International Journal of Environmental Science and Technology (2019) 16:2511–2524 https://doi.org/10.1007/s13762-019-02310-w REVIEW Detecting vegetation stress as a soil contamination proxy: a review of optical proximal and remote sensing techniques A. Gholizadeh1,2 · V. Kopačková1 Received: 26 June 2018 / Revised: 24 January 2019 / Accepted: 2 March 2019 / Published online: 18 March 2019 © Islamic Azad University (IAU) 2019 Abstract Soil contamination is a worldwide crisis, which diminishes food and agricultural production. Alterations in the soil environ- ment due to soil contamination cause biophysical and biochemical changes in vegetation. Due to dynamic nature of these changes, early monitoring can permit for preventive interferences before intense and sometimes inevitable vegetation and soil problems occur. As plants are rooted in soil substrate, vegetation changes can be used as bio-indicators of soil condi- tions. Traditionally, vegetation changes have been usually determined by visual analysis or detected after major destructive sampling during the growth period. As the characteristics of vegetation infuence its spectral properties, efective remote and non-contact detection methods ofer an alternative and near real-time way for detecting plant changes, even prior to visual symptoms and negative efects appearance. The aim of the current study is to review the potential of optical proximal and remote sensing techniques at diferent platforms for indirect assessment of plant–soil interactions via monitoring veg- etation anomalies related to soil contamination. It is strongly felt that this rapidly progressing technological direction will permit extending the use of the techniques to geology, soil science and precision agriculture and an overall broad range of applications. Keywords Bio-indicator · Proximal sensing · Remote sensing · Soil contamination · Vegetation stress Introduction structure, compaction status and soil depth. Both chemical and physical processes can bring water loss and soil toxicity Soil is the main natural resource for food and energy produc- as well as other efects including erosion, deposition and soil tion. It controls the movement of water in the landscape and swelling that all together direct to a reduction in soil pro- operates as a natural flter for probable leaching of contami- ductivity and fertility in space and time (Sahoo et al. 2012; nants into the environmental spheres (Stenberg et al. 2010); Chuncai et al. 2014). however, it can be degraded chemically and physically. Soil contamination, which is a reason for soil degrada- Chemical processes connect to parameters of the soil that tion, is a common and well-known environmental concern. tie to soil chemical components and their reactions, includ- It refers to the inflteration process of non-pedogenic con- ing salinity, fertility decline and contamination, whereas stituents that are not related to the natural generation or physical processes describe alterations in particle size, soil formation of the soil. Soil can be contaminated from dif- ferent sources such as petroleum hydrocarbons (PHCs) and natural gas (from fuel pipelines and tanks leakage) as well Editorial responsibility: Gaurav Sharma. as potentially toxic elements (PTEs) (from opencast mines and anthropogenic activities). Oil and gas accumulation as * A. Gholizadeh well as several chemical alterations in soils can be occured [email protected] due to PHC leakage (Noomen et al. 2006). Anthropogenic 1 Czech Geological Survey, Klarov 3, 11800 Prague 1, activities are also responsible for some signifcant damages Czech Republic to the Earth and mainly cause conversions to the geological, 2 Department of Soil Science and Soil Protection, Faculty hydrological and vegetation condition (Gotze et al. 2016b). of Agrobiology, Food and Natural Resources, Czech Accordingly, such alterations in the soil environment are University of Life Sciences Prague, Kamycka 129, the reasons for some visually perceptible changes including 16500 Prague, Czech Republic Vol.:(0123456789)1 3 2512 International Journal of Environmental Science and Technology (2019) 16:2511–2524 leaf chlorosis, thin vegetative cover and atrophic growth the vegetation’s attributes infuence its spectral properties, of the vegetation (Schumacher 1996; Smith et al. 2004a; efective remote and non-contacted spectroscopic monitor- Rosso et al. 2005). Garnier et al. (2007) stated that there is ing methods ofer an alternative and near real-time method a relationship between vegetation parameters as reactions of plant changes, even before the appearance of visual and changes in soil condition. For example, diferent kinds symptoms (Bayat et al. 2016). Using various spectroscopic of contaminants are picked up from the soil