Biomineralization in plants as a long-term carbon sink

Carbon sequestration in the global carbon cycle is almost always attributed to organic carbon storage alone, while soil mineral carbon is generally neglected. However, due to the longer residence time of mineral carbon in soils (10²–10⁶ years), if stored in large quantities it represents a potentially more efficient sink. The aim of this study is to estimate the mineral carbon accumulation due to the tropical iroko tree (Milicia excelsa) in Ivory Coast. The iroko tree has the ability to accumulate mineral carbon as calcium carbonate (CaCO₃) in ferralitic soils, where CaCO₃ is not expected to precipitate. An estimate of this accumulation was made by titrating carbonate from two characteristic soil profiles in the iroko environment and by identifying calcium (Ca) sources. The system is considered as a net carbon sink because carbonate accumulation involves only atmospheric CO₂ and Ca from Ca-carbonate-free sources. Around one ton of mineral carbon was found in and around an 80-year-old iroko stump, proving the existence of a mineral carbon sink related to the iroko ecosystem. Conservation of iroko trees and the many other biomineralizing plant species is crucial to the maintenance of this mineral carbon sink.     

Impairment of male reproduction in adult rats exposed to hydroxyprogesterone caproate in utero

Hydroxyprogesterone caproate is one of the most effective and widely used drugs for the treatment of uterine bleeding and threatened miscarriage in women. Hydroxyprogesterone caproate was administered to pregnant rats in order to assess the effect of intraperitoneal exposure to supranormal levels of hydroxyprogesterone caproate on the male reproductive potential in the first generation. The cauda epididymal sperm count and motility decreased significantly in rats exposed to hydroxyprogesterone caproate during embryonic development, when compared with control rats. The levels of serum testosterone decreased with an increase in follicle stimulating hormone and luteinizing hormone in adult rats exposed to hydroxyprogesterone caproate during the embryonic stage. It was suggested that the impairment of male reproductive performance could be mediated through the inhibition of testosterone production.     

Climate impact from peat utilisation in Sweden

The climate impact from the useof peat for energy production in Sweden hasbeen evaluated in terms of contribution toatmospheric radiative forcing. This wasdone by attempting to answer the question`What will be the climate impact if onewould use 1 m<sup>2</sup> of mire for peatextraction during 20 years?'. Two differentmethods of after-treatment were studied:afforestation and restoration of wetland.The climate impact from a peatland –wetland scenario and a peatland –forestation – bioenergy scenario wascompared to the climate impact from coal,natural gas and forest residues.Sensitivity analyses were performed toevaluate which parameters that areimportant to take into consideration inorder to minimize the climate impact frompeat utilisation. In a `multiple generationscenario' we investigate the climate impactif 1 Mega Joule (MJ) of energy is produced every yearfor 300 years from peat compared to otherenergy sources.The main conclusions from the study are:?The accumulated radiative forcing from the peatland – forestation – bioenergy scenario over a long time perspective (300 years) is estimated to be 1.35 mJ/m²/m² extraction area assuming a medium-high forest growth rate and medium original methane emissions from the virgin mire. This is below the corresponding values for coal 3.13 mJ/ m²/ m² extraction area and natural gas, 1.71 mJ/ m²/ m² extraction area, but higher than the value for forest residues, 0.42 mJ/ m²/ m² extraction area. A `best-best-case' scenario, i.e. with high forest growth rate combined with high `avoided' methane (CH₄) emissions, will generate accumulated radiative forcing comparable to using forest residues for energy production. A `worst-worst-case' scenario, with low growth rate and low `avoided' CH₄ emissions, will generate radiative forcing somewhere in between natural gas and coal.?The accumulated radiative forcing from the peatland – wetland scenario over a 300-year perspective is estimated to be 0.73 –1.80 mJ/ m²/ m² extraction area depending on the assumed carbon (C) uptake rates for the wetland and assuming a medium-high methane emissions from a restored wetland. The corresponding values for coal is 1.88 mJ/ m²/ m² extraction area, for natural gas 1.06 mJ/ m²/ m² extraction area and for forest residues 0.10 mJ/ m²/ m² extraction area. A `best-best-case' scenario (i.e. with high carbon dioxide CO<sub>2</sub>-uptake combined with high `avoided' CH₄ emissions and low methane emissions from the restored wetland) will generate accumulated radiative forcing that decreases and reaches zero after 240 years. A `worst-worst-case' (i.e. with low CO<sub>2</sub>-uptake combined with low `avoided' CH₄ emissions and high methane emissions from the restored wetland) will generate radiative forcing higher than coal over the entire time period.?The accumulated radiative forcing in the `multiple generations' – scenarios over a 300-year perspective producing 1 MJ/year is estimated to be 0.089 mJ/ m<sup>2</sup> for the scenario `Peat forestation – bioenergy', 0.097 mJ/ m² for the scenario `Peat wetland with high CO<sub>2</sub>-uptake' and 0.140 mJ/ m<sup>2</sup> for the scenario `Peat wetland with low CO₂-uptake'. Corresponding values for coal is 0.160 mJ/ m², for natural gas 0.083 mJ/ m² and for forest residues 0.015 mJ/ m². Using a longer time perspective than 300 years will result in lower accumulated radiative forcing from the scenario `Peat wetland with high CO₂-uptake'. This is due to the negative instantaneous forcing that occurs after 200 years for each added generation.?It is important to consider CH₄ emissions from the virgin mire when choosing mires for utilization. Low original methane emissions give significantly higher total climate impact than high original emissions do.?Afforestation on areas previously used for peat extraction should be performed in a way that gives a high forest growth rate, both for the extraction area and the surrounding area. A high forest growth rate gives lower climate impact than a low forest growth rate.?There are great uncertainties related to the data used for emissions and uptake of greenhouse gases in restored wetlands. The mechanisms affecting these emissions and uptake should be studied further.     

Practical environmental monitoring of major construction projects

Independent teams undertook environmental monitoring of particular concentrations of major construction projects forming part of Hong Kong’s U.S. $20 billion airport infrastructure programme located in dense urban areas. The team combination of environmental specialists with experienced civil engineers enabled pragmatic mitigation measures to be developed and accepted by the construction personnel with the result that potentially significant adverse impacts were averted. The authors discuss the mechanism and success of this innovative approach.     

Carbon mitigation potential and costs of forestry options in Brazil,China, India,Indonesia, Mexico,the Philippines and Tanzania

This paper summarizes studies of carbon (C) mitigation potential and costs of about 40 forestry options in seven developing countries. Each study uses the same methodological approach – Comprehensive Mitigation Assessment Process (COMAP) – to estimate the above parameters between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios. Coupled with data on a per ha basis on C sequestration or avoidance, and costs and benefits, it allows the estimation of monetary benefit per Mg C, and the total costs and carbon potential. The results show that about half (3.0 Pg C) the cumulative mitigation potential of 6.2 Petagram (Pg) C between 2000 and 2030 in the seven countries (about 200× 10⁶ Mg C yr^-1) could be achieved at a negative cost and the remainder at costs ranging up to $100 Mg C^-1. About 5 Pg C could be achieved, at a cost less than $20 per Mg C. Negative cost potential indicates that non-carbon revenue is sufficient to offset direct costs of these options. The achievable potential is likely to be smaller, however, due to market, institutional, and sociocultural barriers that can delay or prevent the implementation of the analyzed options.