Physical and biochemical assessment of Mexican Palo Verde response to chromium toxicity.

More About This Textbook

Overview

In the United States, about 1/3 of the 1400 superfund sites have been reported to be chromium contaminated, making chromium the second most common metal found in superfund chemical contamination sites. Chromium removal from soil has commonly been carried out via chemical, physical, and thermal processes. However, these methods are expensive and/or invasive to local ecosystems. In contrast to these techniques, phytoremediation (the use of plants to remove toxic substances from areas containing contamination at low or medium levels) appears to be a cost-effective and environmentally friendly process for chromium removal. However, most reports on chromium phytoremediation suggest that this element is stored in roots and very few amounts are translocated to the frond. Parkinsonia aculeata (Leguminosae, Fabaceae), a shrub/tree native to the southwestern United States and northern Mexico, where it is commonly known as the Mexican Palo Verde (MPV), was selected as a model plant to investigate its potential for chromium phytoremediation in desert areas.;In these studies, plants were exposed to chromium(III) and chromium(VI) ions under different experimental conditions, including the use of phytohormones in hydroponics and soil. The objectives of this research were to understand the Cr uptake, distribution, and accumulation in MPV, as well as the effect of phytohormones in response to Cr stress on MPV. This project was performed in four phases. In phase one, MPV plants were treated with different concentrations of Cr(III) and Cr(VI) in hydroponics to assess its tolerance to Cr stress, as well as to determine the main signs of Cr toxicity. The results from phase one were used in phase two, where plants were sown in soil with a range of Cr(III) and Cr(VI) concentrations to determine the real potential of MPV for Cr absorption. In phase three, MPV plants were grown both in soil containing tolerable concentrations of Cr(III) and Cr(VI), as well as different concentrations of phytohormones so as to determine their influence on MPV's response to Cr stress. In phase four, a 6-month long experiment was carried out to evaluate the long term effect of Cr stress in MPV plants and the Cr distribution pattern in plant organs. A series of inductively coupled plasma-optical emission spectrometry and other spectroscopic techniques as well as biochemical assays were used in this research.;Results demonstrated that Cr(VI) treatment produced shorter and weaker plants compared to Cr(III) treatment. In both cases the translocation of Cr into the stems increased with time. Results have also shown that the uptake of nutrient elements varied with time and Cr species. For instance, in Cr(III)-treated plants, Fe accumulation in stems decreased with time but no changes were observed in leaves, although Cr(VI)-treated plants displayed similar Fe accumulation in all tissues throughout the 6-month growth period. The IR spectra of tissues revealed that Cr altered plant lignin in the cortex and xylem, and the degree of lignification and protein content increased under Cr stress. The study also showed that the phytohormone kinetin (KN) at 250 muM reduced catalase (CAT) but increased ascorbate peroxidase (APOX) activity in the roots of Cr(VI)-treated plants. Both CAT and APOX were reduced in the leaves of plants treated with Cr(III) and KN. However, under Cr(VI) stress neither CAT nor APOX were reduced by the presence of KN.;The electron probe microanalyzer proved to be a feasible and practical tool for metal analysis in plant tissues. X-ray fluorescence images showed that for both of the Cr(III) and Cr(VI) treatments, Cr was mainly located at the cortex section in the root, and Cr distribution was essentially homogenous in stems. However, Cr(VI)-treated roots and stems had more Cr accumulation than the corresponding part in Cr(III) treatments. X-ray absorption spectroscopy data showed that Cr(VI) was reduced to Cr(III) in/on plant roots and transported as Cr(III) to the stems and leaves. Overall, this research demonstrated not only that MPV can uptake and store Cr inside plant tissues, but also, that kinetin is capable of increasing the translocation of Cr from roots to stems in plants treated with both Cr ions, improving the MPV's ability to phytoremediate Cr in moderately impacted soils.
Read More Show Less

Product Details

  • BN ID: 2940043405449
  • Publisher: ProQuest LLC
  • Sold by: Barnes & Noble
  • Format: eTextbook
  • Pages: 123

Customer Reviews

Be the first to write a review
( 0 )
Rating Distribution

5 Star

(0)

4 Star

(0)

3 Star

(0)

2 Star

(0)

1 Star

(0)

Your Rating:

Your Name: Create a Pen Name or

Barnes & Noble.com Review Rules

Our reader reviews allow you to share your comments on titles you liked, or didn't, with others. By submitting an online review, you are representing to Barnes & Noble.com that all information contained in your review is original and accurate in all respects, and that the submission of such content by you and the posting of such content by Barnes & Noble.com does not and will not violate the rights of any third party. Please follow the rules below to help ensure that your review can be posted.

Reviews by Our Customers Under the Age of 13

We highly value and respect everyone's opinion concerning the titles we offer. However, we cannot allow persons under the age of 13 to have accounts at BN.com or to post customer reviews. Please see our Terms of Use for more details.

What to exclude from your review:

Please do not write about reviews, commentary, or information posted on the product page. If you see any errors in the information on the product page, please send us an email.

Reviews should not contain any of the following:

  • - HTML tags, profanity, obscenities, vulgarities, or comments that defame anyone
  • - Time-sensitive information such as tour dates, signings, lectures, etc.
  • - Single-word reviews. Other people will read your review to discover why you liked or didn't like the title. Be descriptive.
  • - Comments focusing on the author or that may ruin the ending for others
  • - Phone numbers, addresses, URLs
  • - Pricing and availability information or alternative ordering information
  • - Advertisements or commercial solicitation

Reminder:

  • - By submitting a review, you grant to Barnes & Noble.com and its sublicensees the royalty-free, perpetual, irrevocable right and license to use the review in accordance with the Barnes & Noble.com Terms of Use.
  • - Barnes & Noble.com reserves the right not to post any review -- particularly those that do not follow the terms and conditions of these Rules. Barnes & Noble.com also reserves the right to remove any review at any time without notice.
  • - See Terms of Use for other conditions and disclaimers.
Search for Products You'd Like to Recommend

Recommend other products that relate to your review. Just search for them below and share!

Create a Pen Name

Your Pen Name is your unique identity on BN.com. It will appear on the reviews you write and other website activities. Your Pen Name cannot be edited, changed or deleted once submitted.

 
Your Pen Name can be any combination of alphanumeric characters (plus - and _), and must be at least two characters long.

Continue Anonymously

    If you find inappropriate content, please report it to Barnes & Noble
    Why is this product inappropriate?
    Comments (optional)