# Special Issue on \"Ecotechnological Green Approaches to Environmental Remediation and Restoration\"
###### Abstract
(5) Ecosystems are used for the benefit of humankind without destroying ecological balance, for example, through multispecies aquaculture/polyculture, mixed culture, integrated farming, sustainable agriculture, and sustainable aquaculture. (6) Ecosystems' components are used for environmental remediation and the production of value-added products. The papers in this Special Issue, contributed by scientists from Asia, America, and Europe, deal with remediation of degraded land, in situ electrokinetic remediation, the use of permeable reactive barriers, chemical manipulation of micronutrients and macronutrients for reducing toxicant load in crop plants, biodegradation of antibiotics, biofloculation for heavy metal removal, biosurfactants for bioremediation of kerosene contamination in soil, biomonitoring of land use changes using enzymatic signatures, and biofuel feedstock production on metal-contaminated land. They represent a broad spectrum of ectotechnological processes involved in environmental remediation and restoration. [PERSON] et al. (contribution 1) describe how extracellular enzymatic (catalase, sucarse, urease and alkaline phosphatase) activities in soil show temporal variation subject to land-use change during different vegetative growth periods following afforestation, and can serve as excellent biochemical indicators of soil functions and ecosystem services. The results illustrated that soil enzyme activities increased significantly following afforestation due to characteristic microbial assemblages, associated activities and soil properties, and both alkaline phosphatase and sucarse were more sensitive to temporal variation than catalase and urease. These results highlight the importance of soil enzyme activities for maintaining soil nutrients in general, particularly dissolved organic carbon and dissolved organic nitrogen, which have immense importance in formulating fertilization and plantation management protocols in the Loess Plateau, China and elsewhere. [PERSON] and [PERSON] (contribution 2) evaluated the performance of in situ electrokinetic remediation (EK) and permeable reactive barriers (PRBs) filled with recyclable food scrap ash (FSA) of soil co-contaminated with heavy metal and organic contaminants. FSA was chosen as a PRB-filling material due to its high potential for adsorptive removal of contaminants. Acetic acid and Brij30 were used as enhancers on copper and phenanthrene, respectively, to improve EK remediation performance in removing heavy metals and organic contaminants. Copper adsorption to PRB accomplished a removal efficiency of up to 90%, whereas phenanthrene was hardly detected due to its low recovery rate in kaolinite; this indicates that further studies of pretreatment conducted on phenanthrene-contaminated kaolinite are needed. The study of [PERSON] et al. (contribution 3) delved into the bioavailability, uptake, accumulation, and toxicity of arsenic in rice plants and the impact of chemical manipulation (using two micronutrients and two macronutrients as fertilizer) in reducing As uptake and transport in rice. Adding micronutrients and macronutrients proved to offer dual benefits: it acts both to fertilize rice, improving the plant's growth and health, and to reduce arsenic uptake and toxicity. Other studies [18; 19] have shown that significant amounts of As can be transmitted to rice shoots and grains depending on the genotype and soil conditions, and As partitioning and loading in different plant parts can be moderated by various agro-management interventions. Arsenite [As (III)] and methylated organic species enter rice using the Si and P transport routes. The use of Si in rice fields reduces the concentration of As (III) in rice, which is more toxic than As (V)]. Although removing Si from soil particles can increase the bioavailability of As, due to the common pathway of these two elements, when Si is added to the culture medium, the competition between them increases and thus reduces the uptake of As by rice.