New techniques in the use of X-rays become important allies in achieving better environmental control. With them, it is possible to detect concentrations of metal in water, in effluents and in the air much more accurately than using the conventional methods of chemical analysis. In Brazil, the pioneering use of these new techniques in the environmental field was carried out in various studies in the Campinas region, coordinated by professor Silvana Moreira Simabuco, of the Civil Engineering School of Campinas State University (Unicamp). And the results were not good for people’s health. She detected the presence of metal at levels above those permitted by legislation. Chrome and nickel were detected in dumps and industrial effluent, copper, nickel, and iron in the waters of the rivers Capivari and Atibaia and copper, lead, and cobalt in the air in Campinas.
Silvana’s research used X-rays in two versions, Energy Dispersive X-ray Fluorescence (ED-XRF) and by total reflection (TXRF). In these cases, the X-rays are bombarded against a sample, stimulating the chemical elements in it. It is discovered which chemical element it is based on the response of the energy emitted by each of the components of the object being analyzed. This technique has been used since the late 90’s to assess both qualitatively and quantitatively the chemical composition of various types of samples concerning farming, manufacturing, geologists, and environmentalists. One of its advantages is that it is not destructive. It enables various elements to be analyzed in a single measurement without changing the sample, maintaining the quality of the trials.
The environmental studies in Campinas got started in 1995 with financial support from FAPESP. One of the first results emerged from the so-called “Big Garbage Dump” in Americana, where it is estimated that there are around 150,000 tons of solid toxic waste deposited. “We observed that the presence of various elements contained in the landfill samples was well above the level permitted by federal legislation”, points out the researcher. The most serious point is that the garbage dump is close to the confluence of the Atibaia and Jaguari rivers where they join to form the Piracicaba river.
Another study that also showed the risks of aggression against nature and human health was prepared in the town of Limeira, which is home to the biggest jewelry manufacturing complex in Latin America and various auto-parts companies. Silvana analyzed the galvanoplastics companies effluent, industry in the branch of metallurgy dealing with metals and chemical derivatives for lining metal parts. The results enabled her to conclude, for example, that the total chrome concentrations in the solid waste (sludge) in the industrial effluent samples in Limeira were well above the maximum limit laid down by the Brazilian Technical Standard Association (ABTN), namely, 100 mg of chrome per kilo.
“The level of heavy metals in these companies’ effluent is quite high, meaning that it should not be deposited in landfills and it causes the companies to deposit the effluent in drums. This does not solve the problem because they deteriorate over time. In addition, due to the large amounts of toxic waste that is formed, the problem of physical space also arises”, explains the professor.”The effluent situation in the region is quite serious but it can change. Some companies have already come to us to find alternatives against pollution and to recycle the effluent”, comments the researcher. One of the options that the galvanic plastic industry is seeking to establish is to reuse the metals in liquid effluent, before it is treated, or to use the treated sludge as a raw material in the construction industry.
Nickel per million
The studies also detected the presence of nickel in the liquid effluent in concentrations of around 977 to 3.794 parts per million (ppm), which accentuated the danger of this waste. This survey was carried out at the request of a company in the auto-parts business, with manufacturing plants in Limeira. Silvana comments that after this company, other companies in the region came to them to carry out the same work. Agreements and service provision contracts were signed between Unicamp and various companies and public bodies. Another important project that Silvana and her team undertook, made up of eight Unicamp masters and doctoral students, working with grants given by FAPESP and the CNPq, was to monitor the heavy metals in the water of rivers and in treated water in the Campinas region, done with samples provided by the Water Supply and Sanitation Company (Sanasa) of Campinas.
Analysis of the material showed that, in the river samples, the concentrations of some metals were above the acceptable limits of federal legislation, in particular in the case of copper, nickel, cobalt, and iron. Of these elements, the copper and the nickel are the most harmful to human health when found at concentrations above those allowed by law. In the river water, the presence of zinc, manganese, and chrome was also detected, which increased the concern of the researchers. In the sample of treated river water, the results were considered normal.
