**4. Heavy metals in the environment**

Environmental research on heavy metals requires a basis in environmental chemistry, ecotoxicology, and ecology. The study of xenobiotics in food chains is a significant field of research with important environmental, ecological, and economic implications. According to Ali et al. [38], marine chemistry has public health implications: "Aquatic chemistry is a key component of public health".

Understanding heavy metal pollution in coastal areas of certain countries, such as Asian and Oceania countries, is vital due to a lack of research and advanced xenobiotic monitoring methods. In recent years, several methods for detecting heavy metals in environmental matrices have been developed. Supercritical fluid extractions [39], acid extraction, alkaline extraction digestion with sodium hydroxide, and subsequent *Heavy Metal Contamination in the Coastal Environment and Trace Level Identification DOI: http://dx.doi.org/10.5772/intechopen.106653*

extraction with tetra ethyl ammonium hydroxide are examples of these methods [40]. When heavy metals are present in matrices at very low levels (ppb and ppt), however, extracting these chemicals is time-consuming, costly, and a source of inaccuracy and cross-contamination [41]. As a result, in many regions around the world, detecting heavy metals in aquatic settings has become difficult and inaccessible. solid phase extraction (SPE) and liquid-liquid extraction (LLE) are the most prevalent methods for separating metal compounds from matrices [42]. SPE cartridges, on the other hand, are costly and nonreusable, while LLE extraction procedures require a substantial volume of organic solvents. Bandara et al. [20] have optimized an automated solid phase micro extraction (SPME) method to detect tributyltin at ultra-trace concentrations (ppt levels) because it reduces sample preparation, solvent usage, and analytical costs.

For the quantitative determination of metals, atomic absorption spectrometry (AAS), inductively coupled plasma-mass spectrometry (ICP-MS), and gas chromatography-mass spectrometry (GC-MS) are widely employed.

#### **4.1 Heavy metal quantification**

For the assessment and implementation of heavy metal pollution management methods, environmental monitoring and quantification are required. The concentrations of potentially toxic metals and metalloids in diverse environmental media, such as water, sediments, and biota, should be monitored regularly. This environmental analysis will provide important information on the distribution, major sources, destination, and bioaccumulation of these elements in the environment, as well as on their bioaccumulation.

#### **4.2 Assessment of heavy metal pollution using biomarkers and bioindicators**

Łuczynska et al. [43] explain the use of bioindicators for heavy metal pollution monitoring and evaluation as follows: "Measuring metal concentrations in selected species of the resident biota could provide a more meaningful assessment of the impact of metal pollution." To assess heavy metal contamination and environmental pollution, a variety of plant and animal species have been used as bioindicators. Bandara et al. [20] studied the impact of tributyltin contamination in the Sri Lankan coastal stretch employing mollusks *Perna perna*, *Thias clavigera*, and *Perna viridis* at commercial and fishery harbors as the first record of tributyltin contamination.

#### **4.3 Atomic absorption spectrometry (AAS)**

By its simplicity and the fact that it can quantify a large number of metals (cobalt, chromium, cadmium, copper, iron, manganese, nickel, lead, and zinc) with a minimum detection limit of 1 ppb, flame atomic absorption spectrometry (FAAS) is extensively used for metal determination from the soil, water, and biological samples. A graphite furnace and greater atomization temperatures are required for electrothermal atomic absorption spectrometry (ETAAS). This method has the advantage of requiring a minimal sample volume (20–50 uL) and having excellent minimum detection limits at parts per billion level.

The use of chemical modifiers in ETAAS analysis of volatile elements (arsenic, antimony) is required to stabilize the analysis, which would otherwise evaporate at temperatures above 400o C. One of the most successful methods for determining trace elements in various matrices is chemical vapor production in combination with atomic absorption spectroscopy. HGAAS (hydride generation atomic absorption spectroscopy) and cold vapor atomic absorption spectroscopy are two examples of this technology (CVAAS). HGAAS is used for the analysis of hydride-forming metals (selenium, arsenic, tin, and lead) while CVAAS is used for mercury analysis from various samples.
