殺蟲劑毒害河川 科學家繪全球風險地圖 | 台灣環境資訊協會-環境資訊中心

殺蟲劑毒害河川 科學家繪全球風險地圖

2015年03月05日
摘譯自2015年2月27日ENS德國,萊比錫報導;姜唯編譯;蔡麗伶審校

新研究顯示,殺蟲劑污染了全球40%地表的河川,其中尤以美國、地中海、中美洲和東南亞河川的污染風險最高。

全球殺蟲劑逕流汙染風險地圖。(來源:荷姆霍茲環境研究中心)

全球殺蟲劑熱點 繪出水體汙染地圖

畫出第一個全球地表殺蟲劑逕流地圖的國際科學團隊,是由荷姆霍茲環境研究中心(Helmholtz Center for Environmental Research)、科布倫茨─蘭道大學(University of Koblenz-Landau)、米蘭大學(University of Milan)、奧胡斯大學(Aarhus University)和亞琛大學(Aachen University)組成,並將此研究發表於「環境污染」(Environmental Pollution)期刊。

「我們畫出全球的殺蟲劑熱點,找出水體生物多樣性最受影響的地區。據我們所知,這是第一個評估全球性殺蟲劑水體污染的研究。」荷姆霍茲環境研究中心Matthias Liess教授說。

根據作者的估計,全世界每年使用4百萬噸農業用殺蟲劑,等於平均每公頃地表有0.27公斤。

氣候變遷影響 殺蟲劑越用越多

但作者也指出,目前為止,科學界對於殺蟲劑的水污染效應所知仍有限。

殺蟲劑污染河川,會殺死河川裡的無脊椎動物,包括昆蟲、甲殼類、蝸牛和蠕蟲。這些小型生物的存在常用來作為河川健康的指標。

「從過去的研究可以知道,殺蟲劑減少淡水生態系統42%的脊椎動物生物多樣性,而由於氣候變遷的關係,我們的殺蟲劑用量會越來越高。」Liess說。

Liess警告,在許多開發中國家,因為逐漸從傳統農業轉向密集農業,殺蟲劑的用量也會增加。

列舉多個參數 越往南越「毒」

研究作者們依據不同參數畫出多個世界地圖。

脆弱地區地圖顯示出因地理和氣候特性而容易受影響的地區;風險地圖顯示出人類的土地利用對這些地區造成的風險高低。

「在歐洲、北美和亞洲,越往南,殺蟲劑對水體造成的風險顯著增加,主要原因是平均溫度越高,殺蟲劑用量越高。」瑞士聯邦水文科學研究所研究員Mira Kattwinkel博士說。

南半球許多國家的經濟與人口正在快速增長,研究人員預測,這些國家未來的農業產量會增加,殺蟲劑用量也會更高。

「每日降雨強度、地形坡度、殺蟲劑用量和所種植的作物等因素都扮演重要的角色。」科布倫茨─蘭道大學助理教授Ralf Schäfer說,「為了測試這個複雜的模型,我們從4個不同地區的淡水生態系統進行控制測量。」

約旦河西岸地區的農藥噴灑。(來源:荷姆霍茲環境研究中心)

減少殺蟲劑用量 活化生態系統

東南亞,菲律賓和越南等國的污染情況特別嚴重。荷姆霍茲環境研究中心正和國際萊斯研究所合作,找出減少殺蟲劑用量的方法。

一種方式是重新活化生態系統的功能,讓作物害蟲的天然競爭物種預防害蟲大量繁殖、進而破壞收成。另一個方式是沿著水體邊緣建立不使用殺蟲劑的緩衝區,減少殺蟲劑的危害。

研究人員欲利用這些地圖,呼籲脆弱地區居民和有關當局正視此議題,進而激發當地主動的調查。

First Global Pesticide Runoff Map Shows Streams At Risk
LEIPZIG, Germany, February 27, 2015 (ENS)

The application of insecticides poisons streams in roughly 40 percent of the global land surface, new research reveals. Streams in the United States, the Mediterranean, Central America and Southeast Asia are most at risk.

These findings are drawn from the first global map to be modeled on insecticide runoff to surface waters, which has just been published in the journal “Environmental Pollution” by an international team of scientists.

Until now the global extent of the potential water pollution from the application of insecticides has remained largely unknown, according to the authors, who are researchers from the Helmholtz Center for Environmental Research and the University of Koblenz-Landau together with scientists from the University of Milan, Aarhus University and Aachen University.

“Our analysis provides a global map of hotspots for insecticide contamination that are a major risk for biodiversity in water bodies. To our knowledge this is the first study that assesses insecticide contamination of water bodies on a global scale,” says Professor Dr. Matthias Liess from the Helmholtz Center.

The authors estimate that about four million tons of agricultural pesticides are applied annually around the world, equating to an average of 0.27 kilograms per hectare of the global land surface.

Pesticide contamination of streams kills their invertebrate inhabitants such as insects, crustaceans, snails and worms. These small creatures are often used as indicators of the health of streams.

“We know from earlier investigations that pesticides can reduce the biodiversity of invertebrates in freshwater ecosystems by up to 42 percent and that we can expect an increased application of pesticides as a result of climate change,” explains Dr. Liess.

He warns also of an increase in the application of pesticides in many developing countries as farmers switch from traditional agricultural practices to more intensive ones.

The researchers produced several world maps. The vulnerability map only takes into account the geographic and climatic background.

The risk map shows the risks from this natural vulnerability through human land use.

“The risks of insecticide exposure to water bodies increased significantly the further South one travelled on a North-South gradient in Europe, North America and Asia, mainly driven by a higher insecticide application rate as a result of higher average temperatures,” said Dr. Mira Kattwinkel, a researcher at the Swiss Federal Institute of Aquatic Science and Technology.

Because the economy and the population are growing rapidly in many countries of the southern hemisphere, scientists expect a higher insecticide application rate in those countries in the future to cover an increase in agricultural production.

“Daily rainfall intensity, terrain slope, and insecticide application rate play an equally important role as well as the crops cultivated,” explains junior professor Dr. Ralf Schäfer from the University of Koblenz-Landau.

“In order to test such complex models, we therefore carried out control measurements of insecticide contamination in freshwater ecosystems from four different regions,” he said.

In Southeast Asia, countries such as the Philippines or Vietnam are greatly affected. Helmholtz Center researchers are looking into solutions for such regions together with the International Rice Research Institute, in an attempt to reduce pesticide application rates.

One approach could be to revitalize the functioning of ecosystems so that the natural competitors of rice pests can help to avoid their mass reproduction and subsequent harvest yield losses.

In another approach, buffer zones along the edges of water bodies where chemicals are not applied can reduce the negative impacts of pesticides.

The researchers intend to use the global map to sensitize citizens and authorities about this issue in vulnerable regions and to stimulate local investigations.

※ 全文及圖片詳見:ENS

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