We studied the effect of electron competition on chromate (Cr(VI)) reduction in a methane (CH)-based membrane biofilm reactor (MBfR), since the reduction rate was usually limited by electron supply. A low surface loading of SO promoted Cr(VI) reduction. The Cr(VI) removal percentage increased from 60 to 70% when the SO loading increased from 0 to 4.7 mg SO/m-d. After the SO loading decreased back to zero, the Cr(VI) removal further increased to 90%, suggesting that some sulfate-reducing bacteria (SRB) stayed in the reactor to reduce Cr(VI). However, a high surface loading of SO (26.6 mg SO/m-d) significantly slowed down the Cr(VI) reduction to 40% removal, which was probably due to competition between Cr(VI) and SO reduction. Similarly, when 0.5 mg/L of Se(VI) was introduced into the MBfR, Cr(VI) removal percentage slightly decreased to 60% and then increased to 80% when input Se(VI) was removed again. The microbial community strongly depended on the loadings of Cr(VI) and SO. In the sulfate effect experiment, three genera were dominant. Based on the correlation between the abundances of the three genera and the loadings of Cr(VI) and SO, we conclude that Methylocystis, a type II methanotroph, reduced both Cr(VI) and sulfate, Meiothermus only reduced Cr(VI), and Ferruginibacter only reduced SO.
Introduction
Payments for Ecosystem Services (PES) programs have been implemented globally to protect ecosystems while securing the well-being of affected people. Reasonable payment standards are key to successful PES programs. Although some approaches are available for determining payment standards, few studies have applied them for grassland conservation with location indicators and socioeconomic contexts properly considered.
Methods
Using China’s first pilot Grassland Ecological Compensation Policy (GECP) as an example, we analyzed the effects of payment levels, other natural and socioeconomic factors on herders’ willingness to participate in the GECP in Damao County in Inner Mongolia where grassland degradation is happening at an alarming rate due to overgrazing and cropland expansion.
Outcomes
Our results show that households with lower herding income, older age, higher education, larger grassland areas, and worse social relationships are more inclined to participate in the GECP. Conservation payment level, as well as natural and socioeconomic contextual factors, significantly affect the response of herdsmen, and a reasonable grassland payment standard with a 95% policy compliance rate should be 8.8 yuan mu
−1
.
Discussion and Conclusion
Our findings can inform governments to develop effective PES programs to balance the need of human well-being improvement and grassland conservation in China and beyond.
This paper concludes that there is a long-term and stable equilibrium relationship between copper price and supply and demand in China through empirical research on supply and demand of copper in China. The equilibrium relationship is mainly affected by refined copper output and scrap copper import value. However, Consumer Price Index has the biggest impact on Copper prices.
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