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我国科学家新发现46个南极冰下湖_我的网站

金陵十三钗

一 |

Drivers queue at a petrol station to refuel in Tehran, on August 25, 2026. Photo: VCG
As military strikes and diplomatic negotiations have both failed to bring an early end to the roughly six‑month‑old US-Iran conflict, Washington rolled out new sanctions against Tehran on Monday local time intended to further strangle its economy. Iran, for its part, has vowed a tougher pushback.
In a news conference on Monday, Treasury Secretary Scott Bessent threatened new sanctions on countries refusing to cut economic ties with Iran, following recent rhetoric from Washington threatening an "economic D-Day" for Iran.
Meanwhile, the Office of Foreign Assets Control (OFAC) under the US Treasury announced secondary sanctions on nearly 60 entities, individuals, and vessels in multiple jurisdictions which, according to the US' claims, enable Iran's activities, including so-called nuclear and missile technology procurement, cyber operations, and oil-revenue generation networks.
According to Reuters, those sanctions targeted businesses in China, the UAE, Singapore and several other countries, including a cooking-oil refinery in France, but did not include any of the Chinese financial institutions suspected of facilitating Iran's oil trade.
In response to US Treasury Secretary Scott Bessent laying out plans for economic asphyxiation of Iran, expanding Washington's secondary sanction threats and warning of dire consequences for countries that do not join the campaign, Chinese Foreign Ministry spokesperson Lin Jian said at a press briefing on Tuesday that China has made clear on many occasions its firm opposition to illicit unilateral sanctions that have no basis in international law or the authorization of the UN Security Council.
"Economic warfare and maximum pressure provide no solution. On the contrary, they only serve to fuel tensions and lead to risk spillover, which will disrupt the global economic and financial order, and harm the legitimate rights and interests of other countries," the spokesperson said.
The pressing task is to facilitate the deescalation of the situation and return to dialogue and negotiation as soon as possible, Lin said, adding that China will do everything necessary to firmly safeguard its rights and interests, Lin added. Lin also said China's cooperation with Iran is conducted within the framework of international law, thus should not be disrupted.
When asked whether China has received any such timeline, as the US stated it would give countries a timeline on when to shut down the actions that it has identified, and how China intends to respond to the relevant announcements by the US Treasury involving China-based entities and individuals, Chinese Foreign Ministry spokesperson Lin Jian stated on Tuesday that China is closely following the developments, and will do everything necessary to firmly safeguard our rights and interests.
In May this year, China's Ministry of Commerce issued a blocking ban prohibiting any recognition, enforcement or compliance with US sanctions imposed on five Chinese companies on the grounds of their alleged involvement in Iranian petroleum transactions.
Relying on its financial hegemony and long‑arm jurisdiction, the US enforces unilateral sanctions with no basis in international law. Such measures severely undermine fundamental consensus for international trade and erode the existing international order, Zhou Mi, senior research fellow at the Chinese Academy of International Trade and Economic Cooperation, told the Global Times on Tuesday.
In essence, Washington is imposing its Iran‑focused policies to enterprises across the globe, compelling third‑party actors to fall in line with its diplomatic objectives, Zhou noted.
The latest sanctions would affect a broader range of countries, industries and firms. They will not only draw wider opposition from the international community, but also boomerang on the interests of US‑owned enterprises, he added.
Fewer levers left
"We are launching an economic onslaught against Iran's financial connections around the globe," Bessent claimed at a press conference. "Our objective is to sever every economic lifeline" that sustains the country, he said, according to a Treasury release.
The US Treasury Department said in a release that the new sectoral sanctions determinations target five critical sectors - digital assets, technology, gold, aviation and shipping - that the US claimed Iran has relied on to support its economy.
US Treasury claimed that "any entity that facilitates money laundering or sanctions evasion on behalf of Iran risks being cut off from the US financial system."
OFAC also suspended several general licenses that previously authorized certain remittance payments to Iran and Iranian access to the US cultural and academic system. The office also issued additional guidance on the so-called sanctions risks of bowing to Iranian demands related to shipping in the Strait of Hormuz.
Mohammad Mokhber, an aide to Supreme Leader Mojtaba Khamenei, said in an X post on Monday that Iran's response to US sanctions and pressure will be "more decisive than before."
Iranian Economy Minister Ali Madanizadeh said that Tehran "is and was ready," with a two-year plan to counter Washington's new sanctions. He told state television that "it seems they wished to suffer yet another defeat," per an AFP report.
Iranian Parliament Speaker Mohammad Bagher Ghalibaf responded in an X post that "the Americans know no one will believe their nonsense," noting that the US is not in a position economically to restrict its relations with other countries.
Alan Eyre, a distinguished diplomatic fellow at the Middle East Institute, told NBC News that after six months of combat, the US government "has few remaining levers it can use to convince Iran's major trading partners to materially reduce their economic ties."
While Washington's maximum‑pressure campaign may deliver short‑term shocks to Iran's economy, it can hardly "strangle" the country completely, said Liu Zhongmin, a professor at the Middle East Studies Institute of Shanghai International Studies University.
He added that Iran's economic resilience cannot be underestimated. Having borne decades of crippling sanctions from the US and Western nations, Tehran has built substantial experience in sanction‑busting and developed coping mechanisms ranging from basic‑industry self‑reliance and regional trade networks to oil‑for‑goods swaps and non‑US dollar‑denominated trade. Furthermore, the Strait of Hormuz remains a source of strategic leverage for Iran to push back against US pressure.
The expert said that Tehran and Washington are encountering "a battle of wills," and Iran believes the economic costs the US would suffer from a Hormuz blockade would outweigh the damage inflicted on Iran by sanctions.
Washington's "economic strangulation" policy risks ending in failure unless it yields short‑term outcomes, particularly securing the opening of the Strait of Hormuz, Liu added.
Self-created dilemma
As the US ramps up pressure on Iran, Americans are growing averse to a protracted war.
According to a Reuters/Ipsos poll that closed on Monday, US ‌public approval of the war with Iran fell to its lowest level since the conflict's early days, with just 31 percent of Americans supporting US military action.
On June 18, the US and Iran signed an MoU, under which the two were scheduled to hold negotiations within a period of 60 days, which ended on August 17, to reach a final agreement. However, the talks' fate remains unclear following renewed escalation between the two countries.
Iranian political analyst Mostafa Khoshcheschm told Al Jazeera that the new US sanctions intended to create an "economic onslaught" were a "political show" of intimidation.
Liu said that by resorting to an "economic strangulation" tactic after miring itself in a fruitless military quagmire over Iran, the US has laid bare its practical predicament and strategic dilemma, and seemingly running out of cards.
Citing sources, CNN reported earlier this month that the US military has exhausted nearly 80 percent of its interceptors for a key missile defense system as senior US military commanders are warning that the Pentagon's munitions stockpile is "dangerously low."
Faced with depleted ammunition stockpiles and insufficient military‑industrial capacity, and amid growing domestic criticism of its Middle East policy, the White House has opted for tough economic measures against Iran, Liu said. "Less costly than military coercion, such moves help Washington strike a tough posture before voters and shun political risks from further military escalation," said the expert.
There is, however, an increasingly obvious paradox in Washington's economic warfare against Iran: the tighter the sanctions, the tighter global energy supplies become, and the higher costs borne by American consumers and businesses, the expert added.
。新华社上海4月20日电（记者张建松）神秘遥远的冰雪大陆南极洲，覆盖着平均厚度超过2400米的冰盖，下面隐藏了许多令人叹为观止、形态各异的冰下湖。我国科学家利用一种新的分析方法，在东南极冰盖下新发现了46个冰下湖。

