Environmental perspectives of microplastic pollution in the aquatic environment:a review

Microplastics are a highly concerning pollutant that have gained attention from the scientific community and other regulatory authorities due to their potential risks to organisms and ecosystems.Microplastics are widespread in both terrestrial and aquatic ecosystems and can be found even in Antarctica and deep-sea sediments.The ability to survive for long periods in the environment and their aptitude of inter-and intra-environmental translocation can prompt poor environmental outcomes.The adsorption of heavy metals and other toxic persistent organic pollutants is a further cause for concern.Furthermore,microplastics enable the development of a distinct microbial niche within an ecosystem,which could potentially impair ecosystem function by promoting the growth of selective microbial communities.The acquisition of metal-resistant,antibiotic-resistant genes,and the enrichment of antibiotic-resistant bacteria on microplastic surfaces have recently been reported.Moreover,some studies have also reported the colonizahon of pathogenic bacterial strains such as Vibrio spp.on microplastic surfaces.This review aims to address the sources of microplastic pollution in the freshwater and marine environments and to discuss their potential functions in the environment.

Characteristics of nonpoint source pollution load from crop farming in the context of livelihood diversification

Based on objective data collected from interviews in typical villages of the Three Gorges Reservoir Area, the present study devised three livelihood scenarios related to rural transformation development： agriculturally dominant livelihood, multiple-type livelihood and non-agriculturally dominant livelihood. Moreover, the present study reports the trend characteristics of nonpoint source pollution load of crop farming in relation to the transformation of dominant livelihood types, and discussed the primary factors which affect livelihood type transformations. Results indicated the following：（1） The current farmland pattern shows a trend of diversification as self-cultivation, cropland transfer and fallow in the sample region. Dynamic characteristics of cultivated land present a special feature that is more ＂transfer-into＂ than ＂transfer-out＂. Various scales of planting are represented among the various households, according to the following decreasing order： half-labor household ＆gt; non-labor household ＆gt; adequate labor household.（2） The highest pollution loading produced by crop farming occurs in half-labor households while the lowest occurs in non-labor households. With increasing labor, the pollution load per unit area tends to first increase and then decrease within families with enough labor.（3） As the type of livelihood transitions from agriculturally dominant to non-agriculturally dominant, the maximum reduction of total pollution loading produced by the agricultural industry can reach 72.01%. Compared to agriculturally dominant livelihoods, multiple-type livelihoods produce a pollution load reduction yield of 19.61%-29.85%, and non-agriculturally dominant livelihoods reduce the pollution load yield by 35.20%-72.01%. However, the rate of reduction of total nitrogen is not the same as total phosphorus.（4） The non-agricultural characteristics of labor allocation and income promote the transformation from dominant livelihood types to non-agricultural livelihoods, while potential revenue conversion follows a similar trend. In addition, different household types do not display identical conversion rates, according to the following decreasing order： enough labor household ＆gt; half-labor household ＆gt; non-labor household.（5） During rapid urbanization and the building of new industrial systems, the livelihood types of rural households have been further transformed to off-farm household types in the mountainous region; this process will lead to the further reduction of pollution load generated by planting and agriculture. Hence, significant decreases in the planting pollution load necessitate the development of control measures to enhance transformations from agricultural to off-farm livelihoods.