Technical solutions for the safe utilization of heavy metal‐contaminated farmland in China: A critical review

Abstract

China is suffering from farmland heavy metal pollution. Different strategies have been explored in the past decades to address the problem, mainly metal removal, substitute planting, and safe farming. Safe farming aims to produce metal‐safe food crops in heavy metal‐polluted farmland without purposefully removing the excess metals. Safe farming was intended to address the soil‐borne food heavy metal issue and has been advocated as a priority solution for farmland pollution by the government. Many conventional and novel technologies have been tested for safe farming in recent years. Although most reduced heavy metals in grains, none of the technologies alone were found to be sufficient in field practice to meet national food standards. The current best practice is recognized as the combination of several agronomic measures, including pollution‐safe cultivars, optimal water management, liming, and conventional metal immobilizers. Unfortunately, field trials have not achieved a robust technical framework effective for farmland with different soil properties and climatic conditions. We propose that a practical technical framework may be biotechnology centered with a minimal use of chemical immobilizers, particularly liming and phosphate minerals. Foliar sprays and microbial biosorbents seem promising for safe farming. A biotechnology‐centered framework may largely simplify the field practice of safe farming and is more acceptable to governments and farmers.

Land Use Land Cover Changes and Their Impact on the Lake Ecosystem of the Central Rift Valley of Ethiopia

“…Expansion of urban due to the population growth and movement of people to towns to search job in the commercial farms established around the study areas has resulted in the acquisition of most suitable agricultural lands for urban development. Finding of (Moges and Bhat 2018) confirm that also urban expansion has resulted in increased price of agricultural lands, overconsumption of irrigable water, and increased price of food and fuel.…”

Metagenomic screening of microbiomes identifies pathogen-enriched environments

“…Meanwhile, dry soil environments like desert soil and desert tailings were found to contain relatively less toxin factors. It is still unclear to what extent the environments stressed by long-lasting drought or metal pollution suppress the colonization and development of pathogens [83]. In all, the association between environmental factors and pathogen abundance merits a systematic exploration in the future.…”

Variability in plant trace element uptake across different crops, soil contamination levels and soil properties in the Xinjiang Uygur Autonomous Region of northwest China

“…The exceedance rates of Cd, Cr, Hg, Pb and Zn were higher than that of As, Cu, and Ni in three farmland soils (Table 1 ), suggesting they were the major pollutants. This was due to the fact that most of these elements in farmland were introduced from anthropogenic activities and easily affected by human 1 , 2 , 13 . For example, automobile exhaust and industrial emissions, waste incineration, sewage irrigation and the overuse of fertilizers and pesticides all increased their contents in farmland 1 , 10 , 13 , 39 .…”

“…The contents of Cu, Zn, Pb and Cd in farmland soils of Nanchang were 33.2, 87.6, 45.5 and 0.66 mg·kg −1 , respectively 6 . This difference may be attributed to the lower levels of economic development and shorter cultivation periods 2 , 3 . Xinjiang is located in an economically underdeveloped region in the inland northwest, China, the lower industrial and traffic conditions introduced less trace elements into the farmland soils compared with the central and eastern China 3 , 41 .…”