Implementing a sustainable framework for agriculture to promote food security and produce safe food is a facet of goal two within the UN’s 17 Sustainable Development Goals (United Nations, 2022). However, as the world becomes increasingly industrialized, environmental contaminants are released from more and more anthropogenic sources, particularly from the fields of agriculture and industry, threatening the UN’s objective (Rai et al., 2019). These practices include smelting, the use of fertilizers and pesticides, and the burning of fossil fuels (Alengebawy et al., 2021). These contaminants include heavy metals and metalloids such as mercury, arsenic, lead, and cadmium (Rai et al., 2019). This issue and the risks it poses have become an urgent concern for the environment as contaminants accumulate in the soil and makes their way into the food chain (França et al., 2017).
The soil, an integral part of crop development, can be contaminated through pollution from a single point-source, such as coal mines and thermal power plants or a variety of non-point sources, such as agricultural runoff from several crop fields (Rai et al., 2019). The accumulation of heavy metals in the soil has been shown to have consequences on both abiotic and biotic ecosystem components (Gall, Boyd and Rajakaruna, 2015). These metals affect the properties and fertility of the soil, such as the pH, salinity, cation exchange capacity, and texture. Additionally, interactions between multiple heavy metals can affect the quantity of compounds accessible for uptake in the soil (Alengebawy et al., 2021). However, their most pronounced effect on the soil is their destruction of microbial and soil-microbial interactions, as heavy metals denature microbial cell membranes (Rai et al., 2019; Xie et al., 2016).
These alterations in the soil can cause plants to have biochemical and mineral deficiencies (Shahid et al., 2011). In addition, heavy metals can cause elevated levels of reactive oxygen species (ROS) within the plant. The plant can not keep up with this increase, and the resulting oxidative stress causes molecular damage to structures like proteins and nucleic acids. This deterioration causes physiological issues such as inhibited enzymatic activities and can ultimately lead to necrosis (Alengebawy et al., 2021). The route heavy metals take from accumulation in the soil to the plant, and the negative impacts they cause are depicted in Figure 1.
While these heavy metals are critical toxins for the soil and plants, they also have detrimental effects on human health. Humans are constantly exposed to these pollutants through ingestion and inhalation (Rai et al., 2019). These pollutants can accumulate in organs such as the kidney, liver, and bone causing damage to vital body systems (endocrine, reproductive, immune, circulatory, etc.). Several diseases are also associated with heavy metal toxicity, such as several types of cancer, osteoporosis, neurodegenerative disorders, diabetes, and hypertension (Alengebawy et al., 2021). There are many additional health risks as each metal compound has different diseases associated with it, and added adverse health effects arise from accumulated heavy metals interacting in the body (Rai et al., 2019; Alengebawy et al., 2021).
Action must be taken to remediate the number of heavy metals released into the environment. There are environment-based solutions, such as growing hyperaccumulator crops like Alyssum murale, to extract the heavy metals from the soil through phytoremediation (Wiszniewska et al., 2016). There are also human-based solutions to remove heavy metals from the body through specific diets and supplements, like spirulina and ginseng (Zhai, Narbad and Chen, 2014). Ultimately, humans must recognize the disruption of ecosystems caused by these contaminants and stop the unsustainable production of products polluting the planet.
Resources
Alengebawy, A., Abdelkhalek, S.T., Qureshi, S.R. and Wang, M.-Q., 2021. Heavy Metals and Pesticides Toxicity in Agricultural Soil and Plants: Ecological Risks and Human Health Implications. Toxics, 9(3), p.42. https://doi.org/10.3390/toxics9030042.
França, F.C.S.S., Albuuerque, A.M.A., Almeida, A.C., Silveira, P.B., Filho, C.A., Hazin, C.A. and Honorato, E.V., 2017. Heavy metals deposited in the culture of lettuce (Lactuca sativa L.) by the influence of vehicular traffic in Pernambuco, Brazil. Food Chemistry, 215, pp.171–176. https://doi.org/10.1016/j.foodchem.2016.07.168.
Gall, J.E., Boyd, R.S. and Rajakaruna, N., 2015. Transfer of heavy metals through terrestrial food webs: a review. Environmental Monitoring and Assessment, 187(4), p.201. https://doi.org/10.1007/s10661-015-4436-3.
Rai, P.K., Lee, S.S., Zhang, M., Tsang, Y.F. and Kim, K.-H., 2019. Heavy metals in food crops: Health risks, fate, mechanisms, and management. Environment International, 125, pp.365–385. https://doi.org/10.1016/j.envint.2019.01.067.
Shahid, M., Pinelli, E., Pourrut, B., Silvestre, J. and Dumat, C., 2011. Lead-induced genotoxicity to Vicia faba L. roots in relation with metal cell uptake and initial speciation. Ecotoxicology and Environmental Safety, 74(1), pp.78–84. https://doi.org/10.1016/j.ecoenv.2010.08.037.
United Nations, 2022. Food security and nutrition and sustainable agriculture .:. Sustainable Development Knowledge Platform. [online] Available at: <https://sustainabledevelopment.un.org/topics/foodagriculture> [Accessed 20 October 2022].
Wiszniewska, A., Hanus-fajerska, E., Muszyńska, E. and Ciarkowska, K., 2016. Natural Organic Amendments for Improved Phytoremediation of Polluted Soils: A Review of Recent Progress. Pedosphere, 26(1), pp.1–12. https://doi.org/10.1016/S1002-0160(15)60017-0.
