tension and climate-induced stressors remain crucial constraints in achieving policy targets. This study examines whether climate change and political instability significantly threaten rice production in Nigeria. First, we employed nonparametric methods to estimate the country's rainfall and temperature trends between 1980Q1 and 2015Q4. Second, we employed the autoregressive distributed lag (ARDL) technique to examine the effects of climate change and political instability on rice production. The results show that while temperature has an increasing pattern, rainfall exhibits no significant trend. The findings from the ARDL estimate reveal that rice production responds negatively to temperature changes but is less sensitive to changes in rainfall. In addition, political instability adversely affects rice production in Nigeria. We argue that Nigeria's slow growth in rice production can be traced back to the impact of climate change and political tension in rice farming areas. As a result, reducing the overall degree of conflict to ensure political stability is critical to boosting the country's self-sufficiency in rice production. We also recommend that farmers be supported and trained to adopt improved rice varieties less prone to extreme climate events while supporting them with irrigation facilities to facilitate rice production.

AbstractA bioreactor system composed of a stirred tank and three tubular bioreactors in series was established, and continuous ethanol fermentation was carried out using a general Saccharomyces cerevisiae strain and a very high gravity medium containing 280 g L−1 glucose, supplemented with 5 g L−1 yeast extract and 3 g L−1 peptone. Sustainable oscillations of glucose, ethanol, and biomass were observed when the tank was operated at the dilution rate of 0.027 h−1, which significantly affected ethanol fermentation performance of the system. After the tubular bioreactors were packed with 1/2″ Intalox ceramic saddles, the oscillations were attenuated and quasi‐steady states were achieved. Residence time distributions were studied for the packed bioreactors by the step input response technique using xylose as a tracer, which was added into the medium at a concentration of 20 g L−1, indicating that the backmixing alleviation assumed for the packed tubular bioreactors could not be established, and its contribution to the oscillation attenuation could not be verified. Furthermore, the role of the packing's yeast cell immobilization in the oscillation attenuation was investigated by packing the tubular bioreactors with packings with significant difference in yeast cell immobilization effects, and the experimental results revealed that only the Intalox ceramic saddles and wood chips with moderate yeast cell immobilization effects could attenuate the oscillations, and correspondingly, improved the ethanol fermentation performance of the system, while the porous polyurethane particles with good yeast cell immobilization effect could not. And the viability analysis for the immobilized yeast cells illustrated that the extremely lower yeast cell viability within the tubular bioreactors packed with the porous polyurethane particles could be the reason for their inefficiency, while the yeast cells loosely immobilized onto the surfaces of the Intalox ceramic saddles and wood chips could be renewed during the fermentation, guaranteeing their viability and making them more efficient in attenuating the oscillations. The packing Raschig rings without yeast cell immobilization effect did not affect the oscillatory behavior of the tubular bioreactors, further supporting the role of the yeast cell immobilization in the oscillation attenuation. Biotechnol. Bioeng. 2009;102: 113–121. © 2008 Wiley Periodicals, Inc.

Response of aquatic organisms to eutrophication have been well reported, while less studies are available for the recovery of eutrophic lakes following a reduction in the external loading, especially for systems where nitrogen is reduced but the phosphorus concentration is maintained high due to internal loading. Diatoms are nitrate (NO3-N) opportunists but can also use ammonium (NH4-N). They may, therefore, be more sensitive to nitrogen reduction than other algae that typically prefer NH4-N. We document the variations of nutrients and diatoms in subtropical, eutrophic Lake Taihu over 28 yr during which a reduction of the external loading resulted from lake management. According to the results of change point analysis, data on environmental variables were divided into two periods (P1: 1992-2006; P2: 2007-2019) with two different seasons (WS: Winter-Spring; SA: Summer-Autumn), respectively. Compared with P1-WS, the concentration of NH4-N decreased significantly whereas NO3-N showed no significant change in P2-WS. In contrast, NH4-N concentrations were low and showed no significant changes in P1-SA and P2-SA and NO3-N decreased significantly in the latter period. Accordingly, NO3-N: NH4-N mass ratios in P1-SA and P2-WS were all significantly higher than those in P2-SA and P1-WS, respectively. The biomass of WS diatom increased significantly and the timing of the peak biomass shifted from P1-SA to P2-WS since 2007. The SEM analysis showed that NO3-N was retained as a statistically significant predictor for diatom biomass in P1-SA and significant effects of windspeed, zooplankton and NH4-N on diatom biomass in P2-WS. Windspeed and zooplankton have further changed the biomass of diatoms in the case of declining inorganic nitrogen. We conclude that the magnitude of vernal suppression or stimulation of diatom assemblages has increased, concomitant with the variations of NH4-N and NO3-N: NH4-N mass ratios. Diatoms response to NH4-N or NO3-N is apparently changing in response to water temperature in this eutrophic shallow lake. Thus, parallel reductions in external nitrogen loading, along with variations in dominant inorganic nitrogen, will stimulate the growth of diatom and therefore increase the total biomass of phytoplankton in still high internal phosphorus loading, which is should be regarded as a good sign of restoration measures.

