Environmental Impacts of Heavy Metals and Their Bioremediation

Abstract

Fast consumption, increasing energy needs, unplanned urbanization, and unconscious discharge of industrial wastes cause pollution of air, soil, food and water resources. Among these pollutants, heavy metals and metalloids are not biodegradable and accumulate in compartments such as water, soil and plants, threatening human and environmental health. Monitoring studies show that heavy metals such as arsenic, lead, mercury, cadmium, nickel, zinc, copper, chromium and trace elements are in first place according to their availability in the environment. Preventive and remedial measures should be taken to reduce the effects of heavy metals. Legal regulations, monitoring studies, the use of soluble and non-toxic compounds in environmental compartments (air, water, soil and plants) in industrial processes, heavy metal-free pesticides, appropriate wastewater treatment plants and use of renewable energy sources instead of fossil fuels are among the priority measures to reduce concentrations of heavy metals in the environment. As a bioremediation approach, removing toxic wastes from the environment by using bioaccumulatory organisms such as plants or mussels maintains its importance among studies aimed at recovery. Studies have shown that integrated methods - especially the combination of suitable plants and microorganisms - are very effective in mitigating the effect of heavy metals in the environment.

Biosensor Constructs for the Monitoring of Persistent Emerging Pollutants in Environmental Matrices

“…When their presence exceeds the natural requirements, they are a potential threat to the environment, diversity, functioning of soil microorganisms, food security, and human health. 130 Therefore, effective monitoring of these compounds is an urgent need for the development of preventive and remedial measures. 124 Thus, oxidoreductases (such as tyrosinase, PPy-GOx, and nitrate reductase, among others) and hydrolases (ALP) are the most used enzymes for the identification and quantification of heavy metals/metalloids.…”

“…Also, EBBs based on isomerases have been employed for Hg 2+ detection. 120,130 Based on the enzyme inhibition mechanism, where heavy metals interact with thiol or methylthiol groups of amino acids, it has been possible to use enzymes as pyrroloquinoline quinone dependent glucose dehydrogenase, ALP, and horseradish peroxidase with very low detection boundaries, such as 2, 0.5, 5, and 40 ppm for Zn 2+ and Co 2+ , Cd 2+ , Ni 2+ , and Pb 2+ , respectively. 131 Likewise, by using the enzymatic amperometric method, it was possible to sense chromium in urine samples from the tannery wastewater.…”

“…134 Commonly detected drugs include nonsteroidal anti-inflammatory drugs (NSAIDs), antihypertensive drugs, and antibiotics, and because humans consume them, they are found primarily in untreated municipal wastewater and in effluents and biosolids from wastewater treatment plants. 130 Therefore, with the aim to tackle this crisis, the most recurrent enzymes for their sensing are peroxidases, laccases, and tyrosinases. 124 For example, a peroxidase-electrochemical biosensor was developed to detect levetiracetam (a drug prescribed for epilepsy and a derivative of pyrrolidine).…”

“…Some of them are essential for biological processes, such as copper (Cu), nickel (Ni), iron (Fe), and zinc (Zn), but also, some of them are nonessential elements for living organisms, such as lead (Pb), mercury (Hg), cadmium (Cd), and tin (Sn). When their presence exceeds the natural requirements, they are a potential threat to the environment, diversity, functioning of soil microorganisms, food security, and human health . Therefore, effective monitoring of these compounds is an urgent need for the development of preventive and remedial measures .…”

“…Some of the identified cations are Ag 2+ , Cd 2+ , Cr 3+ , Cr 6+ , Cu 2+ , Hg 2+ , Ni 2+ , Pb 2+ , and Zn 2+ , among others. Also, EBBs based on isomerases have been employed for Hg 2+ detection. , …”