The Effects of Heavy Metal Pollution on Collembola in Urban Soils and Associated Recovery Using Biochar Remediation: A Review

Abstract

Heavy metal pollution in urban soil continues to be a global issue that poses a serious hazard to invertebrates and human lives through oral ingestion and inhalation of soil particles. Though the toxicity of several heavy metals on invertebrates like Collembola has been studied, lead (Pb) and cadmium (Cd) have been extensively studied due to their high toxicity to collembolans. As a ubiquitous soil organism all over the world, collembolans have been used as a model species to study the effects of heavy metals on invertebrate communities. To reduce the effects of heavy metals on ecosystem functions, biotic and abiotic measures have been used for heavy metal remediation; biochar seems to be the most effective approach that not only increases the physical absorption of heavy metals but also indirectly benefits soil organisms. In this study, we briefly reviewed the application of biochar in Pb and Cd polluted soil and showed its potential in soil remediation. Furthermore, we outlined the potentially toxic effects of Pb- and Cd-polluted urban soil on the collembolan species. We searched peer-reviewed publications that investigated: (1) the level of Pb and Cd contamination on urban soil in different cities around the world; and (2) the different sources of Pb and Cd as well as factors influencing their toxicity to collembolan communities. The obtained information offers new perspectives on the interactions and effects between collembolans, Pb, and Cd, and their remediation in urban soils.

Elemental distribution and source analysis of atmospheric aerosols from Meycauayan, Bulacan, Philippines

“…Although there are studies of potentially toxic elements in outdoor and street dusts, there are limited to no publications on heavy metals measured in different land use settings. The observed concentrations of heavy metals are within the range measured in other cities in Asia and the world [ [4] , [5] , [6] , 28 ]. The variations in the heavy metal concentrations suggests the possible effects from anthropogenic sources such as urbanization, human sources, traffic density, and types of fuels used.…”

“…Major anthropogenic and natural sources of heavy metals in atmospheric aerosols and urban dusts include industrial emissions, household and traffic effluents, weathering, and erosion [ 1 , 2 ]. The increasing population growth in urbanized cities leads to higher values of heavy metals as observed in different urban areas in Asia and the World [ [3] , [4] , [5] , [6] ].…”

Cadmium Toxicity and Health Effects—A Brief Summary

“…Soil washing and phytoremediation are the best available technologies for treating heavy-metal-contaminated soils, but are often practiced only in developed countries. However, these technologies are also recommended in developing countries, where agriculture, urbanization, and industrialization contribute to environmental degradation [ 14 , 20 ].…”

“…Around 600 million people are annually affected by a contaminated environment. Contamination of food with heavy metals is more common in polluted agricultural regions, posing a very serious problem worldwide [ 13 , 14 ]. It is also estimated that more than 13% (about 0.24 billion hectares) of the world’s total arable land and about 40% of lakes and rivers are contaminated with heavy metals [ 14 ].…”

“…Contamination of food with heavy metals is more common in polluted agricultural regions, posing a very serious problem worldwide [ 13 , 14 ]. It is also estimated that more than 13% (about 0.24 billion hectares) of the world’s total arable land and about 40% of lakes and rivers are contaminated with heavy metals [ 14 ]. The continued use of Cd in industry drastically affects the environment, resulting in high exposure of humans to the element [ 15 ].…”