Navigation Links
Car tracks beyond the asphalt
Date:2/24/2012

The contamination caused by road traffic not only affects the air, it also seeps under the asphalt and harms the adjacent soil and plants. Jos Antonio Carrero, a chemist at the University of the Basque Country (UPV/EHU), has delved into the subject and studied the extent of the impact of the metals emitted by cars. Likewise, he has analysed their consequences in the short, medium and long term and for this purpose has taken samples from roadsides in Bizkaia (Basque Country) of differing ages; these include the old road connecting Bilbao and Mungia where it passes through Artebakarra (over 60 years old), the motorway that runs parallel with it (over 20 years old), a roundabout in Berango (4-5 years old) and another in Sopelana (1-2 years old). His thesis is entitled Evaluacin del impacto del trfico rodado en suelos y plantas de margen de carretera (Evaluation of the impact of road traffic on roadside soil and plants).

Lead is the most well-known metal among those emitted by road traffic; even though over a decade has passed since leaded petrol was banned, the presence of this contaminant remains on the edges of roads. Nevertheless, Carrero has confirmed that despite its great toxicity, there are other metals that can pose even greater risks for the environment, due to the fact that they can filter through deeper soil layers. Apart from lead, this researcher has studied zinc oxide (produced by tyre wear) and barium, copper and antimony (resulting from brake pad wear), for example.

The older they are, the more there is

Carrero has extracted the metals found in the samples taken and has determined the concentration in which most of them occur. It can be seen that there is a greater accumulation of metals linked to traffic in the upper levels of the soil closest to the veteran roads. "It depends on how long the road has been in use. It is in the older roads that the metals accumulate and a gradient of concentration with the depth can be seen, while in the remainder of the spots an accumulation like this has not yet had time to develop," explains the researcher.

Likewise, the presence of zinc is well-known, since the deterioration of the zinc plating covering the crash barriers leads to a high concentration of this contaminant in the soil immediately below.

Toxicity is not the whole story

The preliminary studies were followed up by a Raman spectroscopy analysis, which is used to identify the molecular forms in which the compounds are found. Knowing these forms helps to determine the danger posed by each metal for the environment. And the fact is, as Carrero explains, the actual toxicity of each metal is not the only factor to bear in mind: "It matters whether the metal is in the form of a carbonate, or a nitrate... They are different salts with different solubility. The metals can be retained in the soil, so the toxicity would not be as significant as if they had been in the form of a more soluble substrate, in which case, this substrate could be dissolved by the rainwater and move to other compartments. Then, the toxicity could move to underground water tables or be taken up by plants."

In connection with this, Carrero has simulated the actual conditions that are produced in the environment to observe how the metals react in their presence and whether they become more soluble and, therefore, more hazardous. It turns out that barium and zinc are the metals that need to be closely monitored: "They are emitted as a result of tyre or brake wear, and they are accumulating in the form of oxide in the upper layers, and this has less mobility. However, we have seen that they react with atmospheric CO2 and form carbonates, which are more soluble and permeate. In fact, we have come across a great concentration of carbonate in deeper layers. In the upper layers barium and zinc are present in the form of oxide, and in the lower ones in the form of carbonate."

So, are barium and zinc more hazardous than lead? "Lead is one of the most toxic metals, but it is retained in the soil and this reduces its danger," replies Carrero.

In the thesis, steps have also been taken to analyse the concentration of metals in roadside plants, a line that Carrero will be continuing to do research on from now onwards: "We are going to study the isotopic relationship of the lead in these plant families, because we have seen that it is possible to determine the origin of the lead (whether it is anthropogenic or natural)."


'/>"/>

Contact: Amaia Portugal
a.portugal@elhuyar.com
34-943-363-040
Elhuyar Fundazioa
Source:Eurekalert

Related biology news :

1. Survey tracks 55+ attitudes about the environment
2. DNA motor programmed to navigate a network of tracks
3. A radar for ADAR: Altered gene tracks RNA editing in neurons
4. Label-free imaging tool tracks nanotubes in cells, blood for biomedical research
5. Study tracks mutations causing CDA II back to the Roman Empire
6. Toxic red tides: USC scientist tracks neurotoxin-producing algae
7. Will new drugs block hepatitis C virus in its tracks?
8. Marine lab research tracks pollutants in dolphins and beluga whales
9. Lichen evolved on 2 tracks, like marsupials and mammals
10. New technique tracks viral infections, aids development of antiviral drugs
11. Enzyme can steer cells or possibly stop them in their tracks
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/2/2016)... , June 2, 2016 ... Manned Platforms, Unmanned Systems, Physical Infrastructure, Support & Other ... provider visiongain offers comprehensive analysis of the ... this market will generate revenues of $17.98 billion in ... acquired DVTEL Inc, a leader in software and hardware ...
(Date:5/20/2016)... , May 20, 2016  VoiceIt is ... partnership with VoicePass. By working together, ... experience.  Because VoiceIt and VoicePass take slightly different ... engines increases both security and usability. ... excitement about this new partnership. "This ...
(Date:5/9/2016)... -- Elevay is currently known as the ... high net worth professionals seeking travel for work   ... there is still no substitute for a face-to-face meeting. ... deal with a firm handshake. This is why wealthy ... citizenship via investment programs like those offered by the ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... , ... June 23, 2016 , ... ... release of its second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” Partnering ... retention in this eBook by providing practical tips, tools, and strategies for clinical ...
(Date:6/23/2016)... /PRNewswire/ - FACIT has announced the creation of ... company, Propellon Therapeutics Inc. ("Propellon" or "the Company"), ... portfolio of first-in-class WDR5 inhibitors for the treatment ... represent an exciting class of therapies, possessing the ... cancer patients. Substantial advances have been achieved with ...
(Date:6/23/2016)... Lawrence, MA (PRWEB) , ... June 23, 2016 ... ... the Peel Plate® YM (Yeast and Mold) microbial test has received AOAC Research ... test platform of microbial tests introduced last year,” stated Bob Salter, Vice President ...
(Date:6/23/2016)... , June 23, 2016   EpiBiome , ... secured $1 million in debt financing from Silicon Valley ... up automation and to advance its drug development efforts, ... new facility. "SVB has been an incredible ... the services a traditional bank would provide," said Dr. ...
Breaking Biology Technology: