Fourier transform infrared (FTIR) spectroscopy has been extensively used in microplastic (MP) pollution research since 2004. The aim of this review is to discuss and highlight the recent advances in FTIR (spectroscopy and chemical imaging) techniques that are used to characterize various polymer types of MPs and to trace their fate and transport in different environmental matrices. More than 400 research papers dealing with FTIR techniques in MP pollution research, which are published between January 2010 and December 2019, have been identified from the Scopus and Web of Science databases. The MPs present in sediment, water (marine and freshwater), biota, air/dust, waste water treatment plants and salt are further classified according to (1) characterization and identification, (2) weathering and aging, (3) ecotoxicology, and (4) analytical methods. The results revealed that the ATR-FTIR technique is mostly used to identify and characterize the MPs found in water and sediment. The mFTIR (FTIR imaging) is extensively used to study the ingestion of MPs in biota (both marine and freshwater). In this article, we have summarized the current knowledge of application of FTIR spectroscopy to MP research and provided insights to future challenges for understanding the risk of MPs.
Wave data collected off Ratnagiri, Goa and Dwarka along the west coast of India during winter season (NE monsoon and early pre‐monsoon) present distinct wave characteristics with periodicity ranging between 2 and 5 days associated with shamal events. The notable wave characteristics during these events are: an increase in wave height, decrease in swell period and a common propagation direction (northwest) for wind sea and swell. IFREMER/CERSAT blended winds clearly show the presence of strong northwesterly winds in the Arabian Peninsula and northwestern Arabian Sea, which are associated with the winter shamal events. The winds during such events generate large northwesterly swells (shamal swells) in the northwestern Arabian Sea and propagate towards the west coast of India in the NW direction with mean periods ranging between 6 and 8 s. Numerical simulations reproduce the shamal swells over the Arabian Sea, and they can be traced all along the west coast of India, however, with lesser order of magnitude from north to south. Generation and propagation of shamal swells and their influence along the west coast of India have been described.
An analysis of wind and wave data collected in the coastal region of Goa, west coast of India, during fair weather season reveals a distinct and systematic diurnal variation in wind speed, wave height and wave period, especially simultaneous increase in wave height and decrease in wave period with increase in local wind speeds due to sea breeze system. During a typical daily cycle, the wave height reaches its peak early in the afternoon, then it decays progressively back to the swell conditions within 5 or 6 hours. Measured wave spectra distinctly bring out salient features of deep water swell and wind seas generated by the local sea breeze. Numerical simulations reproduce the characteristics of this daily cycle. The exposure of Goa coast to long distant swells from the southwest and to the local wind seas from the northwest leads to complex cross-sea conditions.
This study describes the climatology of shamal winds in the Arabian Sea using recent 30 years of ERA-Interim winds. The shamal events were distinguished based on the typical directions, duration and intensity of the winds. Three potential zones of shamal winds were identified in the northwestern Arabian Sea, which are the areas where the predominant shamal swells have been generated. The number of events, duration and intensity of shamal winds were estimated for various months and years. The climatology and trends of shamal winds were derived and the spatial extent of the winds was assessed. The results show that the number of events and the duration of shamals decrease in the northwestern Arabian Sea. Contrasting trends have been observed in the shamal intensities-significant positive trends in the Gulf of Oman and significant negative trends along the east coast of Oman. The trends of the total winds are in contrast with those of the shamals winds.
Spectral and statistical wave parameters obtained from the measured time series wave data off Paradip, east coast of India during May 1996-January 1997 were analysed along with MIKE 21 spectral wave model (SW) results. Statistical wave parameters and directional wave energy spectra distinctly separate out the wave conditions that prevailed off Paradip in the monsoon, fair weather and extreme weather events during the above period. Frequency-energy spectra during extreme events are single peaked, and the maximum energy distribution is in a narrow frequency band with an average directional spreading of 20°. Spectra for other seasons are multi-peaked, and energy is distributed over a wide range of frequencies and directions. The NCEP re-analysis winds were used in the model, and the results clearly bring out the wave features during depressions. The simulated wave parameters reasonably show good match with the measurements. For example, the correlation coefficient between the measured and modelled significant wave height is 0.87 and the bias -0.25.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.