최근 미국 남서부 지역에서 깨끗한 물에 대한 접근이 어려워지면서 애리조나 주에서는 빗물을 저장해 사용하는 사람들이 늘고 있다. 그러나 수집된 빗물의 오염물질에 대한 데이터는 거의 없는 실정이다.

프로젝트 하베스트(Project Harvest)라고 불리는 애리조나 대학교가 주도하는 지역사회 파트너십은 지난 6년 동안 빗물 샘플을 수집해 다양한 오염물질을 분석해 왔다.

모니카 라미레스 안드레오타(Mónica Ramírez-Andreotta) 농생명환경과학대학 환경과학부 부교수는 소노라 환경연구소(Sonora Environmental Research Institute Inc.) 및 애리조나 전역의 지역사회와 협력해 프로젝트 하베스트를 조직했다.

프로젝트 하베스트는 채집된 물샘플에서 납, 비소, PFAS(과불화화합물), 살충제와 같은 미량의 오염물질을 비롯해 대장균, 총대장균과 같은 미생물 관련 오염물질을 검출했다.

프로젝트 하베스트는 공동 개발 연구 프로그램으로, 지역사회 구성원과 협력해 모든 연구 결과를 이중언어로 번역해 제공하고 있다.

납부터 살충제, 심지어 대장균까지 모든 연구 결과는 공통점을 갖고 있다. 즉, 먼지 활동의 증가로 장마철에 오염물질이 증가했다는 것이다.

한 연구에서는 협력 지역사회의 옥상에서 수집한 빗물에서 납과 비소를 검출했다고 보고했다. 이러한 오염물질의 수준은 대부분 EPA가 시행하는 식수 기준을 충족했지만, 인간에게 안전한 납과 비소의 노출 수준은 없다.

또한 먼지를 운반하는 오염물질은 장마철 동안 프로메톤 및 시마진 살충제 증가의 원인이 될 수 있다. 프로메톤은 일반적으로 포장 도로 및 주차장 주변에서 흔히 사용된다.

PFOA, PFOS 등의 오염물질은 EPA의 최신 식수 권고 사항보다 더 높은 농도로 주 전역의 샘플에서 관찰됐다. PFOA와 PFOS는 자연에 오랫동안 잔재돼 있기 때문에 종종 '영원한 화학 물질'이라고 불리는 인간이 만든 계면활성제다.

이 연구에서는 수집된 빗물에 대장균의 수준은 상대적으로 낮았다. 대부분은 EPA에서 안전하다고 간주하는 수준 이하였다. 그러나 동물과 인간의 배설물을 통해 퍼져나가는 거의 무해한 박테리아 집단인 총대장균은 같은 기준 이상의 농도에서 더 빈번하게 검출됐다.

계절 외에 지역은 대부분의 오염물질 농도를 결정하는 주요 요인이며, 납과 비소의 경우 주로 정부 및 산업 현장과 관련이 있다. 특정 지역사회에서는 이러한 현장로부터의 거리가 멀어질수록 옥상에서 수집한 빗물의 납과 비소 농도가 크게 감소하는 것을 확인했다.

또한 옥상에서 수집된 빗물 샘플은 대조 빗물보다 PFOA, PFOS 등의 평균 농도가 더 높았으며, 이는 오염이 산업활동과 연관돼 있을 가능성이 매우 높은 것을 나타내며, 정확한 원인은 확인할 수 없다.

이 연구의 결론은 옥상에서 수집한 빗물에서 오염물질이 관찰될 수 있다는 것이다. 오염물질, 농도, 수집된 빗물을 어떻게 사용하는지에 따라 여과, 장비 세척 등의 조치가 권장된다. 개인이 오염을 방지하기 위해 노력할 수 있지만 라미레스 안드레오타 교수는 오염물질의 출처에 대해 생각하는 것도 중요하다고 말했다.

라미레스 안드레오타 교수는 "대부분의 경우, 개인의 행동으로 빗물에서 이러한 오염물질이 검출된다고 생각하지만 이는 더 광범위한 시스템에서 비롯된다"라고 설명했다.

[원문보기]

From the skies to your roof, what does a raindrop pick up along the way?

Teaming up with community scientists, University of Arizona's Project Harvest and the Sonora Environmental Research Institute tested thousands of harvested rainwater samples to measure levels of contamination.