二 | 　　这项研究由中国极地研究中心冰雪所极地冰盖多圈层相互作用与气候变化研究团队，联合中国地质大学（武汉）地球物理与空间信息学院傅磊教授团队、南方科技大学地球与空间科学系陈晓非教授团队共同完成。国际学术期刊《冰冻圈》近日刊登了相关研究论文。　　我国“雪鹰601”固定翼飞机在南极冰盖进行冰下湖探测调查。新华社发　　据中国极地研究中心冰雪所极地冰盖多圈层相互作用与气候变化研究团队负责人唐学远介绍，当处于融化状态的冰流流过南极冰盖冰底的凹陷，并以当地最小的水势聚集时，冰盖底部就会形成冰下湖。根据现在的统计，科学家在南极冰盖下方共发现675个冰下湖，其中有3个冰下湖被成功钻探取样。　　“南极冰下湖通常位于数千米厚的冰层之下，具有高压、低温、黑暗、寡营养等极端环境特征，具有极其独特的生态系统，包含丰富的冰盖历史和气候变化信息。越过接地线、进入冰架下空腔的湖水，还可能改变冰架-海洋相互作用，进而引发海洋环流变异。因此，开展南极冰下湖研究对于冰盖动力学、沉积过程和冰下地球化学环境以及生命演化等都具有重要意义。”唐学远说。　　中国第40次南极考察队员在麒麟冰下湖的冰面架设气象站。新华社发（李传金摄）　　冰雷达探测是搜寻南极冰下湖并解析其结构的主要方法之一。在冰雷达图像中，冰下湖通常被记录为冰岩界面附近清晰、明亮且平坦的二维反射特征。早期有关冰下湖的发现主要来自对冰雷达图像中的这些特殊视觉特征的判读与解译。随着冰雷达探测技术发展，基于人工经验的自动或半自动判读方法受到了巨量数据的限制，繁复费时且易产生误判。　　经过深入研究，我国科学家团队提出了一种针对冰雷达数据显示的冰底反射波形特征，进行变分自动编码（VAE）的新方法，实现了对冰底单道雷达反射回波信号的科学分类。利用该方法，研究团队对东南极甘布尔采夫山脉AGAP-S区域的冰雷达图像进行了全面扫描。结果发现，该区域存在许多基于传统方法未能识别的几何轮廓更为狭小的冰下湖，数量多达46个。　　变分自动编码器(VAE)从冰雷达图像中揭示的新冰下湖。新华社发（中国极地研究中心供图）　　业内专家认为，这种自动检测南极冰下湖的VAE聚类新方法，不仅可以显著提高冰下湖的发现效率与精确度，还有望扩展到检测和标记更多的南极冰下环境类型，为南极冰盖底部和内部结构的深入研究提供技术支撑。