To fix CO2 emissions efficiently from flue gas of coal-fired power plants, the culture medium, light intensity and bioreactors were comprehensively optimized in the process of CO2 fixation by Chlorella PY-ZU1. To make up for relative insufficiency of nutrients (except for the carbon source) resulting from continuous bubbling of 15% CO2, three chemicals were added into the culture to optimize the molar ratios of nitrogen to carbon, phosphorus to carbon, and magnesium to carbon in culture from 0.17 to 0.69, from 0.093 to 0.096, and from 0.018 to 0.030, respectively. Such adjustments led to a 1.25-fold increase in biomass (from 2.41 to 5.42 g L(-1)). By enhancing light intensity from 4500 to 6000 lux, the peak growth rate of Chlorella PY-ZU1 increased by 99% and reached to 0.95 g L(-1) day(-1). Use of a multi-stage sequential bioreactor notably improved the peak CO2 fixation efficiency to 85.6%.

In this study, a combination of microcosmic and chemical analysis methods was used to investigate deep eutectic solvent (DES) pretreatment effects on cell wall's micromorphology and lignin's dissolution regular, in order to achieve high-performance biorefinery. The atomic force microscope observed that DES pretreatment peeled off non-cellulose components to reduced "anti-degradation barrier", resulting to improve the enzymatic saccharification from 12.36 % to 90.56 %. In addition, DES pretreatment can break the β-O-4 bond between the lignin units resulting in a decline in molecular weight from 3187 g/mol to 1112 g/mol (0-6 h). However, long pretreatment time resulted regenerated lignin samples repolymerization. Finally, DES has good recoverability which showed saccharification still can reach 51.51 % at 6 h following four recycling rounds and regenerated lignin also had a typical and well-preserved structure. In general, this work offers important information for industrial biorefinery technologies and lignin valorization.

Abstract Phosphorus (P) is an important nutrient that can restrict plant growth. However, the influence of P deficiency on elemental homeostasis and application of the growth rate hypothesis in higher plants remain to be assessed. Two shrubs, Zygophyllum xanthoxylum and Nitraria tangutorum, were used as experiment material and subjected to five P addition treatments: 0, 17.5, 35.0, 52.5 and 70.0 mg P·kg−1 soil. The biomass and relative growth rate of Z. xanthoxylum did not change with altered P supply. There was no significant difference in P concentration among the treatments for Z. xanthoxylum, but N. tangutorum showed an upward trend. The P stoichiometric homeostasis of Z. xanthoxylum was higher than that of N. tangutorum. For Z. xanthoxylum, available P in the rhizosphere improved significantly under extreme P deficiency conditions, and P concentrations in all treatments were lower than in N. tangutorum, showing that Z. xanthoxylum had stronger P absorption and P utilization capacity. No relationships between growth rate and C:N:P ratios were found in Z. xanthoxylum. The strong P efficiency, and high and stable dry matter accumulation, are likely contributors in maintaining stoichiometric homeostasis. In addition, the relatively high biomass accumulation and high P utilization efficiency for Z. xanthoxylum does not support the growth rate hypothesis for this species.

The influence of elemental sulfur (S(0)) amendment on methylmercury (MeHg) accumulation in rice and the chemical form of Hg in the rhizosphere were investigated under waterlogged conditions in Hg-contaminated soil (the majority of the Hg (˜70%) in forms similar to HgS). Different levels of S(0) addition increased the MeHg accumulation in rice. After a sequential extraction analysis of the chemical forms of Hg in the rhizosphere, the results showed that S(0) addition increased the organic bound Hg and decreased the residual Hg in the soils. An Hg LIII XANES further showed that S(0) addition increased the proportion of Hg in the form of RS-Hg-SR and decreased the proportion of Hg in the form of HgS, indicating that S(0) input may reactivate the non-bioavailable Hg in the rhizosphere and improve the net Hg methylation. These findings suggest that the application of S fertilizers to Hg-contaminated paddy soils may increase the MeHg concentration in the edible parts of crops, which may lead to more potential health problems in humans depending on the crop type. However, our study also suggests that S(0) addition could be an effective measure for mobilizing the insoluble Hg and accelerating the phytoremediation process in Hg-contaminated paddy soils.

One of the biggest challenges in forestry research is the effective and accurate measuring and monitoring of forest variables, as the exploitation potential of forest inventory products largely depends on the accuracy of estimates and on the cost of data collection. This paper presented a novel computational method of low-cost forest inventory using global navigation satellite system (GNSS) signals in a crowdsourcing approach. Statistical features of GNSS signals were extracted from widely available GNSS devices and were used for predicting forest attributes, including tree height, diameter at breast height, basal area, stem volume, and above-ground biomass, in boreal forest conditions. The basic evidence of the predictions is the physical correlations between forest variables and the responses of GNSS signals penetrating through the forest. The random forest algorithm was applied to the predictions. GNSS-derived prediction accuracies were comparable with those of the most accurate 2-D remote sensing techniques, and the predictions can be improved further by integration with other publicly available data sources without additional cost. This type of crowdsourcing technique enables the collection of up-to-date forest data at low cost, and it significantly contributes to the development of new reference data collection techniques for forest inventory. Currently, field reference can account for half of the total costs of forest inventory.

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