and transferred techniques at diferent ranges and platforms afects the total to the leaves via transpiration (Brentner et al. 2010), which precision of results; however, one of the gaps in monitor- are then transformed and conjugated with other compounds ing soil contamination using the spectral signatures of veg- in the cell wall (Komossa et al. 1995; Verkleij et al. 2009). etation is the lack of an efciency assessment for diferent Furthermore, some of the contaminants accumulate in leaf platforms, which needs further work. If vegetation status is tissues, bringing stress and interrupting photosynthetic pro- to be used as indicators of soil contamination contents, then cesses (Zinnert et al. 2013). Due to the dynamic nature of the intention of this review is to prepare a source of up-to- these efects, early monitoring of contaminants can allow date information on the past and current role of proximal suppressive interventions before severe and irreversible veg- and remote sensing techniques employing optical sensor etation and soil problems arise. data, when assessing vegetation anomalies due to soil con- The conventional methods of soil contamination assess- tamination. To illustrate this, soil contaminants and their ment in large areas involve feld data collection, chemical relationship with vegetation condition are discussed, as they analyses in a laboratory as well as geostatistical interpola- afect vegetation structure, functioning, growth and yield. tion, which are expensive and time-consuming. For instance There then follows a discussion on capability and accuracy according to Shi et al. (2016), little attention has been given of proximal and remote sensing techniques (in various plat- to soils contaminated with heavy metals due to limited forms) for indirect prediction of soil contamination using funds. In addition, conventional methods are inefective vegetation symptoms, and fnally, there is a short conclu- for detecting small soil changes; therefore, controlling the sion of the issues surrounding the use of remote detection efects of contaminants before causing irreparable impacts, methods for soil analysis based on vegetation parameters for will be neglected (Sanches et al. 2013a). future research. Vegetation changes around areas with contaminated and unhealthy soil have been reported. Due to plant–soil inter- action, change in plants morphological and physiological properties can be used as indicators of the ecological, geo- Soil contamination and its relationship chemical and hydrological situation (Zinnert et al. 2013). to vegetation health Furthermore, Roelofsen et al. (2015) stated that in the con- text of nature management, acquiring the soil conditions In order to quantify the vegetation and soil health relation- using their efects on vegetation is an efective alterna- ship, one approach is to understand vegetation stressors, tive due to rather narrow tolerance of plants communities which directly relate to soil condition. Vegetation plays an towards soil factors, which makes them representatives of important role in the movement of contaminants through the site’s conditions. Changes in plants traditionally have the soil; however, vegetation health faces diferent types been investigated by visual inspection or detecting via broad of stresses and changes negatively due to biotic and abi- analysis of destructive sampling during the growth period otic environmental factors (Fig. 1) (Schulze et al. 2005; (Chaerle and Van der Straeten 2001; Fedotov et al. 2016). As Tuominen et al. 2009). Fig. 1 Biotic and abiotic environmental stressors 1 3 International Journal of Environmental Science and Technology (2019) 16:2511–2524 2513 The above-mentioned environmental stressors are global several reasons, for instance, Van der Werf (2006) analysed concerns and afect vegetation structure, health, function- the soil parameters in and around a seep. No signifcant dif- ing and growth in various ways (Bayat et al. 2016). Thus, ferences in mineral composition and pH between the soils research on them and their relation to vegetation and soil were found. However, the level of soil moisture was 13% condition should receive more attention. Due to the insist- lower in the soil close to the seep than the soil at 20 m dis- ing character and long biological half-lives of soil contami- tance from the centre of the seepage. Since long-term seep- nants and their irreparable infuence on soil quality as well age of gas and oil bring groundwater to the surface (Jones as vegetation and human health (Wu et al. 2005; Gholizadeh and Drozd 1983), it is possible that groundwater collected et al. 2015), some of the most common soil contaminants at the edges of the halo causing changes in vegetation pat- and their efects on vegetation