As clean water access becomes more difficult in the American Southwest, more people are turning to harvesting rainwater as a solution, especially in Arizona. But with little data on contaminants in harvested rainwater, communities are wondering how clean it really is.

To answer that question, a University of Arizona-led community partnership, called Project Harvest, has for the past six years collected harvested rainwater samples and analyzed them for a variety of contaminants.

Mónica Ramírez-Andreotta, an associate professor in the Department of Environmental Science, in the College of Agriculture, Life, and Environmental Sciences, created Project Harvest with a team of researchers in partnership with Sonora Environmental Research Institute Inc. and communities throughout Arizona.

Across a suite of papers, Project Harvest observed that samples contained lead and arsenic; micropollutants such as per- and polyfluoroalkyl substances – chemicals known as PFAS – and pesticides; and microbial pollutants such as E. coli and total coliform.

As a co-created research program, Project Harvest worked with community members to train, collect and translate all of their findings into bilingual interactive visualizations, available to the public.

"These individuals are trying to do the right thing – conserve water, grow their own healthy food, and reduce their carbon footprint," Ramírez-Androetta said. "Pollution interferes with these environmental public health interventions, so people want to know what the quality of the water is and how they can use it."

Contamination season

From lead to pesticides and even E. coli, all findings shared a common thread: increased contaminants during monsoon season, possibly due to increased dust activity.

One paper detected lead and arsenic in rooftop harvested rainwater in the partnering communities. While most levels were within the EPA's enforceable drinking water standards, no level of exposure to lead and arsenic is safe for humans.

Dust-carrying contaminants could also be the cause for increased prometon and simazine pesticides during monsoon season. Prometon is commonly used in areas along paved roads and parking lots.

Perfluorooctanoic acid, known as PFOA, and perfluorooctane sulfonic acid, or PFOS, were also observed in samples across the state in concentrations greater than the EPA's most recent drinking water health advisories. PFOA and PFOS are human-made surfactants often called "forever chemicals" due to their longevity in nature.

Presence of E. coli in harvested rainwater was relatively low in this study – most were under the levels deemed safe by the Environmental Protection Agency. However, total coliforms, a mostly harmless group of bacteria often spread through animal and human waste, were detected more often at concentrations above the same standards.

Location, location, location

Other than season, location is another major factor for most contaminant concentrations, and with regard to lead and arsenic, this is mainly related to government and industrial sites. In select communities, as distance from these sites increased, researchers observed a significant decrease in lead and arsenic concentrations in rooftop-harvested rainwater.

Additionally, roof-harvested rainwater samples had greater PFOA, perfluorononanoic acid and perfluorobutane sulfonic acid mean concentrations than the control rainwater, indicating the contamination is most likely tied to industrial activities. However, the exact sources cannot be confirmed.

Working with the community, for the community

By partnering with communities that are disproportionately impacted by climate change and pollution, consisting of more than 150 participants, Project Harvest collected and analyzed over 3,000 rainwater samples.

Communication and training during the program were led by promotoras, or community members with an understanding of community dynamics and local health and social issues. The promotoras served as cultural knowledge brokers between UArizona and the larger groups of community scientists.

"This project would not have been possible without our community scientist partners and project promotoras who maintained contact with the community scientists," Ramírez-Andreotta said. "They shared their expertise and experiences with us, which in turn improved our methodologies, reduced program barriers, increased access to the program and enhanced data-sharing strategies."

Setting the foundation for co-created research

The bottom line is that contaminants can be observed in rooftop harvested rainwater. Depending on the contaminant, concentration and how someone uses their harvested rainwater, measures such as filtering and equipment cleaning are recommended. While individuals can try to prevent contamination, Ramírez-Andreotta said it is also important to think about the source of the contaminants.

"In most cases, it is not the individual behavior that's leading to these concentrations in the rainwater," Ramírez-Andreotta said. "The burden is being placed on them, but it's coming from these broader systems."

In addition to the data, Ramírez-Andreotta said this study shows how building relationships with communities will support environmental health literacy and nurture a new or renewed relationship with science.

"Co-created community science is a model that can not only transform science education and teaching and meaningfully connect with communities at risk," Ramírez-Andreotta wrote, "it can be used to build capacity, inform decision-making, and address climate change and water scarcity challenges."

[출처 = The University of Arizona(https://news.arizona.edu/story/skies-your-roof-what-does-raindrop-pick-along-way) / 2023년 10월 17일]

[번역 = 배민지 차장]