\n
\n
![\"EarthSnap\"\/](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2026\/01\/earthsnap-banner-news.webp.webp\")
\n<\/a><\/p>\n
In mud cores lifted beside the barrels, white halos appeared as hardened crusts and powdery patches in otherwise dark sediment.<\/p>\n
Sampling along those halos, a team at Scripps Institution of Oceanography<\/a> traced the crust to leaking alkaline waste.<\/p>\n Microbiologist Dr. Johanna Gutleben at Scripps compared halo sediments with nearby controls and found almost no microbial genetic material in the halo<\/a> cores.<\/p>\n Because the halos stay visible, they let researchers spot likely leakage sites quickly, even before they sample what escaped.<\/p>\n Mapping the graveyard<\/p>\n A deep-sea survey<\/a> scanned about 58 square miles of the San Pedro Basin. Robot submarines crisscrossed the bottom with sound and cameras, turning rough guesses into a tight map of debris.<\/p>\n Across that patch, analysts logged over 74,000 debris targets, including about 27,000 barrel<\/a>-shaped objects scattered off Los Angeles.<\/p>\n Such counts make every follow-up dive a triage job, since each sample<\/a> run reaches only a tiny fraction of sites.<\/p>\n DDT was not<\/p>\n For years, many people tied the rusting barrels to DDT<\/a>, a pesticide that lingers for decades, already measured in nearby seafloor sediments.<\/p>\n In the new tests, DDT stayed high across the dump<\/a> site regardless of how close a core sat to a barrel.<\/p>\n That flat pattern meant the barrels did not act as fresh sources, even where white halos sat right beside them.<\/p>\n Long after its 1972 ban, DDT can still bioaccumulate, build up in animals faster than they break down, in ocean food webs.<\/p>\n Chemistry writes rings<\/p>\n Chemical leaks from some barrels turned soft mud into pale rings, and the process depended on simple seawater reactions.<\/p>\n Measurements showed the sediment<\/a> reached a pH, a scale for acidity and alkalinity, close to 12 while seawater stayed near 8.<\/p>\n Magnesium in the surrounding water reacted with that base, hardening grains into a rim that resisted waves and slow seafloor currents.<\/p>\n Over time, brucite, a magnesium hydroxide mineral that forms in a strong base, helped lock those rings in place for decades.<\/p>\n Microbes meet extremes<\/p>\n Under the halos, the sediment held far fewer microbes than neighboring mud, and the community looked nothing like a typical seafloor mix.<\/p>\n At those high pH levels, alkaliphilic<\/a> bacteria, microbes that grow best in alkaline conditions, dominated samples that once supported many groups.<\/p>\n Instead of many kinds of microbes living together, a handful of lineages took over, leaving little genetic variety for the rest.<\/p>\n Reducing microbial activity can change how the bottom recycles nitrogen and sulfur, with effects that can reach larger seafloor animals.<\/p>\n A scar that persists<\/p>\n Years pass, yet the halos remain, because the mineral crust keeps buffering the sediment toward strong alkalinity.<\/p>\n Brucite dissolves in seawater at a crawl, releasing basic chemicals that raise local pH even after the original spill stops.<\/p>\n Based on dissolution rates, the team estimated the seafloor effects could last several thousand years in parts of the basin.<\/p>\n That timeline means even careful sampling can disturb a long-lived chemical pocket, so planners must choose targets with care.<\/p>\n How dumping became legal<\/p>\n Between the 1930s and early 1970s, agencies and companies treated deep ocean water as a ready-made disposal system.<\/p>\n Records from the U.S. Environmental Protection Agency (EPA<\/a>) describe at least 14 deep-water dump locations off Southern California.<\/p>\n From refinery byproducts to low-level radioactive waste, the dumped material included chemicals, oil drilling debris, and even obsolete military explosives.<\/p>\n Thin steel barrels were never designed for decades underwater, so today\u2019s corroded seams make the original contents hard to pin down.<\/p>\n What stays unknown<\/p>\n Even with new maps, scientists still cannot say which barrels remain sealed and which have already emptied into the mud.<\/p>\n About one-third of the barrels carry white halos, a clue that alkaline waste leaked and changed only the surrounding few feet.<\/p>\n Some leaks can free metals trapped in sediment, and no one yet knows whether those metals have moved into fish and shellfish.<\/p>\n Hard choices underwater<\/p>\n Any cleanup plan faces a tradeoff between disturbing fragile sediment and accepting that damaged barrels may keep leaking.<\/p>\n At about 3,000 feet deep, crews rely on robots and cables, and a wrong move could spread caustic material farther.<\/p>\n EPA has already tested new surveys and sampling around the dumpsites, but the agency still lacks a complete inventory of contents.<\/p>\n For now, scientists can use the halos to set priorities, while EPA and lawmakers decide whether old dumping policies deserve a modern response.<\/p>\n Seeing the leftovers<\/p>\n Rusting barrels and white halos show that industrial waste can keep rewriting seafloor chemistry long after the dumping stopped.<\/p>\n Better maps and careful sampling can narrow the unknowns, but every decision must weigh exposure risks against the damage of intervention.<\/p>\n The study is published in PNAS Nexus<\/a>.<\/p>\n Photo: Schmidt Ocean Institute.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Faded white rings around rusting barrels on the ocean floor have been traced to leaks of highly corrosive…\n","protected":false},"author":2,"featured_media":491677,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[49,48,295,66],"class_list":{"0":"post-491676","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-ca","9":"tag-canada","10":"tag-environment","11":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/491676","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=491676"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/491676\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/491677"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=491676"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=491676"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=491676"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}