Xie, Y., Fan, J., Zhu, W., Amombo, E., Lou, Y., Chen, L. and Fu, J., 2016. Effect of Heavy Metals Pollution on Soil Microbial Diversity and Bermudagrass Genetic Variation. Frontiers in Plant Science, [online] 7. Available at: <https://www.frontiersin.org/articles/10.3389/fpls.2016.00755>.
Zhai, Q., Narbad, A. and Chen, W., 2014. Dietary Strategies for the Treatment of Cadmium and Lead Toxicity. Nutrients, 7(1), pp.552–571. https://doi.org/10.3390/nu7010552.
Comments
7 Responses to “Heavy Metals and Crop Contamination”
Hello iSci! I came across the contamination of vineyards due to high concentrations of heavy metals in the soil in some of my wine science research and thought the topic was interesting. Additionally, it related to concepts we learned in both wine science and climate change. I did my blog post on this topic to give an overview of the impact of heavy metals on different aspects of the environment. I hope you found it informative!
Hi Paige,
A wonderfully written blog post! It was super informational and enjoyable to read. I had a few suggestions for you:
Something else I noticed were two short sentences that I believe can be joined to better improve the flow of the paragraph. Rather than writing “These metals affect the properties and fertility of the soil. For example, they can alter the pH, salinity, cation exchange capacity, and texture”, I suggest combining them into a single sentence such as “These metals affect the properties and fertility of soil, such as the pH, salinity, cation exchange capacity, and texture.”
In the last sentence of your third paragraph, I believe you accidentally wrote “cause” in plural form rather than singular form. I would change “they causes” to “they cause”.
Your figure also contained the abbreviation of reactive oxygen species, ROS, but you never mentioned the abberviation prior to presenting it in the graph, so I would recommend including that in brackets during your first mention of the term. I think it would also be helpful for readers that are unfamiliar with the terms to define free radicals and reactive oxygen species.
In your final paragraph where you discuss possible solutions to remediate the issue, you give potential solutions but no specific examples. You talked about “growing certain crops” and “specific diets and supplements”. I think it would be more informative if you were to include specific examples from the literature you analyzed.
I look forward to reading your final copy!
Kavin
Hey Kavin!
I have changed some of my sentences to improve the flow, as you suggested. I added the short form of reactive oxygen species in brackets and briefly explained free radicals and reactive oxygen species in the figure caption. I also added some specific examples to the solutions I discussed. Thanks for your feedback; I found it very helpful!
Paige
Hello Paige!
This is a really topical blog post with all of the things we have been talking about in climate change! I always find it interesting examining how the effects of pollution accumulate, amplify, and end up negatively impacting us (as dark as it can get sometimes). I have a few suggestions that you may want to consider:
In the last sentence of paragraph one, you could replace ‘environment as it accumulates’ with ‘ as contaminants accumulate’ to make your point more specific.
In your second paragraph, you could replace ‘components of the earth’ with ‘ecosystem components’ which is much less awkward. You may also want to provide examples for the last two sentences in your second paragraph as those effects are interesting and elaborating on them would further your point about the overall negative impact on plant life.
Finally, in the fourth paragraph the second half of your last sentence flows awkwardly from the first half. You could rewrite it as ‘and additional adverse health effects arise from accumulated heavy metals interacting in the body’.
Overall, your blog post is an important reminder about the far-reaching effects of human actions and I enjoyed reading it. Good luck with your editing!
Matthew
Hello Matthew,
I have rewritten the sentences you mentioned, as you suggested. I also added an example of how microbial soil interactions are altered but, unfortunately, didn’t have enough space in my word count to explain more about interactions between heavy metals.
Thank you for all your feedback!
Paige
Hi Paige!
I really enjoyed reading your blog post. It integrated many topics while making a call to action on a very pertinent issue.
Just some suggestions:
– In your first sentence, I like how you mention that implementing a sustainable framework for agriculture is currently one of the UN’s objectives, but it may be even more effective to state where exactly this objective lies within the UN. For example, is it under the UN’s 17 Sustainable Development Goals (SDGs)?
– In your first paragraph, you mention how increased industrialization has lead to more environmental contaminants. If you have the space, it would be extremely interesting to read about what principle practices within various industries is leading to this contamination. For example, is there a specific harvesting practice within the agricultural industry causing lots of contamination? This would also allow you to make your call to action in the last paragraph even clearer as you could mention possible alternatives to these detrimental practices.
– In your second paragraph, you may want to distinguish between point and non-point sources to add clarity.
– In your fourth paragraph you mention that there are adverse effects of metals interacting with one another. Does this apply to all metals, or is it the interactions of heavy metals specifically?
– I love your call to action in the last sentence, but for added flow, it could be reworded. Instead try, “Ultimately, humans must recognize the disruption of ecosystems caused by these contaminants and stop the unsustainable mass production of products that is polluting the planet.”
Overall, amazing work. I am excited to read the final copy!
Hi Tazeen!
I added the specific sustainable development goal that mentions the UN objectives I talked about. I also added some examples of specific practices that cause the release of these contaminants and added more explanation as to what a point source is. The interactions I mentioned are for heavy metals; specifically, I rewrote that sentence to make this more clear. I reworded the final sentence, as you mentioned.
Thanks for your suggestions!
Paige