Question: where are salt marshes located in the us
[{'answer': 'rivers of the Mississippi Delta', 'provenance': [{'wikipedia_id': '265062', 'title': 'Salt marsh', 'start_paragraph_id': 5, 'start_character': 424, 'end_paragraph_id': 5, 'end_character': 455, 'bleu_score': 1.0, 'section': 'Section::::Basic information.\n'}]}, {'answer': 'much of the eastern coast', 'provenance': [{'wikipedia_id': '265062', 'title': 'Salt marsh', 'start_paragraph_id': 5, 'start_character': 881, 'end_paragraph_id': 5, 'end_character': 906, 'bleu_score': 1.0, 'section': 'Section::::Basic information.\n'}]}, {'provenance': [{'wikipedia_id': '265062', 'title': 'Salt marsh', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 1110, 'bleu_score': 0.880295276577251, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1485467545283219295}, 'section': 'Section::::Basic information.\n'}]}]