Graham Nickson’s large, multifigure oil paintings have a peculiar intensity all their own. His colors celebrate light with tropical exuberance, while his drawing agonizes over the geometry of the figures. For me, the relentless pressure of his hues sometimes brilliantly supports their gestures, and at other times overwhelms them.

His ninth exhibition at Salander-O’Reilly is devoted to watercolors of sunrises and sunsets, a subject that has intrigued the artist for over three decades. These more than two dozen works show the artist at his most enticing.

Their settings — mostly Italy, Tahiti, or Australia — are nothing if not exotic, and Mr. Nickson responds with a perfect mixture of ardor and control. In a work such as “Sarageto Sunset XXXI, Italy” (2006), colors glow and brushstrokes articulate space in lush coordination, shaping the drama of sunlight piercing roiling tiers of clouds. The artist takes full advantage of his watercolor medium, surrounding a luminous orange wash with cottonlike masses of granulating purples. Other notes of scarlet, purple-brown, and blue succinctly locate the receding ground plane and upper reaches of sky.

Though always energetic, Mr. Nickson’s watercolors show a startling range of temperaments. Several capture with almost hallucinogenic vigor the sight of Australia’s Uluru (also known as Ayers Rock) behind raking rainstorms. On another wall, the restrained simplicity of some watercolors of Sarageto recall Chinese scroll paintings; in “Todi XII, Italy” (2006), a broad orchestration of pale reds and pink-violets beautifully catches a sunrise above fogladen fields.

Occasionally Mr. Nickson’s colors freeze at high pitch. The dazzling but equally weighted hues of “Sarageto Dawn XII, Italy” (2006), for instance, make for a relatively airless composition. “Sarageto Sunset XXIII, Italy” (2006), however, has it all: fiery orange penetrating layers of steel-blue clouds; expansive fields slipping away to distant hills. There’s a new ingredient here, too: a Bonnard-like, intermediate zone of illumination in the foreground, its grayish, greenish hues hard to identify but highly specific in their description of light and occupation of space. This passage mysteriously complements the sunset’s Sturm und Drang. It’s a surprising touch — and one imagines it surprised the artist, too, as he stood rooted to his vantage point at dawn, laying down washes with formidable intent.

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Since when has the local recycling center yielded such cultured morsels?

Constructed almost completely of bits of discarded books, Maureen Mullarkey’s playful collages are considerably closer in spirit to Joseph Cornell’s reserved urbanity than Picasso’s brash, pasted-on headlines.

Ms. Mullarkey, who writes art reviews for these pages, clearly has a special fondness for the printed word. The materials for her collages are dog-eared scraps of yellowed paper, scuffed book covers, and the interiors of spines, with signature threads still attached in eerily skeletal grids. Her more than 20 works at George Billis deftly combine all these ingredients, plus bits of text printed in Greek, German, and Portuguese, as well as English.

The materials may be dated, but her compositions are spry. “Natural History” (2006) creates a neat grid of opposing rectangles of spines (including one from a tome by Immanuel Kant) and the interiors of spines, with threads and page fragments still raggedly attached. Here time seems stilled, and culture preserved as raw but delicate shards. “Reading Stendhal” (2006) forms a pleasingly dynamic pattern from black and red portions of book covers and pale endpapers.

Most compelling are the personal lives glimpsed in the carefully penned words of the book owners. One such notation in “Learning Technology/Elementary Circuit” (2007) runs three lines, as if a poem: “Alfred Ludy / is this Book / January 11th 1886” — prophetic words, as Ludy, for us, lives nowhere else. Another scrap of paper in “A Collect for Aman” (2006) reads: “Aman bought sheep at 1 dol. and 11cts. per head.” Plucked by Ms. Mullarkey to play in her silently jostling worlds, these personal notations keep her work from appearing nostalgic or hermetically literary.

In “A Usable Past” (2007), book covers crowd a bit uncomfortably, as if the artist loved them not wisely but too well. But “For Everyman” (2006) offers a deliciously varied journey from a pale, floral patterned endpaper to the dark, sturdy, spread-eagled cover of a Greek tome, to a bare piece of board with just a child’s scribbled star, to the genial orange glow of a small section of a cover. In this discreet but spacious arena, they thrive off each other’s company.

Nickson until March 3 (22 E. 71st St., between Fifth and Madison avenues, 212-879-6606);

Mullarkey until March 3 (511 W. 25th St., between Tenth and Eleventh avenues, 212-645-2621).