A review of the occurrence and degradation of biodegradable microplastics in soil environments.

The use of plastics for manufacturing of products and packaging has become ubiquitous. This is because plastics are cheap, pliable, and durable. However, these characteristics of plastics have also led to their disposal in landfill, where they persist. To overcome the environmental challenge posed by conventional plastics (CPs), biodegradable plastics (BDPs) are increasingly being used. However, BDPs form residual microplastics (MPs) at a rate that far exceeds that of CPs, and MPs have negative impacts on the soil environment. This review aimed to evaluate whether the move away from CPs to BDPs is having an overall positive impact on the environment considering the formation of MPs. Topics focused on in this review include the degradation of BDPs in the soil environment and the impacts of MPs originating from BDPs on soil physical and chemical properties, microbial communities, animals, and plants. The information collated in this review can provide scientific guidance for sustainable development of the BDPs industry.

Denitrification potential of riparian soils in relation to multiscale spatial environmental factors: a case study of a typical watershed, China.

The objective of this study was to test the hypothesis that environmental regulators of riparian zone soil denitrification potential differ according to spatial scale within a watershed; consequently, a second objective was to provide spatial strategies for conserving and restoring the purification function of runoff in riparian ecosystems. The results show that soil denitrification in riparian zones was more heterogeneous at the profile scale than at the cross-section and landscape scales. At the profile scale, biogeochemical factors (including soil total organic carbon, total nitrogen, and nitrate-nitrogen) were the major direct regulators of the spatial distribution of soil denitrification enzyme activity (DEA). At the cross-section scale, factors included distance from river bank and vegetation density, while landscape-scale factors, including topographic index, elevation, and land use types, indirectly regulated the spatial distribution of DEA. At the profile scale, soil DEA was greatest in the upper soil layers. At the cross-section scale, maximum soil DEA occurred in the mid-part of the riparian zone. At the landscape scale, soil DEA showed an increasing trend towards downstream sites, except for those in urbanized areas.

[An ecological compensation standard based on water environmental capacity of Kouhe River, Liaoning Province, China].

Kouhe River water pollution caused by industry, agriculture and life sewage, not only reduced the water use function, but also directly affected the quality of Qinghe River. Due to the lack of effective management of water resources, the irrational use and water environment pollution occurred in Kouhe River basin. In this paper, in order to maintain the sustainable development of Kouhe River basin, taking Xifeng County and Kaiyuan City as two control units, COD as pollution factor, the water environmental capacity of Kouhe River basin was calculated. Combined with water quality monitoring data, river environment functional zone, pollution census data and the recovery cost of COD, an ecological compensation standard was determined. When the guarantee rates were 50%, 75%, and the average flow of the driest month in recent 10 years, the corresponding compensation standards of Xifeng County to downstream Kaiyuan City were 390.9 x 10(4), 448.6 x 10(4) and 514 x 10(4) yuan · a(-1), respectively. The river basin ecological compensation mechanism was put forward which should include ecological compensation fund raising, allocation and supervision.

[Assessment of eco-economic system sustainable development of Liaoning province based on emergy analysis].

By constructing an evaluation system based on emergy analysis which included emergy flow, source of emergy index, social subsystem evaluation index, economic subsystem evaluation index, natural subsystem evaluation index and composite index, the development and sustainability of the eco-economic system of Liaoning Province between 2000 and 2010 were evaluated. The result showed that from 2000 to 2010, the total used emergy increased from 3440.12 x 10(20) sej to 7636.33 x 10(20) sej, among which the proportion of the nonrenewable emergy in 2010 occupied the most in the total by 68.6% , and the emergy per capita increased from 8.32 x 10(15) sej to 17.96 x 10(15) sej. The emergy self-support ratio in the system was generally higher, while it dropped from 91.1% in 2000 to 79.9% in 2010. The emergy loading ratio increased from 3.22 to 7.80, the emergy sustainable index dropped from 3.47 to 0.64, and the emergy index for sustainable development decreased from 6.73 to 1.56. It suggested the eco-economic system of Liaoning Province presented an unsustainable development trend. The development level of Liaoning in 2010 merely equaled to the level of Japan and America in the 1980s.