Beam of light
One of the most efficient, rapid and economical variations of the technique of nuclear X-ray fluorescence is the one obtained by stirring the chemical elements of the sample through synchrotron light radiation. This luminous beam is different from the light (it does not emit heat) emitted by common X-rays because it has a broad electromagnetic spectrum, with special intensity, covering the infrared and the ultraviolet, as well as the visible light spectrum. The researcher has carried out various works in partnership with the National Synchrotron Light Laboratory (LNLS), in Campinas.
Synchrotron light detects the lowest levels of a chemical element, to an accuracy of parts per billion. One of these projects measured the concentration of chrome III and VI in industrial effluent samples discharged into the rivers Capivari, Atibaia and the mouth of the Pinheiros stream, close to Piracicaba and Campinas. The results showed that the concentration of the two types of chrome in the effluent is high.
In Silvana’s opinion, the problems brought up by the survey could be solved by greater efforts from business people and the public authorities. “Nowadays, there are ways of treating water and various techniques for rejecting and reusing industrial waste that reduce or even eliminate the levels of contamination”.
Lead in the air
Professor Silvana also used the fluorescence of X-rays and synchrotron light radiation to measure the levels of air pollution. In this case, she employed the help of the leaves of two ornamental plants: the common oleander, Nerium Oleander and the azalea Rhododendron ferrigineum, very common in parks and public squares in the region. “The choice fell on these vegetable species because of the ready availability of literature on their bio-indicating properties and because they were easily found on Campinas, in various places and in other towns around the country”, explains Silvana.
They work as an alternative analysis technique for the conventional method of filtering particulate material in the air using suction pumps coupled to porous membrane filters. The idea was to measure pollutants in areas where there was a high concentration of manufacturing plants and heavy vehicle traffic. In addition to Campinas, the study employed experiments carried out in the city of Rio de Janeiro, with the help of researchers at the Federal University of Rio de Janeiro (UFRJ). Titanium, manganese, vanadium, iron, copper, zinc, bromine, and lead concentrations were analyzed.
The azaleas captured the level of pollution in the center of Campinas, in the Av. Francisco Glicério, where 2,199 vehicles per hour circulate, and in Jardim Shangrilá, a condominium, where the flow is less than 100 vehicles an hour. The results obtained by the synchrotron light source confirmed that the authorities must consider the growing levels of air pollution in towns the size of Campinas and Rio de Janeiro as very serious. Copper, lead, and cobalt were the elements that the oleanders and azaleas, located at points of heavy vehicle traffic in the two cities, most detected.
Silvana Simabuco now intends, in the current stage of her work, to measure blood samples and mothers’ milk to assess the concentration of metals in these fluids. “We will be using a new variation of the nuclear X-ray technique to carry out the analysis of small samples in micro-liter size”. Collecting these samples will be done by people resident in various places in the town of Campinas and from various social classes.
The work undertaken by the researcher may also cover other applications, such as the recent requirements by the World Health Organization (WHO), which now requires the products of the pharmaceutical industry to be analyzed, focusing in particular on the elements, cadmium, lead, arsenic and mercury. Two companies in São Paulo have already anticipated the requirement and taken samples of guaraná in powder and eucalyptus oil to be analyzed. The figures resulting from the experiment carried out by Silvana’s team at the LNLS, using the X-ray fluorescence by total reflection technique, indicated the elements were not present in the samples tested.
A thousand uses
In the long list of projects, the priorities are those that measure the accumulation of metals in sediment in the rivers Atibaia and Capivari. Another important project is to analyze lubricating oil and gasoline additives, also in partnership with the LNLS. “This year, we also have projects jointly with the Ribeirão Preto Pharmaceutical School of the University of São Paulo (USP), on medicinal plants and medications and we are working in Limeira, with the Limeira Water company to assess the effects of irrigating corn plantations with treated household waste”. The idea, in this case, is to measure the concentration of metals in cornfields, in the leaves, roots and grains. A task, which like the others, is essential for good human health.
Introduction of the Nuclear and Instrumental Analytical Technique using Energy Dispersive X-ray Fluorescence in Environmental and Industrial Research (nº 95/00647-4); Type Normal support of research line; Coordinator Silvana Moreira Simabuco – Unicamp; Investment R$ 28,228.48 and US$ 44,618.00