Human activities have introduced large amounts of heavy metals into natural ecosystems in recent years. As a result, the accumulation of heavy metals and metalloids in plants, animals, and humans, which may have caused some health problems. Chemical and physical methods can remove the heavy metal in contaminated soil, but both are very expensive and ineffective. Arbuscular Mycorrhizal Fungi (AMF) are mutualistic symbionts in most plant roots. Furthermore, AMF are the essential mycorrhizae for phytoremediation, and the extensive hyphal network of them can increase the uptake of micro and macronutrients, water and heavy metals from the soil. However, AMF hyphae colonized in plant roots have an ability for compartmentalizing heavy metals inside plant roots. Furthermore, AMF hyphae are capable of secreting a glycoprotein, named glomalin, which can bind heavy metals and subsequently remove heavy metals absorbed by the plants from contaminated soil. Glomalin can develop the properties and structure of the soil, which helps to enhance soil fertility. This paper presents the role of AMF in the ecosystems and as potential tools for bioremediation of heavy metals in the soil.

This study assessed the potential uptake of soil-contaminated heavy metals by Azolla pinnata and Lemna gibba in combination with and without arbuscular mycorrhizal fungi (AMF) in traditional and improved rice varieties. Total levels of cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) in soil, rice roots, shoots, grains, A. pinnata, and L. gibba were estimated using ICP-MS. The percentage colonization in AMF-inoculated and AMF-uninoculated rice varied from 1.13–30.67% and 1.33–5.42%, respectively. These findings suggested that AMF provide protection to rice plants against the combined toxicity of Cd, As, Pb, and Hg in rice field soil. The combined interaction of AMF, organic fertilizer, and A. pinnata decreased heavy metal accumulation in rice roots, shoots, and grains in both tested varieties. The intake and subsequent accumulation of Cd, As, Pb, and Hg in the rice grains differed significantly (p < 0.05) between the two rice varieties. Furthermore, it was revealed that the AMF-inoculated rice plants reduced the translocation of heavy metals from root to shoot. Therefore, it can be concluded that heavy metal absorption and accumulation in rice can be reduced by the application of AMF, organic fertilizer, and A. pinnata together in rice farming.

Using them to phase out chemical fertilizers. Chemical fertilizers generate environmental pollution and negatively impact benefi cial organisms as well as human and animal wellbeing, causing a paradigm shift towards safer improved biofertilizers. Hence, improving the arsenal of microbial inoculants such as plant-growth-promoting rhizobacteria (PGPR) and plant growth-promoting fungi (PGPF), use of microbial consortia, use of uncommon inoculants such as extremophiles and microalgae, development of customized biofertilizers to suit the conditions of the fi elds and their geographical locations, identifying and popularizing other benefi cial aspects of biofertilizers to use them as tools for bioremediation, improved plant physiology and degradation of pesticides have become the trends of biofertilizers. However, soil application of biofertilizers has limited success yet and to be explored. Because of the interactions of soil- introduced PGPR and PGPF can be excluded by the more resilient microbiome in soil. Therefore, different strategies have to be employed to facilitate complex interactions with soil, environment and phytomicrobiomes. New molecular technologies allow for using metagenomics, metatranscriptomics, metaproteomics and metabolomics to spur development. Phytomicrobiome engineering is also used in synthetic biology also may offer new trend. These will be key in developing the next generation of biofertilizers.

The present study was conducted to evaluate the water quality of the inlet, irrigation outlet, and edges linked to Nuwarawewa reservoir, Mahakanadarawa reservoir, Hurulu wewa reservoir, Sangilikandarawa reservoir, and Nachchaduwa perennial reservoir in Anuradhapura, Sri Lanka. Water samples were taken from a designated position of each inlet, irrigation output, and edges in the second inter-monsoon, northeast monsoon, and first inter-monsoon seasons. Water quality indicators such as pH, electrical conductivity (EC), total dissolved solids (TDS), Na, K, Ca, Mg, Sodium Adsorption Ratio (SAR), NO3- -N, NH4+-N, dissolved reactive phosphorus (DRP), and heavy metals (Cd, As, Pb, and Hg) concentrations were measured in each water sample. Data was analyzed using SPSS statistica software. Considerable temporal fluctuations in water quality indicators were detected in inlets, irrigation outflows, and edges over the research period. The findings revealed that NO3- -N, NH4+-N, and DRP in Sangilikandarawa reservoir during the northeast monsoon were close but not above the FAO (1985) maximum levels guidelines for irrigation water. pH, EC, TDS, and heavy metals (Cd, As, Pb, and Hg) in all the other tanks were within permitted values according to WHO drinking water quality standards and FAO (1985) guidelines for irrigation water. This finding further demonstrated that the consequences of surrounding land use on water pollution in inlet water canals linked to Sangilikandarawa and Nuwarawewa are greater. It could be concluded that a pollution management plan needs to be implemented in order to stop further pollution.

Currently, the prevalent levels of carbon emissions driving up global temperatures are primarily due to fossil fuel burning in transportation. Carbon-neutral renewable fuel types are currently seen as the main way forward in dealing with this problem. Biodiesel is seen as a major carbon-neutral replacement fuel source that can significantly reduce the dependence on fossil fuel sources. However, the currently available raw materials, technology, and infrastructure are insufficient for production of biodiesel in substantial quantities that may replace its fossil fuel counterpart to a larger extent. Novel feedstock types for production of biodiesel and more innovative methods for production and downstream processing optimization are therefore required to increase biodiesel production to substantial levels. Recent literature lacks a comprehensive analysis that can let researchers and policy makers know the current and emerging technologies that may enable cost-effective and large-scale biodiesel production from feedstocks that do not compete directly with other critical aspects, such as food production. This book chapter aims to identify the most prominent recent scientific advances made in organic feedstock types into biodiesel. Furthermore, it provides a comprehensive outlook on biomass types, genetically engineered feedstock types, and process optimization of raw material extraction for biodiesel production.